changeset 8041:c6443e78cf2d v7.4.1315

commit https://github.com/vim/vim/commit/7707344ddec9069b495b2a5ed41f2104466fc88b Author: Bram Moolenaar <Bram@vim.org> Date: Sat Feb 13 23:23:53 2016 +0100 patch 7.4.1315 Problem: Using a channel handle does not allow for freeing it when unused. Solution: Add the Channel variable type.
author Christian Brabandt <cb@256bit.org>
date Sat, 13 Feb 2016 23:30:05 +0100
parents 306f639c99a8
children 34bbac68276e
files src/channel.c src/eval.c src/gui_w48.c src/if_python.c src/if_python3.c src/json.c src/misc2.c src/netbeans.c src/os_unix.c src/proto/channel.pro src/structs.h src/testdir/test_channel.py src/testdir/test_channel.vim src/version.c
diffstat 14 files changed, 731 insertions(+), 586 deletions(-) [+]
line wrap: on
line diff
--- a/src/channel.c
+++ b/src/channel.c
@@ -54,12 +54,6 @@
 extern HWND s_hwnd;			/* Gvim's Window handle */
 #endif
 
-/*
- * Information about all channels.
- * There can be gaps for closed channels, they will be reused later.
- */
-static channel_T *channels = NULL;
-static int channel_count = 0;
 
 /* Log file opened with ch_logfile(). */
 static FILE *log_fd = NULL;
@@ -75,89 +69,89 @@ ch_logfile(FILE *file)
 }
 
     static void
-ch_log_lead(char *what, int ch_idx)
+ch_log_lead(char *what, channel_T *ch)
 {
     if (log_fd != NULL)
     {
-	if (ch_idx >= 0)
-	    fprintf(log_fd, "%son %d: ", what, ch_idx);
+	if (ch != NULL)
+	    fprintf(log_fd, "%son %d: ", what, ch->ch_id);
 	else
 	    fprintf(log_fd, "%s: ", what);
     }
 }
 
     static void
-ch_log(int ch_idx, char *msg)
+ch_log(channel_T *ch, char *msg)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("", ch_idx);
+	ch_log_lead("", ch);
 	fputs(msg, log_fd);
 	fflush(log_fd);
     }
 }
 
     static void
-ch_logn(int ch_idx, char *msg, int nr)
+ch_logn(channel_T *ch, char *msg, int nr)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("", ch_idx);
+	ch_log_lead("", ch);
 	fprintf(log_fd, msg, nr);
 	fflush(log_fd);
     }
 }
 
     static void
-ch_logs(int ch_idx, char *msg, char *name)
+ch_logs(channel_T *ch, char *msg, char *name)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("", ch_idx);
+	ch_log_lead("", ch);
 	fprintf(log_fd, msg, name);
 	fflush(log_fd);
     }
 }
 
     static void
-ch_logsn(int ch_idx, char *msg, char *name, int nr)
+ch_logsn(channel_T *ch, char *msg, char *name, int nr)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("", ch_idx);
+	ch_log_lead("", ch);
 	fprintf(log_fd, msg, name, nr);
 	fflush(log_fd);
     }
 }
 
     static void
-ch_error(int ch_idx, char *msg)
+ch_error(channel_T *ch, char *msg)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("ERR ", ch_idx);
+	ch_log_lead("ERR ", ch);
 	fputs(msg, log_fd);
 	fflush(log_fd);
     }
 }
 
     static void
-ch_errorn(int ch_idx, char *msg, int nr)
+ch_errorn(channel_T *ch, char *msg, int nr)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("ERR ", ch_idx);
+	ch_log_lead("ERR ", ch);
 	fprintf(log_fd, msg, nr);
 	fflush(log_fd);
     }
 }
 
     static void
-ch_errors(int ch_idx, char *msg, char *arg)
+ch_errors(channel_T *ch, char *msg, char *arg)
 {
     if (log_fd != NULL)
     {
-	ch_log_lead("ERR ", ch_idx);
+	ch_log_lead("ERR ", ch);
 	fprintf(log_fd, msg, arg);
 	fflush(log_fd);
     }
@@ -205,76 +199,101 @@ strerror_win32(int eno)
 }
 #endif
 
-    static void
-init_channel(int ch_idx)
-{
-    channel_T	*ch;
+/*
+ * The list of all allocated channels.
+ */
+static channel_T *first_channel = NULL;
+static int next_ch_id = 0;
 
-    ch = &channels[ch_idx];
-    (void)vim_memset(ch, 0, sizeof(channel_T));
+/*
+ * Allocate a new channel.  The refcount is set to 1.
+ * The channel isn't actually used until it is opened.
+ * Returns NULL if out of memory.
+ */
+    channel_T *
+add_channel(void)
+{
+    channel_T *channel = (channel_T *)alloc_clear((int)sizeof(channel_T));
 
-    ch->ch_sock = (sock_T)-1;
+    if (channel == NULL)
+	return NULL;
+
+    channel->ch_id = next_ch_id++;
+    ch_log(channel, "Opening channel\n");
+
+    channel->ch_sock = (sock_T)-1;
 #ifdef CHANNEL_PIPES
-    ch->ch_in = -1;
-    ch->ch_out = -1;
-    ch->ch_err = -1;
+    channel->ch_in = -1;
+    channel->ch_out = -1;
+    channel->ch_err = -1;
 #endif
 #ifdef FEAT_GUI_X11
-    ch->ch_inputHandler = (XtInputId)NULL;
+    channel->ch_inputHandler = (XtInputId)NULL;
 #endif
 #ifdef FEAT_GUI_GTK
-    ch->ch_inputHandler = 0;
+    channel->ch_inputHandler = 0;
 #endif
 #ifdef FEAT_GUI_W32
-    ch->ch_inputHandler = -1;
+    channel->ch_inputHandler = -1;
 #endif
-    /* initialize circular queues */
-    ch->ch_head.next = &ch->ch_head;
-    ch->ch_head.prev = &ch->ch_head;
-    ch->ch_cb_head.next = &ch->ch_cb_head;
-    ch->ch_cb_head.prev = &ch->ch_cb_head;
-    ch->ch_json_head.next = &ch->ch_json_head;
-    ch->ch_json_head.prev = &ch->ch_json_head;
+
+    channel->ch_timeout = 2000;
 
-    ch->ch_timeout = 2000;
+    if (first_channel != NULL)
+    {
+	first_channel->ch_prev = channel;
+	channel->ch_next = first_channel;
+    }
+    first_channel = channel;
+
+    channel->ch_refcount = 1;
+    return channel;
 }
 
 /*
- * Add a new channel slot, return the index.
- * The channel isn't actually used into ch_sock is set >= 0;
- * Returns -1 if all channels are in use.
+ * Close a channel and free all its resources.
  */
-    int
-add_channel(void)
+    void
+channel_free(channel_T *channel)
 {
-    int		ch_idx;
-
-    if (channels != NULL)
-    {
-	for (ch_idx = 0; ch_idx < channel_count; ++ch_idx)
-	    if (!channel_is_open(ch_idx))
-	    {
-		/* re-use a closed channel slot */
-		init_channel(ch_idx);
-		ch_log(ch_idx, "Opening channel (used before)\n");
-		return ch_idx;
-	    }
-	if (channel_count == MAX_OPEN_CHANNELS)
-	    return -1;
-    }
+    channel_close(channel);
+    if (channel->ch_next != NULL)
+	channel->ch_next->ch_prev = channel->ch_prev;
+    if (channel->ch_prev == NULL)
+	first_channel = channel->ch_next;
     else
-    {
-	channels = (channel_T *)alloc((int)sizeof(channel_T)
-							 * MAX_OPEN_CHANNELS);
-	if (channels == NULL)
-	    return -1;
-    }
-    init_channel(channel_count);
-    ch_log(channel_count, "Opening new channel\n");
-    return channel_count++;
+	channel->ch_prev->ch_next = channel->ch_next;
+    vim_free(channel);
 }
 
+#if defined(FEAT_GUI_X11) || defined(FEAT_GUI_GTK)
+    static channel_T *
+channel_from_id(int id)
+{
+    channel_T *channel;
+
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
+	if (channel->ch_id == id)
+	    return channel;
+    return NULL;
+}
+#endif
+
 #if defined(FEAT_GUI) || defined(PROTO)
+
+#if defined(FEAT_GUI_X11) || defined(FEAT_GUI_GTK)
+    static void
+channel_read_netbeans(int id)
+{
+    channel_T *channel = channel_from_id(id);
+
+    if (channel == NULL)
+	ch_errorn(NULL, "Channel %d not found", id);
+    else
+	channel_read(channel, FALSE, "messageFromNetbeans");
+}
+#endif
+
 /*
  * Read a command from netbeans.
  */
@@ -284,7 +303,7 @@ messageFromNetbeans(XtPointer clientData
 		    int *unused1 UNUSED,
 		    XtInputId *unused2 UNUSED)
 {
-    channel_read((int)(long)clientData, FALSE, "messageFromNetbeans");
+    channel_read_netbeans((int)(long)clientData);
 }
 #endif
 
@@ -294,15 +313,13 @@ messageFromNetbeans(gpointer clientData,
 		    gint unused1 UNUSED,
 		    GdkInputCondition unused2 UNUSED)
 {
-    channel_read((int)(long)clientData, FALSE, "messageFromNetbeans");
+    channel_read_netbeans((int)(long)clientData);
 }
 #endif
 
     static void
-channel_gui_register(int ch_idx)
+channel_gui_register(channel_T *channel)
 {
-    channel_T	*channel = &channels[ch_idx];
-
     if (!CH_HAS_GUI)
 	return;
 
@@ -315,7 +332,7 @@ channel_gui_register(int ch_idx)
 	channel->ch_inputHandler =
 	    XtAppAddInput((XtAppContext)app_context, channel->ch_sock,
 			 (XtPointer)(XtInputReadMask + XtInputExceptMask),
-				messageFromNetbeans, (XtPointer)(long)ch_idx);
+			messageFromNetbeans, (XtPointer)(long)channel->ch_id);
 # else
 #  ifdef FEAT_GUI_GTK
     /*
@@ -326,7 +343,7 @@ channel_gui_register(int ch_idx)
 	channel->ch_inputHandler =
 	    gdk_input_add((gint)channel->ch_sock, (GdkInputCondition)
 			     ((int)GDK_INPUT_READ + (int)GDK_INPUT_EXCEPTION),
-				 messageFromNetbeans, (gpointer)(long)ch_idx);
+			 messageFromNetbeans, (gpointer)(long)channel->ch_id);
 #  else
 #   ifdef FEAT_GUI_W32
     /*
@@ -348,19 +365,17 @@ channel_gui_register(int ch_idx)
     void
 channel_gui_register_all(void)
 {
-    int i;
+    channel_T *channel;
 
-    for (i = 0; i < channel_count; ++i)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
 	/* TODO: pipes */
-	if (channels[i].ch_sock >= 0)
-	    channel_gui_register(i);
+	if (channel->ch_sock >= 0)
+	    channel_gui_register(channel);
 }
 
     static void
-channel_gui_unregister(int ch_idx)
+channel_gui_unregister(channel_T *channel)
 {
-    channel_T	*channel = &channels[ch_idx];
-
     /* TODO: pipes */
 # ifdef FEAT_GUI_X11
     if (channel->ch_inputHandler != (XtInputId)NULL)
@@ -391,10 +406,10 @@ channel_gui_unregister(int ch_idx)
 
 /*
  * Open a socket channel to "hostname":"port".
- * Returns the channel number for success.
- * Returns a negative number for failure.
+ * Returns the channel for success.
+ * Returns NULL for failure.
  */
-    int
+    channel_T *
 channel_open(char *hostname, int port_in, int waittime, void (*close_cb)(void))
 {
     int			sd;
@@ -406,26 +421,26 @@ channel_open(char *hostname, int port_in
 #else
     int			port = port_in;
 #endif
-    int			ch_idx;
+    channel_T		*channel;
     int			ret;
 
 #ifdef WIN32
     channel_init_winsock();
 #endif
 
-    ch_idx = add_channel();
-    if (ch_idx < 0)
+    channel = add_channel();
+    if (channel == NULL)
     {
-	ch_error(-1, "All channels are in use.\n");
+	ch_error(NULL, "Cannot allocate channel.\n");
 	EMSG(_("E897: All channels are in use"));
-	return -1;
+	return NULL;
     }
 
     if ((sd = (sock_T)socket(AF_INET, SOCK_STREAM, 0)) == (sock_T)-1)
     {
-	ch_error(-1, "in socket() in channel_open().\n");
+	ch_error(NULL, "in socket() in channel_open().\n");
 	PERROR("E898: socket() in channel_open()");
-	return -1;
+	return NULL;
     }
 
     /* Get the server internet address and put into addr structure */
@@ -435,10 +450,10 @@ channel_open(char *hostname, int port_in
     server.sin_port = htons(port);
     if ((host = gethostbyname(hostname)) == NULL)
     {
-	ch_error(-1, "in gethostbyname() in channel_open()\n");
+	ch_error(NULL, "in gethostbyname() in channel_open()\n");
 	PERROR("E901: gethostbyname() in channel_open()");
 	sock_close(sd);
-	return -1;
+	return NULL;
     }
     memcpy((char *)&server.sin_addr, host->h_addr, host->h_length);
 
@@ -454,15 +469,15 @@ channel_open(char *hostname, int port_in
 	   )
 	{
 	    SOCK_ERRNO;
-	    ch_errorn(-1, "channel_open: Connect failed with errno %d\n",
+	    ch_errorn(NULL, "channel_open: Connect failed with errno %d\n",
 								       errno);
 	    sock_close(sd);
-	    return -1;
+	    return NULL;
 	}
     }
 
     /* Try connecting to the server. */
-    ch_logsn(-1, "Connecting to %s port %d", hostname, port);
+    ch_logsn(NULL, "Connecting to %s port %d", hostname, port);
     ret = connect(sd, (struct sockaddr *)&server, sizeof(server));
     SOCK_ERRNO;
     if (ret < 0)
@@ -473,11 +488,11 @@ channel_open(char *hostname, int port_in
 #endif
 		)
 	{
-	    ch_errorn(-1, "channel_open: Connect failed with errno %d\n",
+	    ch_errorn(NULL, "channel_open: Connect failed with errno %d\n",
 								       errno);
 	    PERROR(_("E902: Cannot connect to port"));
 	    sock_close(sd);
-	    return -1;
+	    return NULL;
 	}
     }
 
@@ -494,17 +509,17 @@ channel_open(char *hostname, int port_in
 	if (ret < 0)
 	{
 	    SOCK_ERRNO;
-	    ch_errorn(-1, "channel_open: Connect failed with errno %d\n",
+	    ch_errorn(NULL, "channel_open: Connect failed with errno %d\n",
 								       errno);
 	    PERROR(_("E902: Cannot connect to port"));
 	    sock_close(sd);
-	    return -1;
+	    return NULL;
 	}
 	if (!FD_ISSET(sd, &wfds))
 	{
 	    /* don't give an error, we just timed out. */
 	    sock_close(sd);
-	    return -1;
+	    return NULL;
 	}
     }
 
@@ -525,9 +540,9 @@ channel_open(char *hostname, int port_in
 	if ((sd = (sock_T)socket(AF_INET, SOCK_STREAM, 0)) == (sock_T)-1)
 	{
 	    SOCK_ERRNO;
-	    ch_log(-1, "socket() retry in channel_open()\n");
+	    ch_log(NULL, "socket() retry in channel_open()\n");
 	    PERROR("E900: socket() retry in channel_open()");
-	    return -1;
+	    return NULL;
 	}
 	if (connect(sd, (struct sockaddr *)&server, sizeof(server)))
 	{
@@ -538,7 +553,7 @@ channel_open(char *hostname, int port_in
 	    while (retries-- && ((errno == ECONNREFUSED)
 						     || (errno == EINTR)))
 	    {
-		ch_log(-1, "retrying...\n");
+		ch_log(NULL, "retrying...\n");
 		mch_delay(3000L, TRUE);
 		ui_breakcheck();
 		if (got_int)
@@ -557,30 +572,28 @@ channel_open(char *hostname, int port_in
 	    if (!success)
 	    {
 		/* Get here when the server can't be found. */
-		ch_error(-1, "Cannot connect to port after retry\n");
+		ch_error(NULL, "Cannot connect to port after retry\n");
 		PERROR(_("E899: Cannot connect to port after retry2"));
 		sock_close(sd);
-		return -1;
+		return NULL;
 	    }
 	}
     }
 
-    channels[ch_idx].ch_sock = sd;
-    channels[ch_idx].ch_close_cb = close_cb;
+    channel->ch_sock = sd;
+    channel->ch_close_cb = close_cb;
 
 #ifdef FEAT_GUI
-    channel_gui_register(ch_idx);
+    channel_gui_register(channel);
 #endif
 
-    return ch_idx;
+    return channel;
 }
 
 #if defined(CHANNEL_PIPES) || defined(PROTO)
     void
-channel_set_pipes(int ch_idx, int in, int out, int err)
+channel_set_pipes(channel_T *channel, int in, int out, int err)
 {
-    channel_T *channel = &channels[ch_idx];
-
     channel->ch_in = in;
     channel->ch_out = out;
     channel->ch_err = err;
@@ -588,70 +601,73 @@ channel_set_pipes(int ch_idx, int in, in
 #endif
 
     void
-channel_set_job(int ch_idx, job_T *job)
+channel_set_job(channel_T *channel, job_T *job)
 {
-    channels[ch_idx].ch_job = job;
+    channel->ch_job = job;
 }
 
 /*
- * Set the json mode of channel "ch_idx" to "ch_mode".
+ * Set the json mode of channel "channel" to "ch_mode".
  */
     void
-channel_set_json_mode(int ch_idx, ch_mode_T ch_mode)
+channel_set_json_mode(channel_T *channel, ch_mode_T ch_mode)
 {
-    channels[ch_idx].ch_mode = ch_mode;
+    channel->ch_mode = ch_mode;
 }
 
 /*
- * Set the read timeout of channel "ch_idx".
+ * Set the read timeout of channel "channel".
  */
     void
-channel_set_timeout(int ch_idx, int timeout)
+channel_set_timeout(channel_T *channel, int timeout)
 {
-    channels[ch_idx].ch_timeout = timeout;
+    channel->ch_timeout = timeout;
 }
 
 /*
- * Set the callback for channel "ch_idx".
+ * Set the callback for channel "channel".
  */
     void
-channel_set_callback(int ch_idx, char_u *callback)
+channel_set_callback(channel_T *channel, char_u *callback)
 {
-    vim_free(channels[ch_idx].ch_callback);
-    channels[ch_idx].ch_callback = vim_strsave(callback);
+    vim_free(channel->ch_callback);
+    channel->ch_callback = vim_strsave(callback);
 }
 
 /*
- * Set the callback for channel "ch_idx" for the response with "id".
+ * Set the callback for channel "channel" for the response with "id".
  */
     void
-channel_set_req_callback(int ch_idx, char_u *callback, int id)
+channel_set_req_callback(channel_T *channel, char_u *callback, int id)
 {
-    cbq_T *cbhead = &channels[ch_idx].ch_cb_head;
+    cbq_T *head = &channel->ch_cb_head;
     cbq_T *item = (cbq_T *)alloc((int)sizeof(cbq_T));
 
     if (item != NULL)
     {
-	item->callback = vim_strsave(callback);
-	item->seq_nr = id;
-	item->prev = cbhead->prev;
-	cbhead->prev = item;
-	item->next = cbhead;
-	item->prev->next = item;
+	item->cq_callback = vim_strsave(callback);
+	item->cq_seq_nr = id;
+	item->cq_prev = head->cq_prev;
+	head->cq_prev = item;
+	item->cq_next = NULL;
+	if (item->cq_prev == NULL)
+	    head->cq_next = item;
+	else
+	    item->cq_prev->cq_next = item;
     }
 }
 
 /*
- * Invoke the "callback" on channel "ch_idx".
+ * Invoke the "callback" on channel "channel".
  */
     static void
-invoke_callback(int ch_idx, char_u *callback, typval_T *argv)
+invoke_callback(channel_T *channel, char_u *callback, typval_T *argv)
 {
     typval_T	rettv;
     int		dummy;
 
-    argv[0].v_type = VAR_NUMBER;
-    argv[0].vval.v_number = ch_idx;
+    argv[0].v_type = VAR_CHANNEL;
+    argv[0].vval.v_channel = channel;
 
     call_func(callback, (int)STRLEN(callback),
 			     &rettv, 2, argv, 0L, 0L, &dummy, TRUE, NULL);
@@ -668,19 +684,21 @@ invoke_callback(int ch_idx, char_u *call
  * Returns NULL if there is nothing.
  */
     char_u *
-channel_get(int ch_idx)
+channel_get(channel_T *channel)
 {
-    readq_T *head = &channels[ch_idx].ch_head;
-    readq_T *node;
+    readq_T *head = &channel->ch_head;
+    readq_T *node = head->rq_next;
     char_u *p;
 
-    if (head->next == head || head->next == NULL)
+    if (node == NULL)
 	return NULL;
-    node = head->next;
     /* dispose of the node but keep the buffer */
-    p = node->buffer;
-    head->next = node->next;
-    node->next->prev = node->prev;
+    p = node->rq_buffer;
+    head->rq_next = node->rq_next;
+    if (node->rq_next == NULL)
+	head->rq_prev = NULL;
+    else
+	node->rq_next->rq_prev = NULL;
     vim_free(node);
     return p;
 }
@@ -689,71 +707,70 @@ channel_get(int ch_idx)
  * Returns the whole buffer contents concatenated.
  */
     static char_u *
-channel_get_all(int ch_idx)
+channel_get_all(channel_T *channel)
 {
     /* Concatenate everything into one buffer.
      * TODO: avoid multiple allocations. */
-    while (channel_collapse(ch_idx) == OK)
+    while (channel_collapse(channel) == OK)
 	;
-    return channel_get(ch_idx);
+    return channel_get(channel);
 }
 
 /*
- * Collapses the first and second buffer in the channel "ch_idx".
+ * Collapses the first and second buffer in the channel "channel".
  * Returns FAIL if that is not possible.
  */
     int
-channel_collapse(int ch_idx)
+channel_collapse(channel_T *channel)
 {
-    readq_T *head = &channels[ch_idx].ch_head;
-    readq_T *node = head->next;
+    readq_T *head = &channel->ch_head;
+    readq_T *node = head->rq_next;
     char_u  *p;
 
-    if (node == head || node == NULL || node->next == head)
+    if (node == NULL || node->rq_next == NULL)
 	return FAIL;
 
-    p = alloc((unsigned)(STRLEN(node->buffer)
-					   + STRLEN(node->next->buffer) + 1));
+    p = alloc((unsigned)(STRLEN(node->rq_buffer)
+				     + STRLEN(node->rq_next->rq_buffer) + 1));
     if (p == NULL)
 	return FAIL;	    /* out of memory */
-    STRCPY(p, node->buffer);
-    STRCAT(p, node->next->buffer);
-    vim_free(node->next->buffer);
-    node->next->buffer = p;
+    STRCPY(p, node->rq_buffer);
+    STRCAT(p, node->rq_next->rq_buffer);
+    vim_free(node->rq_next->rq_buffer);
+    node->rq_next->rq_buffer = p;
 
-    /* dispose of the node and buffer */
-    head->next = node->next;
-    node->next->prev = node->prev;
-    vim_free(node->buffer);
+    /* dispose of the node and its buffer */
+    head->rq_next = node->rq_next;
+    head->rq_next->rq_prev = NULL;
+    vim_free(node->rq_buffer);
     vim_free(node);
     return OK;
 }
 
 /*
- * Use the read buffer of channel "ch_idx" and parse a JSON messages that is
+ * Use the read buffer of channel "channel" and parse a JSON messages that is
  * complete.  The messages are added to the queue.
  * Return TRUE if there is more to read.
  */
     static int
-channel_parse_json(int ch_idx)
+channel_parse_json(channel_T *channel)
 {
     js_read_T	reader;
     typval_T	listtv;
     jsonq_T	*item;
-    channel_T	*channel = &channels[ch_idx];
     jsonq_T	*head = &channel->ch_json_head;
     int		ret;
 
-    if (channel_peek(ch_idx) == NULL)
+    if (channel_peek(channel) == NULL)
 	return FALSE;
 
     /* TODO: make reader work properly */
-    /* reader.js_buf = channel_peek(ch_idx); */
-    reader.js_buf = channel_get_all(ch_idx);
+    /* reader.js_buf = channel_peek(channel); */
+    reader.js_buf = channel_get_all(channel);
     reader.js_used = 0;
     reader.js_fill = NULL;
     /* reader.js_fill = channel_fill; */
-    reader.js_cookie = &ch_idx;
+    reader.js_cookie = channel;
     ret = json_decode(&reader, &listtv,
 				   channel->ch_mode == MODE_JS ? JSON_JS : 0);
     if (ret == OK)
@@ -772,19 +789,22 @@ channel_parse_json(int ch_idx)
 		clear_tv(&listtv);
 	    else
 	    {
-		item->value = alloc_tv();
-		if (item->value == NULL)
+		item->jq_value = alloc_tv();
+		if (item->jq_value == NULL)
 		{
 		    vim_free(item);
 		    clear_tv(&listtv);
 		}
 		else
 		{
-		    *item->value = listtv;
-		    item->prev = head->prev;
-		    head->prev = item;
-		    item->next = head;
-		    item->prev->next = item;
+		    *item->jq_value = listtv;
+		    item->jq_prev = head->jq_prev;
+		    head->jq_prev = item;
+		    item->jq_next = NULL;
+		    if (item->jq_prev == NULL)
+			head->jq_next = item;
+		    else
+			item->jq_prev->jq_next = item;
 		}
 	    }
 	}
@@ -794,7 +814,7 @@ channel_parse_json(int ch_idx)
      * TODO: insert in front */
     if (reader.js_buf[reader.js_used] != NUL)
     {
-	channel_save(ch_idx, reader.js_buf + reader.js_used,
+	channel_save(channel, reader.js_buf + reader.js_used,
 		(int)(reader.js_end - reader.js_buf) - reader.js_used);
 	ret = TRUE;
     }
@@ -810,28 +830,40 @@ channel_parse_json(int ch_idx)
  * Also frees the contained callback name.
  */
     static void
-remove_cb_node(cbq_T *node)
+remove_cb_node(cbq_T *head, cbq_T *node)
 {
-    node->prev->next = node->next;
-    node->next->prev = node->prev;
-    vim_free(node->callback);
+    if (node->cq_prev == NULL)
+	head->cq_next = node->cq_next;
+    else
+	node->cq_prev->cq_next = node->cq_next;
+    if (node->cq_next == NULL)
+	head->cq_prev = node->cq_prev;
+    else
+	node->cq_next->cq_prev = node->cq_prev;
+    vim_free(node->cq_callback);
     vim_free(node);
 }
 
 /*
  * Remove "node" from the queue that it is in and free it.
- * Caller should have freed or used node->value.
+ * Caller should have freed or used node->jq_value.
  */
     static void
-remove_json_node(jsonq_T *node)
+remove_json_node(jsonq_T *head, jsonq_T *node)
 {
-    node->prev->next = node->next;
-    node->next->prev = node->prev;
+    if (node->jq_prev == NULL)
+	head->jq_next = node->jq_next;
+    else
+	node->jq_prev->jq_next = node->jq_next;
+    if (node->jq_next == NULL)
+	head->jq_prev = node->jq_prev;
+    else
+	node->jq_next->jq_prev = node->jq_prev;
     vim_free(node);
 }
 
 /*
- * Get a message from the JSON queue for channel "ch_idx".
+ * Get a message from the JSON queue for channel "channel".
  * When "id" is positive it must match the first number in the list.
  * When "id" is zero or negative jut get the first message.  But not the one
  * with id ch_block_id.
@@ -839,15 +871,14 @@ remove_json_node(jsonq_T *node)
  * Return FAIL otherwise.
  */
     static int
-channel_get_json(int ch_idx, int id, typval_T **rettv)
+channel_get_json(channel_T *channel, int id, typval_T **rettv)
 {
-    channel_T *channel = &channels[ch_idx];
     jsonq_T   *head = &channel->ch_json_head;
-    jsonq_T   *item = head->next;
+    jsonq_T   *item = head->jq_next;
 
-    while (item != head)
+    while (item != NULL)
     {
-	list_T	    *l = item->value->vval.v_list;
+	list_T	    *l = item->jq_value->vval.v_list;
 	typval_T    *tv = &l->lv_first->li_tv;
 
 	if ((id > 0 && tv->v_type == VAR_NUMBER && tv->vval.v_number == id)
@@ -855,22 +886,22 @@ channel_get_json(int ch_idx, int id, typ
 			       || tv->vval.v_number == 0
 			       || tv->vval.v_number != channel->ch_block_id)))
 	{
-	    *rettv = item->value;
-	    remove_json_node(item);
+	    *rettv = item->jq_value;
+	    remove_json_node(head, item);
 	    return OK;
 	}
-	item = item->next;
+	item = item->jq_next;
     }
     return FAIL;
 }
 
 /*
- * Execute a command received over channel "ch_idx".
+ * Execute a command received over channel "channel".
  * "cmd" is the command string, "arg2" the second argument.
  * "arg3" is the third argument, NULL if missing.
  */
     static void
-channel_exe_cmd(int ch_idx, char_u *cmd, typval_T *arg2, typval_T *arg3)
+channel_exe_cmd(channel_T *channel, char_u *cmd, typval_T *arg2, typval_T *arg3)
 {
     char_u *arg;
 
@@ -928,7 +959,6 @@ channel_exe_cmd(int ch_idx, char_u *cmd,
 	    typval_T	*tv;
 	    typval_T	err_tv;
 	    char_u	*json = NULL;
-	    channel_T	*channel = &channels[ch_idx];
 	    int		options = channel->ch_mode == MODE_JS ? JSON_JS : 0;
 
 	    /* Don't pollute the display with errors. */
@@ -943,6 +973,8 @@ channel_exe_cmd(int ch_idx, char_u *cmd,
 		{
 		    /* If evaluation failed or the result can't be encoded
 		     * then return the string "ERROR". */
+		    vim_free(json);
+		    free_tv(tv);
 		    err_tv.v_type = VAR_STRING;
 		    err_tv.vval.v_string = (char_u *)"ERROR";
 		    tv = &err_tv;
@@ -951,7 +983,7 @@ channel_exe_cmd(int ch_idx, char_u *cmd,
 		}
 		if (json != NULL)
 		{
-		    channel_send(ch_idx, json, "eval");
+		    channel_send(channel, json, "eval");
 		    vim_free(json);
 		}
 	    }
@@ -965,11 +997,11 @@ channel_exe_cmd(int ch_idx, char_u *cmd,
 }
 
 /*
- * Invoke a callback for channel "ch_idx" if needed.
+ * Invoke a callback for channel "channel" if needed.
  * Return OK when a message was handled, there might be another one.
  */
     static int
-may_invoke_callback(int ch_idx)
+may_invoke_callback(channel_T *channel)
 {
     char_u	*msg = NULL;
     typval_T	*listtv = NULL;
@@ -977,7 +1009,6 @@ may_invoke_callback(int ch_idx)
     typval_T	*typetv;
     typval_T	argv[3];
     int		seq_nr = -1;
-    channel_T	*channel = &channels[ch_idx];
     ch_mode_T	ch_mode = channel->ch_mode;
 
     if (channel->ch_close_cb != NULL)
@@ -987,11 +1018,11 @@ may_invoke_callback(int ch_idx)
     if (ch_mode != MODE_RAW)
     {
 	/* Get any json message in the queue. */
-	if (channel_get_json(ch_idx, -1, &listtv) == FAIL)
+	if (channel_get_json(channel, -1, &listtv) == FAIL)
 	{
 	    /* Parse readahead, return when there is still no message. */
-	    channel_parse_json(ch_idx);
-	    if (channel_get_json(ch_idx, -1, &listtv) == FAIL)
+	    channel_parse_json(channel);
+	    if (channel_get_json(channel, -1, &listtv) == FAIL)
 		return FALSE;
 	}
 
@@ -1006,22 +1037,22 @@ may_invoke_callback(int ch_idx)
 	    /* ["cmd", arg] or ["cmd", arg, arg] */
 	    if (list->lv_len == 3)
 		arg3 = &list->lv_last->li_tv;
-	    ch_logs(ch_idx, "Executing %s command", (char *)cmd);
-	    channel_exe_cmd(ch_idx, cmd, &argv[1], arg3);
-	    clear_tv(listtv);
+	    ch_logs(channel, "Executing %s command", (char *)cmd);
+	    channel_exe_cmd(channel, cmd, &argv[1], arg3);
+	    free_tv(listtv);
 	    return TRUE;
 	}
 
 	if (typetv->v_type != VAR_NUMBER)
 	{
-	    ch_error(ch_idx,
+	    ch_error(channel,
 		      "Dropping message with invalid sequence number type\n");
-	    clear_tv(listtv);
+	    free_tv(listtv);
 	    return FALSE;
 	}
 	seq_nr = typetv->vval.v_number;
     }
-    else if (channel_peek(ch_idx) == NULL)
+    else if (channel_peek(channel) == NULL)
     {
 	/* nothing to read on raw channel */
 	return FALSE;
@@ -1034,91 +1065,100 @@ may_invoke_callback(int ch_idx)
 
 	/* For a raw channel we don't know where the message ends, just get
 	 * everything. */
-	msg = channel_get_all(ch_idx);
+	msg = channel_get_all(channel);
 	argv[1].v_type = VAR_STRING;
 	argv[1].vval.v_string = msg;
     }
 
     if (seq_nr > 0)
     {
-	cbq_T	*cbhead = &channel->ch_cb_head;
-	cbq_T	*cbitem = cbhead->next;
+	cbq_T	*head = &channel->ch_cb_head;
+	cbq_T	*item = head->cq_next;
 	int	done = FALSE;
 
 	/* invoke the one-time callback with the matching nr */
-	while (cbitem != cbhead)
+	while (item != NULL)
 	{
-	    if (cbitem->seq_nr == seq_nr)
+	    if (item->cq_seq_nr == seq_nr)
 	    {
-		ch_log(ch_idx, "Invoking one-time callback\n");
-		invoke_callback(ch_idx, cbitem->callback, argv);
-		remove_cb_node(cbitem);
+		ch_log(channel, "Invoking one-time callback\n");
+		invoke_callback(channel, item->cq_callback, argv);
+		remove_cb_node(head, item);
 		done = TRUE;
 		break;
 	    }
-	    cbitem = cbitem->next;
+	    item = item->cq_next;
 	}
 	if (!done)
-	    ch_log(ch_idx, "Dropping message without callback\n");
+	    ch_log(channel, "Dropping message without callback\n");
     }
     else if (channel->ch_callback != NULL)
     {
 	/* invoke the channel callback */
-	ch_log(ch_idx, "Invoking channel callback\n");
-	invoke_callback(ch_idx, channel->ch_callback, argv);
+	ch_log(channel, "Invoking channel callback\n");
+	invoke_callback(channel, channel->ch_callback, argv);
     }
     else
-	ch_log(ch_idx, "Dropping message\n");
+	ch_log(channel, "Dropping message\n");
 
     if (listtv != NULL)
-	clear_tv(listtv);
+	free_tv(listtv);
     vim_free(msg);
 
     return TRUE;
 }
 
 /*
- * Return TRUE when channel "ch_idx" is open for writing to.
- * Also returns FALSE or invalid "ch_idx".
+ * Return TRUE when channel "channel" is open for writing to.
+ * Also returns FALSE or invalid "channel".
  */
     int
-channel_can_write_to(int ch_idx)
+channel_can_write_to(channel_T *channel)
 {
-    return ch_idx >= 0 && ch_idx < channel_count
-		  && (channels[ch_idx].ch_sock >= 0
+    return channel != NULL && (channel->ch_sock >= 0
 #ifdef CHANNEL_PIPES
-			  || channels[ch_idx].ch_in >= 0
+			  || channel->ch_in >= 0
 #endif
 			  );
 }
 
 /*
- * Return TRUE when channel "ch_idx" is open for reading or writing.
- * Also returns FALSE or invalid "ch_idx".
+ * Return TRUE when channel "channel" is open for reading or writing.
+ * Also returns FALSE for invalid "channel".
  */
     int
-channel_is_open(int ch_idx)
+channel_is_open(channel_T *channel)
 {
-    return ch_idx >= 0 && ch_idx < channel_count
-		  && (channels[ch_idx].ch_sock >= 0
+    return channel != NULL && (channel->ch_sock >= 0
 #ifdef CHANNEL_PIPES
-			  || channels[ch_idx].ch_in >= 0
-			  || channels[ch_idx].ch_out >= 0
-			  || channels[ch_idx].ch_err >= 0
+			  || channel->ch_in >= 0
+			  || channel->ch_out >= 0
+			  || channel->ch_err >= 0
 #endif
 			  );
 }
 
 /*
- * Close channel "ch_idx".
+ * Return a string indicating the status of the channel.
+ */
+    char *
+channel_status(channel_T *channel)
+{
+    if (channel == NULL)
+	 return "fail";
+    if (channel_is_open(channel))
+	 return "open";
+    return "closed";
+}
+
+/*
+ * Close channel "channel".
  * This does not trigger the close callback.
  */
     void
-channel_close(int ch_idx)
+channel_close(channel_T *channel)
 {
-    channel_T	*channel = &channels[ch_idx];
-    jsonq_T	*jhead;
-    cbq_T	*cbhead;
+    ch_log(channel, "Closing channel");
 
     if (channel->ch_sock >= 0)
     {
@@ -1126,25 +1166,10 @@ channel_close(int ch_idx)
 	channel->ch_sock = -1;
 	channel->ch_close_cb = NULL;
 #ifdef FEAT_GUI
-	channel_gui_unregister(ch_idx);
+	channel_gui_unregister(channel);
 #endif
 	vim_free(channel->ch_callback);
 	channel->ch_callback = NULL;
-	channel->ch_timeout = 2000;
-
-	while (channel_peek(ch_idx) != NULL)
-	    vim_free(channel_get(ch_idx));
-
-	cbhead = &channel->ch_cb_head;
-	while (cbhead->next != cbhead)
-	    remove_cb_node(cbhead->next);
-
-	jhead = &channel->ch_json_head;
-	while (jhead->next != jhead)
-	{
-	    clear_tv(jhead->next->value);
-	    remove_json_node(jhead->next);
-	}
     }
 #if defined(CHANNEL_PIPES)
     if (channel->ch_in >= 0)
@@ -1163,39 +1188,43 @@ channel_close(int ch_idx)
 	channel->ch_err = -1;
     }
 #endif
+    channel_clear(channel);
 }
 
 /*
- * Store "buf[len]" on channel "ch_idx".
+ * Store "buf[len]" on channel "channel".
  * Returns OK or FAIL.
  */
     int
-channel_save(int ch_idx, char_u *buf, int len)
+channel_save(channel_T *channel, char_u *buf, int len)
 {
     readq_T *node;
-    readq_T *head = &channels[ch_idx].ch_head;
+    readq_T *head = &channel->ch_head;
 
     node = (readq_T *)alloc(sizeof(readq_T));
     if (node == NULL)
 	return FAIL;	    /* out of memory */
-    node->buffer = alloc(len + 1);
-    if (node->buffer == NULL)
+    node->rq_buffer = alloc(len + 1);
+    if (node->rq_buffer == NULL)
     {
 	vim_free(node);
 	return FAIL;	    /* out of memory */
     }
-    mch_memmove(node->buffer, buf, (size_t)len);
-    node->buffer[len] = NUL;
+    mch_memmove(node->rq_buffer, buf, (size_t)len);
+    node->rq_buffer[len] = NUL;
 
-    /* insert node at tail of queue */
-    node->next = head;
-    node->prev = head->prev;
-    head->prev->next = node;
-    head->prev = node;
+    /* append node to the tail of the queue */
+    node->rq_next = NULL;
+    node->rq_prev = head->rq_prev;
+    if (head->rq_prev == NULL)
+	head->rq_next = node;
+    else
+	head->rq_prev->rq_next = node;
+    head->rq_prev = node;
 
     if (log_fd != NULL)
     {
-	ch_log_lead("RECV ", ch_idx);
+	ch_log_lead("RECV ", channel);
 	fprintf(log_fd, "'");
 	if (fwrite(buf, len, 1, log_fd) != 1)
 	    return FAIL;
@@ -1209,40 +1238,49 @@ channel_save(int ch_idx, char_u *buf, in
  * Returns NULL if there is nothing.
  */
     char_u *
-channel_peek(int ch_idx)
+channel_peek(channel_T *channel)
 {
-    readq_T *head = &channels[ch_idx].ch_head;
+    readq_T *head = &channel->ch_head;
 
-    if (head->next == head || head->next == NULL)
+    if (head->rq_next == NULL)
 	return NULL;
-    return head->next->buffer;
+    return head->rq_next->rq_buffer;
 }
 
 /*
- * Clear the read buffer on channel "ch_idx".
+ * Clear the read buffer on channel "channel".
  */
     void
-channel_clear(int ch_idx)
+channel_clear(channel_T *channel)
 {
-    readq_T *head = &channels[ch_idx].ch_head;
-    readq_T *node = head->next;
-    readq_T *next;
+    jsonq_T *json_head = &channel->ch_json_head;
+    cbq_T   *cb_head = &channel->ch_cb_head;
 
-    while (node != NULL && node != head)
+    while (channel_peek(channel) != NULL)
+	vim_free(channel_get(channel));
+
+    while (cb_head->cq_next != NULL)
+	remove_cb_node(cb_head, cb_head->cq_next);
+
+    while (json_head->jq_next != NULL)
     {
-	next = node->next;
-	vim_free(node->buffer);
-	vim_free(node);
-	if (next == head)
-	{
-	    head->next = head;
-	    head->prev = head;
-	    break;
-	}
-	node = next;
+	free_tv(json_head->jq_next->jq_value);
+	remove_json_node(json_head, json_head->jq_next);
     }
 }
 
+#if defined(EXITFREE) || defined(PROTO)
+    void
+channel_free_all(void)
+{
+    channel_T *channel;
+
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
+	channel_clear(channel);
+}
+#endif
+
+
 /* Sent when the channel is found closed when reading. */
 #define DETACH_MSG "\"DETACH\"\n"
 
@@ -1255,7 +1293,7 @@ channel_clear(int ch_idx)
  * Always returns OK for FEAT_GUI_W32.
  */
     static int
-channel_wait(int ch_idx, int fd, int timeout)
+channel_wait(channel_T *channel, int fd, int timeout)
 {
 #if defined(HAVE_SELECT) && !defined(FEAT_GUI_W32)
     struct timeval	tval;
@@ -1263,7 +1301,7 @@ channel_wait(int ch_idx, int fd, int tim
     int			ret;
 
     if (timeout > 0)
-	ch_logn(ch_idx, "Waiting for %d msec\n", timeout);
+	ch_logn(channel, "Waiting for %d msec\n", timeout);
     FD_ZERO(&rfds);
     FD_SET(fd, &rfds);
     tval.tv_sec = timeout / 1000;
@@ -1277,7 +1315,7 @@ channel_wait(int ch_idx, int fd, int tim
 # endif
 	if (ret <= 0)
 	{
-	    ch_log(ch_idx, "Nothing to read\n");
+	    ch_log(channel, "Nothing to read\n");
 	    return FAIL;
 	}
 	break;
@@ -1287,12 +1325,12 @@ channel_wait(int ch_idx, int fd, int tim
     struct pollfd	fds;
 
     if (timeout > 0)
-	ch_logn(ch_idx, "Waiting for %d msec\n", timeout);
+	ch_logn(channel, "Waiting for %d msec\n", timeout);
     fds.fd = fd;
     fds.events = POLLIN;
     if (poll(&fds, 1, timeout) <= 0)
     {
-	ch_log(ch_idx, "Nothing to read\n");
+	ch_log(channel, "Nothing to read\n");
 	return FAIL;
     }
 # endif
@@ -1315,10 +1353,8 @@ channel_get_id(void)
  * Get the file descriptor to read from, either the socket or stdout.
  */
     static int
-get_read_fd(int ch_idx, int use_stderr)
+get_read_fd(channel_T *channel, int use_stderr)
 {
-    channel_T		*channel = &channels[ch_idx];
-
     if (channel->ch_sock >= 0)
 	return channel->ch_sock;
 #if defined(CHANNEL_PIPES)
@@ -1327,25 +1363,24 @@ get_read_fd(int ch_idx, int use_stderr)
     if (use_stderr && channel->ch_err >= 0)
 	return channel->ch_err;
 #endif
-    ch_error(ch_idx, "channel_read() called while socket is closed\n");
+    ch_error(channel, "channel_read() called while socket is closed\n");
     return -1;
 }
 
 /*
- * Read from channel "ch_idx" for as long as there is something to read.
+ * Read from channel "channel" for as long as there is something to read.
  * The data is put in the read queue.
  */
     void
-channel_read(int ch_idx, int use_stderr, char *func)
+channel_read(channel_T *channel, int use_stderr, char *func)
 {
-    channel_T		*channel = &channels[ch_idx];
     static char_u	*buf = NULL;
     int			len = 0;
     int			readlen = 0;
     int			fd;
     int			use_socket = FALSE;
 
-    fd = get_read_fd(ch_idx, use_stderr);
+    fd = get_read_fd(channel, use_stderr);
     if (fd < 0)
 	return;
     use_socket = channel->ch_sock >= 0;
@@ -1363,7 +1398,7 @@ channel_read(int ch_idx, int use_stderr,
      * MAXMSGSIZE long. */
     for (;;)
     {
-	if (channel_wait(ch_idx, fd, 0) == FAIL)
+	if (channel_wait(channel, fd, 0) == FAIL)
 	    break;
 	if (use_socket)
 	    len = sock_read(fd, buf, MAXMSGSIZE);
@@ -1373,7 +1408,7 @@ channel_read(int ch_idx, int use_stderr,
 	    break;	/* error or nothing more to read */
 
 	/* Store the read message in the queue. */
-	channel_save(ch_idx, buf, len);
+	channel_save(channel, buf, len);
 	readlen += len;
 	if (len < MAXMSGSIZE)
 	    break;	/* did read everything that's available */
@@ -1402,12 +1437,12 @@ channel_read(int ch_idx, int use_stderr,
 	 *		    -> gui event loop or select loop
 	 *			-> channel_read()
 	 */
-	ch_errors(ch_idx, "%s(): Cannot read\n", func);
-	channel_save(ch_idx, (char_u *)DETACH_MSG, (int)STRLEN(DETACH_MSG));
+	ch_errors(channel, "%s(): Cannot read\n", func);
+	channel_save(channel, (char_u *)DETACH_MSG, (int)STRLEN(DETACH_MSG));
 
 	if (use_socket)
 	{
-	    channel_close(ch_idx);
+	    channel_close(channel);
 	    if (channel->ch_close_cb != NULL)
 		(*channel->ch_close_cb)();
 	}
@@ -1421,7 +1456,7 @@ channel_read(int ch_idx, int use_stderr,
 
 	if (len < 0)
 	{
-	    ch_error(ch_idx, "channel_read(): cannot read from channel\n");
+	    ch_error(channel, "channel_read(): cannot read from channel\n");
 	    PERROR(_("E896: read from channel"));
 	}
     }
@@ -1434,52 +1469,50 @@ channel_read(int ch_idx, int use_stderr,
 }
 
 /*
- * Read from raw channel "ch_idx".  Blocks until there is something to read or
+ * Read from raw channel "channel".  Blocks until there is something to read or
  * the timeout expires.
  * Returns what was read in allocated memory.
  * Returns NULL in case of error or timeout.
  */
     char_u *
-channel_read_block(int ch_idx)
+channel_read_block(channel_T *channel)
 {
-    ch_log(ch_idx, "Reading raw\n");
-    if (channel_peek(ch_idx) == NULL)
+    ch_log(channel, "Reading raw\n");
+    if (channel_peek(channel) == NULL)
     {
-	int fd = get_read_fd(ch_idx, FALSE);
+	int fd = get_read_fd(channel, FALSE);
 
-	ch_log(ch_idx, "No readahead\n");
+	ch_log(channel, "No readahead\n");
 	/* Wait for up to the channel timeout. */
-	if (fd < 0 || channel_wait(ch_idx, fd,
-					 channels[ch_idx].ch_timeout) == FAIL)
+	if (fd < 0 || channel_wait(channel, fd, channel->ch_timeout) == FAIL)
 	    return NULL;
-	channel_read(ch_idx, FALSE, "channel_read_block");
+	channel_read(channel, FALSE, "channel_read_block");
     }
 
     /* TODO: only get the first message */
-    ch_log(ch_idx, "Returning readahead\n");
-    return channel_get_all(ch_idx);
+    ch_log(channel, "Returning readahead\n");
+    return channel_get_all(channel);
 }
 
 /*
- * Read one JSON message from channel "ch_idx" with ID "id" and store the
+ * Read one JSON message with ID "id" from channel "channel" and store the
  * result in "rettv".
  * Blocks until the message is received or the timeout is reached.
  */
     int
-channel_read_json_block(int ch_idx, int id, typval_T **rettv)
+channel_read_json_block(channel_T *channel, int id, typval_T **rettv)
 {
     int		more;
-    channel_T	*channel = &channels[ch_idx];
     int		fd;
 
-    ch_log(ch_idx, "Reading JSON\n");
+    ch_log(channel, "Reading JSON\n");
     channel->ch_block_id = id;
     for (;;)
     {
-	more = channel_parse_json(ch_idx);
+	more = channel_parse_json(channel);
 
 	/* search for messsage "id" */
-	if (channel_get_json(ch_idx, id, rettv) == OK)
+	if (channel_get_json(channel, id, rettv) == OK)
 	{
 	    channel->ch_block_id = 0;
 	    return OK;
@@ -1493,10 +1526,11 @@ channel_read_json_block(int ch_idx, int 
 		continue;
 
 	    /* Wait for up to the channel timeout. */
-	    fd = get_read_fd(ch_idx, FALSE);
-	    if (fd < 0 || channel_wait(ch_idx, fd, channel->ch_timeout) == FAIL)
+	    fd = get_read_fd(channel, FALSE);
+	    if (fd < 0 || channel_wait(channel, fd, channel->ch_timeout)
+								      == FAIL)
 		break;
-	    channel_read(ch_idx, FALSE, "channel_read_json_block");
+	    channel_read(channel, FALSE, "channel_read_json_block");
 	}
     }
     channel->ch_block_id = 0;
@@ -1505,36 +1539,36 @@ channel_read_json_block(int ch_idx, int 
 
 # if defined(WIN32) || defined(PROTO)
 /*
- * Lookup the channel index from the socket.
- * Returns -1 when the socket isn't found.
+ * Lookup the channel from the socket.
+ * Returns NULL when the socket isn't found.
  */
-    int
-channel_fd2idx(sock_T fd)
+    channel_T *
+channel_fd2channel(sock_T fd)
 {
-    int i;
+    channel_T *channel;
 
     if (fd >= 0)
-	for (i = 0; i < channel_count; ++i)
-	    if (channels[i].ch_sock == fd
+	for (channel = first_channel; channel != NULL;
+						   channel = channel->ch_next)
+	    if (channel->ch_sock == fd
 #  if defined(CHANNEL_PIPES)
-		    || channels[i].ch_out == fd
-		    || channels[i].ch_err == fd
+		    || channel->ch_out == fd
+		    || channel->ch_err == fd
 #  endif
 		    )
-		return i;
-    return -1;
+		return channel;
+    return NULL;
 }
 # endif
 
 /*
- * Write "buf" (NUL terminated string) to channel "ch_idx".
+ * Write "buf" (NUL terminated string) to channel "channel".
  * When "fun" is not NULL an error message might be given.
  * Return FAIL or OK.
  */
     int
-channel_send(int ch_idx, char_u *buf, char *fun)
+channel_send(channel_T *channel, char_u *buf, char *fun)
 {
-    channel_T	*channel = &channels[ch_idx];
     int		len = (int)STRLEN(buf);
     int		res;
     int		fd = -1;
@@ -1553,7 +1587,7 @@ channel_send(int ch_idx, char_u *buf, ch
     {
 	if (!channel->ch_error && fun != NULL)
 	{
-	    ch_errors(ch_idx, "%s(): write while not connected\n", fun);
+	    ch_errors(channel, "%s(): write while not connected\n", fun);
 	    EMSG2("E630: %s(): write while not connected", fun);
 	}
 	channel->ch_error = TRUE;
@@ -1562,7 +1596,7 @@ channel_send(int ch_idx, char_u *buf, ch
 
     if (log_fd != NULL)
     {
-	ch_log_lead("SEND ", ch_idx);
+	ch_log_lead("SEND ", channel);
 	fprintf(log_fd, "'");
 	ignored = fwrite(buf, len, 1, log_fd);
 	fprintf(log_fd, "'\n");
@@ -1577,7 +1611,7 @@ channel_send(int ch_idx, char_u *buf, ch
     {
 	if (!channel->ch_error && fun != NULL)
 	{
-	    ch_errors(ch_idx, "%s(): write failed\n", fun);
+	    ch_errors(channel, "%s(): write failed\n", fun);
 	    EMSG2("E631: %s(): write failed", fun);
 	}
 	channel->ch_error = TRUE;
@@ -1598,41 +1632,41 @@ channel_send(int ch_idx, char_u *buf, ch
 channel_poll_setup(int nfd_in, void *fds_in)
 {
     int nfd = nfd_in;
-    int i;
+    channel_T *channel;
     struct pollfd *fds = fds_in;
 
-    for (i = 0; i < channel_count; ++i)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
     {
-	if (channels[i].ch_sock >= 0)
+	if (channel->ch_sock >= 0)
 	{
-	    channels[i].ch_sock_idx = nfd;
-	    fds[nfd].fd = channels[i].ch_sock;
+	    channel->ch_sock_idx = nfd;
+	    fds[nfd].fd = channel->ch_sock;
 	    fds[nfd].events = POLLIN;
 	    nfd++;
 	}
 	else
-	    channels[i].ch_sock_idx = -1;
+	    channel->ch_sock_idx = -1;
 
 #  ifdef CHANNEL_PIPES
-	if (channels[i].ch_out >= 0)
+	if (channel->ch_out >= 0)
 	{
-	    channels[i].ch_out_idx = nfd;
-	    fds[nfd].fd = channels[i].ch_out;
+	    channel->ch_out_idx = nfd;
+	    fds[nfd].fd = channel->ch_out;
 	    fds[nfd].events = POLLIN;
 	    nfd++;
 	}
 	else
-	    channels[i].ch_out_idx = -1;
+	    channel->ch_out_idx = -1;
 
-	if (channels[i].ch_err >= 0)
+	if (channel->ch_err >= 0)
 	{
-	    channels[i].ch_err_idx = nfd;
-	    fds[nfd].fd = channels[i].ch_err;
+	    channel->ch_err_idx = nfd;
+	    fds[nfd].fd = channel->ch_err;
 	    fds[nfd].events = POLLIN;
 	    nfd++;
 	}
 	else
-	    channels[i].ch_err_idx = -1;
+	    channel->ch_err_idx = -1;
 #  endif
     }
 
@@ -1646,28 +1680,28 @@ channel_poll_setup(int nfd_in, void *fds
 channel_poll_check(int ret_in, void *fds_in)
 {
     int ret = ret_in;
-    int i;
+    channel_T *channel;
     struct pollfd *fds = fds_in;
 
-    for (i = 0; i < channel_count; ++i)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
     {
-	if (ret > 0 && channels[i].ch_sock_idx != -1
-			     && fds[channels[i].ch_sock_idx].revents & POLLIN)
+	if (ret > 0 && channel->ch_sock_idx != -1
+			     && fds[channel->ch_sock_idx].revents & POLLIN)
 	{
-	    channel_read(i, FALSE, "channel_poll_check");
+	    channel_read(channel, FALSE, "channel_poll_check");
 	    --ret;
 	}
 #  ifdef CHANNEL_PIPES
-	if (ret > 0 && channels[i].ch_out_idx != -1
-			       && fds[channels[i].ch_out_idx].revents & POLLIN)
+	if (ret > 0 && channel->ch_out_idx != -1
+			       && fds[channel->ch_out_idx].revents & POLLIN)
 	{
-	    channel_read(i, FALSE, "channel_poll_check");
+	    channel_read(channel, FALSE, "channel_poll_check");
 	    --ret;
 	}
-	if (ret > 0 && channels[i].ch_err_idx != -1
-			       && fds[channels[i].ch_err_idx].revents & POLLIN)
+	if (ret > 0 && channel->ch_err_idx != -1
+			       && fds[channel->ch_err_idx].revents & POLLIN)
 	{
-	    channel_read(i, TRUE, "channel_poll_check");
+	    channel_read(channel, TRUE, "channel_poll_check");
 	    --ret;
 	}
 #  endif
@@ -1685,29 +1719,29 @@ channel_poll_check(int ret_in, void *fds
 channel_select_setup(int maxfd_in, void *rfds_in)
 {
     int	    maxfd = maxfd_in;
-    int	    i;
+    channel_T *channel;
     fd_set  *rfds = rfds_in;
 
-    for (i = 0; i < channel_count; ++i)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
     {
-	if (channels[i].ch_sock >= 0)
+	if (channel->ch_sock >= 0)
 	{
-	    FD_SET(channels[i].ch_sock, rfds);
-	    if (maxfd < channels[i].ch_sock)
-		maxfd = channels[i].ch_sock;
+	    FD_SET(channel->ch_sock, rfds);
+	    if (maxfd < channel->ch_sock)
+		maxfd = channel->ch_sock;
 	}
 #  ifdef CHANNEL_PIPES
-	if (channels[i].ch_out >= 0)
+	if (channel->ch_out >= 0)
 	{
-	    FD_SET(channels[i].ch_out, rfds);
-	    if (maxfd < channels[i].ch_out)
-		maxfd = channels[i].ch_out;
+	    FD_SET(channel->ch_out, rfds);
+	    if (maxfd < channel->ch_out)
+		maxfd = channel->ch_out;
 	}
-	if (channels[i].ch_err >= 0)
+	if (channel->ch_err >= 0)
 	{
-	    FD_SET(channels[i].ch_err, rfds);
-	    if (maxfd < channels[i].ch_err)
-		maxfd = channels[i].ch_err;
+	    FD_SET(channel->ch_err, rfds);
+	    if (maxfd < channel->ch_err)
+		maxfd = channel->ch_err;
 	}
 #  endif
     }
@@ -1722,28 +1756,28 @@ channel_select_setup(int maxfd_in, void 
 channel_select_check(int ret_in, void *rfds_in)
 {
     int	    ret = ret_in;
-    int	    i;
+    channel_T *channel;
     fd_set  *rfds = rfds_in;
 
-    for (i = 0; i < channel_count; ++i)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
     {
-	if (ret > 0 && channels[i].ch_sock >= 0
-				       && FD_ISSET(channels[i].ch_sock, rfds))
+	if (ret > 0 && channel->ch_sock >= 0
+				       && FD_ISSET(channel->ch_sock, rfds))
 	{
-	    channel_read(i, FALSE, "channel_select_check");
+	    channel_read(channel, FALSE, "channel_select_check");
 	    --ret;
 	}
 #  ifdef CHANNEL_PIPES
-	if (ret > 0 && channels[i].ch_out >= 0
-				       && FD_ISSET(channels[i].ch_out, rfds))
+	if (ret > 0 && channel->ch_out >= 0
+				       && FD_ISSET(channel->ch_out, rfds))
 	{
-	    channel_read(i, FALSE, "channel_select_check");
+	    channel_read(channel, FALSE, "channel_select_check");
 	    --ret;
 	}
-	if (ret > 0 && channels[i].ch_err >= 0
-				       && FD_ISSET(channels[i].ch_err, rfds))
+	if (ret > 0 && channel->ch_err >= 0
+				       && FD_ISSET(channel->ch_err, rfds))
 	{
-	    channel_read(i, TRUE, "channel_select_check");
+	    channel_read(channel, TRUE, "channel_select_check");
 	    --ret;
 	}
 #  endif
@@ -1761,13 +1795,13 @@ channel_select_check(int ret_in, void *r
     int
 channel_parse_messages(void)
 {
-    int	    i;
+    channel_T *channel;
     int	    ret = FALSE;
 
-    for (i = 0; i < channel_count; ++i)
-	while (may_invoke_callback(i) == OK)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
+	while (may_invoke_callback(channel) == OK)
 	{
-	    i = 0;  /* start over */
+	    channel = first_channel;  /* start over */
 	    ret = TRUE;
 	}
     return ret;
@@ -1779,39 +1813,39 @@ channel_parse_messages(void)
     int
 set_ref_in_channel(int copyID)
 {
-    int	    i;
-    int	    abort = FALSE;
+    int		abort = FALSE;
+    channel_T	*channel;
 
-    for (i = 0; i < channel_count; ++i)
+    for (channel = first_channel; channel != NULL; channel = channel->ch_next)
     {
-	jsonq_T *head = &channels[i].ch_json_head;
-	jsonq_T *item = head->next;
+	jsonq_T *head = &channel->ch_json_head;
+	jsonq_T *item = head->jq_next;
 
-	while (item != head)
+	while (item != NULL)
 	{
-	    list_T	*l = item->value->vval.v_list;
+	    list_T	*l = item->jq_value->vval.v_list;
 
 	    if (l->lv_copyID != copyID)
 	    {
 		l->lv_copyID = copyID;
 		abort = abort || set_ref_in_list(l, copyID, NULL);
 	    }
-	    item = item->next;
+	    item = item->jq_next;
 	}
     }
     return abort;
 }
 
 /*
- * Return the mode of channel "ch_idx".
- * If "ch_idx" is invalid returns MODE_JSON.
+ * Return the mode of channel "channel".
+ * If "channel" is invalid returns MODE_JSON.
  */
     ch_mode_T
-channel_get_mode(int ch_idx)
+channel_get_mode(channel_T *channel)
 {
-    if (ch_idx < 0 || ch_idx >= channel_count)
+    if (channel == NULL)
 	return MODE_JSON;
-    return channels[ch_idx].ch_mode;
+    return channel->ch_mode;
 }
 
 #endif /* FEAT_CHANNEL */
--- a/src/eval.c
+++ b/src/eval.c
@@ -509,6 +509,7 @@ static void f_ch_open(typval_T *argvars,
 static void f_ch_readraw(typval_T *argvars, typval_T *rettv);
 static void f_ch_sendexpr(typval_T *argvars, typval_T *rettv);
 static void f_ch_sendraw(typval_T *argvars, typval_T *rettv);
+static void f_ch_status(typval_T *argvars, typval_T *rettv);
 #endif
 static void f_changenr(typval_T *argvars, typval_T *rettv);
 static void f_char2nr(typval_T *argvars, typval_T *rettv);
@@ -3084,6 +3085,7 @@ tv_op(typval_T *tv1, typval_T *tv2, char
 	    case VAR_FUNC:
 	    case VAR_SPECIAL:
 	    case VAR_JOB:
+	    case VAR_CHANNEL:
 		break;
 
 	    case VAR_LIST:
@@ -3863,6 +3865,7 @@ item_lock(typval_T *tv, int deep, int lo
 	case VAR_FLOAT:
 	case VAR_SPECIAL:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    break;
 
 	case VAR_LIST:
@@ -5359,6 +5362,7 @@ eval_index(
 #endif
 	case VAR_SPECIAL:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    if (verbose)
 		EMSG(_("E909: Cannot index a special variable"));
 	    return FAIL;
@@ -5471,6 +5475,7 @@ eval_index(
 	    case VAR_FLOAT:
 	    case VAR_SPECIAL:
 	    case VAR_JOB:
+	    case VAR_CHANNEL:
 		break; /* not evaluating, skipping over subscript */
 
 	    case VAR_NUMBER:
@@ -6224,6 +6229,10 @@ tv_equal(
 #ifdef FEAT_JOB
 	    return tv1->vval.v_job == tv2->vval.v_job;
 #endif
+	case VAR_CHANNEL:
+#ifdef FEAT_CHANNEL
+	    return tv1->vval.v_channel == tv2->vval.v_channel;
+#endif
 	case VAR_UNKNOWN:
 	    break;
     }
@@ -7719,12 +7728,26 @@ failret:
     return OK;
 }
 
+#ifdef FEAT_CHANNEL
+    static void
+channel_unref(channel_T *channel)
+{
+    if (channel != NULL && --channel->ch_refcount <= 0)
+	channel_free(channel);
+}
+#endif
+
 #ifdef FEAT_JOB
     static void
 job_free(job_T *job)
 {
-    if (job->jv_channel >= 0)
-	channel_close(job->jv_channel);
+    if (job->jv_channel != NULL)
+    {
+	/* The channel doesn't count as a references for the job, we need to
+	 * NULL the reference when the job is freed. */
+	job->jv_channel->ch_job = NULL;
+	channel_unref(job->jv_channel);
+    }
     mch_clear_job(job);
     vim_free(job);
 }
@@ -7746,9 +7769,7 @@ job_alloc(void)
 
     job = (job_T *)alloc_clear(sizeof(job_T));
     if (job != NULL)
-    {
 	job->jv_refcount = 1;
-    }
     return job;
 }
 
@@ -7850,6 +7871,7 @@ echo_string(
 	case VAR_NUMBER:
 	case VAR_UNKNOWN:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    *tofree = NULL;
 	    r = get_tv_string_buf(tv, numbuf);
 	    break;
@@ -7906,6 +7928,7 @@ tv2string(
 	case VAR_DICT:
 	case VAR_SPECIAL:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	case VAR_UNKNOWN:
 	    break;
     }
@@ -8093,6 +8116,7 @@ static struct fst
     {"ch_readraw",	1, 2, f_ch_readraw},
     {"ch_sendexpr",	2, 3, f_ch_sendexpr},
     {"ch_sendraw",	2, 3, f_ch_sendraw},
+    {"ch_status",	1, 1, f_ch_status},
 #endif
     {"changenr",	0, 0, f_changenr},
     {"char2nr",		1, 2, f_char2nr},
@@ -9781,27 +9805,27 @@ f_ceil(typval_T *argvars, typval_T *rett
 
 #ifdef FEAT_CHANNEL
 /*
- * Get the channel index from the handle argument.
- * Returns -1 if the handle is invalid or the channel is closed.
- */
-    static int
+ * Get the channel from the argument.
+ * Returns NULL if the handle is invalid.
+ */
+    static channel_T *
 get_channel_arg(typval_T *tv)
 {
-    int ch_idx;
-
-    if (tv->v_type != VAR_NUMBER)
+    channel_T *channel;
+
+    if (tv->v_type != VAR_CHANNEL)
     {
 	EMSG2(_(e_invarg2), get_tv_string(tv));
-	return -1;
-    }
-    ch_idx = tv->vval.v_number;
-
-    if (!channel_can_write_to(ch_idx))
-    {
-	EMSGN(_("E906: not an open channel"), ch_idx);
-	return -1;
-    }
-    return ch_idx;
+	return NULL;
+    }
+    channel = tv->vval.v_channel;
+
+    if (channel == NULL || !channel_is_open(channel))
+    {
+	EMSG(_("E906: not an open channel"));
+	return NULL;
+    }
+    return channel;
 }
 
 /*
@@ -9810,10 +9834,10 @@ get_channel_arg(typval_T *tv)
     static void
 f_ch_close(typval_T *argvars, typval_T *rettv UNUSED)
 {
-    int ch_idx = get_channel_arg(&argvars[0]);
-
-    if (ch_idx >= 0)
-	channel_close(ch_idx);
+    channel_T *channel = get_channel_arg(&argvars[0]);
+
+    if (channel != NULL)
+	channel_close(channel);
 }
 
 /*
@@ -9873,10 +9897,11 @@ f_ch_open(typval_T *argvars, typval_T *r
     int		waittime = 0;
     int		timeout = 2000;
     ch_mode_T	ch_mode = MODE_JSON;
-    int		ch_idx;
+    channel_T	*channel;
 
     /* default: fail */
-    rettv->vval.v_number = -1;
+    rettv->v_type = VAR_CHANNEL;
+    rettv->vval.v_channel = NULL;
 
     address = get_tv_string(&argvars[0]);
     if (argvars[1].v_type != VAR_UNKNOWN
@@ -9936,15 +9961,15 @@ f_ch_open(typval_T *argvars, typval_T *r
 	return;
     }
 
-    ch_idx = channel_open((char *)address, port, waittime, NULL);
-    if (ch_idx >= 0)
-    {
-	channel_set_json_mode(ch_idx, ch_mode);
-	channel_set_timeout(ch_idx, timeout);
+    channel = channel_open((char *)address, port, waittime, NULL);
+    if (channel != NULL)
+    {
+	channel_set_json_mode(channel, ch_mode);
+	channel_set_timeout(channel, timeout);
 	if (callback != NULL && *callback != NUL)
-	    channel_set_callback(ch_idx, callback);
-    }
-    rettv->vval.v_number = ch_idx;
+	    channel_set_callback(channel, callback);
+    }
+    rettv->vval.v_channel = channel;
 }
 
 /*
@@ -9953,53 +9978,65 @@ f_ch_open(typval_T *argvars, typval_T *r
     static void
 f_ch_readraw(typval_T *argvars, typval_T *rettv)
 {
-    int		ch_idx;
+    channel_T *channel;
 
     /* return an empty string by default */
     rettv->v_type = VAR_STRING;
     rettv->vval.v_string = NULL;
 
-    ch_idx = get_channel_arg(&argvars[0]);
-    if (ch_idx < 0)
-    {
-	EMSG(_(e_invarg));
-	return;
-    }
-    rettv->vval.v_string = channel_read_block(ch_idx);
+    channel = get_channel_arg(&argvars[0]);
+    if (channel != NULL)
+	rettv->vval.v_string = channel_read_block(channel);
+}
+
+/*
+ * "ch_status()" function
+ */
+    static void
+f_ch_status(typval_T *argvars, typval_T *rettv)
+{
+    /* return an empty string by default */
+    rettv->v_type = VAR_STRING;
+
+    if (argvars[0].v_type != VAR_CHANNEL)
+    {
+	EMSG2(_(e_invarg2), get_tv_string(&argvars[0]));
+	rettv->vval.v_string = NULL;
+    }
+    else
+	rettv->vval.v_string = vim_strsave(
+			 (char_u *)channel_status(argvars[0].vval.v_channel));
 }
 
 /*
  * common for "sendexpr()" and "sendraw()"
- * Returns the channel index if the caller should read the response.
- * Otherwise returns -1.
- */
-    static int
+ * Returns the channel if the caller should read the response.
+ * Otherwise returns NULL.
+ */
+    static channel_T *
 send_common(typval_T *argvars, char_u *text, int id, char *fun)
 {
-    int		ch_idx;
+    channel_T	*channel;
     char_u	*callback = NULL;
 
-    ch_idx = get_channel_arg(&argvars[0]);
-    if (ch_idx < 0)
-    {
-	EMSG(_(e_invarg));
-	return -1;
-    }
+    channel = get_channel_arg(&argvars[0]);
+    if (channel == NULL)
+	return NULL;
 
     if (argvars[2].v_type != VAR_UNKNOWN)
     {
 	callback = get_callback(&argvars[2]);
 	if (callback == NULL)
-	    return -1;
+	    return NULL;
     }
     /* Set the callback. An empty callback means no callback and not reading
      * the response. */
     if (callback != NULL && *callback != NUL)
-	channel_set_req_callback(ch_idx, callback, id);
-
-    if (channel_send(ch_idx, text, fun) == OK && callback == NULL)
-	return ch_idx;
-    return -1;
+	channel_set_req_callback(channel, callback, id);
+
+    if (channel_send(channel, text, fun) == OK && callback == NULL)
+	return channel;
+    return NULL;
 }
 
 /*
@@ -10010,7 +10047,7 @@ f_ch_sendexpr(typval_T *argvars, typval_
 {
     char_u	*text;
     typval_T	*listtv;
-    int		ch_idx;
+    channel_T	*channel;
     int		id;
     ch_mode_T	ch_mode;
 
@@ -10018,14 +10055,11 @@ f_ch_sendexpr(typval_T *argvars, typval_
     rettv->v_type = VAR_STRING;
     rettv->vval.v_string = NULL;
 
-    ch_idx = get_channel_arg(&argvars[0]);
-    if (ch_idx < 0)
-    {
-	EMSG(_(e_invarg));
-	return;
-    }
-
-    ch_mode = channel_get_mode(ch_idx);
+    channel = get_channel_arg(&argvars[0]);
+    if (channel == NULL)
+	return;
+
+    ch_mode = channel_get_mode(channel);
     if (ch_mode == MODE_RAW)
     {
 	EMSG(_("E912: cannot use ch_sendexpr() with a raw channel"));
@@ -10038,11 +10072,11 @@ f_ch_sendexpr(typval_T *argvars, typval_
     if (text == NULL)
 	return;
 
-    ch_idx = send_common(argvars, text, id, "sendexpr");
+    channel = send_common(argvars, text, id, "sendexpr");
     vim_free(text);
-    if (ch_idx >= 0)
-    {
-	if (channel_read_json_block(ch_idx, id, &listtv) == OK)
+    if (channel != NULL)
+    {
+	if (channel_read_json_block(channel, id, &listtv) == OK)
 	{
 	    list_T *list = listtv->vval.v_list;
 
@@ -10050,7 +10084,7 @@ f_ch_sendexpr(typval_T *argvars, typval_
 	     * avoid the value being freed. */
 	    *rettv = list->lv_last->li_tv;
 	    list->lv_last->li_tv.v_type = VAR_NUMBER;
-	    clear_tv(listtv);
+	    free_tv(listtv);
 	}
     }
 }
@@ -10063,16 +10097,16 @@ f_ch_sendraw(typval_T *argvars, typval_T
 {
     char_u	buf[NUMBUFLEN];
     char_u	*text;
-    int		ch_idx;
+    channel_T	*channel;
 
     /* return an empty string by default */
     rettv->v_type = VAR_STRING;
     rettv->vval.v_string = NULL;
 
     text = get_tv_string_buf(&argvars[1], buf);
-    ch_idx = send_common(argvars, text, 0, "sendraw");
-    if (ch_idx >= 0)
-	rettv->vval.v_string = channel_read_block(ch_idx);
+    channel = send_common(argvars, text, 0, "sendraw");
+    if (channel != NULL)
+	rettv->vval.v_string = channel_read_block(channel);
 }
 #endif
 
@@ -10708,7 +10742,14 @@ f_empty(typval_T *argvars, typval_T *ret
 
 	case VAR_JOB:
 #ifdef FEAT_JOB
-	    n = argvars[0].vval.v_job->jv_status != JOB_STARTED;
+	    n = argvars[0].vval.v_job == NULL
+			   || argvars[0].vval.v_job->jv_status != JOB_STARTED;
+	    break;
+#endif
+	case VAR_CHANNEL:
+#ifdef FEAT_CMDWIN
+	    n = argvars[0].vval.v_channel == NULL
+			       || !channel_is_open(argvars[0].vval.v_channel);
 	    break;
 #endif
 	case VAR_UNKNOWN:
@@ -14366,8 +14407,10 @@ f_job_getchannel(typval_T *argvars, typv
     {
 	job_T *job = argvars[0].vval.v_job;
 
-	rettv->v_type = VAR_NUMBER;
-	rettv->vval.v_number = job->jv_channel;
+	rettv->v_type = VAR_CHANNEL;
+	rettv->vval.v_channel = job->jv_channel;
+	if (job->jv_channel != NULL)
+	    ++job->jv_channel->ch_refcount;
     }
 }
 
@@ -14659,6 +14702,7 @@ f_len(typval_T *argvars, typval_T *rettv
 	case VAR_FLOAT:
 	case VAR_FUNC:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    EMSG(_("E701: Invalid type for len()"));
 	    break;
     }
@@ -20040,7 +20084,8 @@ f_type(typval_T *argvars, typval_T *rett
 	     else
 		 n = 7;
 	     break;
-	case VAR_JOB:    n = 8; break;
+	case VAR_JOB:     n = 8; break;
+	case VAR_CHANNEL: n = 9; break;
 	case VAR_UNKNOWN:
 	     EMSG2(_(e_intern2), "f_type(UNKNOWN)");
 	     n = -1;
@@ -21412,6 +21457,11 @@ free_tv(typval_T *varp)
 		job_unref(varp->vval.v_job);
 		break;
 #endif
+	    case VAR_CHANNEL:
+#ifdef FEAT_CHANNEL
+		channel_unref(varp->vval.v_channel);
+		break;
+#endif
 	    case VAR_NUMBER:
 	    case VAR_FLOAT:
 	    case VAR_UNKNOWN:
@@ -21462,6 +21512,11 @@ clear_tv(typval_T *varp)
 		varp->vval.v_job = NULL;
 #endif
 		break;
+	    case VAR_CHANNEL:
+#ifdef FEAT_CHANNEL
+		channel_unref(varp->vval.v_channel);
+		varp->vval.v_channel = NULL;
+#endif
 	    case VAR_UNKNOWN:
 		break;
 	}
@@ -21531,6 +21586,11 @@ get_tv_number_chk(typval_T *varp, int *d
 	    EMSG(_("E910: Using a Job as a Number"));
 	    break;
 #endif
+	case VAR_CHANNEL:
+#ifdef FEAT_CHANNEL
+	    EMSG(_("E913: Using a Channel as a Number"));
+	    break;
+#endif
 	case VAR_UNKNOWN:
 	    EMSG2(_(e_intern2), "get_tv_number(UNKNOWN)");
 	    break;
@@ -21572,6 +21632,11 @@ get_tv_float(typval_T *varp)
 	    EMSG(_("E911: Using a Job as a Float"));
 	    break;
 # endif
+	case VAR_CHANNEL:
+# ifdef FEAT_CHANNEL
+	    EMSG(_("E914: Using a Channel as a Float"));
+	    break;
+# endif
 	case VAR_UNKNOWN:
 	    EMSG2(_(e_intern2), "get_tv_float(UNKNOWN)");
 	    break;
@@ -21707,6 +21772,18 @@ get_tv_string_buf_chk(typval_T *varp, ch
 	    }
 #endif
 	    break;
+	case VAR_CHANNEL:
+#ifdef FEAT_CHANNEL
+	    {
+		channel_T *channel = varp->vval.v_channel;
+		char      *status = channel_status(channel);
+
+		vim_snprintf((char *)buf, NUMBUFLEN,
+				     "channel %d %s", channel->ch_id, status);
+		return buf;
+	    }
+#endif
+	    break;
 	case VAR_UNKNOWN:
 	    EMSG(_("E908: using an invalid value as a String"));
 	    break;
@@ -22337,6 +22414,12 @@ copy_tv(typval_T *from, typval_T *to)
 	    ++to->vval.v_job->jv_refcount;
 	    break;
 #endif
+	case VAR_CHANNEL:
+#ifdef FEAT_CHANNEL
+	    to->vval.v_channel = from->vval.v_channel;
+	    ++to->vval.v_channel->ch_refcount;
+	    break;
+#endif
 	case VAR_STRING:
 	case VAR_FUNC:
 	    if (from->vval.v_string == NULL)
@@ -22404,6 +22487,7 @@ item_copy(
 	case VAR_FUNC:
 	case VAR_SPECIAL:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    copy_tv(from, to);
 	    break;
 	case VAR_LIST:
@@ -25076,6 +25160,7 @@ write_viminfo_varlist(FILE *fp)
 		    case VAR_UNKNOWN:
 		    case VAR_FUNC:
 		    case VAR_JOB:
+		    case VAR_CHANNEL:
 				     continue;
 		}
 		fprintf(fp, "!%s\t%s\t", this_var->di_key, s);
--- a/src/gui_w48.c
+++ b/src/gui_w48.c
@@ -1780,14 +1780,14 @@ process_message(void)
 #ifdef FEAT_CHANNEL
     if (msg.message == WM_NETBEANS)
     {
-	int channel_idx = channel_fd2idx((sock_T)msg.wParam);
-
-	if (channel_idx >= 0)
+	channel_T *channel = channel_fd2channel((sock_T)msg.wParam);
+
+	if (channel != NULL)
 	{
 	    /* Disable error messages, they can mess up the display and throw
 	     * an exception. */
 	    ++emsg_off;
-	    channel_read(channel_idx, FALSE, "process_message");
+	    channel_read(channel, FALSE, "process_message");
 	    --emsg_off;
 	}
 	return;
--- a/src/if_python.c
+++ b/src/if_python.c
@@ -1561,6 +1561,7 @@ do_pyeval (char_u *str, typval_T *rettv)
 	case VAR_FLOAT:
 	case VAR_SPECIAL:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    break;
     }
 }
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -1654,6 +1654,7 @@ do_py3eval (char_u *str, typval_T *rettv
 	case VAR_FLOAT:
 	case VAR_SPECIAL:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    break;
     }
 }
--- a/src/json.c
+++ b/src/json.c
@@ -183,6 +183,7 @@ json_encode_item(garray_T *gap, typval_T
 
 	case VAR_FUNC:
 	case VAR_JOB:
+	case VAR_CHANNEL:
 	    /* no JSON equivalent TODO: better error */
 	    EMSG(_(e_invarg));
 	    return FAIL;
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -1139,6 +1139,9 @@ free_all_mem(void)
 # ifdef FEAT_DIFF
     diff_clear(curtab);
 # endif
+# ifdef FEAT_CHANNEL
+    channel_free_all();
+# endif
     clear_sb_text();	      /* free any scrollback text */
 
     /* Free some global vars. */
--- a/src/netbeans.c
+++ b/src/netbeans.c
@@ -63,8 +63,8 @@ static int  nb_do_cmd(int, char_u *, int
 static void nb_send(char *buf, char *fun);
 static void nb_free(void);
 
-#define NETBEANS_OPEN (nb_channel_idx >= 0 && channel_is_open(nb_channel_idx))
-static int nb_channel_idx = -1;
+#define NETBEANS_OPEN (channel_can_write_to(nb_channel))
+static channel_T *nb_channel = NULL;
 
 static int r_cmdno;			/* current command number for reply */
 static int dosetvisible = FALSE;
@@ -85,7 +85,7 @@ static int inAtomic = 0;
     static void
 nb_channel_closed(void)
 {
-    nb_channel_idx = -1;
+    nb_channel = NULL;
 }
 
 /*
@@ -98,10 +98,10 @@ netbeans_close(void)
     if (NETBEANS_OPEN)
     {
 	netbeans_send_disconnect();
-	if (nb_channel_idx >= 0)
+	if (nb_channel != NULL)
 	    /* Close the socket and remove the input handlers. */
-	    channel_close(nb_channel_idx);
-	nb_channel_idx = -1;
+	    channel_close(nb_channel);
+	nb_channel = NULL;
     }
 
 #ifdef FEAT_BEVAL
@@ -213,8 +213,8 @@ netbeans_connect(char *params, int doabo
     if (hostname != NULL && address != NULL && password != NULL)
     {
 	port = atoi(address);
-	nb_channel_idx = channel_open(hostname, port, 0, nb_channel_closed);
-	if (nb_channel_idx >= 0)
+	nb_channel = channel_open(hostname, port, 0, nb_channel_closed);
+	if (nb_channel != NULL)
 	{
 	    /* success */
 # ifdef FEAT_BEVAL
@@ -230,7 +230,7 @@ netbeans_connect(char *params, int doabo
 	}
     }
 
-    if (nb_channel_idx < 0 && doabort)
+    if (nb_channel == NULL && doabort)
 	getout(1);
 
     vim_free(hostname);
@@ -383,9 +383,9 @@ netbeans_parse_messages(void)
     char_u	*p;
     int		own_node;
 
-    while (nb_channel_idx >= 0)
+    while (nb_channel != NULL)
     {
-	buffer = channel_peek(nb_channel_idx);
+	buffer = channel_peek(nb_channel);
 	if (buffer == NULL)
 	    break;	/* nothing to read */
 
@@ -396,7 +396,7 @@ netbeans_parse_messages(void)
 	    /* Command isn't complete.  If there is no following buffer,
 	     * return (wait for more). If there is another buffer following,
 	     * prepend the text to that buffer and delete this one.  */
-	    if (channel_collapse(nb_channel_idx) == FAIL)
+	    if (channel_collapse(nb_channel) == FAIL)
 		return;
 	}
 	else
@@ -409,7 +409,7 @@ netbeans_parse_messages(void)
 	    if (*p == NUL)
 	    {
 		own_node = TRUE;
-		channel_get(nb_channel_idx);
+		channel_get(nb_channel);
 	    }
 	    else
 		own_node = FALSE;
@@ -600,8 +600,8 @@ nb_free(void)
     }
 
     /* free the queued netbeans commands */
-    if (nb_channel_idx >= 0)
-	channel_clear(nb_channel_idx);
+    if (nb_channel != NULL)
+	channel_clear(nb_channel);
 }
 
 /*
@@ -756,8 +756,8 @@ netbeans_end(void)
     static void
 nb_send(char *buf, char *fun)
 {
-    if (nb_channel_idx >= 0)
-	channel_send(nb_channel_idx, (char_u *)buf, fun);
+    if (nb_channel != NULL)
+	channel_send(nb_channel, (char_u *)buf, fun);
 }
 
 /*
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -5043,7 +5043,7 @@ mch_start_job(char **argv, job_T *job)
     int		fd_in[2];	/* for stdin */
     int		fd_out[2];	/* for stdout */
     int		fd_err[2];	/* for stderr */
-    int		ch_idx;
+    channel_T	*channel;
 
     /* default is to fail */
     job->jv_status = JOB_FAILED;
@@ -5055,8 +5055,8 @@ mch_start_job(char **argv, job_T *job)
     if ((pipe(fd_in) < 0) || (pipe(fd_out) < 0) ||(pipe(fd_err) < 0))
 	goto failed;
 
-    ch_idx = add_channel();
-    if (ch_idx < 0)
+    channel = add_channel();
+    if (channel == NULL)
 	goto failed;
 
     pid = fork();	/* maybe we should use vfork() */
@@ -5108,14 +5108,14 @@ mch_start_job(char **argv, job_T *job)
     /* parent */
     job->jv_pid = pid;
     job->jv_status = JOB_STARTED;
-    job->jv_channel = ch_idx;
+    job->jv_channel = channel;
 
     /* child stdin, stdout and stderr */
     close(fd_in[0]);
     close(fd_out[1]);
     close(fd_err[1]);
-    channel_set_pipes(ch_idx, fd_in[1], fd_out[0], fd_err[0]);
-    channel_set_job(ch_idx, job);
+    channel_set_pipes(channel, fd_in[1], fd_out[0], fd_err[0]);
+    channel_set_job(channel, job);
 
     return;
 
--- a/src/proto/channel.pro
+++ b/src/proto/channel.pro
@@ -1,33 +1,36 @@
 /* channel.c */
 void ch_logfile(FILE *file);
-int add_channel(void);
+channel_T *add_channel(void);
+void channel_free(channel_T *channel);
 void channel_gui_register_all(void);
-int channel_open(char *hostname, int port_in, int waittime, void (*close_cb)(void));
-void channel_set_pipes(int idx, int in, int out, int err);
-void channel_set_job(int idx, job_T *job);
-void channel_set_json_mode(int idx, ch_mode_T ch_mode);
-void channel_set_timeout(int idx, int timeout);
-void channel_set_callback(int idx, char_u *callback);
-void channel_set_req_callback(int idx, char_u *callback, int id);
-char_u *channel_get(int idx);
-int channel_collapse(int idx);
-int channel_can_write_to(int idx);
-int channel_is_open(int idx);
-void channel_close(int idx);
-int channel_save(int idx, char_u *buf, int len);
-char_u *channel_peek(int idx);
-void channel_clear(int idx);
+channel_T *channel_open(char *hostname, int port_in, int waittime, void (*close_cb)(void));
+void channel_set_pipes(channel_T *channel, int in, int out, int err);
+void channel_set_job(channel_T *channel, job_T *job);
+void channel_set_json_mode(channel_T *channel, ch_mode_T ch_mode);
+void channel_set_timeout(channel_T *channel, int timeout);
+void channel_set_callback(channel_T *channel, char_u *callback);
+void channel_set_req_callback(channel_T *channel, char_u *callback, int id);
+char_u *channel_get(channel_T *channel);
+int channel_collapse(channel_T *channel);
+int channel_can_write_to(channel_T *channel);
+int channel_is_open(channel_T *channel);
+char *channel_status(channel_T *channel);
+void channel_close(channel_T *channel);
+int channel_save(channel_T *channel, char_u *buf, int len);
+char_u *channel_peek(channel_T *channel);
+void channel_clear(channel_T *channel);
+void channel_free_all(void);
 int channel_get_id(void);
-void channel_read(int idx, int use_stderr, char *func);
-char_u *channel_read_block(int idx);
-int channel_read_json_block(int ch_idx, int id, typval_T **rettv);
-int channel_fd2idx(sock_T fd);
-int channel_send(int idx, char_u *buf, char *fun);
+void channel_read(channel_T *channel, int use_stderr, char *func);
+char_u *channel_read_block(channel_T *channel);
+int channel_read_json_block(channel_T *channel, int id, typval_T **rettv);
+channel_T *channel_fd2channel(sock_T fd);
+int channel_send(channel_T *channel, char_u *buf, char *fun);
 int channel_poll_setup(int nfd_in, void *fds_in);
 int channel_poll_check(int ret_in, void *fds_in);
 int channel_select_setup(int maxfd_in, void *rfds_in);
 int channel_select_check(int ret_in, void *rfds_in);
 int channel_parse_messages(void);
 int set_ref_in_channel(int copyID);
-ch_mode_T channel_get_mode(int idx);
+ch_mode_T channel_get_mode(channel_T *channel);
 /* vim: set ft=c : */
--- a/src/structs.h
+++ b/src/structs.h
@@ -1127,7 +1127,8 @@ typedef enum
     VAR_DICT,	 /* "v_dict" is used */
     VAR_FLOAT,	 /* "v_float" is used */
     VAR_SPECIAL, /* "v_number" is used */
-    VAR_JOB	 /* "v_job" is used */
+    VAR_JOB,	 /* "v_job" is used */
+    VAR_CHANNEL	 /* "v_channel" is used */
 } vartype_T;
 
 /*
@@ -1149,6 +1150,9 @@ typedef struct
 #ifdef FEAT_JOB
 	job_T		*v_job;		/* job value (can be NULL!) */
 #endif
+#ifdef FEAT_CHANNEL
+	channel_T	*v_channel;	/* channel value (can be NULL!) */
+#endif
     }		vval;
 } typval_T;
 
@@ -1260,7 +1264,7 @@ struct jobvar_S
     jobstatus_T	jv_status;
 
     int		jv_refcount;	/* reference count */
-    int		jv_channel;	/* channel for I/O */
+    channel_T	*jv_channel;	/* channel for I/O, reference counted */
 };
 
 /*
@@ -1268,35 +1272,41 @@ struct jobvar_S
  */
 struct readq_S
 {
-    char_u	*buffer;
-    readq_T	*next;
-    readq_T	*prev;
+    char_u	*rq_buffer;
+    readq_T	*rq_next;
+    readq_T	*rq_prev;
 };
 
 struct jsonq_S
 {
-    typval_T	*value;
-    jsonq_T	*next;
-    jsonq_T	*prev;
+    typval_T	*jq_value;
+    jsonq_T	*jq_next;
+    jsonq_T	*jq_prev;
 };
 
 struct cbq_S
 {
-    char_u	*callback;
-    int		seq_nr;
-    cbq_T	*next;
-    cbq_T	*prev;
+    char_u	*cq_callback;
+    int		cq_seq_nr;
+    cbq_T	*cq_next;
+    cbq_T	*cq_prev;
 };
 
 /* mode for a channel */
 typedef enum
 {
-    MODE_RAW = 0,
+    MODE_NL = 0,
+    MODE_RAW,
     MODE_JSON,
     MODE_JS
 } ch_mode_T;
 
 struct channel_S {
+    channel_T	*ch_next;
+    channel_T	*ch_prev;
+
+    int		ch_id;		/* ID of the channel */
+
     sock_T	ch_sock;	/* the socket, -1 for a closed channel */
 
 #ifdef UNIX
@@ -1342,7 +1352,11 @@ struct channel_S {
 
     int		ch_timeout;	/* request timeout in msec */
 
-    job_T	*ch_job;	/* job that uses this channel */
+    job_T	*ch_job;	/* Job that uses this channel; this does not
+				 * count as a reference to avoid a circular
+				 * reference. */
+
+    int		ch_refcount;	/* reference count */
 };
 
 
--- a/src/testdir/test_channel.py
+++ b/src/testdir/test_channel.py
@@ -1,13 +1,7 @@
 #!/usr/bin/python
 #
 # Server that will accept connections from a Vim channel.
-# Run this server and then in Vim you can open the channel:
-#  :let handle = ch_open('localhost:8765', 'json')
-#
-# Then Vim can send requests to the server:
-#  :let response = ch_sendexpr(handle, 'hello!')
-#
-# See ":help channel-demo" in Vim.
+# Used by test_channel.vim.
 #
 # This requires Python 2.6 or later.
 
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -83,7 +83,6 @@ func s:kill_server()
   endif
 endfunc
 
-let s:responseHandle = -1
 let s:responseMsg = ''
 func s:RequestHandler(handle, msg)
   let s:responseHandle = a:handle
@@ -92,7 +91,7 @@ endfunc
 
 func s:communicate(port)
   let handle = ch_open('localhost:' . a:port, s:chopt)
-  if handle < 0
+  if ch_status(handle) == "fail"
     call assert_false(1, "Can't open channel")
     return
   endif
@@ -115,14 +114,22 @@ func s:communicate(port)
   " Send a request with a specific handler.
   call ch_sendexpr(handle, 'hello!', 's:RequestHandler')
   sleep 10m
-  call assert_equal(handle, s:responseHandle)
+  if !exists('s:responseHandle')
+    call assert_false(1, 's:responseHandle was not set')
+  else
+    call assert_equal(handle, s:responseHandle)
+  endif
   call assert_equal('got it', s:responseMsg)
 
-  let s:responseHandle = -1
+  unlet s:responseHandle
   let s:responseMsg = ''
   call ch_sendexpr(handle, 'hello!', function('s:RequestHandler'))
   sleep 10m
-  call assert_equal(handle, s:responseHandle)
+  if !exists('s:responseHandle')
+    call assert_false(1, 's:responseHandle was not set')
+  else
+    call assert_equal(handle, s:responseHandle)
+  endif
   call assert_equal('got it', s:responseMsg)
 
   " Send an eval request that works.
@@ -169,7 +176,7 @@ endfunc
 " Test that we can open two channels.
 func s:two_channels(port)
   let handle = ch_open('localhost:' . a:port, s:chopt)
-  if handle < 0
+  if ch_status(handle) == "fail"
     call assert_false(1, "Can't open channel")
     return
   endif
@@ -177,7 +184,7 @@ func s:two_channels(port)
   call assert_equal('got it', ch_sendexpr(handle, 'hello!'))
 
   let newhandle = ch_open('localhost:' . a:port, s:chopt)
-  if newhandle < 0
+  if ch_status(newhandle) == "fail"
     call assert_false(1, "Can't open second channel")
     return
   endif
@@ -197,7 +204,7 @@ endfunc
 " Test that a server crash is handled gracefully.
 func s:server_crash(port)
   let handle = ch_open('localhost:' . a:port, s:chopt)
-  if handle < 0
+  if ch_status(handle) == "fail"
     call assert_false(1, "Can't open channel")
     return
   endif
@@ -219,7 +226,7 @@ endfunc
 
 func s:channel_handler(port)
   let handle = ch_open('localhost:' . a:port, s:chopt)
-  if handle < 0
+  if ch_status(handle) == "fail"
     call assert_false(1, "Can't open channel")
     return
   endif
@@ -247,7 +254,7 @@ endfunc
 func Test_connect_waittime()
   let start = reltime()
   let handle = ch_open('localhost:9876', s:chopt)
-  if handle >= 0
+  if ch_status(handle) == "fail"
     " Oops, port does exists.
     call ch_close(handle)
   else
@@ -257,7 +264,7 @@ func Test_connect_waittime()
 
   let start = reltime()
   let handle = ch_open('localhost:9867', {'waittime': 2000})
-  if handle >= 0
+  if ch_status(handle) != "fail"
     " Oops, port does exists.
     call ch_close(handle)
   else
--- a/src/version.c
+++ b/src/version.c
@@ -748,6 +748,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1315,
+/**/
     1314,
 /**/
     1313,