[PATCH 1/3] Do not trigger user disconnect at g_at_shutdown

[PATCH 1/3] Do not trigger user disconnect at g_at_shutdown

[Zhenhua Zhang]

[-- Attachment #1: Type: text/plain, Size: 3756 bytes --]

Similar to gatchat, introduce read_watcher_destroy_notify and do
not trigger user disconnect at g_at_shutdown. Delay destroy of
gatserver until read_watcher is destroyed.
---
 gatchat/gatserver.c |   44 ++++++++++++++++++++++++++++++--------------
 1 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/gatchat/gatserver.c b/gatchat/gatserver.c
index d131b0c..bf7e847 100644
--- a/gatchat/gatserver.c
+++ b/gatchat/gatserver.c
@@ -89,7 +89,7 @@ struct _GAtServer {
 	gint ref_count;				/* Ref count */
 	struct v250_settings v250;		/* V.250 command setting */
 	GIOChannel *channel;			/* Server IO */
-	int server_watch;			/* Watch for server IO */
+	guint read_watch;			/* GSource read id, 0 if none */
 	guint read_so_far;			/* Number of bytes processed */
 	GAtDisconnectFunc user_disconnect;	/* User disconnect func */
 	gpointer user_disconnect_data;		/* User disconnect data */
@@ -98,6 +98,7 @@ struct _GAtServer {
 	struct ring_buffer *read_buf;		/* Current read buffer */
 	guint max_read_attempts;		/* Max reads per select */
 	enum ParserState parser_state;
+	gboolean destroyed;			/* Re-entrancy guard */
 };
 
 static void g_at_server_send_result(GAtServer *server, GAtServerResult result)
@@ -380,7 +381,7 @@ static void new_bytes(GAtServer *p)
 
 	/* We're overflowing the buffer, shutdown the socket */
 	if (p->read_buf && ring_buffer_avail(p->read_buf) == 0)
-		g_source_remove(p->server_watch);
+		g_source_remove(p->read_watch);
 }
 
 static gboolean received_data(GIOChannel *channel, GIOCondition cond,
@@ -431,17 +432,27 @@ static gboolean received_data(GIOChannel *channel, GIOCondition cond,
 	return TRUE;
 }
 
-static void server_watcher_destroy_notify(GAtServer *server)
+static void g_at_server_cleanup(GAtServer *server)
 {
-	server->server_watch = 0;
-
+	/* Cleanup all received data */
 	ring_buffer_free(server->read_buf);
 	server->read_buf = NULL;
 
 	server->channel = NULL;
+}
+
+static void read_watcher_destroy_notify(GAtServer *server)
+{
+	g_at_server_cleanup(server);
+	server->read_watch = 0;
+
+	server->channel = NULL;
 
 	if (server->user_disconnect)
 		server->user_disconnect(server->user_disconnect_data);
+
+	if (server->destroyed)
+		g_free(server);
 }
 
 static void v250_settings_create(struct v250_settings *v250)
@@ -480,10 +491,10 @@ GAtServer *g_at_server_new(GIOChannel *io)
 	if (!g_at_util_setup_io(server->channel, G_IO_FLAG_NONBLOCK))
 		goto error;
 
-	server->server_watch = g_io_add_watch_full(io, G_PRIORITY_DEFAULT,
+	server->read_watch = g_io_add_watch_full(io, G_PRIORITY_DEFAULT,
 				G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_NVAL,
 				received_data, server,
-				(GDestroyNotify)server_watcher_destroy_notify);
+				(GDestroyNotify)read_watcher_destroy_notify);
 
 	return server;
 
@@ -520,6 +531,16 @@ void g_at_server_unref(GAtServer *server)
 		return;
 
 	g_at_server_shutdown(server);
+
+	/* glib delays the destruction of the watcher until it exits, this
+	 * means we can't free the data just yet, even though we've been
+	 * destroyed already.  We have to wait until the read_watcher
+	 * destroy function gets called
+	 */
+	if (server->read_watch != 0)
+		server->destroyed = TRUE;
+	else
+		g_free(server);
 }
 
 gboolean g_at_server_shutdown(GAtServer *server)
@@ -531,13 +552,8 @@ gboolean g_at_server_shutdown(GAtServer *server)
 	server->user_disconnect = NULL;
 	server->user_disconnect_data = NULL;
 
-	if (server->server_watch) {
-		g_source_remove(server->server_watch);
-		server->server_watch = 0;
-	}
-
-	g_free(server);
-	server = NULL;
+	if (server->read_watch)
+		g_source_remove(server->read_watch);
 
 	return TRUE;
 }
-- 
1.6.6.1

[PATCH 2/3] Add write buffer for non-blocking write

[Zhenhua Zhang]

[-- Attachment #1: Type: text/plain, Size: 7232 bytes --]

Use two layers to cache server side response data to client.
1. A fixed-length ring buffer, that is write_buf.
2. A list of full ring buffer. The head is to write data out to the
client and the tail is to cache response data in. At least one buffer
is in the list.

When the first layer buffer is full, a free buffer is allocated and
appended at the tail of the full list. It replaces original write
buffer as current write_buf.
---
 gatchat/gatserver.c |  130 +++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 117 insertions(+), 13 deletions(-)

diff --git a/gatchat/gatserver.c b/gatchat/gatserver.c
index bf7e847..7e11359 100644
--- a/gatchat/gatserver.c
+++ b/gatchat/gatserver.c
@@ -32,6 +32,14 @@
 #include "ringbuffer.h"
 #include "gatserver.h"
 
+#define READ_BUF_SIZE 4096
+/* #define WRITE_SCHEDULER_DEBUG 1 */
+#ifdef WRITE_SCHEDULER_DEBUG
+#define WRITE_BUF_SIZE 4
+#else
+#define WRITE_BUF_SIZE 4096
+#endif
+
 enum ParserState {
 	PARSER_STATE_IDLE,
 	PARSER_STATE_A,
@@ -90,17 +98,75 @@ struct _GAtServer {
 	struct v250_settings v250;		/* V.250 command setting */
 	GIOChannel *channel;			/* Server IO */
 	guint read_watch;			/* GSource read id, 0 if none */
+	guint write_watch;			/* GSource write id, 0 if none */
 	guint read_so_far;			/* Number of bytes processed */
 	GAtDisconnectFunc user_disconnect;	/* User disconnect func */
 	gpointer user_disconnect_data;		/* User disconnect data */
 	GAtDebugFunc debugf;			/* Debugging output function */
 	gpointer debug_data;			/* Data to pass to debug func */
 	struct ring_buffer *read_buf;		/* Current read buffer */
+	struct ring_buffer *write_buf;		/* Current write buffer */
+	GSList *full_list;			/* List of full ring buffer */
 	guint max_read_attempts;		/* Max reads per select */
 	enum ParserState parser_state;
 	gboolean destroyed;			/* Re-entrancy guard */
 };
 
+static void g_at_server_wakeup_writer(GAtServer *server);
+
+static gboolean replace_write_buf(GAtServer *server)
+{
+	struct ring_buffer *free_buf = ring_buffer_new(WRITE_BUF_SIZE);
+
+	/* Append this free buf into full list and replace current write
+	 * buffer by this free buffer */
+	server->full_list = g_slist_append(server->full_list, free_buf);
+
+	server->write_buf = free_buf;
+
+	return TRUE;
+}
+
+static void send_common(GAtServer *server, const char *buf, unsigned int len)
+{
+	gsize avail = ring_buffer_avail(server->write_buf);
+	gsize towrite = len;
+	gsize bytes_written;
+	gsize offset = 0;
+
+	if (avail > towrite) {
+		ring_buffer_write(server->write_buf, buf, towrite);
+
+		g_at_server_wakeup_writer(server);
+
+		return;
+	}
+
+	/* Write as much as we can */
+	bytes_written = ring_buffer_write(server->write_buf, buf, avail);
+	towrite -= bytes_written;
+	offset = bytes_written;
+
+	/* If current write buf is full, replace it with next free buffer */
+	if (!replace_write_buf(server))
+		return;
+
+	bytes_written = ring_buffer_write(server->write_buf, buf + offset,
+						towrite);
+	while (bytes_written < towrite) {
+		/* The next free buf is full, replace with next free one */
+		if (!replace_write_buf(server))
+			return;
+
+		towrite -= bytes_written;
+		offset += bytes_written;
+		bytes_written = ring_buffer_write(server->write_buf,
+							buf + offset, towrite);
+	}
+
+	g_at_server_wakeup_writer(server);
+}
+
 static void g_at_server_send_result(GAtServer *server, GAtServerResult result)
 {
 	struct v250_settings v250 = server->v250;
@@ -108,7 +174,7 @@ static void g_at_server_send_result(GAtServer *server, GAtServerResult result)
 	char buf[1024];
 	char t = v250.s3;
 	char r = v250.s4;
-	gsize wbuf;
+	unsigned int len;
 
 	if (v250.quiet)
 		return;
@@ -117,16 +183,13 @@ static void g_at_server_send_result(GAtServer *server, GAtServerResult result)
 		return;
 
 	if (v250.is_v1)
-		snprintf(buf, sizeof(buf), "%c%c%s%c%c", t, r, result_str,
+		len = snprintf(buf, sizeof(buf), "%c%c%s%c%c", t, r, result_str,
 				t, r);
 	else
-		snprintf(buf, sizeof(buf), "%u%c", (unsigned int) result, t);
-
-	g_at_util_debug_chat(FALSE, buf, strlen(buf),
-				server->debugf, server->debug_data);
+		len = snprintf(buf, sizeof(buf), "%u%c", (unsigned int) result,
+				t);
 
-	g_io_channel_write(server->channel, (char *) buf, strlen(buf),
-							&wbuf);
+	send_common(server, buf, len);
 }
 
 static inline gboolean is_at_command_prefix(const char c)
@@ -432,12 +495,23 @@ static gboolean received_data(GIOChannel *channel, GIOCondition cond,
 	return TRUE;
 }
 
+static gboolean can_write_data(GIOChannel *channel, GIOCondition cond,
+				gpointer data)
+{
+	return FALSE;
+}
+
 static void g_at_server_cleanup(GAtServer *server)
 {
 	/* Cleanup all received data */
 	ring_buffer_free(server->read_buf);
 	server->read_buf = NULL;
 
+	/* Cleanup pending data to write */
+	if (server->full_list)
+		g_slist_foreach(server->full_list, (GFunc)ring_buffer_free,
+					NULL);
+
 	server->channel = NULL;
 }
 
@@ -446,8 +520,6 @@ static void read_watcher_destroy_notify(GAtServer *server)
 	g_at_server_cleanup(server);
 	server->read_watch = 0;
 
-	server->channel = NULL;
-
 	if (server->user_disconnect)
 		server->user_disconnect(server->user_disconnect_data);
 
@@ -455,6 +527,23 @@ static void read_watcher_destroy_notify(GAtServer *server)
 		g_free(server);
 }
 
+static void write_watcher_destroy_notify(GAtServer *server)
+{
+	server->write_watch = 0;
+}
+
+static void g_at_server_wakeup_writer(GAtServer *server)
+{
+	if (server->write_watch != 0)
+		return;
+
+	server->write_watch = g_io_add_watch_full(server->channel,
+			G_PRIORITY_DEFAULT,
+			G_IO_OUT | G_IO_HUP | G_IO_ERR | G_IO_NVAL,
+			can_write_data, server,
+			(GDestroyNotify)write_watcher_destroy_notify);
+}
+
 static void v250_settings_create(struct v250_settings *v250)
 {
 	v250->s3 = '\r';
@@ -482,12 +571,20 @@ GAtServer *g_at_server_new(GIOChannel *io)
 	server->ref_count = 1;
 	v250_settings_create(&server->v250);
 	server->channel = io;
-	server->read_buf = ring_buffer_new(4096);
-	server->max_read_attempts = 3;
-
+	server->read_buf = ring_buffer_new(READ_BUF_SIZE);
 	if (!server->read_buf)
 		goto error;
 
+	server->write_buf = ring_buffer_new(WRITE_BUF_SIZE);
+	if (!server->write_buf)
+		goto error;
+
+	/* Current write buf becomes the tail of full list */
+	server->full_list = g_slist_append(server->full_list,
+						server->write_buf);
+
+	server->max_read_attempts = 3;
+
 	if (!g_at_util_setup_io(server->channel, G_IO_FLAG_NONBLOCK))
 		goto error;
 
@@ -502,6 +599,10 @@ error:
 	if (server->read_buf)
 		ring_buffer_free(server->read_buf);
 
+	if (server->full_list)
+		g_slist_foreach(server->full_list, (GFunc)ring_buffer_free,
+					NULL);
+
 	if (server)
 		g_free(server);
 
@@ -552,6 +653,9 @@ gboolean g_at_server_shutdown(GAtServer *server)
 	server->user_disconnect = NULL;
 	server->user_disconnect_data = NULL;
 
+	if (server->write_watch)
+		g_source_remove(server->write_watch);
+
 	if (server->read_watch)
 		g_source_remove(server->read_watch);
 
-- 
1.6.6.1

[PATCH 3/3] Add write server response into non-blocking IO

[Zhenhua Zhang]

[-- Attachment #1: Type: text/plain, Size: 2161 bytes --]

Write server response into non-blocking GIOChannel when we have
G_IO_OUT signal.
---
 gatchat/gatserver.c |   68 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 68 insertions(+), 0 deletions(-)

diff --git a/gatchat/gatserver.c b/gatchat/gatserver.c
index 7e11359..a9e0341 100644
--- a/gatchat/gatserver.c
+++ b/gatchat/gatserver.c
@@ -498,6 +498,74 @@ static gboolean received_data(GIOChannel *channel, GIOCondition cond,
 static gboolean can_write_data(GIOChannel *channel, GIOCondition cond,
 				gpointer data)
 {
+	GAtServer *server = data;
+	GIOError err;
+	gsize bytes_written;
+	gsize towrite;
+	struct ring_buffer *write_buf;
+	unsigned char *buf;
+	gboolean write_again = FALSE;
+#ifdef WRITE_SCHEDULER_DEBUG
+	int limiter;
+#endif
+
+	if (cond & (G_IO_NVAL | G_IO_HUP | G_IO_ERR))
+		return FALSE;
+
+	if (!server->full_list)
+		return FALSE;
+
+	/* Write data out from the head of full buffer */
+	write_buf = server->full_list->data;
+
+	buf = ring_buffer_read_ptr(write_buf, 0);
+
+	towrite = ring_buffer_len_no_wrap(write_buf);
+	if (towrite < (gsize)ring_buffer_len(write_buf))
+		write_again = TRUE;
+
+#ifdef WRITE_SCHEDULER_DEBUG
+	limiter = towrite;
+
+	if (limiter > 5)
+		limiter = 5;
+#endif
+
+	err = g_io_channel_write(server->channel,
+			(char *)buf,
+#ifdef WRITE_SCHEDULER_DEBUG
+			limiter,
+#else
+			towrite,
+#endif
+			&bytes_written);
+
+	if (err != G_IO_ERROR_NONE) {
+		g_source_remove(server->read_watch);
+		return FALSE;
+	}
+
+	g_at_util_debug_chat(FALSE, (char *)buf, bytes_written, server->debugf,
+				server->debug_data);
+
+	ring_buffer_drain(write_buf, bytes_written);
+
+	/* All data in current full buffer is written, free it
+	 * unless it's the tail of the list.
+	 */
+	if ((ring_buffer_len(write_buf) == 0) &&
+			(g_slist_length(server->full_list) > 1)) {
+		server->full_list = g_slist_remove(server->full_list,
+							write_buf);
+
+		ring_buffer_free(write_buf);
+
+		return TRUE;
+	}
+
+	if (bytes_written < towrite || write_again == TRUE)
+		return TRUE;
+
 	return FALSE;
 }
 
-- 
1.6.6.1

Re: [PATCH 1/3] Do not trigger user disconnect at g_at_shutdown

[Zhenhua Zhang]

[-- Attachment #1: Type: text/plain, Size: 346 bytes --]

Hi,

I rebased my patches for modem emulator and did some updates:

1. Patch 1/3 is the same as 4/4 sent on Feb 9th.
2. Patch 2/3 is updated according to Denis's comments. So we only have 
one full list at all.
3. Patch 3/3 is to fetch data from full list and write them into non 
blocking IO.

Please review them.

Thanks.
Zhenhua

Re: [PATCH 2/3] Add write buffer for non-blocking write

[Denis Kenzior]

[-- Attachment #1: Type: text/plain, Size: 8831 bytes --]

Hi Zhenhua,

> Use two layers to cache server side response data to client.
> 1. A fixed-length ring buffer, that is write_buf.
> 2. A list of full ring buffer. The head is to write data out to the
> client and the tail is to cache response data in. At least one buffer
> is in the list.
> 
> When the first layer buffer is full, a free buffer is allocated and
> appended at the tail of the full list. It replaces original write
> buffer as current write_buf.
> ---
>  gatchat/gatserver.c |  130
>  +++++++++++++++++++++++++++++++++++++++++++++----- 1 files changed, 117
>  insertions(+), 13 deletions(-)
> 
> diff --git a/gatchat/gatserver.c b/gatchat/gatserver.c
> index bf7e847..7e11359 100644
> --- a/gatchat/gatserver.c
> +++ b/gatchat/gatserver.c
> @@ -32,6 +32,14 @@
>  #include "ringbuffer.h"
>  #include "gatserver.h"
> 
> +#define READ_BUF_SIZE 4096

Separate patch please

> +/* #define WRITE_SCHEDULER_DEBUG 1 */
> +#ifdef WRITE_SCHEDULER_DEBUG
> +#define WRITE_BUF_SIZE 4
> +#else
> +#define WRITE_BUF_SIZE 4096
> +#endif
> +

Don't do this, you're confusing the intentions of what WRITE_SCHEDULER_DEBUG 
did in atchat vs the way you're using it here.

>  enum ParserState {
>  	PARSER_STATE_IDLE,
>  	PARSER_STATE_A,
> @@ -90,17 +98,75 @@ struct _GAtServer {
>  	struct v250_settings v250;		/* V.250 command setting */
>  	GIOChannel *channel;			/* Server IO */
>  	guint read_watch;			/* GSource read id, 0 if none */
> +	guint write_watch;			/* GSource write id, 0 if none */
>  	guint read_so_far;			/* Number of bytes processed */
>  	GAtDisconnectFunc user_disconnect;	/* User disconnect func */
>  	gpointer user_disconnect_data;		/* User disconnect data */
>  	GAtDebugFunc debugf;			/* Debugging output function */
>  	gpointer debug_data;			/* Data to pass to debug func */
>  	struct ring_buffer *read_buf;		/* Current read buffer */
> +	struct ring_buffer *write_buf;		/* Current write buffer */
> +	GSList *full_list;			/* List of full ring buffer */

Use a GQueue here instead of write_buf and full_list.  The head of the queue 
is the stuff to be written, the tail of the queue is the free buffer to stuff 
data into.

>  	guint max_read_attempts;		/* Max reads per select */
>  	enum ParserState parser_state;
>  	gboolean destroyed;			/* Re-entrancy guard */
>  };
> 
> +static void g_at_server_wakeup_writer(GAtServer *server);
> +
> +static gboolean replace_write_buf(GAtServer *server)
> +{
> +	struct ring_buffer *free_buf = ring_buffer_new(WRITE_BUF_SIZE);
> +
> +	/* Append this free buf into full list and replace current write
> +	 * buffer by this free buffer */
> +	server->full_list = g_slist_append(server->full_list, free_buf);
> +
> +	server->write_buf = free_buf;
> +
> +	return TRUE;
> +}
> +
> +static void send_common(GAtServer *server, const char *buf, unsigned int
>  len) +{
> +	gsize avail = ring_buffer_avail(server->write_buf);
> +	gsize towrite = len;
> +	gsize bytes_written;
> +	gsize offset = 0;
> +
> +	if (avail > towrite) {
> +		ring_buffer_write(server->write_buf, buf, towrite);
> +
> +		g_at_server_wakeup_writer(server);
> +
> +		return;
> +	}

I suggest using only the while loop version, no need to short-circuit here.

> +
> +	/* Write as much as we can */
> +	bytes_written = ring_buffer_write(server->write_buf, buf, avail);
> +	towrite -= bytes_written;
> +	offset = bytes_written;
> +
> +	/* If current write buf is full, replace it with next free buffer */
> +	if (!replace_write_buf(server))
> +		return;

This looks wrong, perhaps we should simply forcefully shutdown here in the 
unlikely event that this happens?

> +
> +	bytes_written = ring_buffer_write(server->write_buf, buf + offset,
> +						towrite);
> +	while (bytes_written < towrite) {
> +		/* The next free buf is full, replace with next free one */
> +		if (!replace_write_buf(server))
> +			return;
> +
> +		towrite -= bytes_written;
> +		offset += bytes_written;
> +		bytes_written = ring_buffer_write(server->write_buf,
> +							buf + offset, towrite);
> +	}

My brain hurts, you're using ring_buffer_write like three times.  Please 
restructure the loop to be more concise.  Something like:

while (bytes_written < towrite) {
	bytes_written += ring_buffer_write(buffer,
						MIN(ring_buffer_avail(buffer), towrite-bytes_written);

	if (ring_buffer_avail(buffer) == 0)
		allocate_next();
}

> +
> +	g_at_server_wakeup_writer(server);
> +}
> +
>  static void g_at_server_send_result(GAtServer *server, GAtServerResult
>  result) {
>  	struct v250_settings v250 = server->v250;
> @@ -108,7 +174,7 @@ static void g_at_server_send_result(GAtServer *server,
>  GAtServerResult result) char buf[1024];
>  	char t = v250.s3;
>  	char r = v250.s4;
> -	gsize wbuf;
> +	unsigned int len;
> 
>  	if (v250.quiet)
>  		return;
> @@ -117,16 +183,13 @@ static void g_at_server_send_result(GAtServer
>  *server, GAtServerResult result) return;
> 
>  	if (v250.is_v1)
> -		snprintf(buf, sizeof(buf), "%c%c%s%c%c", t, r, result_str,
> +		len = snprintf(buf, sizeof(buf), "%c%c%s%c%c", t, r, result_str,
>  				t, r);
>  	else
> -		snprintf(buf, sizeof(buf), "%u%c", (unsigned int) result, t);
> -
> -	g_at_util_debug_chat(FALSE, buf, strlen(buf),
> -				server->debugf, server->debug_data);
> +		len = snprintf(buf, sizeof(buf), "%u%c", (unsigned int) result,
> +				t);
> 
> -	g_io_channel_write(server->channel, (char *) buf, strlen(buf),
> -							&wbuf);
> +	send_common(server, buf, len);

So strictly speaking this is wrong.  man snprintf for the Return Value.  If 
you insist on using len, at least use MIN(len, sizeof(buf)-1) or something 
like that.

>  }
> 
>  static inline gboolean is_at_command_prefix(const char c)
> @@ -432,12 +495,23 @@ static gboolean received_data(GIOChannel *channel,
>  GIOCondition cond, return TRUE;
>  }
> 
> +static gboolean can_write_data(GIOChannel *channel, GIOCondition cond,
> +				gpointer data)
> +{
> +	return FALSE;
> +}
> +
>  static void g_at_server_cleanup(GAtServer *server)
>  {
>  	/* Cleanup all received data */
>  	ring_buffer_free(server->read_buf);
>  	server->read_buf = NULL;
> 
> +	/* Cleanup pending data to write */
> +	if (server->full_list)

Is server->full_list ever NULL?

> +		g_slist_foreach(server->full_list, (GFunc)ring_buffer_free,
> +					NULL);
> +
>  	server->channel = NULL;
>  }
> 
> @@ -446,8 +520,6 @@ static void read_watcher_destroy_notify(GAtServer
>  *server) g_at_server_cleanup(server);
>  	server->read_watch = 0;
> 
> -	server->channel = NULL;
> -
>  	if (server->user_disconnect)
>  		server->user_disconnect(server->user_disconnect_data);
> 
> @@ -455,6 +527,23 @@ static void read_watcher_destroy_notify(GAtServer
>  *server) g_free(server);
>  }
> 
> +static void write_watcher_destroy_notify(GAtServer *server)
> +{
> +	server->write_watch = 0;
> +}
> +
> +static void g_at_server_wakeup_writer(GAtServer *server)
> +{
> +	if (server->write_watch != 0)
> +		return;
> +
> +	server->write_watch = g_io_add_watch_full(server->channel,
> +			G_PRIORITY_DEFAULT,
> +			G_IO_OUT | G_IO_HUP | G_IO_ERR | G_IO_NVAL,
> +			can_write_data, server,
> +			(GDestroyNotify)write_watcher_destroy_notify);
> +}
> +
>  static void v250_settings_create(struct v250_settings *v250)
>  {
>  	v250->s3 = '\r';
> @@ -482,12 +571,20 @@ GAtServer *g_at_server_new(GIOChannel *io)
>  	server->ref_count = 1;
>  	v250_settings_create(&server->v250);
>  	server->channel = io;
> -	server->read_buf = ring_buffer_new(4096);
> -	server->max_read_attempts = 3;
> -
> +	server->read_buf = ring_buffer_new(READ_BUF_SIZE);
>  	if (!server->read_buf)
>  		goto error;
> 
> +	server->write_buf = ring_buffer_new(WRITE_BUF_SIZE);
> +	if (!server->write_buf)
> +		goto error;
> +
> +	/* Current write buf becomes the tail of full list */
> +	server->full_list = g_slist_append(server->full_list,
> +						server->write_buf);
> +
> +	server->max_read_attempts = 3;
> +
>  	if (!g_at_util_setup_io(server->channel, G_IO_FLAG_NONBLOCK))
>  		goto error;
> 
> @@ -502,6 +599,10 @@ error:
>  	if (server->read_buf)
>  		ring_buffer_free(server->read_buf);
> 
> +	if (server->full_list)
> +		g_slist_foreach(server->full_list, (GFunc)ring_buffer_free,
> +					NULL);
> +

Is server->full_list ever NULL?

>  	if (server)
>  		g_free(server);
> 
> @@ -552,6 +653,9 @@ gboolean g_at_server_shutdown(GAtServer *server)
>  	server->user_disconnect = NULL;
>  	server->user_disconnect_data = NULL;
> 
> +	if (server->write_watch)
> +		g_source_remove(server->write_watch);
> +
>  	if (server->read_watch)
>  		g_source_remove(server->read_watch);
> 

Regards,
-Denis