[Xcb] [PATCH] allow runtime change of XCB buffer size

[Julien Danjou]

Signed-off-by: Julien Danjou <julien at danjou.info>
---
 src/xcb_conn.c |   16 ++++++++++++++--
 src/xcb_in.c   |   10 ++++++++--
 src/xcb_out.c  |    9 +++++++--
 src/xcbint.h   |   10 ++++++----
 4 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/src/xcb_conn.c b/src/xcb_conn.c
index 02f60bd..f75f55e 100644
--- a/src/xcb_conn.c
+++ b/src/xcb_conn.c
@@ -220,6 +220,8 @@ int xcb_connection_has_error(xcb_connection_t *c)
 xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
 {
     xcb_connection_t* c;
+    char *xcb_buffer_size;
+    int queue_size;
 
     c = calloc(1, sizeof(xcb_connection_t));
     if(!c)
@@ -227,12 +229,22 @@ xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
 
     c->fd = fd;
 
+    xcb_buffer_size = getenv("LIBXCB_QUEUE_BUFFER_SIZE");
+    if(xcb_buffer_size)
+    {
+        queue_size = 1024 * strtol(xcb_buffer_size, NULL, 10);
+        if(queue_size < 1024)
+            queue_size = 1024;
+    }
+    else
+        queue_size = XCB_QUEUE_BUFFER_SIZE;
+
     if(!(
         set_fd_flags(fd) &&
         pthread_mutex_init(&c->iolock, 0) == 0 &&
         _xcb_xlib_init(&c->xlib) &&
-        _xcb_in_init(&c->in) &&
-        _xcb_out_init(&c->out) &&
+        _xcb_in_init(&c->in, queue_size) &&
+        _xcb_out_init(&c->out, queue_size) &&
         write_setup(c, auth_info) &&
         read_setup(c) &&
         _xcb_ext_init(c) &&
diff --git a/src/xcb_in.c b/src/xcb_in.c
index f613772..5cbef5b 100644
--- a/src/xcb_in.c
+++ b/src/xcb_in.c
@@ -455,12 +455,18 @@ xcb_generic_error_t *xcb_request_check(xcb_connection_t *c, xcb_void_cookie_t co
 
 /* Private interface */
 
-int _xcb_in_init(_xcb_in *in)
+int _xcb_in_init(_xcb_in *in, int queue_size)
 {
     if(pthread_cond_init(&in->event_cond, 0))
         return 0;
     in->reading = 0;
 
+    in->queue = calloc(1, queue_size);
+    if(!in->queue)
+        return 0;
+
+    in->queue_size = queue_size;
+
     in->queue_len = 0;
 
     in->request_read = 0;
@@ -517,7 +523,7 @@ int _xcb_in_expect_reply(xcb_connection_t *c, unsigned int request, enum workaro
 
 int _xcb_in_read(xcb_connection_t *c)
 {
-    int n = read(c->fd, c->in.queue + c->in.queue_len, sizeof(c->in.queue) - c->in.queue_len);
+    int n = read(c->fd, c->in.queue + c->in.queue_len, c->in.queue_size - c->in.queue_len);
     if(n > 0)
         c->in.queue_len += n;
     while(read_packet(c))
diff --git a/src/xcb_out.c b/src/xcb_out.c
index 000b121..55af007 100644
--- a/src/xcb_out.c
+++ b/src/xcb_out.c
@@ -37,7 +37,7 @@
 
 static int write_block(xcb_connection_t *c, struct iovec *vector, int count)
 {
-    while(count && c->out.queue_len + vector[0].iov_len <= sizeof(c->out.queue))
+    while(count && c->out.queue_len + vector[0].iov_len <= c->out.queue_size)
     {
         memcpy(c->out.queue + c->out.queue_len, vector[0].iov_base, vector[0].iov_len);
         c->out.queue_len += vector[0].iov_len;
@@ -248,12 +248,17 @@ int xcb_flush(xcb_connection_t *c)
 
 /* Private interface */
 
-int _xcb_out_init(_xcb_out *out)
+int _xcb_out_init(_xcb_out *out, int queue_size)
 {
     if(pthread_cond_init(&out->cond, 0))
         return 0;
     out->writing = 0;
 
+    out->queue = calloc(1, queue_size);
+    if(!out->queue)
+        return 0;
+
+    out->queue_size = queue_size;
     out->queue_len = 0;
 
     out->request = 0;
diff --git a/src/xcbint.h b/src/xcbint.h
index 2bc6d33..2089fa2 100644
--- a/src/xcbint.h
+++ b/src/xcbint.h
@@ -72,7 +72,8 @@ typedef struct _xcb_out {
     pthread_cond_t cond;
     int writing;
 
-    char queue[XCB_QUEUE_BUFFER_SIZE];
+    char *queue;
+    int queue_size;
     int queue_len;
 
     unsigned int request;
@@ -86,7 +87,7 @@ typedef struct _xcb_out {
     } maximum_request_length;
 } _xcb_out;
 
-int _xcb_out_init(_xcb_out *out);
+int _xcb_out_init(_xcb_out *out, int queue_size);
 void _xcb_out_destroy(_xcb_out *out);
 
 int _xcb_out_send(xcb_connection_t *c, struct iovec **vector, int *count);
@@ -99,7 +100,8 @@ typedef struct _xcb_in {
     pthread_cond_t event_cond;
     int reading;
 
-    char queue[XCB_QUEUE_BUFFER_SIZE];
+    char *queue;
+    int queue_size;
     int queue_len;
 
     unsigned int request_expected;
@@ -117,7 +119,7 @@ typedef struct _xcb_in {
     struct pending_reply **pending_replies_tail;
 } _xcb_in;
 
-int _xcb_in_init(_xcb_in *in);
+int _xcb_in_init(_xcb_in *in, int queue_size);
 void _xcb_in_destroy(_xcb_in *in);
 
 int _xcb_in_expect_reply(xcb_connection_t *c, unsigned int request, enum workarounds workaround, int flags);
-- 
1.6.0.1