Implement xcb_total_read() and xcb_total_written().

Returns raw byte counts that have been read or written to the
xcb_connection_t.

I found it very useful when developing a high level widget toolkit, to
track down inefficient/sub-optimum code that generates a lot of X
protocol traffic.

Signed-off-by: Sam Varshavchik <mrsam@courier-mta.com>

src/xcb.h

@@ -599,6 +599,35 @@ xcb_connection_t *xcb_connect_to_display_with_auth_info(const char *display, xcb
 uint32_t xcb_generate_id(xcb_connection_t *c);
 
 
+/**
+ * @brief Obtain number of bytes read from the connection.
+ * @param c The connection
+ * @return Number of bytes read from the server.
+ *
+ * Returns cumulative number of bytes received from the connection.
+ *
+ * This retrieves the total number of bytes read from this connection,
+ * to be used for diagnostic/monitoring/informative purposes.
+ */
+
+uint64_t
+xcb_total_read(xcb_connection_t *c);
+
+/**
+ *
+ * @brief Obtain number of bytes written to the connection.
+ * @param c The connection
+ * @return Number of bytes written to the server.
+ *
+ * Returns cumulative number of bytes sent to the connection.
+ *
+ * This retrieves the total number of bytes written to this connection,
+ * to be used for diagnostic/monitoring/informative purposes.
+ */
+
+uint64_t
+xcb_total_written(xcb_connection_t *c);
+
 /**
  * @}
  */

src/xcb_conn.c

@@ -287,6 +287,7 @@ static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
         return 0;
     }
 
+    c->out.total_written += n;
     for(; *count; --*count, ++*vector)
     {
         int cur = (*vector)->iov_len;
@@ -528,3 +529,30 @@ int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vec
 
     return ret;
 }
+
+uint64_t xcb_total_read(xcb_connection_t *c)
+{
+    uint64_t n;
+
+    if (xcb_connection_has_error(c))
+        return 0;
+
+    pthread_mutex_lock(&c->iolock);
+    n = c->in.total_read;
+    pthread_mutex_unlock(&c->iolock);
+    return n;
+}
+
+uint64_t xcb_total_written(xcb_connection_t *c)
+{
+    uint64_t n;
+
+    if (xcb_connection_has_error(c))
+        return 0;
+
+    pthread_mutex_lock(&c->iolock);
+    n = c->out.total_written;
+    pthread_mutex_unlock(&c->iolock);
+
+    return n;
+}

src/xcb_in.c

@@ -1025,6 +1025,7 @@ int _xcb_in_read(xcb_connection_t *c)
             }
         }
 #endif
+        c->in.total_read += n;
         c->in.queue_len += n;
     }
     while(read_packet(c))

src/xcbint.h

@@ -103,6 +103,7 @@ typedef struct _xcb_out {
 
     uint64_t request;
     uint64_t request_written;
+    uint64_t total_written;
 
     pthread_mutex_t reqlenlock;
     enum lazy_reply_tag maximum_request_length_tag;
@@ -135,6 +136,7 @@ typedef struct _xcb_in {
     uint64_t request_expected;
     uint64_t request_read;
     uint64_t request_completed;
+    uint64_t total_read;
     struct reply_list *current_reply;
     struct reply_list **current_reply_tail;