MEDIUM: buffer: add a new buf_wanted dummy buffer to report failed allocations
Doing so ensures that even when no memory is available, we leave the
channel in a sane condition. There's a special case in proto_http.c
regarding the compression, we simply pre-allocate the tmpbuf to point
to the dummy buffer. Not reusing &buf_empty for this allows the rest
of the code to differenciate an empty buffer that's not used from an
empty buffer that results from a failed allocation which has the same
semantics as a buffer full.
diff --git a/src/buffer.c b/src/buffer.c
index 7691026..d9301bf 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -22,10 +22,14 @@
struct pool_head *pool2_buffer;
-/* this buffer is used to have a valid pointer to an empty buffer in channels
- * which convey no more data.
+/* These buffers are used to always have a valid pointer to an empty buffer in
+ * channels. The first buffer is set once a buffer is empty. The second one is
+ * set when a buffer is desired but no more are available. It helps knowing
+ * what channel wants a buffer. They can reliably be exchanged, the split
+ * between the two is only an optimization.
*/
struct buffer buf_empty = { .p = buf_empty.data };
+struct buffer buf_wanted = { .p = buf_wanted.data };
/* perform minimal intializations, report 0 in case of error, 1 if OK. */
int init_buffer()