MAJOR: channel: add a new flag CF_WAKE_WRITE to notify the task of writes
Since commit 6b66f3e ([MAJOR] implement autonomous inter-socket forwarding)
introduced in 1.3.16-rc1, we've been relying on a stupid mechanism to wake
up the task after a write, which was an exact copy-paste of the reader side.
The principle was that if we empty a buffer and there's no forwarding
scheduled or if the *producer* is not in a connected state, then we wake
the task up.
That does not make any sense. It happens to wake up too late sometimes (eg,
when the request analyser waits for some room in the buffer to start to
work), and leads to unneeded wakeups in client-side keep-alive, because
the task is woken up when the response is sent, while the analysers are
simply waiting for a new request.
In order to fix this, we introduce a new channel flag : CF_WAKE_WRITE. It
is designed so that an analyser can explicitly request being notified when
some data were written. It is used only when the HTTP request or response
analysers need to wait for more room in the buffers. It is automatically
cleared upon wake up.
The flag is also automatically set by the functions which try to write into
a buffer from an applet when they fail (bi_putblk() etc...).
That allows us to remove the stupid condition above and avoid some wakeups.
In http-server-close and in http-keep-alive modes, this reduces from 4 to 3
the average number of wakeups per request, and increases the overall
performance by about 1.5%.
diff --git a/include/types/channel.h b/include/types/channel.h
index 7f524c1..905308e 100644
--- a/include/types/channel.h
+++ b/include/types/channel.h
@@ -70,7 +70,7 @@
#define CF_WRITE_ERROR 0x00000800 /* unrecoverable error on consumer side */
#define CF_WRITE_ACTIVITY (CF_WRITE_NULL|CF_WRITE_PARTIAL|CF_WRITE_ERROR)
-/* unused: 0x00001000 */
+#define CF_WAKE_WRITE 0x00001000 /* wake the task up when there's write activity */
#define CF_SHUTW 0x00002000 /* consumer has already shut down */
#define CF_SHUTW_NOW 0x00004000 /* the consumer must shut down for writes ASAP */
#define CF_AUTO_CLOSE 0x00008000 /* producer can forward shutdown to other side */
@@ -120,11 +120,6 @@
#define CF_WAKE_ONCE 0x10000000 /* pretend there is activity on this channel (one-shoot) */
/* unused: 0x20000000, 0x40000000, 0x80000000 */
-/* Use these masks to clear the flags before going back to lower layers */
-#define CF_CLEAR_READ (~(CF_READ_NULL|CF_READ_PARTIAL|CF_READ_ERROR|CF_READ_ATTACHED))
-#define CF_CLEAR_WRITE (~(CF_WRITE_NULL|CF_WRITE_PARTIAL|CF_WRITE_ERROR))
-#define CF_CLEAR_TIMEOUT (~(CF_READ_TIMEOUT|CF_WRITE_TIMEOUT|CF_ANA_TIMEOUT))
-
/* Masks which define input events for stream analysers */
#define CF_MASK_ANALYSER (CF_READ_ATTACHED|CF_READ_ACTIVITY|CF_READ_TIMEOUT|CF_ANA_TIMEOUT|CF_WRITE_ACTIVITY|CF_WAKE_ONCE)