MAJOR: channel: remove the BF_OUT_EMPTY flag
This flag was very problematic because it was composite in that both changes
to the pipe or to the buffer had to cause this flag to be updated, which is
not always simple (eg: there may not even be a channel attached to a buffer
at all).
There were not that many users of this flags, mostly setters. So the flag got
replaced with a macro which reports whether the channel is empty or not, by
checking both the pipe and the buffer.
One part of the change is sensible : the flag was also part of BF_MASK_STATIC,
which is used by process_session() to rescan all analysers in case the flag's
status changes. At first glance, none of the analysers seems to change its
mind base on this flag when it is subject to change, so it seems fine not to
add variation checks here. Otherwise it's possible that checking the buffer's
output size is more useful than checking the flag's replacement.
diff --git a/include/types/channel.h b/include/types/channel.h
index cd16d9c..67016d1 100644
--- a/include/types/channel.h
+++ b/include/types/channel.h
@@ -70,7 +70,7 @@
#define BF_WRITE_ERROR 0x000800 /* unrecoverable error on consumer side */
#define BF_WRITE_ACTIVITY (BF_WRITE_NULL|BF_WRITE_PARTIAL|BF_WRITE_ERROR)
-#define BF_OUT_EMPTY 0x001000 /* out and pipe are empty. Set by last change. */
+/* unused: 0x001000 */
#define BF_SHUTW 0x002000 /* consumer has already shut down */
#define BF_SHUTW_NOW 0x004000 /* the consumer must shut down for writes ASAP */
#define BF_AUTO_CLOSE 0x008000 /* producer can forward shutdown to other side */
@@ -129,7 +129,7 @@
#define BF_MASK_ANALYSER (BF_READ_ATTACHED|BF_READ_ACTIVITY|BF_READ_TIMEOUT|BF_ANA_TIMEOUT|BF_WRITE_ACTIVITY|BF_WAKE_ONCE)
/* Mask for static flags which cause analysers to be woken up when they change */
-#define BF_MASK_STATIC (BF_OUT_EMPTY|BF_FULL|BF_SHUTR|BF_SHUTW|BF_SHUTR_NOW|BF_SHUTW_NOW)
+#define BF_MASK_STATIC (BF_FULL|BF_SHUTR|BF_SHUTW|BF_SHUTR_NOW|BF_SHUTW_NOW)
/* Analysers (channel->analysers).