dovecot-2.2: lib: Added o_stream_flush_parent_if_needed() for wr...

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-2.2/rev/5740cb57d02c
changeset: 17590:5740cb57d02c
user:      Timo Sirainen <tss at iki.fi>
date:      Thu Jul 03 21:54:52 2014 +0300
description:
lib: Added o_stream_flush_parent_if_needed() for wrapper ostreams.

diffstat:

 src/lib/ostream-private.h |   4 ++++
 src/lib/ostream.c         |  17 +++++++++++++++++
 2 files changed, 21 insertions(+), 0 deletions(-)

diffs (40 lines):

diff -r 5f21c78cd7b2 -r 5740cb57d02c src/lib/ostream-private.h
--- a/src/lib/ostream-private.h	Thu Jul 03 20:42:08 2014 +0300
+++ b/src/lib/ostream-private.h	Thu Jul 03 21:54:52 2014 +0300
@@ -50,5 +50,9 @@
 		     size_t block_size);
 
 void o_stream_copy_error_from_parent(struct ostream_private *_stream);
+/* This should be called before sending data to parent stream. It makes sure
+   that the parent stream's output buffer doesn't become too large.
+   Returns 1 if more data can be safely added, 0 if not, -1 if error. */
+int o_stream_flush_parent_if_needed(struct ostream_private *_stream);
 
 #endif
diff -r 5f21c78cd7b2 -r 5740cb57d02c src/lib/ostream.c
--- a/src/lib/ostream.c	Thu Jul 03 20:42:08 2014 +0300
+++ b/src/lib/ostream.c	Thu Jul 03 21:54:52 2014 +0300
@@ -451,6 +451,23 @@
 		o_stream_close(dest);
 }
 
+int o_stream_flush_parent_if_needed(struct ostream_private *_stream)
+{
+	if (o_stream_get_buffer_used_size(_stream->parent) >= IO_BLOCK_SIZE) {
+		/* we already have quite a lot of data in parent stream.
+		   unless we can flush it, don't add any more to it or we
+		   could keep wasting memory by just increasing the buffer
+		   size all the time. */
+		if (o_stream_flush(_stream->parent) < 0) {
+			o_stream_copy_error_from_parent(_stream);
+			return -1;
+		}
+		if (o_stream_get_buffer_used_size(_stream->parent) >= IO_BLOCK_SIZE)
+			return 0;
+	}
+	return 1;
+}
+
 static int o_stream_default_flush(struct ostream_private *_stream)
 {
 	int ret;