From 0b7894460092b8b3939f2d89ba9ebde15843d6ab Mon Sep 17 00:00:00 2001
From: Wayne Davison <wayned@samba.org>
Date: Sun, 24 Aug 2008 12:56:33 -0700
Subject: [PATCH] Some minor improvements to the flushing code to try to make
 it even more solid.

---
 io.c | 88 +++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 48 insertions(+), 40 deletions(-)

diff --git a/io.c b/io.c
index 9f819ee9..cc2561fe 100644
--- a/io.c
+++ b/io.c
@@ -101,7 +101,7 @@ static char ff_lastchar;
 #ifdef ICONV_OPTION
 static xbuf iconv_buf = EMPTY_XBUF;
 #endif
-static int defer_forwarding_messages = 0, defer_forwarding_keep = 0;
+static int defer_forwarding_messages = 0, keep_defer_forwarding = 0;
 static int select_timeout = SELECT_TIMEOUT;
 static int active_filecnt = 0;
 static OFF_T active_bytecnt = 0;
@@ -294,33 +294,32 @@ static void msg_list_add(struct msg_list *lst, int code, const char *buf, int le
 	lst->tail = m;
 }
 
+static inline int flush_a_msg(int fd)
+{
+	struct msg_list_item *m = msg_queue.head;
+	int len = IVAL(m->buf, 0) & 0xFFFFFF;
+	int tag = *((uchar*)m->buf+3) - MPLEX_BASE;
+
+	if (!(msg_queue.head = m->next))
+		msg_queue.tail = NULL;
+
+	defer_forwarding_messages++;
+	mplex_write(fd, tag, m->buf + 4, len, m->convert);
+	defer_forwarding_messages--;
+
+	free(m);
+
+	return len;
+}
+
 static void msg_flush(void)
 {
 	if (am_generator) {
-		while (msg_queue.head && io_multiplexing_out) {
-			struct msg_list_item *m = msg_queue.head;
-			int len = IVAL(m->buf, 0) & 0xFFFFFF;
-			int tag = *((uchar*)m->buf+3) - MPLEX_BASE;
-			if (!(msg_queue.head = m->next))
-				msg_queue.tail = NULL;
-			stats.total_written += len + 4;
-			defer_forwarding_messages++;
-			mplex_write(sock_f_out, tag, m->buf + 4, len, m->convert);
-			defer_forwarding_messages--;
-			free(m);
-		}
+		while (msg_queue.head && io_multiplexing_out)
+			stats.total_written += flush_a_msg(sock_f_out) + 4;
 	} else {
-		while (msg_queue.head) {
-			struct msg_list_item *m = msg_queue.head;
-			int len = IVAL(m->buf, 0) & 0xFFFFFF;
-			int tag = *((uchar*)m->buf+3) - MPLEX_BASE;
-			if (!(msg_queue.head = m->next))
-				msg_queue.tail = NULL;
-			defer_forwarding_messages++;
-			mplex_write(msg_fd_out, tag, m->buf + 4, len, m->convert);
-			defer_forwarding_messages--;
-			free(m);
-		}
+		while (msg_queue.head)
+			(void)flush_a_msg(msg_fd_out);
 	}
 }
 
@@ -535,9 +534,9 @@ static void mplex_write(int fd, enum msgcode code, const char *buf, size_t len,
 
 	SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
 
-	defer_forwarding_keep = 1; /* defer_forwarding_messages++ on return */
+	keep_defer_forwarding++; /* defer_forwarding_messages++ on return */
 	writefd_unbuffered(fd, buffer, n+4);
-	defer_forwarding_keep = 0;
+	keep_defer_forwarding--;
 
 	if (len > n)
 		writefd_unbuffered(fd, buf+n, len-n);
@@ -572,10 +571,9 @@ void send_msg_int(enum msgcode code, int num)
 
 void wait_for_receiver(void)
 {
-	if (iobuf_out_cnt)
-		io_flush(NORMAL_FLUSH);
-	else
-		read_msg_fd();
+	if (io_flush(FULL_FLUSH))
+		return;
+	read_msg_fd();
 }
 
 int get_redo_num(void)
@@ -1559,24 +1557,34 @@ static void writefd_unbuffered(int fd, const char *buf, size_t len)
 	}
 
 	no_flush--;
-	defer_inc -= defer_forwarding_keep;
+	if (keep_defer_forwarding)
+		defer_inc--;
 	if (!(defer_forwarding_messages -= defer_inc) && !no_flush)
 		msg_flush();
 }
 
-void io_flush(int flush_it_all)
+int io_flush(int flush_it_all)
 {
-	if (!iobuf_out_cnt || no_flush)
-		return;
+	int flushed_something = 0;
 
-	if (io_multiplexing_out)
-		mplex_write(sock_f_out, MSG_DATA, iobuf_out, iobuf_out_cnt, 0);
-	else
-		writefd_unbuffered(iobuf_f_out, iobuf_out, iobuf_out_cnt);
-	iobuf_out_cnt = 0;
+	if (no_flush)
+		return 0;
 
-	if (flush_it_all && !defer_forwarding_messages)
+	if (iobuf_out_cnt) {
+		if (io_multiplexing_out)
+			mplex_write(sock_f_out, MSG_DATA, iobuf_out, iobuf_out_cnt, 0);
+		else
+			writefd_unbuffered(iobuf_f_out, iobuf_out, iobuf_out_cnt);
+		iobuf_out_cnt = 0;
+		flushed_something = 1;
+	}
+
+	if (flush_it_all && !defer_forwarding_messages && msg_queue.head) {
 		msg_flush();
+		flushed_something = 1;
+	}
+
+	return flushed_something;
 }
 
 static void writefd(int fd, const char *buf, size_t len)
-- 
2.34.1