From 6d3ed0657d1be559cc3376ed3f8473ddfa2aadb6 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Wed, 14 Jan 2009 14:58:48 +0000
Subject: [PATCH] Simplify evbuffer_write logic: combine nearly all of WSASend
 and writev cases.

svn:r1004
---
 buffer.c            | 106 +++++++++++++++++++++++---------------------
 evbuffer-internal.h |   4 --
 2 files changed, 55 insertions(+), 55 deletions(-)

diff --git a/buffer.c b/buffer.c
index b7e70421..3f638358 100644
--- a/buffer.c
+++ b/buffer.c
@@ -888,6 +888,27 @@ evbuffer_read(struct evbuffer *buf, evutil_socket_t fd, int howmuch)
 	return (n);
 }
 
+#if defined(HAVE_SYS_UIO_H)
+#define USE_IOVEC_IMPL
+#endif
+
+#ifdef USE_IOVEC_IMPL
+
+#ifdef HAVE_SYS_UIO_H
+/* number of iovec we use for writev, fragmentation is going to determine
+ * how much we end up writing */
+#define NUM_IOVEC 128
+#define IOV_TYPE struct iovec
+#define IOV_PTR_FIELD iov_base
+#define IOV_LEN_FIELD iov_len
+#else
+#define NUM_IOVEC 16
+#define IOV_TYPE WSABUF
+#define IOV_PTR_FIELD buf
+#define IOV_LEN_FIELD len
+#endif
+#endif
+
 int
 evbuffer_write_atmost(struct evbuffer *buffer, evutil_socket_t fd,
 					  ssize_t howmuch)
@@ -898,60 +919,43 @@ evbuffer_write_atmost(struct evbuffer *buffer, evutil_socket_t fd,
 		howmuch = buffer->total_len;
 
 	{
-#ifndef WIN32
-  #ifdef HAVE_SYS_UIO_H
-	struct iovec iov[NUM_IOVEC];
-	struct evbuffer_chain *chain = buffer->first;
-	int i = 0;
-	/* XXX make this top out at some maximal data length? if the buffer has
-	 * (say) 1MB in it, split over 128 chains, there's no way it all gets
-	 * written in one go. */
-	while (chain != NULL && i < NUM_IOVEC && howmuch) {
-		iov[i].iov_base = chain->buffer + chain->misalign;
-		if (howmuch >= chain->off) {
-			iov[i++].iov_len = chain->off;
-			howmuch -= chain->off;
-		} else {
-			iov[i++].iov_len = howmuch;
-			break;
+#ifdef USE_IOVEC_IMPL
+		IOV_TYPE iov[NUM_IOVEC];
+		struct evbuffer_chain *chain = buffer->first;
+		int i = 0;
+		/* XXX make this top out at some maximal data length? if the buffer has
+		 * (say) 1MB in it, split over 128 chains, there's no way it all gets
+		 * written in one go. */
+		while (chain != NULL && i < NUM_IOVEC && howmuch) {
+			iov[i].IOV_PTR_FIELD = chain->buffer + chain->misalign;
+			if (howmuch >= chain->off) {
+				iov[i++].IOV_LEN_FIELD = chain->off;
+				howmuch -= chain->off;
+			} else {
+				iov[i++].IOV_LEN_FIELD = howmuch;
+				break;
+			}
+			chain = chain->next;
 		}
-		chain = chain->next;
-	}
-	n = writev(fd, iov, i);
-  #else /* !HAVE_SYS_UIO_H */
-	void *p = evbuffer_pullup(buffer, howmuch);
-	n = write(fd, p, howmuch, 0);
+  #ifdef WIN32
+		{
+			DWORD byteSent;
+			if (WSASend(fd, buffers, i, &bytesSent, 0, NULL, NULL))
+				n = -1;
+			else
+				n = bytesSent;
+		}
+  #else
+		n = writev(fd, iov, i);
   #endif
-#elif 0
-	const int N_BUFFERS = 8;
-	WSABUF buffers[N_BUFFERS];
-	struct evbuffer_chain *chain = buffer->first;
-	int i = 0;
-	DWORD bytesSent;
-	/* XXX make this top out at some maximal data length? if the buffer has
-	 * (say) 1MB in it, split over 128 chains, there's no way it all gets
-	 * written in one go. */
-	while (chain != NULL && i < N_BUFFERS && howmuch) {
-		buffers[i].buf = chain->buffer + chain->misalign;
-		if (howmuch >= chain->off) {
-			buffers[i++].len = chain->off;
-			howmuch -= chain->off;
-		} else {
-			buffers[i++].len = howmuch;
-			break;
-		}
-		chain = chain->next;
-	}
-
-	if (WSASend(fd, buffers, i, &bytesSent, 0, NULL, NULL))
-		n = -1;
-	else
-		n = bytesSent;
+#elif defined(WIN32)
+		/* XXX(nickm) Don't disable this code until we know if the WSARecv
+		 * code above works. */
+		void *p = evbuffer_pullup(buffer, howmuch);
+		n = send(fd, p, howmuch, 0);
 #else
-	/* XXX(nickm) Don't disable this code until we know if the WSARecv
-	 * code above works. */
-	void *p = evbuffer_pullup(buffer, howmuch);
-	n = send(fd, p, howmuch, 0);
+		void *p = evbuffer_pullup(buffer, howmuch);
+		n = write(fd, p, howmuch);
 #endif
 	}
 
diff --git a/evbuffer-internal.h b/evbuffer-internal.h
index 4a08877b..4637d87f 100644
--- a/evbuffer-internal.h
+++ b/evbuffer-internal.h
@@ -37,10 +37,6 @@ extern "C" {
 /* minimum allocation */
 #define MIN_BUFFER_SIZE	256
 
-/* number of iovec we use for writev, fragmentation is going to determine
- * how much we end up writing */
-#define NUM_IOVEC 128
-
 struct evbuffer_chain;
 struct evbuffer {
 	struct evbuffer_chain *first;