OPTIM: splice: assume by default that splice is working correctly
Versions of splice between 2.6.25 and 2.6.27.12 were bogus and would return EAGAIN
on incoming shutdowns. On these versions, we have to call recv() after such a return
in order to find whether splice is OK or not. Since 2.6.27.13 we don't need to do
this anymore, saving one useless recv() call after each splice() returning EAGAIN,
and we can avoid this logic by defining ASSUME_SPLICE_WORKS.
Building with linux2628 automatically enables splice and the flag above since the
kernel is safe. People enabling splice for custom kernels will be able to disable
this logic by hand too.
diff --git a/Makefile b/Makefile
index fb6ce98..f1eed55 100644
--- a/Makefile
+++ b/Makefile
@@ -243,6 +243,7 @@
USE_ACCEPT4 = implicit
USE_FUTEX = implicit
USE_CPU_AFFINITY= implicit
+ ASSUME_SPLICE_WORKS= implicit
else
ifeq ($(TARGET),solaris)
# This is for Solaris 8
@@ -449,6 +450,11 @@
BUILD_OPTIONS += $(call ignore_implicit,USE_MY_SPLICE)
endif
+ifneq ($(ASSUME_SPLICE_WORKS),)
+OPTIONS_CFLAGS += -DASSUME_SPLICE_WORKS
+BUILD_OPTIONS += $(call ignore_implicit,ASSUME_SPLICE_WORKS)
+endif
+
ifneq ($(USE_ACCEPT4),)
OPTIONS_CFLAGS += -DUSE_ACCEPT4
BUILD_OPTIONS += $(call ignore_implicit,USE_ACCEPT4)
diff --git a/src/raw_sock.c b/src/raw_sock.c
index 9528911..ad4a0aa 100644
--- a/src/raw_sock.c
+++ b/src/raw_sock.c
@@ -54,6 +54,12 @@
* infinite forwarding */
#define MAX_SPLICE_AT_ONCE (1<<30)
+/* Versions of splice between 2.6.25 and 2.6.27.12 were bogus and would return EAGAIN
+ * on incoming shutdowns. On these versions, we have to call recv() after such a return
+ * in order to find whether splice is OK or not. Since 2.6.27.13 we don't need to do
+ * this anymore, and we can avoid this logic by defining ASSUME_SPLICE_WORKS.
+ */
+
/* Returns :
* -1 if splice() is not supported
* >= 0 to report the amount of spliced bytes.
@@ -62,7 +68,9 @@
*/
int raw_sock_to_pipe(struct connection *conn, struct pipe *pipe, unsigned int count)
{
+#ifndef ASSUME_SPLICE_WORKS
static int splice_detects_close;
+#endif
int ret;
int retval = 0;
@@ -95,7 +103,9 @@
* recent kernels (>= 2.6.27.13). If we notice
* it works, we store the info for later use.
*/
+#ifndef ASSUME_SPLICE_WORKS
splice_detects_close = 1;
+#endif
goto out_read0;
}
@@ -125,7 +135,9 @@
* try to fall back to the normal recv scheme
* which will be able to deal with the situation.
*/
+#ifndef ASSUME_SPLICE_WORKS
if (splice_detects_close)
+#endif
__conn_data_poll_recv(conn); /* we know for sure that it's EAGAIN */
break;
}