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cache: use sendfile() instead of a pair of read() + write()

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sendfile() does the same job and avoids to copy the content into userland
and back. One has to define NO_SENDFILE in case the OS (kernel / libc)
does not supported. It is disabled by default on non-linux environemnts.
According to the glibc, sendfile64() was added in Linux 2.4 (so it has
been there for a while) but after browsing over the mapage of FreeBSD's I
noticed that the prototype is little different.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
This commit is contained in:
Sebastian Andrzej Siewior 2014-01-18 21:24:58 +01:00 committed by Jason A. Donenfeld
parent ea7210bef3
commit d3581b5889
3 changed files with 34 additions and 1 deletions
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1
Makefile
View File

@ -29,6 +29,7 @@ DOC_PDF = $(patsubst %.txt,%.pdf,$(MAN_TXT))
# j, z, t. (representing long long int, char, intmax_t, size_t, ptrdiff_t). # j, z, t. (representing long long int, char, intmax_t, size_t, ptrdiff_t).
# some C compilers supported these specifiers prior to C99 as an extension. # some C compilers supported these specifiers prior to C99 as an extension.
# #
# Define HAVE_LINUX_SENDFILE to use sendfile()
#-include config.mak #-include config.mak

26
cache.c
View File

@ -13,6 +13,9 @@
* *
*/ */
#ifdef HAVE_LINUX_SENDFILE
#include <sys/sendfile.h>
#endif
#include "cgit.h" #include "cgit.h"
#include "cache.h" #include "cache.h"
#include "html.h" #include "html.h"
@ -30,7 +33,6 @@ struct cache_slot {
const char *lock_name; const char *lock_name;
int match; int match;
struct stat cache_st; struct stat cache_st;
struct stat lock_st;
int bufsize; int bufsize;
char buf[CACHE_BUFSIZE]; char buf[CACHE_BUFSIZE];
}; };
@ -81,6 +83,23 @@ static int close_slot(struct cache_slot *slot)
/* Print the content of the active cache slot (but skip the key). */ /* Print the content of the active cache slot (but skip the key). */
static int print_slot(struct cache_slot *slot) static int print_slot(struct cache_slot *slot)
{ {
#ifdef HAVE_LINUX_SENDFILE
off_t start_off;
int ret;
start_off = slot->keylen + 1;
do {
ret = sendfile(STDOUT_FILENO, slot->cache_fd, &start_off,
slot->cache_st.st_size - start_off);
if (ret < 0) {
if (errno == EAGAIN || errno == EINTR)
continue;
return errno;
}
return 0;
} while (1);
#else
ssize_t i, j; ssize_t i, j;
i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET); i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET);
@ -97,6 +116,7 @@ static int print_slot(struct cache_slot *slot)
return errno; return errno;
else else
return 0; return 0;
#endif
} }
/* Check if the slot has expired */ /* Check if the slot has expired */
@ -188,6 +208,10 @@ static int fill_slot(struct cache_slot *slot)
/* Generate cache content */ /* Generate cache content */
slot->fn(); slot->fn();
/* update stat info */
if (fstat(slot->lock_fd, &slot->cache_st))
return errno;
/* Restore stdout */ /* Restore stdout */
if (dup2(tmp, STDOUT_FILENO) == -1) if (dup2(tmp, STDOUT_FILENO) == -1)
return errno; return errno;

8
cgit.mk
View File

@ -68,6 +68,14 @@ ifeq ($(findstring BSD,$(uname_S)),)
CGIT_LIBS += -ldl CGIT_LIBS += -ldl
endif endif
# glibc 2.1+ offers sendfile which the most common C library on Linux
ifeq ($(uname_S),Linux)
HAVE_LINUX_SENDFILE = YesPlease
endif
ifdef HAVE_LINUX_SENDFILE
CGIT_CFLAGS += -DHAVE_LINUX_SENDFILE
endif
CGIT_OBJ_NAMES += cgit.o CGIT_OBJ_NAMES += cgit.o
CGIT_OBJ_NAMES += cache.o CGIT_OBJ_NAMES += cache.o