cache: use sendfile() instead of a pair of read() + write() 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>
Sebastian Andrzej Siewior sebastian@breakpoint.cc
Sat, 18 Jan 2014 21:24:58 +0100
M
Makefile
→
Makefile
@@ -29,6 +29,7 @@ # do not support the 'size specifiers' introduced by C99, namely ll, hh,
# 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. # +# Define HAVE_LINUX_SENDFILE to use sendfile() #-include config.mak
M
cache.c
→
cache.c
@@ -13,6 +13,9 @@ * key.
* */ +#ifdef HAVE_LINUX_SENDFILE +#include <sys/sendfile.h> +#endif #include "cgit.h" #include "cache.h" #include "html.h"@@ -30,7 +33,6 @@ const char *cache_name;
const char *lock_name; int match; struct stat cache_st; - struct stat lock_st; int bufsize; char buf[CACHE_BUFSIZE]; };@@ -81,6 +83,23 @@
/* Print the content of the active cache slot (but skip the key). */ 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; i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET);@@ -97,6 +116,7 @@ if (i < 0 || j != i)
return errno; else return 0; +#endif } /* Check if the slot has expired */@@ -187,6 +207,10 @@ return errno;
/* Generate cache content */ slot->fn(); + + /* update stat info */ + if (fstat(slot->lock_fd, &slot->cache_st)) + return errno; /* Restore stdout */ if (dup2(tmp, STDOUT_FILENO) == -1)
M
cgit.mk
→
cgit.mk
@@ -68,6 +68,14 @@ ifeq ($(findstring BSD,$(uname_S)),)
CGIT_LIBS += -ldl 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 += cache.o