From mboxrd@z Thu Jan 1 00:00:00 1970 From: cgit at ml.breakpoint.cc (Sebastian Andrzej Siewior) Date: Sat, 23 Jun 2012 21:25:23 +0200 Subject: [PATCH 2/3 v2] cache: use sendfile() instead of a pair of read() + write() In-Reply-To: References: <1340262588-24202-1-git-send-email-cgit@ml.breakpoint.cc> <1340262588-24202-2-git-send-email-cgit@ml.breakpoint.cc> Message-ID: <20120623192523.GB23924@breakpoint.cc> From: Sebastian Andrzej Siewior sendfile() does the same job and avoids to copy the content into userland and back. One has to define HAVE_LINUX_SENDFILE in case the OS (kernel & libc) supports the Linux/glibc interface. It is disabled by default on non-linux environments. 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 --- On Sat, Jun 23, 2012 at 10:27:25AM +0000, Ben Boeckel wrote: > On Thu, Jun 21, 2012 at 07:09:47 GMT, cgit at ml.breakpoint.cc wrote: > > From: Sebastian Andrzej Siewior > > +ifneq ($(uname_S),Linux) > > + NO_SENDFILE = YesPlease > > +endif > > Double negatives suck. Can the option be made HAVE_SENDFILE? Yes it does. What about this. Makefile | 9 +++++++++ cache.c | 26 +++++++++++++++++++++++++- 2 files changed, 34 insertions(+), 1 deletions(-) diff --git a/Makefile b/Makefile index eac24ad..20cae98 100644 --- a/Makefile +++ b/Makefile @@ -33,6 +33,8 @@ DOC_PDF = $(patsubst %.txt,%.pdf,$(MAN_TXT)) # 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() as offered by glibc on Linux. +# #-include config.mak @@ -49,6 +51,10 @@ ifeq ($(uname_O),Cygwin) NEEDS_LIBICONV = YesPlease endif +ifeq ($(uname_S),Linux) + HAVE_LINUX_SENDFILE = YesPlease +endif + # # Let the user override the above settings. # @@ -157,6 +163,9 @@ ifdef NO_OPENSSL else EXTLIBS += -lcrypto endif +ifdef HAVE_LINUX_SENDFILE + CFLAGS += -DHAVE_LINUX_SENDFILE +endif cgit: $(OBJECTS) libgit $(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o cgit $(OBJECTS) $(EXTLIBS) diff --git a/cache.c b/cache.c index d7a8d5a..963ec3a 100644 --- a/cache.c +++ b/cache.c @@ -13,6 +13,9 @@ * */ +#ifdef HAVE_LINUX_SENDFILE +#include +#endif #include "cgit.h" #include "cache.h" @@ -30,7 +33,6 @@ struct cache_slot { const char *lock_name; int match; struct stat cache_st; - struct stat lock_st; int 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). */ 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 @@ static int print_slot(struct cache_slot *slot) return errno; else return 0; +#endif } /* Check if the slot has expired */ @@ -188,6 +208,10 @@ static int fill_slot(struct cache_slot *slot) /* Generate cache content */ slot->fn(slot->cbdata); + /* update stat info */ + if (fstat(slot->lock_fd, &slot->cache_st)) + return errno; + /* Restore stdout */ if (dup2(tmp, STDOUT_FILENO) == -1) return errno; -- 1.7.2.5