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authorNicolas Pitre <nico@cam.org>2008-09-02 10:22:20 -0400
committerJunio C Hamano <gitster@pobox.com>2008-09-02 17:05:47 -0700
commita8032d12241f2226a6ab98272b12a1d98ca446a5 (patch)
tree4c05ad594960539a478a2646fcb2b22c66a68aaa /csum-file.c
parent59d94bc9c851f9f4086a857bc6277feca6a48824 (diff)
downloadgit-a8032d12241f2226a6ab98272b12a1d98ca446a5.tar.gz
sha1write: don't copy full sized buffers
No need to memcpy() source buffer data when we might just process the data in place instead of accumulating it into a separate buffer. This is the case when a whole buffer would have been copied, summed, written out and then discarded right away. Also move the CRC32 processing within the loop so the data is more likely to remain in the L1 CPU cache between the CRC32 sum, SHA1 sum and the write call. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'csum-file.c')
-rw-r--r--csum-file.c27
1 files changed, 17 insertions, 10 deletions
diff --git a/csum-file.c b/csum-file.c
index 28389541a3..bb70c75ee1 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -11,10 +11,8 @@
#include "progress.h"
#include "csum-file.h"
-static void sha1flush(struct sha1file *f, unsigned int count)
+static void sha1flush(struct sha1file *f, void *buf, unsigned int count)
{
- void *buf = f->buffer;
-
for (;;) {
int ret = xwrite(f->fd, buf, count);
if (ret > 0) {
@@ -39,7 +37,7 @@ int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
if (offset) {
SHA1_Update(&f->ctx, f->buffer, offset);
- sha1flush(f, offset);
+ sha1flush(f, f->buffer, offset);
f->offset = 0;
}
SHA1_Final(f->buffer, &f->ctx);
@@ -47,7 +45,7 @@ int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
hashcpy(result, f->buffer);
if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
/* write checksum and close fd */
- sha1flush(f, 20);
+ sha1flush(f, f->buffer, 20);
if (flags & CSUM_FSYNC)
fsync_or_die(f->fd, f->name);
if (close(f->fd))
@@ -62,21 +60,30 @@ int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
int sha1write(struct sha1file *f, void *buf, unsigned int count)
{
- if (f->do_crc)
- f->crc32 = crc32(f->crc32, buf, count);
while (count) {
unsigned offset = f->offset;
unsigned left = sizeof(f->buffer) - offset;
unsigned nr = count > left ? left : count;
+ void *data;
+
+ if (f->do_crc)
+ f->crc32 = crc32(f->crc32, buf, nr);
+
+ if (nr == sizeof(f->buffer)) {
+ /* process full buffer directly without copy */
+ data = buf;
+ } else {
+ memcpy(f->buffer + offset, buf, nr);
+ data = f->buffer;
+ }
- memcpy(f->buffer + offset, buf, nr);
count -= nr;
offset += nr;
buf = (char *) buf + nr;
left -= nr;
if (!left) {
- SHA1_Update(&f->ctx, f->buffer, offset);
- sha1flush(f, offset);
+ SHA1_Update(&f->ctx, data, offset);
+ sha1flush(f, data, offset);
offset = 0;
}
f->offset = offset;