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Speed up index file writing by chunking it nicely.

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No point in making 17,000 small writes when you can make just
a couple of hundred nice 8kB writes instead and save a lot
of time.
This commit is contained in:
Linus Torvalds 2005-04-20 12:16:57 -07:00
parent 706bc531a1
commit 4990aadc4c
1 changed files with 39 additions and 4 deletions
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43
read-cache.c
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@ -227,6 +227,42 @@ unmap:
return error("verify header failed");
}
#define WRITE_BUFFER_SIZE 8192
static char write_buffer[WRITE_BUFFER_SIZE];
static unsigned long write_buffer_len;
static int ce_write(int fd, void *data, unsigned int len)
{
while (len) {
unsigned int buffered = write_buffer_len;
unsigned int partial = WRITE_BUFFER_SIZE - buffered;
if (partial > len)
partial = len;
memcpy(write_buffer + buffered, data, partial);
buffered += partial;
if (buffered == WRITE_BUFFER_SIZE) {
if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
return -1;
buffered = 0;
}
write_buffer_len = buffered;
len -= partial;
data += partial;
}
return 0;
}
static int ce_flush(int fd)
{
unsigned int left = write_buffer_len;
if (left) {
write_buffer_len = 0;
if (write(fd, write_buffer, left) != left)
return -1;
}
return 0;
}
int write_cache(int newfd, struct cache_entry **cache, int entries)
{
SHA_CTX c;
@ -246,14 +282,13 @@ int write_cache(int newfd, struct cache_entry **cache, int entries)
}
SHA1_Final(hdr.sha1, &c);
if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
if (ce_write(newfd, &hdr, sizeof(hdr)) < 0)
return -1;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
int size = ce_size(ce);
if (write(newfd, ce, size) != size)
if (ce_write(newfd, ce, ce_size(ce)) < 0)
return -1;
}
return 0;
return ce_flush(newfd);
}