On Sat, Dec 29, 2012 at 12:27:47AM -0500, Jeff King wrote:
> > I think I tried the partial decompression for commit header and it did
> > not help much (or I misremember it, not so sure).
>
> I'll see if I can dig up the reference, as it was something I was going
> to look at next.
I tried the simple patch below, but it actually made things slower! I'm
assuming it is because the streaming setup is not micro-optimized very
well. A custom read_sha1_until_blank_line() could probably do better.
diff --git a/commit.c b/commit.c
index e8eb0ae..efd6c06 100644
--- a/commit.c
+++ b/commit.c
@@ -8,6 +8,7 @@
#include "notes.h"
#include "gpg-interface.h"
#include "mergesort.h"
+#include "streaming.h"
static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
@@ -306,6 +307,39 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
return 0;
}
+static void *read_commit_header(const unsigned char *sha1,
+ enum object_type *type,
+ unsigned long *size)
+{
+ static const int chunk_size = 256;
+ struct strbuf buf = STRBUF_INIT;
+ struct git_istream *st;
+
+ st = open_istream(sha1, type, size, NULL);
+ if (!st)
+ return NULL;
+ while (1) {
+ size_t start = buf.len;
+ ssize_t readlen;
+
+ strbuf_grow(&buf, chunk_size);
+ readlen = read_istream(st, buf.buf + start, chunk_size);
+ buf.buf[start + readlen + 1] = '\0';
+ buf.len += readlen;
+
+ if (readlen < 0) {
+ close_istream(st);
+ strbuf_release(&buf);
+ return NULL;
+ }
+ if (!readlen || strstr(buf.buf + start, "\n\n"))
+ break;
+ }
+
+ close_istream(st);
+ return strbuf_detach(&buf, size);
+}
+
int parse_commit(struct commit *item)
{
enum object_type type;
@@ -317,7 +351,11 @@ int parse_commit(struct commit *item)
return -1;
if (item->object.parsed)
return 0;
- buffer = read_sha1_file(item->object.sha1, &type, &size);
+
+ if (!save_commit_buffer)
+ buffer = read_commit_header(item->object.sha1, &type, &size);
+ else
+ buffer = read_sha1_file(item->object.sha1, &type, &size);
if (!buffer)
return error("Could not read %s",
sha1_to_hex(item->object.sha1));
--
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