On Sun, Mar 28, 2010 at 12:56:46PM -0400, Jeff King wrote:
> Better, but not perfect. My script is below. I get:
>
> $ time git show >/dev/null
> real 0m1.036s
> user 0m0.412s
> sys 0m0.672s
>
> which is still a 2.5x speedup (versus my other fast-textconv solution
> earlier in the thread), but I suspect we can do better. The notes
> mechanism does some up-front work to get very fast lookups, but because
> we invoke git-notes repeatedly, we never get the amortized benefit of
> that up-front work. Doing it in-core would fix that.
Here is a quick and dirty in-core implementation. The most notable
defect is that all textconvs store under refs/notes/textconv, which is
obviously bogus if you might textconv the same blob in two different
ways.
It was relatively easy to code thanks to a very nice notes interface
from Johan Herland. That same commit is now:
$ time git show >/dev/null
real 0m0.350s
user 0m0.172s
sys 0m0.176s
which is starting to feel sufficiently snappy.
Patch is on top of 1/3 from my earlier series (it uses some of the
centralizing cleanup).
diff --git a/diff.c b/diff.c
index 3ddc05e..e1ef25e 100644
--- a/diff.c
+++ b/diff.c
@@ -14,6 +14,8 @@
#include "userdiff.h"
#include "sigchain.h"
#include "submodule.h"
+#include "notes.h"
+#include "refs.h"
#ifdef NO_FAST_WORKING_DIRECTORY
#define FAST_WORKING_DIRECTORY 0
@@ -3881,19 +3883,57 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
return strbuf_detach(&buf, outsize);
}
+static struct notes_tree textconv_notes;
+static int textconv_notes_initialized;
+
+static const unsigned char *run_and_cache_textconv(const char *cmd,
+ struct diff_filespec *df)
+{
+ char *data;
+ size_t size;
+ unsigned char blob_sha1[20];
+ unsigned char tree_sha1[20];
+
+ data = run_textconv(cmd, df, &size);
+ if (!data)
+ die("unable to read files to diff");
+ if (write_sha1_file(data, size, "blob", blob_sha1) < 0)
+ die("unable to write textconv cache blob");
+ free(data);
+
+ add_note(&textconv_notes, df->sha1, blob_sha1, combine_notes_overwrite);
+ if (write_notes_tree(&textconv_notes, tree_sha1) < 0)
+ die("unable to write textconv cache notes tree");
+ update_ref("textconv cache update", "refs/notes/textconv",
+ tree_sha1, NULL, 0, DIE_ON_ERR);
+
+ return get_note(&textconv_notes, df->sha1);
+}
+
static size_t fill_textconv(const char *cmd,
struct diff_filespec *df,
char **outbuf)
{
- size_t size;
+ const unsigned char *sha1;
+ unsigned long size;
+ enum object_type type;
if (!cmd) {
*outbuf = df->data;
return df->size;
}
- *outbuf = run_textconv(cmd, df, &size);
+ if (!textconv_notes_initialized) {
+ init_notes(&textconv_notes, "refs/notes/textconv", 0, 0);
+ textconv_notes_initialized = 1;
+ }
+
+ sha1 = get_note(&textconv_notes, df->sha1);
+ if (!sha1)
+ sha1 = run_and_cache_textconv(cmd, df);
+
+ *outbuf = read_sha1_file(sha1, &type, &size);
if (!*outbuf)
- die("unable to read files to diff");
+ die("unable to read textconv cache object");
return size;
}
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