Junio C Hamano <gitster@xxxxxxxxx> writes:
> David Barr <davidbarr@xxxxxxxxxx> writes:
>
>> As I am hacking on WebKit daily, I'll try out this series and give feedback.
>
> Thanks; the write-out codepath needs to learn to keep the format of the
> index it originally read from when there is no preferred format defined, I
> think, as I do not think core.indexformat configuration is particularly a
> good idea, by the way.
Here is the first of two patches that should replace 9/9 (write index v4 format)
of the yesterday's 9-patch series.
-- >8 --
Subject: [PATCH 1/2] read-cache.c: write prefix-compressed names in the index
Teach the code to write the index in the v4 on-disk format.
Record the format version of the on-disk index we read from in the
index_state, and use the format when writing the new index out.
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
---
cache.h | 4 ++++
read-cache.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++---------
2 files changed, 58 insertions(+), 10 deletions(-)
diff --git a/cache.h b/cache.h
index 65a7aba..a3f1279 100644
--- a/cache.h
+++ b/cache.h
@@ -105,6 +105,9 @@ struct cache_header {
unsigned int hdr_entries;
};
+#define INDEX_FORMAT_LB 2
+#define INDEX_FORMAT_UB 4
+
/*
* The "cache_time" is just the low 32 bits of the
* time. It doesn't matter if it overflows - we only
@@ -265,6 +268,7 @@ static inline unsigned int canon_mode(unsigned int mode)
struct index_state {
struct cache_entry **cache;
+ unsigned int version;
unsigned int cache_nr, cache_alloc, cache_changed;
struct string_list *resolve_undo;
struct cache_tree *cache_tree;
diff --git a/read-cache.c b/read-cache.c
index 1c173f7..adda1da 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1196,6 +1196,8 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int reall
* Index File I/O
*****************************************************************/
+#define INDEX_FORMAT_DEFAULT 3
+
/*
* dev/ino/uid/gid/size are also just tracked to the low 32 bits
* Again - this is just a (very strong in practice) heuristic that
@@ -1443,12 +1445,13 @@ int read_index_from(struct index_state *istate, const char *path)
if (verify_hdr(hdr, mmap_size) < 0)
goto unmap;
+ istate->version = ntohl(hdr->hdr_version);
istate->cache_nr = ntohl(hdr->hdr_entries);
istate->cache_alloc = alloc_nr(istate->cache_nr);
istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
istate->initialized = 1;
- if (hdr->hdr_version == htonl(4))
+ if (istate->version == 4)
previous_name = &previous_name_buf;
else
previous_name = NULL;
@@ -1676,15 +1679,45 @@ static char *copy_cache_entry_to_ondisk(struct ondisk_cache_entry *ondisk,
}
}
-static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce)
+static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce,
+ struct strbuf *previous_name)
{
- int size = ondisk_ce_size(ce);
- struct ondisk_cache_entry *ondisk = xcalloc(1, size);
+ int size;
+ struct ondisk_cache_entry *ondisk;
char *name;
int result;
- name = copy_cache_entry_to_ondisk(ondisk, ce);
- memcpy(name, ce->name, ce_namelen(ce));
+ if (!previous_name) {
+ size = ondisk_ce_size(ce);
+ ondisk = xcalloc(1, size);
+ name = copy_cache_entry_to_ondisk(ondisk, ce);
+ memcpy(name, ce->name, ce_namelen(ce));
+ } else {
+ int common, to_remove, prefix_size;
+ unsigned char to_remove_vi[16];
+ for (common = 0;
+ (ce->name[common] &&
+ common < previous_name->len &&
+ ce->name[common] == previous_name->buf[common]);
+ common++)
+ ; /* still matching */
+ to_remove = previous_name->len - common;
+ prefix_size = encode_varint(to_remove, to_remove_vi);
+
+ if (ce->ce_flags & CE_EXTENDED)
+ size = offsetof(struct ondisk_cache_entry_extended, name);
+ else
+ size = offsetof(struct ondisk_cache_entry, name);
+ size += prefix_size + (ce_namelen(ce) - common + 1);
+
+ ondisk = xcalloc(1, size);
+ name = copy_cache_entry_to_ondisk(ondisk, ce);
+ memcpy(name, to_remove_vi, prefix_size);
+ memcpy(name + prefix_size, ce->name + common, ce_namelen(ce) - common);
+
+ strbuf_splice(previous_name, common, to_remove,
+ ce->name + common, ce_namelen(ce) - common);
+ }
result = ce_write(c, fd, ondisk, size);
free(ondisk);
@@ -1720,10 +1753,11 @@ int write_index(struct index_state *istate, int newfd)
{
git_SHA_CTX c;
struct cache_header hdr;
- int i, err, removed, extended;
+ int i, err, removed, extended, hdr_version;
struct cache_entry **cache = istate->cache;
int entries = istate->cache_nr;
struct stat st;
+ struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
for (i = removed = extended = 0; i < entries; i++) {
if (cache[i]->ce_flags & CE_REMOVE)
@@ -1737,24 +1771,34 @@ int write_index(struct index_state *istate, int newfd)
}
}
+ if (!istate->version)
+ istate->version = INDEX_FORMAT_DEFAULT;
+
+ /* demote version 3 to version 2 when the latter suffices */
+ if (istate->version == 3 || istate->version == 2)
+ istate->version = extended ? 3 : 2;
+
+ hdr_version = istate->version;
+
hdr.hdr_signature = htonl(CACHE_SIGNATURE);
- /* for extended format, increase version so older git won't try to read it */
- hdr.hdr_version = htonl(extended ? 3 : 2);
+ hdr.hdr_version = htonl(hdr_version);
hdr.hdr_entries = htonl(entries - removed);
git_SHA1_Init(&c);
if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
return -1;
+ previous_name = (hdr_version == 4) ? &previous_name_buf : NULL;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
if (ce->ce_flags & CE_REMOVE)
continue;
if (!ce_uptodate(ce) && is_racy_timestamp(istate, ce))
ce_smudge_racily_clean_entry(ce);
- if (ce_write_entry(&c, newfd, ce) < 0)
+ if (ce_write_entry(&c, newfd, ce, previous_name) < 0)
return -1;
}
+ strbuf_release(&previous_name_buf);
/* Write extension data here */
if (istate->cache_tree) {
--
1.7.10.rc4.54.g1d5dd3
--
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