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-rw-r--r--packv4-parse.c158
-rw-r--r--packv4-parse.h2
-rw-r--r--sha1_file.c2
3 files changed, 125 insertions, 37 deletions
diff --git a/packv4-parse.c b/packv4-parse.c
index 38c22b0358..6abd62ee69 100644
--- a/packv4-parse.c
+++ b/packv4-parse.c
@@ -378,6 +378,40 @@ static int copy_canonical_tree_entries(struct packed_git *p, off_t offset,
return 0;
}
+/* ordering is so that member alignment takes the least amount of space */
+struct pv4_tree_cache {
+ off_t base_offset;
+ off_t offset;
+ off_t last_copy_base;
+ struct packed_git *p;
+ unsigned int pos;
+ unsigned int nb_entries;
+};
+
+#define CACHE_SIZE 1024
+static struct pv4_tree_cache pv4_tree_cache[CACHE_SIZE];
+
+static struct pv4_tree_cache *get_tree_offset_cache(struct packed_git *p, off_t base_offset)
+{
+ struct pv4_tree_cache *c;
+ unsigned long hash;
+
+ hash = (unsigned long)p + (unsigned long)base_offset;
+ hash += (hash >> 8) + (hash >> 16);
+ hash %= CACHE_SIZE;
+
+ c = &pv4_tree_cache[hash];
+ if (c->p != p || c->base_offset != base_offset) {
+ c->p = p;
+ c->base_offset = base_offset;
+ c->offset = 0;
+ c->last_copy_base = 0;
+ c->pos = 0;
+ c->nb_entries = 0;
+ }
+ return c;
+}
+
static int tree_entry_prefix(unsigned char *buf, unsigned long size,
const unsigned char *path, int path_len,
unsigned mode)
@@ -405,39 +439,72 @@ static int tree_entry_prefix(unsigned char *buf, unsigned long size,
}
static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
- off_t offset, unsigned int start, unsigned int count,
- unsigned char **dstp, unsigned long *sizep,
- int parse_hdr)
+ off_t obj_offset, unsigned int start, unsigned int count,
+ unsigned char **dstp, unsigned long *sizep)
{
unsigned long avail;
- unsigned int nb_entries;
const unsigned char *src, *scp;
- off_t copy_objoffset = 0;
+ unsigned int curpos;
+ off_t offset, copy_objoffset;
+ struct pv4_tree_cache *c;
+
+ c = get_tree_offset_cache(p, obj_offset);
+ if (count && start < c->nb_entries && start >= c->pos &&
+ count <= c->nb_entries - start) {
+ offset = c->offset;
+ copy_objoffset = c->last_copy_base;
+ curpos = c->pos;
+ start -= curpos;
+ src = NULL;
+ avail = 0;
+ } else {
+ unsigned int nb_entries;
- src = use_pack(p, w_curs, offset, &avail);
- scp = src;
+ src = use_pack(p, w_curs, obj_offset, &avail);
+ scp = src;
- if (parse_hdr) {
/* we need to skip over the object header */
while (*scp & 128)
if (++scp - src >= avail - 20)
return -1;
+
/* is this a canonical tree object? */
- if ((*scp & 0xf) == OBJ_TREE)
+ if ((*scp & 0xf) == OBJ_TREE) {
+ offset = obj_offset + (scp - src);
return copy_canonical_tree_entries(p, offset,
start, count,
dstp, sizep);
+ }
+
/* let's still make sure this is actually a pv4 tree */
if ((*scp++ & 0xf) != OBJ_PV4_TREE)
return -1;
- }
- nb_entries = decode_varint(&scp);
- if (scp == src || start > nb_entries || count > nb_entries - start)
- return -1;
- offset += scp - src;
- avail -= scp - src;
- src = scp;
+ nb_entries = decode_varint(&scp);
+ if (!count)
+ count = nb_entries;
+ if (!nb_entries || start > nb_entries ||
+ count > nb_entries - start)
+ return -1;
+
+ curpos = 0;
+ copy_objoffset = 0;
+ offset = obj_offset + (scp - src);
+ avail -= scp - src;
+ src = scp;
+
+ /*
+ * If this is a partial copy, let's (re)initialize a cache
+ * entry to speed things up if the remaining of this tree
+ * is needed in the future.
+ */
+ if (start + count < nb_entries) {
+ c->offset = offset;
+ c->pos = 0;
+ c->nb_entries = nb_entries;
+ c->last_copy_base = 0;
+ }
+ }
while (count) {
unsigned int what;
@@ -464,6 +531,7 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
else
while (*scp++ & 128);
start--;
+ curpos++;
} else if (!(what & 1) && start == 0) {
/*
* This is an actual tree entry to recreate.
@@ -485,6 +553,7 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
*dstp += len + 20;
*sizep -= len + 20;
count--;
+ curpos++;
} else if (what & 1) {
/*
* Copy from another tree object.
@@ -522,25 +591,41 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
nth_packed_object_offset(p, index - 1);
}
}
- if (!copy_objoffset)
- return -1;
copy_count >>= 1;
+ if (!copy_count || !copy_objoffset)
+ return -1;
if (start >= copy_count) {
start -= copy_count;
+ curpos += copy_count;
} else {
int ret;
+
copy_count -= start;
copy_start += start;
- start = 0;
- if (copy_count > count)
+ if (copy_count > count) {
+ /*
+ * We won't consume the whole of
+ * this copy sequence and the main
+ * loop will be exited. Let's manage
+ * for offset and curpos to remain
+ * unchanged to update the cache.
+ */
copy_count = count;
- count -= copy_count;
- ret = decode_entries(p, w_curs,
- copy_objoffset, copy_start, copy_count,
- dstp, sizep, 1);
+ count = 0;
+ scp = src;
+ } else {
+ count -= copy_count;
+ curpos += start + copy_count;
+ start = 0;
+ }
+
+ ret = decode_entries(p, w_curs, copy_objoffset,
+ copy_start, copy_count,
+ dstp, sizep);
if (ret)
return ret;
+
/* force pack window readjustment */
avail = scp - src;
}
@@ -551,27 +636,30 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
src = scp;
}
+ /*
+ * Update the cache if we didn't run through the entire tree.
+ * We have to "get" it again as a recursion into decode_entries()
+ * could have invalidated what we obtained initially.
+ */
+ c = get_tree_offset_cache(p, obj_offset);
+ if (curpos < c->nb_entries) {
+ c->pos = curpos;
+ c->offset = offset;
+ c->last_copy_base = copy_objoffset;
+ }
+
return 0;
}
void *pv4_get_tree(struct packed_git *p, struct pack_window **w_curs,
- off_t offset, unsigned long size)
+ off_t obj_offset, unsigned long size)
{
- unsigned long avail;
- unsigned int nb_entries;
unsigned char *dst, *dcp;
- const unsigned char *src, *scp;
int ret;
- src = use_pack(p, w_curs, offset, &avail);
- scp = src;
- nb_entries = decode_varint(&scp);
- if (scp == src)
- return NULL;
-
dst = xmallocz(size);
dcp = dst;
- ret = decode_entries(p, w_curs, offset, 0, nb_entries, &dcp, &size, 0);
+ ret = decode_entries(p, w_curs, obj_offset, 0, 0, &dcp, &size);
if (ret < 0 || size != 0) {
free(dst);
return NULL;
diff --git a/packv4-parse.h b/packv4-parse.h
index d674a3fad3..b437159b74 100644
--- a/packv4-parse.h
+++ b/packv4-parse.h
@@ -20,6 +20,6 @@ const unsigned char *get_sha1ref(struct packed_git *p,
void *pv4_get_commit(struct packed_git *p, struct pack_window **w_curs,
off_t offset, unsigned long size);
void *pv4_get_tree(struct packed_git *p, struct pack_window **w_curs,
- off_t offset, unsigned long size);
+ off_t obj_offset, unsigned long size);
#endif
diff --git a/sha1_file.c b/sha1_file.c
index 038e22e559..e98eb8be05 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2178,7 +2178,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
type -= 8;
break;
case OBJ_PV4_TREE:
- data = pv4_get_tree(p, &w_curs, curpos, size);
+ data = pv4_get_tree(p, &w_curs, obj_offset, size);
type -= 8;
break;
case OBJ_COMMIT:
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