Merge pull request #6138 from ccstolley/ccs_packedrefs_fast refs: Speed up packed lookups.
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diff --git a/docs/changelog.md b/docs/changelog.md
index 8060874..3723a08 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -1963,3 +1963,8 @@ v0.22
functions. This is not something which we can know to do. A
last-resort convenience function is provided in sys/openssl.h,
`git_openssl_set_locking()` which can be used to set the locking.
+
+* `git_reference_*()` functions use mmap() + binary search for packed
+ refs lookups when using the fs backend. Previously all entries were
+ read into a hashtable, which could be slow for repositories with a
+ large number of refs.
diff --git a/src/refdb_fs.c b/src/refdb_fs.c
index 055ca25..95bda94 100644
--- a/src/refdb_fs.c
+++ b/src/refdb_fs.c
@@ -65,9 +65,14 @@ typedef struct refdb_fs_backend {
git_iterator_flag_t iterator_flags;
uint32_t direach_flags;
int fsync;
+ git_map packed_refs_map;
+ git_mutex prlock; /* protect packed_refs_map */
+ git_futils_filestamp packed_refs_stamp;
+ bool sorted;
} refdb_fs_backend;
static int refdb_reflog_fs__delete(git_refdb_backend *_backend, const char *name);
+static char *packed_set_peeling_mode(char *data, size_t data_sz, refdb_fs_backend *backend);
GIT_INLINE(int) loose_path(
git_str *out,
@@ -134,31 +139,12 @@ static int packed_reload(refdb_fs_backend *backend)
GIT_UNUSED(git_sortedcache_clear(backend->refcache, false));
- scan = (char *)packedrefs.ptr;
+ scan = packedrefs.ptr;
eof = scan + packedrefs.size;
- backend->peeling_mode = PEELING_NONE;
-
- if (*scan == '#') {
- static const char *traits_header = "# pack-refs with: ";
-
- if (git__prefixcmp(scan, traits_header) == 0) {
- scan += strlen(traits_header);
- eol = strchr(scan, '\n');
-
- if (!eol)
- goto parse_failed;
- *eol = '\0';
-
- if (strstr(scan, " fully-peeled ") != NULL) {
- backend->peeling_mode = PEELING_FULL;
- } else if (strstr(scan, " peeled ") != NULL) {
- backend->peeling_mode = PEELING_STANDARD;
- }
-
- scan = eol + 1;
- }
- }
+ scan = packed_set_peeling_mode(scan, packedrefs.size, backend);
+ if (!scan)
+ goto parse_failed;
while (scan < eof && *scan == '#') {
if (!(eol = strchr(scan, '\n')))
@@ -466,10 +452,198 @@ static int ref_error_notfound(const char *name)
return GIT_ENOTFOUND;
}
-static int packed_lookup(
- git_reference **out,
- refdb_fs_backend *backend,
- const char *ref_name)
+static char *packed_set_peeling_mode(
+ char *data,
+ size_t data_sz,
+ refdb_fs_backend *backend)
+{
+ static const char *traits_header = "# pack-refs with:";
+ char *eol;
+ backend->peeling_mode = PEELING_NONE;
+
+ if (git__prefixncmp(data, data_sz, traits_header) == 0) {
+ size_t hdr_sz = strlen(traits_header);
+ const char *sorted = " sorted ";
+ const char *peeled = " peeled ";
+ const char *fully_peeled = " fully-peeled ";
+ data += hdr_sz;
+ data_sz -= hdr_sz;
+
+ eol = memchr(data, '\n', data_sz);
+
+ if (!eol)
+ return NULL;
+
+ if (git__memmem(data, eol - data, fully_peeled, strlen(fully_peeled)))
+ backend->peeling_mode = PEELING_FULL;
+ else if (git__memmem(data, eol - data, peeled, strlen(peeled)))
+ backend->peeling_mode = PEELING_STANDARD;
+
+ backend->sorted = NULL != git__memmem(data, eol - data, sorted, strlen(sorted));
+
+ return eol + 1;
+ }
+ return data;
+}
+
+static void packed_map_free(refdb_fs_backend *backend)
+{
+ if (backend->packed_refs_map.data) {
+#ifdef GIT_WIN32
+ git__free(backend->packed_refs_map.data);
+#else
+ git_futils_mmap_free(&backend->packed_refs_map);
+#endif
+ backend->packed_refs_map.data = NULL;
+ backend->packed_refs_map.len = 0;
+ git_futils_filestamp_set(&backend->packed_refs_stamp, NULL);
+ }
+}
+
+static int packed_map_check(refdb_fs_backend *backend)
+{
+ int error = 0;
+ git_file fd = -1;
+ struct stat st;
+
+ if ((error = git_mutex_lock(&backend->prlock)) < 0)
+ return error;
+
+ if (backend->packed_refs_map.data &&
+ !git_futils_filestamp_check(
+ &backend->packed_refs_stamp, backend->refcache->path)) {
+ git_mutex_unlock(&backend->prlock);
+ return error;
+ }
+ packed_map_free(backend);
+
+ fd = git_futils_open_ro(backend->refcache->path);
+ if (fd < 0) {
+ git_mutex_unlock(&backend->prlock);
+ if (fd == GIT_ENOTFOUND) {
+ git_error_clear();
+ return 0;
+ }
+ return fd;
+ }
+
+ if (p_fstat(fd, &st) < 0) {
+ p_close(fd);
+ git_mutex_unlock(&backend->prlock);
+ git_error_set(GIT_ERROR_OS, "unable to stat packed-refs '%s'", backend->refcache->path);
+ return -1;
+ }
+
+ if (st.st_size == 0) {
+ p_close(fd);
+ git_mutex_unlock(&backend->prlock);
+ return 0;
+ }
+
+ git_futils_filestamp_set_from_stat(&backend->packed_refs_stamp, &st);
+
+#ifdef GIT_WIN32
+ /* on windows, we copy the entire file into memory rather than using
+ * mmap() because using mmap() on windows also locks the file and this
+ * map is long-lived. */
+ backend->packed_refs_map.len = (size_t)st.st_size;
+ backend->packed_refs_map.data =
+ git__malloc(backend->packed_refs_map.len);
+ GIT_ERROR_CHECK_ALLOC(backend->packed_refs_map.data);
+ {
+ ssize_t bytesread =
+ p_read(fd, backend->packed_refs_map.data,
+ backend->packed_refs_map.len);
+ error = (bytesread == (ssize_t)backend->packed_refs_map.len) ? 0 : -1;
+ }
+#else
+ error = git_futils_mmap_ro(&backend->packed_refs_map, fd, 0, (size_t)st.st_size);
+#endif
+ p_close(fd);
+ if (error < 0) {
+ git_mutex_unlock(&backend->prlock);
+ return error;
+ }
+
+ packed_set_peeling_mode(
+ backend->packed_refs_map.data, backend->packed_refs_map.len,
+ backend);
+
+ git_mutex_unlock(&backend->prlock);
+ return error;
+}
+
+/*
+ * Find beginning of packed-ref record pointed to by p.
+ * buf - a lower-bound pointer to some memory buffer
+ * p - an upper-bound pointer to the same memory buffer
+ */
+static const char *start_of_record(const char *buf, const char *p)
+{
+ const char *nl = p;
+ while (true) {
+ nl = git__memrchr(buf, '\n', nl - buf);
+ if (!nl)
+ return buf;
+
+ if (nl[1] == '^' && nl > buf)
+ --nl;
+ else
+ break;
+ };
+ return nl + 1;
+}
+
+/*
+ * Find end of packed-ref record pointed to by p.
+ * end - an upper-bound pointer to some memory buffer
+ * p - a lower-bound pointer to the same memory buffer
+ */
+static const char *end_of_record(const char *p, const char *end)
+{
+ while (1) {
+ size_t sz = end - p;
+ p = memchr(p, '\n', sz);
+ if (!p)
+ return end;
+ ++p;
+ if (p < end && p[0] == '^')
+ ++p;
+ else
+ break;
+ }
+ return p;
+}
+
+static int
+cmp_record_to_refname(const char *rec, size_t data_end, const char *ref_name)
+{
+ const size_t ref_len = strlen(ref_name);
+ int cmp_val;
+ const char *end;
+
+ rec += GIT_OID_HEXSZ + 1; /* <oid> + space */
+ if (data_end < GIT_OID_HEXSZ + 3) {
+ /* an incomplete (corrupt) record is treated as less than ref_name */
+ return -1;
+ }
+ data_end -= GIT_OID_HEXSZ + 1;
+
+ end = memchr(rec, '\n', data_end);
+ if (end)
+ data_end = end - rec;
+
+ cmp_val = memcmp(rec, ref_name, min(ref_len, data_end));
+
+ if (cmp_val == 0 && data_end != ref_len)
+ return (data_end > ref_len) ? 1 : -1;
+ return cmp_val;
+}
+
+static int packed_unsorted_lookup(
+ git_reference **out,
+ refdb_fs_backend *backend,
+ const char *ref_name)
{
int error = 0;
struct packref *entry;
@@ -494,6 +668,85 @@ static int packed_lookup(
return error;
}
+static int packed_lookup(
+ git_reference **out,
+ refdb_fs_backend *backend,
+ const char *ref_name)
+{
+ int error = 0;
+ const char *left, *right, *data_end;
+
+ if ((error = packed_map_check(backend)) < 0)
+ return error;
+
+ if (!backend->sorted)
+ return packed_unsorted_lookup(out, backend, ref_name);
+
+ left = backend->packed_refs_map.data;
+ right = data_end = (const char *) backend->packed_refs_map.data +
+ backend->packed_refs_map.len;
+
+ while (left < right && *left == '#') {
+ if (!(left = memchr(left, '\n', data_end - left)))
+ goto parse_failed;
+ left++;
+ }
+
+ while (left < right) {
+ const char *mid, *rec;
+ int compare;
+
+ mid = left + (right - left) / 2;
+ rec = start_of_record(left, mid);
+ compare = cmp_record_to_refname(rec, data_end - rec, ref_name);
+
+ if (compare < 0) {
+ left = end_of_record(mid, right);
+ } else if (compare > 0) {
+ right = rec;
+ } else {
+ const char *eol;
+ git_oid oid, peel, *peel_ptr = NULL;
+
+ if (data_end - rec < GIT_OID_HEXSZ ||
+ git_oid_fromstr(&oid, rec) < 0) {
+ goto parse_failed;
+ }
+ rec += GIT_OID_HEXSZ + 1;
+ if (!(eol = memchr(rec, '\n', data_end - rec))) {
+ goto parse_failed;
+ }
+
+ /* look for optional "^<OID>\n" */
+
+ if (eol + 1 < data_end) {
+ rec = eol + 1;
+
+ if (*rec == '^') {
+ rec++;
+ if (data_end - rec < GIT_OID_HEXSZ ||
+ git_oid_fromstr(&peel, rec) < 0) {
+ goto parse_failed;
+ }
+ peel_ptr = &peel;
+ }
+ }
+
+ *out = git_reference__alloc(ref_name, &oid, peel_ptr);
+ if (!*out) {
+ return -1;
+ }
+
+ return 0;
+ }
+ }
+ return GIT_ENOTFOUND;
+
+parse_failed:
+ git_error_set(GIT_ERROR_REFERENCE, "corrupted packed references file");
+ return -1;
+}
+
static int refdb_fs_backend__lookup(
git_reference **out,
git_refdb_backend *_backend,
@@ -513,7 +766,6 @@ static int refdb_fs_backend__lookup(
git_error_clear();
error = packed_lookup(out, backend, ref_name);
}
-
return error;
}
@@ -1081,6 +1333,15 @@ static int packed_write(refdb_fs_backend *backend)
int error, open_flags = 0;
size_t i;
+ /* take lock and close up packed-refs mmap if open */
+ if ((error = git_mutex_lock(&backend->prlock)) < 0) {
+ return error;
+ }
+
+ packed_map_free(backend);
+
+ git_mutex_unlock(&backend->prlock);
+
/* lock the cache to updates while we do this */
if ((error = git_sortedcache_wlock(refcache)) < 0)
return error;
@@ -1568,6 +1829,12 @@ static void refdb_fs_backend__free(git_refdb_backend *_backend)
return;
git_sortedcache_free(backend->refcache);
+
+ git_mutex_lock(&backend->prlock);
+ packed_map_free(backend);
+ git_mutex_unlock(&backend->prlock);
+ git_mutex_free(&backend->prlock);
+
git__free(backend->gitpath);
git__free(backend->commonpath);
git__free(backend);
@@ -2121,6 +2388,11 @@ int git_refdb_backend_fs(
backend = git__calloc(1, sizeof(refdb_fs_backend));
GIT_ERROR_CHECK_ALLOC(backend);
+ if (git_mutex_init(&backend->prlock) < 0) {
+ git__free(backend);
+ return -1;
+ }
+
if (git_refdb_init_backend(&backend->parent, GIT_REFDB_BACKEND_VERSION) < 0)
goto fail;
@@ -2183,6 +2455,7 @@ int git_refdb_backend_fs(
return 0;
fail:
+ git_mutex_free(&backend->prlock);
git_str_dispose(&gitpath);
git__free(backend->gitpath);
git__free(backend->commonpath);
diff --git a/tests/refs/crashes.c b/tests/refs/crashes.c
index 228f479..4f508ae 100644
--- a/tests/refs/crashes.c
+++ b/tests/refs/crashes.c
@@ -1,4 +1,5 @@
#include "clar_libgit2.h"
+#include "refs.h"
void test_refs_crashes__double_free(void)
{
@@ -18,3 +19,26 @@ void test_refs_crashes__double_free(void)
cl_git_sandbox_cleanup();
}
+
+void test_refs_crashes__empty_packedrefs(void)
+{
+ git_repository *repo;
+ git_reference *ref;
+ const char *REFNAME = "refs/heads/xxx";
+ git_str temp_path = GIT_STR_INIT;
+ int fd = 0;
+
+ repo = cl_git_sandbox_init("empty_bare.git");
+
+ /* create zero-length packed-refs file */
+ cl_git_pass(git_str_joinpath(&temp_path, git_repository_path(repo), GIT_PACKEDREFS_FILE));
+ cl_git_pass(((fd = p_creat(temp_path.ptr, 0644)) < 0));
+ cl_git_pass(p_close(fd));
+
+ /* should fail gracefully */
+ cl_git_fail_with(
+ GIT_ENOTFOUND, git_reference_lookup(&ref, repo, REFNAME));
+
+ cl_git_sandbox_cleanup();
+ git_str_dispose(&temp_path);
+}
diff --git a/tests/resources/peeled.git/packed-refs b/tests/resources/peeled.git/packed-refs
index ad053d5..078f237 100644
--- a/tests/resources/peeled.git/packed-refs
+++ b/tests/resources/peeled.git/packed-refs
@@ -1,4 +1,4 @@
-# pack-refs with: peeled fully-peeled
+# pack-refs with: peeled fully-peeled sorted
c2596aa0151888587ec5c0187f261e63412d9e11 refs/foo/tag-outside-tags
^0df1a5865c8abfc09f1f2182e6a31be550e99f07
0df1a5865c8abfc09f1f2182e6a31be550e99f07 refs/heads/master
diff --git a/tests/resources/testrepo.git/packed-refs b/tests/resources/testrepo.git/packed-refs
index 52f5e87..fadd7e8 100644
--- a/tests/resources/testrepo.git/packed-refs
+++ b/tests/resources/testrepo.git/packed-refs
@@ -1,3 +1,3 @@
-# pack-refs with: peeled
+# pack-refs with: peeled sorted
41bc8c69075bbdb46c5c6f0566cc8cc5b46e8bd9 refs/heads/packed
5b5b025afb0b4c913b4c338a42934a3863bf3644 refs/heads/packed-test
diff --git a/tests/resources/testrepo/.gitted/packed-refs b/tests/resources/testrepo/.gitted/packed-refs
index 6018a19..b578986 100644
--- a/tests/resources/testrepo/.gitted/packed-refs
+++ b/tests/resources/testrepo/.gitted/packed-refs
@@ -1,4 +1,4 @@
-# pack-refs with: peeled
+# pack-refs with: peeled sorted
41bc8c69075bbdb46c5c6f0566cc8cc5b46e8bd9 refs/heads/packed
5b5b025afb0b4c913b4c338a42934a3863bf3644 refs/heads/packed-test
b25fa35b38051e4ae45d4222e795f9df2e43f1d1 refs/tags/packed-tag
diff --git a/tests/resources/testrepo2/.gitted/packed-refs b/tests/resources/testrepo2/.gitted/packed-refs
index 97ea6a8..01de871 100644
--- a/tests/resources/testrepo2/.gitted/packed-refs
+++ b/tests/resources/testrepo2/.gitted/packed-refs
@@ -1,4 +1,4 @@
-# pack-refs with: peeled fully-peeled
+# pack-refs with: peeled fully-peeled sorted
36060c58702ed4c2a40832c51758d5344201d89a refs/remotes/origin/master
41bc8c69075bbdb46c5c6f0566cc8cc5b46e8bd9 refs/remotes/origin/packed
5b5b025afb0b4c913b4c338a42934a3863bf3644 refs/tags/v0.9