Do not change the existing info/refs and objects/info/packs
files if they match the existing content on the filesystem.
This is intended to preserve mtime and make it easier for dumb
HTTP pollers to rely on the If-Modified-Since header.
Combined with stdio and kernel buffering; the kernel should be
able to avoid block layer writes and reduce wear for small files.
As a result, the --force option is no longer needed. So stop
documenting it, but let it remain for compatibility (and
debugging, if necessary).
v3: perform incremental comparison while generating to avoid
OOM with giant files. Remove documentation for --force.
Signed-off-by: Eric Wong <e...@80x24.org>
---
OK, performing the incremental comparison wasn't nearly as
bad as thought it'd be. I might be suffering from
compiler-linker-slowness PTSD :x
Interdiff:
diff --git a/Documentation/git-update-server-info.txt
b/Documentation/git-update-server-info.txt
index bd0e36492f..969bb2e15f 100644
--- a/Documentation/git-update-server-info.txt
+++ b/Documentation/git-update-server-info.txt
@@ -9,7 +9,7 @@ git-update-server-info - Update auxiliary info file to help
dumb servers
SYNOPSIS
--------
[verse]
-'git update-server-info' [--force]
+'git update-server-info'
DESCRIPTION
-----------
@@ -19,15 +19,6 @@ $GIT_OBJECT_DIRECTORY/info directories to help clients
discover
what references and packs the server has. This command
generates such auxiliary files.
-
-OPTIONS
--------
-
--f::
---force::
- Update the info files from scratch.
-
-
OUTPUT
------
diff --git a/server-info.c b/server-info.c
index 11515804d4..e68f785c2f 100644
--- a/server-info.c
+++ b/server-info.c
@@ -8,41 +8,54 @@
#include "object-store.h"
#include "strbuf.h"
-static int files_differ(FILE *fp, const char *path)
+struct update_info_ctx {
+ FILE *cur_fp;
+ FILE *old_fp; /* becomes NULL if it differs from cur_fp */
+ struct strbuf cur_sb;
+ struct strbuf old_sb;
+};
+
+static void uic_mark_stale(struct update_info_ctx *uic)
{
- struct stat st;
- git_hash_ctx c;
- struct object_id oid_old, oid_new;
- struct strbuf tmp = STRBUF_INIT;
- long new_len = ftell(fp);
+ fclose(uic->old_fp);
+ uic->old_fp = NULL;
+}
- if (new_len < 0 || stat(path, &st) < 0)
- return 1;
- if (!S_ISREG(st.st_mode))
- return 1;
- if ((off_t)new_len != st.st_size)
- return 1;
+static int uic_is_stale(const struct update_info_ctx *uic)
+{
+ return uic->old_fp == NULL;
+}
- rewind(fp);
- if (strbuf_fread(&tmp, (size_t)new_len, fp) != (size_t)new_len) {
- strbuf_release(&tmp);
- return 1;
- }
- the_hash_algo->init_fn(&c);
- the_hash_algo->update_fn(&c, tmp.buf, tmp.len);
- the_hash_algo->final_fn(oid_new.hash, &c);
- strbuf_release(&tmp);
+static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
+{
+ va_list ap;
+ int ret = -1;
- if (strbuf_read_file(&tmp, path, (size_t)st.st_size) < 0) {
- strbuf_release(&tmp);
- return 1;
+ va_start(ap, fmt);
+
+ if (uic_is_stale(uic)) {
+ ret = vfprintf(uic->cur_fp, fmt, ap);
+ } else {
+ ssize_t r;
+ struct strbuf *cur = &uic->cur_sb;
+ struct strbuf *old = &uic->old_sb;
+
+ strbuf_reset(cur);
+ strbuf_vinsertf(cur, 0, fmt, ap);
+
+ strbuf_reset(old);
+ strbuf_grow(old, cur->len);
+ r = fread(old->buf, 1, cur->len, uic->old_fp);
+ if (r != cur->len || memcmp(old->buf, cur->buf, r))
+ uic_mark_stale(uic);
+
+ if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
+ ret = 0;
}
- the_hash_algo->init_fn(&c);
- the_hash_algo->update_fn(&c, tmp.buf, tmp.len);
- the_hash_algo->final_fn(oid_old.hash, &c);
- strbuf_release(&tmp);
- return hashcmp(oid_old.hash, oid_new.hash);
+ va_end(ap);
+
+ return ret;
}
/*
@@ -50,31 +63,61 @@ static int files_differ(FILE *fp, const char *path)
* it into place. The contents of the file come from "generate", which
* should return non-zero if it encounters an error.
*/
-static int update_info_file(char *path, int (*generate)(FILE *), int force)
+static int update_info_file(char *path,
+ int (*generate)(struct update_info_ctx *),
+ int force)
{
char *tmp = mkpathdup("%s_XXXXXX", path);
int ret = -1;
int fd = -1;
- FILE *fp = NULL, *to_close;
- int do_update;
+ FILE *to_close;
+ struct update_info_ctx uic = {
+ .cur_fp = NULL,
+ .old_fp = NULL,
+ .cur_sb = STRBUF_INIT,
+ .old_sb = STRBUF_INIT
+ };
safe_create_leading_directories(path);
fd = git_mkstemp_mode(tmp, 0666);
if (fd < 0)
goto out;
- to_close = fp = fdopen(fd, "w+");
- if (!fp)
+ to_close = uic.cur_fp = fdopen(fd, "w");
+ if (!uic.cur_fp)
goto out;
fd = -1;
- ret = generate(fp);
+
+ /* no problem on ENOENT and old_fp == NULL, it's stale, now */
+ if (!force)
+ uic.old_fp = fopen_or_warn(path, "r");
+
+ /*
+ * uic_printf will compare incremental comparison aginst old_fp
+ * and mark uic as stale if needed
+ */
+ ret = generate(&uic);
if (ret)
goto out;
- do_update = force || files_differ(fp, path);
- fp = NULL;
+ /* new file may be shorter than the old one, check here */
+ if (!uic_is_stale(&uic)) {
+ struct stat st;
+ long new_len = ftell(uic.cur_fp);
+ int old_fd = fileno(uic.old_fp);
+
+ if (new_len < 0) {
+ ret = -1;
+ goto out;
+ }
+ if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
+ uic_mark_stale(&uic);
+ }
+
+ uic.cur_fp = NULL;
if (fclose(to_close))
goto out;
- if (do_update) {
+
+ if (uic_is_stale(&uic)) {
if (adjust_shared_perm(tmp) < 0)
goto out;
if (rename(tmp, path) < 0)
@@ -87,40 +130,44 @@ static int update_info_file(char *path, int
(*generate)(FILE *), int force)
out:
if (ret) {
error_errno("unable to update %s", path);
- if (fp)
- fclose(fp);
+ if (uic.cur_fp)
+ fclose(uic.cur_fp);
else if (fd >= 0)
close(fd);
unlink(tmp);
}
free(tmp);
+ if (uic.old_fp)
+ fclose(uic.old_fp);
+ strbuf_release(&uic.old_sb);
+ strbuf_release(&uic.cur_sb);
return ret;
}
static int add_info_ref(const char *path, const struct object_id *oid,
int flag, void *cb_data)
{
- FILE *fp = cb_data;
+ struct update_info_ctx *uic = cb_data;
struct object *o = parse_object(the_repository, oid);
if (!o)
return -1;
- if (fprintf(fp, "%s %s\n", oid_to_hex(oid), path) < 0)
+ if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
return -1;
if (o->type == OBJ_TAG) {
o = deref_tag(the_repository, o, path, 0);
if (o)
- if (fprintf(fp, "%s %s^{}\n",
+ if (uic_printf(uic, "%s %s^{}\n",
oid_to_hex(&o->oid), path) < 0)
return -1;
}
return 0;
}
-static int generate_info_refs(FILE *fp)
+static int generate_info_refs(struct update_info_ctx *uic)
{
- return for_each_ref(add_info_ref, fp);
+ return for_each_ref(add_info_ref, uic);
}
static int update_info_refs(int force)
@@ -281,14 +328,14 @@ static void free_pack_info(void)
free(info);
}
-static int write_pack_info_file(FILE *fp)
+static int write_pack_info_file(struct update_info_ctx *uic)
{
int i;
for (i = 0; i < num_pack; i++) {
- if (fprintf(fp, "P %s\n", pack_basename(info[i]->p)) < 0)
+ if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
return -1;
}
- if (fputc('\n', fp) == EOF)
+ if (uic_printf(uic, "\n") < 0)
return -1;
return 0;
}
Documentation/git-update-server-info.txt | 11 +-
server-info.c | 140 +++++++++++++++++++----
t/t5200-update-server-info.sh | 41 +++++++
3 files changed, 158 insertions(+), 34 deletions(-)
create mode 100755 t/t5200-update-server-info.sh
diff --git a/Documentation/git-update-server-info.txt
b/Documentation/git-update-server-info.txt
index bd0e36492f..969bb2e15f 100644
--- a/Documentation/git-update-server-info.txt
+++ b/Documentation/git-update-server-info.txt
@@ -9,7 +9,7 @@ git-update-server-info - Update auxiliary info file to help
dumb servers
SYNOPSIS
--------
[verse]
-'git update-server-info' [--force]
+'git update-server-info'
DESCRIPTION
-----------
@@ -19,15 +19,6 @@ $GIT_OBJECT_DIRECTORY/info directories to help clients
discover
what references and packs the server has. This command
generates such auxiliary files.
-
-OPTIONS
--------
-
--f::
---force::
- Update the info files from scratch.
-
-
OUTPUT
------
diff --git a/server-info.c b/server-info.c
index 41274d098b..e68f785c2f 100644
--- a/server-info.c
+++ b/server-info.c
@@ -6,82 +6,174 @@
#include "tag.h"
#include "packfile.h"
#include "object-store.h"
+#include "strbuf.h"
+
+struct update_info_ctx {
+ FILE *cur_fp;
+ FILE *old_fp; /* becomes NULL if it differs from cur_fp */
+ struct strbuf cur_sb;
+ struct strbuf old_sb;
+};
+
+static void uic_mark_stale(struct update_info_ctx *uic)
+{
+ fclose(uic->old_fp);
+ uic->old_fp = NULL;
+}
+
+static int uic_is_stale(const struct update_info_ctx *uic)
+{
+ return uic->old_fp == NULL;
+}
+
+static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
+{
+ va_list ap;
+ int ret = -1;
+
+ va_start(ap, fmt);
+
+ if (uic_is_stale(uic)) {
+ ret = vfprintf(uic->cur_fp, fmt, ap);
+ } else {
+ ssize_t r;
+ struct strbuf *cur = &uic->cur_sb;
+ struct strbuf *old = &uic->old_sb;
+
+ strbuf_reset(cur);
+ strbuf_vinsertf(cur, 0, fmt, ap);
+
+ strbuf_reset(old);
+ strbuf_grow(old, cur->len);
+ r = fread(old->buf, 1, cur->len, uic->old_fp);
+ if (r != cur->len || memcmp(old->buf, cur->buf, r))
+ uic_mark_stale(uic);
+
+ if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
+ ret = 0;
+ }
+
+ va_end(ap);
+
+ return ret;
+}
/*
* Create the file "path" by writing to a temporary file and renaming
* it into place. The contents of the file come from "generate", which
* should return non-zero if it encounters an error.
*/
-static int update_info_file(char *path, int (*generate)(FILE *))
+static int update_info_file(char *path,
+ int (*generate)(struct update_info_ctx *),
+ int force)
{
char *tmp = mkpathdup("%s_XXXXXX", path);
int ret = -1;
int fd = -1;
- FILE *fp = NULL, *to_close;
+ FILE *to_close;
+ struct update_info_ctx uic = {
+ .cur_fp = NULL,
+ .old_fp = NULL,
+ .cur_sb = STRBUF_INIT,
+ .old_sb = STRBUF_INIT
+ };
safe_create_leading_directories(path);
fd = git_mkstemp_mode(tmp, 0666);
if (fd < 0)
goto out;
- to_close = fp = fdopen(fd, "w");
- if (!fp)
+ to_close = uic.cur_fp = fdopen(fd, "w");
+ if (!uic.cur_fp)
goto out;
fd = -1;
- ret = generate(fp);
+
+ /* no problem on ENOENT and old_fp == NULL, it's stale, now */
+ if (!force)
+ uic.old_fp = fopen_or_warn(path, "r");
+
+ /*
+ * uic_printf will compare incremental comparison aginst old_fp
+ * and mark uic as stale if needed
+ */
+ ret = generate(&uic);
if (ret)
goto out;
- fp = NULL;
+
+ /* new file may be shorter than the old one, check here */
+ if (!uic_is_stale(&uic)) {
+ struct stat st;
+ long new_len = ftell(uic.cur_fp);
+ int old_fd = fileno(uic.old_fp);
+
+ if (new_len < 0) {
+ ret = -1;
+ goto out;
+ }
+ if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
+ uic_mark_stale(&uic);
+ }
+
+ uic.cur_fp = NULL;
if (fclose(to_close))
goto out;
- if (adjust_shared_perm(tmp) < 0)
- goto out;
- if (rename(tmp, path) < 0)
- goto out;
+
+ if (uic_is_stale(&uic)) {
+ if (adjust_shared_perm(tmp) < 0)
+ goto out;
+ if (rename(tmp, path) < 0)
+ goto out;
+ } else {
+ unlink(tmp);
+ }
ret = 0;
out:
if (ret) {
error_errno("unable to update %s", path);
- if (fp)
- fclose(fp);
+ if (uic.cur_fp)
+ fclose(uic.cur_fp);
else if (fd >= 0)
close(fd);
unlink(tmp);
}
free(tmp);
+ if (uic.old_fp)
+ fclose(uic.old_fp);
+ strbuf_release(&uic.old_sb);
+ strbuf_release(&uic.cur_sb);
return ret;
}
static int add_info_ref(const char *path, const struct object_id *oid,
int flag, void *cb_data)
{
- FILE *fp = cb_data;
+ struct update_info_ctx *uic = cb_data;
struct object *o = parse_object(the_repository, oid);
if (!o)
return -1;
- if (fprintf(fp, "%s %s\n", oid_to_hex(oid), path) < 0)
+ if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
return -1;
if (o->type == OBJ_TAG) {
o = deref_tag(the_repository, o, path, 0);
if (o)
- if (fprintf(fp, "%s %s^{}\n",
+ if (uic_printf(uic, "%s %s^{}\n",
oid_to_hex(&o->oid), path) < 0)
return -1;
}
return 0;
}
-static int generate_info_refs(FILE *fp)
+static int generate_info_refs(struct update_info_ctx *uic)
{
- return for_each_ref(add_info_ref, fp);
+ return for_each_ref(add_info_ref, uic);
}
-static int update_info_refs(void)
+static int update_info_refs(int force)
{
char *path = git_pathdup("info/refs");
- int ret = update_info_file(path, generate_info_refs);
+ int ret = update_info_file(path, generate_info_refs, force);
free(path);
return ret;
}
@@ -236,14 +328,14 @@ static void free_pack_info(void)
free(info);
}
-static int write_pack_info_file(FILE *fp)
+static int write_pack_info_file(struct update_info_ctx *uic)
{
int i;
for (i = 0; i < num_pack; i++) {
- if (fprintf(fp, "P %s\n", pack_basename(info[i]->p)) < 0)
+ if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
return -1;
}
- if (fputc('\n', fp) == EOF)
+ if (uic_printf(uic, "\n") < 0)
return -1;
return 0;
}
@@ -254,7 +346,7 @@ static int update_info_packs(int force)
int ret;
init_pack_info(infofile, force);
- ret = update_info_file(infofile, write_pack_info_file);
+ ret = update_info_file(infofile, write_pack_info_file, force);
free_pack_info();
free(infofile);
return ret;
@@ -269,7 +361,7 @@ int update_server_info(int force)
*/
int errs = 0;
- errs = errs | update_info_refs();
+ errs = errs | update_info_refs(force);
errs = errs | update_info_packs(force);
/* remove leftover rev-cache file if there is any */
diff --git a/t/t5200-update-server-info.sh b/t/t5200-update-server-info.sh
new file mode 100755
index 0000000000..21a58eecb9
--- /dev/null
+++ b/t/t5200-update-server-info.sh
@@ -0,0 +1,41 @@
+#!/bin/sh
+
+test_description='Test git update-server-info'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' 'test_commit file'
+
+test_expect_success 'create info/refs' '
+ git update-server-info &&
+ test_path_is_file .git/info/refs
+'
+
+test_expect_success 'modify and store mtime' '
+ test-tool chmtime =0 .git/info/refs &&
+ test-tool chmtime --get .git/info/refs >a
+'
+
+test_expect_success 'info/refs is not needlessly overwritten' '
+ git update-server-info &&
+ test-tool chmtime --get .git/info/refs >b &&
+ test_cmp a b
+'
+
+test_expect_success 'info/refs can be forced to update' '
+ git update-server-info -f &&
+ test-tool chmtime --get .git/info/refs >b &&
+ ! test_cmp a b
+'
+
+test_expect_success 'info/refs updates when changes are made' '
+ test-tool chmtime =0 .git/info/refs &&
+ test-tool chmtime --get .git/info/refs >b &&
+ test_cmp a b &&
+ git update-ref refs/heads/foo HEAD &&
+ git update-server-info &&
+ test-tool chmtime --get .git/info/refs >b &&
+ ! test_cmp a b
+'
+
+test_done
--
EW
