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authorJunio C Hamano <gitster@pobox.com>2015-06-05 12:00:17 -0700
committerJunio C Hamano <gitster@pobox.com>2015-06-05 12:00:17 -0700
commit7c997bcbf68738f2b0cb1a94228ace211c9ba075 (patch)
tree4ab933551ca47ce565e9a1e56c4e98a2524e8823 /refs.c
parent4ba8846208858375fcac08381e47aa987176ef96 (diff)
parent185ce3a98c07a51c23339a372ba08585517802e6 (diff)
downloadgit-7c997bcbf68738f2b0cb1a94228ace211c9ba075.tar.gz
Merge branch 'mh/write-refs-sooner-2.4' into maint
Multi-ref transaction support we merged a few releases ago unnecessarily kept many file descriptors open, risking to fail with resource exhaustion. This is for 2.4.x track. * mh/write-refs-sooner-2.4: ref_transaction_commit(): fix atomicity and avoid fd exhaustion ref_transaction_commit(): remove the local flags variable ref_transaction_commit(): inline call to write_ref_sha1() rename_ref(): inline calls to write_ref_sha1() from this function commit_ref_update(): new function, extracted from write_ref_sha1() write_ref_to_lockfile(): new function, extracted from write_ref_sha1() t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE update-ref: test handling large transactions properly ref_transaction_commit(): fix atomicity and avoid fd exhaustion ref_transaction_commit(): remove the local flags variable ref_transaction_commit(): inline call to write_ref_sha1() rename_ref(): inline calls to write_ref_sha1() from this function commit_ref_update(): new function, extracted from write_ref_sha1() write_ref_to_lockfile(): new function, extracted from write_ref_sha1() t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE update-ref: test handling large transactions properly
Diffstat (limited to 'refs.c')
-rw-r--r--refs.c113
1 files changed, 82 insertions, 31 deletions
diff --git a/refs.c b/refs.c
index 97043fd2ef..67d6745e28 100644
--- a/refs.c
+++ b/refs.c
@@ -58,6 +58,12 @@ static unsigned char refname_disposition[256] = {
#define REF_HAVE_OLD 0x10
/*
+ * Used as a flag in ref_update::flags when the lockfile needs to be
+ * committed.
+ */
+#define REF_NEEDS_COMMIT 0x20
+
+/*
* Try to read one refname component from the front of refname.
* Return the length of the component found, or -1 if the component is
* not legal. It is legal if it is something reasonable to have under
@@ -2851,8 +2857,9 @@ static int rename_ref_available(const char *oldname, const char *newname)
return ret;
}
-static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
- const char *logmsg);
+static int write_ref_to_lockfile(struct ref_lock *lock, const unsigned char *sha1);
+static int commit_ref_update(struct ref_lock *lock,
+ const unsigned char *sha1, const char *logmsg);
int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
{
@@ -2912,7 +2919,9 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
goto rollback;
}
hashcpy(lock->old_sha1, orig_sha1);
- if (write_ref_sha1(lock, orig_sha1, logmsg)) {
+
+ if (write_ref_to_lockfile(lock, orig_sha1) ||
+ commit_ref_update(lock, orig_sha1, logmsg)) {
error("unable to write current sha1 into %s", newrefname);
goto rollback;
}
@@ -2929,7 +2938,8 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
flag = log_all_ref_updates;
log_all_ref_updates = 0;
- if (write_ref_sha1(lock, orig_sha1, NULL))
+ if (write_ref_to_lockfile(lock, orig_sha1) ||
+ commit_ref_update(lock, orig_sha1, NULL))
error("unable to write current sha1 into %s", oldrefname);
log_all_ref_updates = flag;
@@ -3103,11 +3113,11 @@ int is_branch(const char *refname)
}
/*
- * Write sha1 into the ref specified by the lock. Make sure that errno
- * is sane on error.
+ * Write sha1 into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile and set errno to reflect the problem.
*/
-static int write_ref_sha1(struct ref_lock *lock,
- const unsigned char *sha1, const char *logmsg)
+static int write_ref_to_lockfile(struct ref_lock *lock,
+ const unsigned char *sha1)
{
static char term = '\n';
struct object *o;
@@ -3136,6 +3146,17 @@ static int write_ref_sha1(struct ref_lock *lock,
errno = save_errno;
return -1;
}
+ return 0;
+}
+
+/*
+ * Commit a change to a loose reference that has already been written
+ * to the loose reference lockfile. Also update the reflogs if
+ * necessary, using the specified lockmsg (which can be NULL).
+ */
+static int commit_ref_update(struct ref_lock *lock,
+ const unsigned char *sha1, const char *logmsg)
+{
clear_loose_ref_cache(&ref_cache);
if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
(strcmp(lock->ref_name, lock->orig_ref_name) &&
@@ -3822,19 +3843,24 @@ int ref_transaction_commit(struct ref_transaction *transaction,
goto cleanup;
}
- /* Acquire all locks while verifying old values */
+ /*
+ * Acquire all locks, verify old values if provided, check
+ * that new values are valid, and write new values to the
+ * lockfiles, ready to be activated. Only keep one lockfile
+ * open at a time to avoid running out of file descriptors.
+ */
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
- unsigned int flags = update->flags;
- if ((flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
- flags |= REF_DELETING;
+ if ((update->flags & REF_HAVE_NEW) &&
+ is_null_sha1(update->new_sha1))
+ update->flags |= REF_DELETING;
update->lock = lock_ref_sha1_basic(
update->refname,
((update->flags & REF_HAVE_OLD) ?
update->old_sha1 : NULL),
&affected_refnames, NULL,
- flags,
+ update->flags,
&update->type,
err);
if (!update->lock) {
@@ -3849,34 +3875,60 @@ int ref_transaction_commit(struct ref_transaction *transaction,
free(reason);
goto cleanup;
}
- }
-
- /* Perform updates first so live commits remain referenced */
- for (i = 0; i < n; i++) {
- struct ref_update *update = updates[i];
- int flags = update->flags;
-
- if ((flags & REF_HAVE_NEW) && !is_null_sha1(update->new_sha1)) {
+ if ((update->flags & REF_HAVE_NEW) &&
+ !(update->flags & REF_DELETING)) {
int overwriting_symref = ((update->type & REF_ISSYMREF) &&
(update->flags & REF_NODEREF));
- if (!overwriting_symref
- && !hashcmp(update->lock->old_sha1, update->new_sha1)) {
+ if (!overwriting_symref &&
+ !hashcmp(update->lock->old_sha1, update->new_sha1)) {
/*
* The reference already has the desired
* value, so we don't need to write it.
*/
- unlock_ref(update->lock);
+ } else if (write_ref_to_lockfile(update->lock,
+ update->new_sha1)) {
+ /*
+ * The lock was freed upon failure of
+ * write_ref_to_lockfile():
+ */
+ update->lock = NULL;
+ strbuf_addf(err, "Cannot update the ref '%s'.",
+ update->refname);
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ } else {
+ update->flags |= REF_NEEDS_COMMIT;
+ }
+ }
+ if (!(update->flags & REF_NEEDS_COMMIT)) {
+ /*
+ * We didn't have to write anything to the lockfile.
+ * Close it to free up the file descriptor:
+ */
+ if (close_ref(update->lock)) {
+ strbuf_addf(err, "Couldn't close %s.lock",
+ update->refname);
+ goto cleanup;
+ }
+ }
+ }
+
+ /* Perform updates first so live commits remain referenced */
+ for (i = 0; i < n; i++) {
+ struct ref_update *update = updates[i];
+
+ if (update->flags & REF_NEEDS_COMMIT) {
+ if (commit_ref_update(update->lock,
+ update->new_sha1, update->msg)) {
+ /* freed by commit_ref_update(): */
update->lock = NULL;
- } else if (write_ref_sha1(update->lock, update->new_sha1,
- update->msg)) {
- update->lock = NULL; /* freed by write_ref_sha1 */
strbuf_addf(err, "Cannot update the ref '%s'.",
update->refname);
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
} else {
- /* freed by write_ref_sha1(): */
+ /* freed by commit_ref_update(): */
update->lock = NULL;
}
}
@@ -3885,15 +3937,14 @@ int ref_transaction_commit(struct ref_transaction *transaction,
/* Perform deletes now that updates are safely completed */
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
- int flags = update->flags;
- if ((flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1)) {
+ if (update->flags & REF_DELETING) {
if (delete_ref_loose(update->lock, update->type, err)) {
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
}
- if (!(flags & REF_ISPRUNING))
+ if (!(update->flags & REF_ISPRUNING))
string_list_append(&refs_to_delete,
update->lock->ref_name);
}