On 06/20/2014 04:43 PM, Ronnie Sahlberg wrote:
> Switch to using ref transactions in walker_fetch(). As part of the refactoring
> to use ref transactions we also fix a potential memory leak where in the
> original code if write_ref_sha1() would fail we would end up returning from
> the function without free()ing the msg string.
>
> Note that this function is only called when fetching from a remote HTTP
> repository onto the local (most of the time single-user) repository which
> likely means that the type of collissions that the previous locking would
s/collissions/collisions/
> protect against and cause the fetch to fail for to be even more rare.
Grammatico: s/to be/are/ ?
> Reviewed-by: Jonathan Nieder <jrnieder@xxxxxxxxx>
> Signed-off-by: Ronnie Sahlberg <sahlberg@xxxxxxxxxx>
> ---
> walker.c | 59 +++++++++++++++++++++++++++++++++++------------------------
> 1 file changed, 35 insertions(+), 24 deletions(-)
>
> diff --git a/walker.c b/walker.c
> index 1dd86b8..60d9f9e 100644
> --- a/walker.c
> +++ b/walker.c
> @@ -251,39 +251,36 @@ void walker_targets_free(int targets, char **target, const char **write_ref)
> int walker_fetch(struct walker *walker, int targets, char **target,
> const char **write_ref, const char *write_ref_log_details)
> {
> - struct ref_lock **lock = xcalloc(targets, sizeof(struct ref_lock *));
> + struct strbuf ref_name = STRBUF_INIT;
> + struct strbuf err = STRBUF_INIT;
> + struct ref_transaction *transaction = NULL;
> unsigned char *sha1 = xmalloc(targets * 20);
> - char *msg;
> - int ret;
> + char *msg = NULL;
> int i;
>
> save_commit_buffer = 0;
>
> - for (i = 0; i < targets; i++) {
> - if (!write_ref || !write_ref[i])
> - continue;
> -
> - lock[i] = lock_ref_sha1(write_ref[i], NULL);
> - if (!lock[i]) {
> - error("Can't lock ref %s", write_ref[i]);
> - goto unlock_and_fail;
> + if (write_ref) {
> + transaction = ref_transaction_begin(&err);
> + if (!transaction) {
> + error("%s", err.buf);
> + goto rollback_and_fail;
> }
> }
> -
Is there some reason why the transaction cannot be built up during a
single iteration over targets, thereby also avoiding the need for the
sha1[20*i] stuff? This seems like exactly the kind of situation where
transactions should *save* code. But perhaps I've overlooked a
dependency between the two loops.
> if (!walker->get_recover)
> for_each_ref(mark_complete, NULL);
>
> for (i = 0; i < targets; i++) {
> if (interpret_target(walker, target[i], &sha1[20 * i])) {
> error("Could not interpret response from server '%s' as something to pull", target[i]);
> - goto unlock_and_fail;
> + goto rollback_and_fail;
> }
> if (process(walker, lookup_unknown_object(&sha1[20 * i])))
> - goto unlock_and_fail;
> + goto rollback_and_fail;
> }
>
> if (loop(walker))
> - goto unlock_and_fail;
> + goto rollback_and_fail;
>
> if (write_ref_log_details) {
> msg = xmalloc(strlen(write_ref_log_details) + 12);
> @@ -294,19 +291,33 @@ int walker_fetch(struct walker *walker, int targets, char **target,
> for (i = 0; i < targets; i++) {
> if (!write_ref || !write_ref[i])
> continue;
> - ret = write_ref_sha1(lock[i], &sha1[20 * i], msg ? msg : "fetch (unknown)");
> - lock[i] = NULL;
> - if (ret)
> - goto unlock_and_fail;
> + strbuf_reset(&ref_name);
> + strbuf_addf(&ref_name, "refs/%s", write_ref[i]);
> + if (ref_transaction_update(transaction, ref_name.buf,
> + &sha1[20 * i], NULL, 0, 0,
> + &err)) {
> + error("%s", err.buf);
> + goto rollback_and_fail;
> + }
> + }
> + if (write_ref) {
> + if (ref_transaction_commit(transaction,
> + msg ? msg : "fetch (unknown)",
> + &err)) {
> + error("%s", err.buf);
> + goto rollback_and_fail;
> + }
> + ref_transaction_free(transaction);
> }
> - free(msg);
>
> + free(msg);
> return 0;
>
> -unlock_and_fail:
> - for (i = 0; i < targets; i++)
> - if (lock[i])
> - unlock_ref(lock[i]);
> +rollback_and_fail:
> + ref_transaction_free(transaction);
> + free(msg);
> + strbuf_release(&err);
> + strbuf_release(&ref_name);
>
> return -1;
> }
>
Michael
--
Michael Haggerty
mhagger@xxxxxxxxxxxx
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