Re: [PATCH v20 33/48] walker.c: use ref transaction for ref updates
From: Michael Haggerty <hidden>
Date: 2016-06-15 23:01:50
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/ ?
quoted hunk ↗ jump to hunk
Reviewed-by: Jonathan Nieder <redacted> Signed-off-by: Ronnie Sahlberg <redacted> --- 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.
quoted hunk ↗ jump to hunk
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@alum.mit.edu