From: Han-Wen Nienhuys <hanwen@xxxxxxxxxx>
Take packed-refs.lock in the transaction_begin of the packed backend.
This decouples the files backend from the packed backend, allowing the
latter to be swapped out by another ref backend.
Signed-off-by: Han-Wen Nienhuys <hanwen@xxxxxxxxxx>
---
refs.c | 5 ++-
refs/files-backend.c | 78 +++++++++++++++----------------------------
refs/packed-backend.c | 55 ++++++++++++------------------
refs/packed-backend.h | 10 ------
4 files changed, 50 insertions(+), 98 deletions(-)
diff --git a/refs.c b/refs.c
index f7ba3e56284..0611197dc6e 100644
--- a/refs.c
+++ b/refs.c
@@ -2320,10 +2320,9 @@ int ref_transaction_abort(struct ref_transaction *transaction,
int ret = 0;
switch (transaction->state) {
- case REF_TRANSACTION_OPEN:
- /* No need to abort explicitly. */
- break;
case REF_TRANSACTION_PREPARED:
+ case REF_TRANSACTION_OPEN:
+ /* an OPEN transactions may have a lock. */
ret = refs->be->transaction_abort(refs, transaction, err);
break;
case REF_TRANSACTION_CLOSED:
diff --git a/refs/files-backend.c b/refs/files-backend.c
index d83eea8b408..43c1882be3c 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1219,10 +1219,10 @@ static int files_pack_refs(struct ref_store *ref_store,
struct ref_transaction *transaction;
transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
- if (!transaction)
+ if (!transaction) {
+ die("could not start transaction: %s", err.buf);
return -1;
-
- packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
+ }
iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL,
the_repository, 0);
@@ -1262,8 +1262,6 @@ static int files_pack_refs(struct ref_store *ref_store,
ref_transaction_free(transaction);
- packed_refs_unlock(refs->packed_ref_store);
-
prune_refs(refs, &refs_to_prune);
strbuf_release(&err);
return 0;
@@ -1280,16 +1278,10 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg,
if (!refnames->nr)
return 0;
- if (packed_refs_lock(refs->packed_ref_store, 0, &err))
- goto error;
-
if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
- packed_refs_unlock(refs->packed_ref_store);
goto error;
}
- packed_refs_unlock(refs->packed_ref_store);
-
for (i = 0; i < refnames->nr; i++) {
const char *refname = refnames->items[i].string;
@@ -2640,7 +2632,7 @@ out:
struct files_transaction_backend_data {
struct ref_transaction *packed_transaction;
- int packed_refs_locked;
+ int packed_transaction_needed;
};
/*
@@ -2672,10 +2664,8 @@ static void files_transaction_cleanup(struct files_ref_store *refs,
strbuf_release(&err);
}
- if (backend_data->packed_refs_locked)
- packed_refs_unlock(refs->packed_ref_store);
-
free(backend_data);
+ transaction->backend_data = NULL;
}
transaction->state = REF_TRANSACTION_CLOSED;
@@ -2811,14 +2801,9 @@ static int files_transaction_prepare(struct ref_store *ref_store,
}
if (packed_transaction) {
- if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
- ret = TRANSACTION_GENERIC_ERROR;
- goto cleanup;
- }
- backend_data->packed_refs_locked = 1;
-
- if (is_packed_transaction_needed(refs->packed_ref_store,
- packed_transaction)) {
+ backend_data->packed_transaction_needed = is_packed_transaction_needed(refs->packed_ref_store,
+ packed_transaction);
+ if (backend_data->packed_transaction_needed) {
ret = ref_transaction_prepare(packed_transaction, err);
/*
* A failure during the prepare step will abort
@@ -2830,22 +2815,6 @@ static int files_transaction_prepare(struct ref_store *ref_store,
ref_transaction_free(packed_transaction);
backend_data->packed_transaction = NULL;
}
- } else {
- /*
- * We can skip rewriting the `packed-refs`
- * file. But we do need to leave it locked, so
- * that somebody else doesn't pack a reference
- * that we are trying to delete.
- *
- * We need to disconnect our transaction from
- * backend_data, since the abort (whether successful or
- * not) will free it.
- */
- backend_data->packed_transaction = NULL;
- if (ref_transaction_abort(packed_transaction, err)) {
- ret = TRANSACTION_GENERIC_ERROR;
- goto cleanup;
- }
}
}
@@ -2947,13 +2916,24 @@ static int files_transaction_finish(struct ref_store *ref_store,
* First delete any packed versions of the references, while
* retaining the packed-refs lock:
*/
- if (packed_transaction) {
- ret = ref_transaction_commit(packed_transaction, err);
- ref_transaction_free(packed_transaction);
- packed_transaction = NULL;
- backend_data->packed_transaction = NULL;
- if (ret)
- goto cleanup;
+ if (backend_data->packed_transaction) {
+ if (backend_data->packed_transaction_needed) {
+ ret = ref_transaction_commit(packed_transaction, err);
+ if (ret)
+ goto cleanup;
+
+ ref_transaction_free(packed_transaction);
+ packed_transaction = NULL;
+ backend_data->packed_transaction = NULL;
+ } else {
+ ret = ref_transaction_abort(packed_transaction, err);
+ if (ret)
+ goto cleanup;
+
+ /* transaction_commit doesn't free the data, but transaction_abort does. Go figure. */
+ packed_transaction = NULL;
+ backend_data->packed_transaction = NULL;
+ }
}
/* Now delete the loose versions of the references: */
@@ -3094,16 +3074,10 @@ static int files_initial_transaction_commit(struct ref_store *ref_store,
NULL);
}
- if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
- ret = TRANSACTION_GENERIC_ERROR;
- goto cleanup;
- }
-
if (initial_ref_transaction_commit(packed_transaction, err)) {
ret = TRANSACTION_GENERIC_ERROR;
}
- packed_refs_unlock(refs->packed_ref_store);
cleanup:
if (packed_transaction)
ref_transaction_free(packed_transaction);
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 4f5b1025605..f8b27f1afe5 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -1153,7 +1153,7 @@ static int write_packed_entry(FILE *fh, const char *refname,
return 0;
}
-int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
+static int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
{
struct packed_ref_store *refs =
packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN,
@@ -1212,7 +1212,7 @@ int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
return 0;
}
-void packed_refs_unlock(struct ref_store *ref_store)
+static void packed_refs_unlock(struct ref_store *ref_store)
{
struct packed_ref_store *refs = packed_downcast(
ref_store,
@@ -1224,16 +1224,6 @@ void packed_refs_unlock(struct ref_store *ref_store)
rollback_lock_file(&refs->lock);
}
-int packed_refs_is_locked(struct ref_store *ref_store)
-{
- struct packed_ref_store *refs = packed_downcast(
- ref_store,
- REF_STORE_READ | REF_STORE_WRITE,
- "packed_refs_is_locked");
-
- return is_lock_file_locked(&refs->lock);
-}
-
/*
* The packed-refs header line that we write out. Perhaps other traits
* will be added later.
@@ -1552,8 +1542,6 @@ int is_packed_transaction_needed(struct ref_store *ref_store,
struct packed_transaction_backend_data {
/* True iff the transaction owns the packed-refs lock. */
- int own_lock;
-
struct string_list updates;
};
@@ -1568,9 +1556,8 @@ static void packed_transaction_cleanup(struct packed_ref_store *refs,
if (is_tempfile_active(refs->tempfile))
delete_tempfile(&refs->tempfile);
- if (data->own_lock && is_lock_file_locked(&refs->lock)) {
+ if (is_lock_file_locked(&refs->lock)) {
packed_refs_unlock(&refs->base);
- data->own_lock = 0;
}
free(data);
@@ -1580,12 +1567,25 @@ static void packed_transaction_cleanup(struct packed_ref_store *refs,
transaction->state = REF_TRANSACTION_CLOSED;
}
-
static struct ref_transaction *packed_transaction_begin(struct ref_store *ref_store,
- struct strbuf *err) {
- struct ref_transaction *tr;
- CALLOC_ARRAY(tr, 1);
- return tr;
+ struct strbuf *err)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
+ "ref_transaction_begin");
+ struct packed_transaction_backend_data *data;
+ struct ref_transaction *transaction;
+
+ if (!is_lock_file_locked(&refs->lock)) {
+ if (packed_refs_lock(ref_store, 0, err))
+ return NULL;
+ }
+ CALLOC_ARRAY(transaction, 1);
+ CALLOC_ARRAY(data, 1);
+ string_list_init_nodup(&data->updates);
+ transaction->backend_data = data;
+ return transaction;
}
static int packed_transaction_prepare(struct ref_store *ref_store,
@@ -1596,7 +1596,7 @@ static int packed_transaction_prepare(struct ref_store *ref_store,
ref_store,
REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
"ref_transaction_prepare");
- struct packed_transaction_backend_data *data;
+ struct packed_transaction_backend_data *data = transaction->backend_data;
size_t i;
int ret = TRANSACTION_GENERIC_ERROR;
@@ -1609,11 +1609,6 @@ static int packed_transaction_prepare(struct ref_store *ref_store,
* do so itself.
*/
- CALLOC_ARRAY(data, 1);
- string_list_init_nodup(&data->updates);
-
- transaction->backend_data = data;
-
/*
* Stick the updates in a string list by refname so that we
* can sort them:
@@ -1631,12 +1626,6 @@ static int packed_transaction_prepare(struct ref_store *ref_store,
if (ref_update_reject_duplicates(&data->updates, err))
goto failure;
- if (!is_lock_file_locked(&refs->lock)) {
- if (packed_refs_lock(ref_store, 0, err))
- goto failure;
- data->own_lock = 1;
- }
-
if (write_with_updates(refs, &data->updates, err))
goto failure;
diff --git a/refs/packed-backend.h b/refs/packed-backend.h
index 9dd8a344c34..ade3c8a5ac4 100644
--- a/refs/packed-backend.h
+++ b/refs/packed-backend.h
@@ -17,16 +17,6 @@ struct ref_store *packed_ref_store_create(struct repository *repo,
const char *gitdir,
unsigned int store_flags);
-/*
- * Lock the packed-refs file for writing. Flags is passed to
- * hold_lock_file_for_update(). Return 0 on success. On errors, write
- * an error message to `err` and return a nonzero value.
- */
-int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err);
-
-void packed_refs_unlock(struct ref_store *ref_store);
-int packed_refs_is_locked(struct ref_store *ref_store);
-
/*
* Return true if `transaction` really needs to be carried out against
* the specified packed_ref_store, or false if it can be skipped
--
gitgitgadget
