diff options
Diffstat (limited to 'refs.h')
| -rw-r--r-- | refs.h | 154 |
1 files changed, 121 insertions, 33 deletions
@@ -143,30 +143,71 @@ int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref); int dwim_log(const char *str, int len, unsigned char *sha1, char **ref); /* - * A ref_transaction represents a collection of ref updates - * that should succeed or fail together. + * A ref_transaction represents a collection of reference updates that + * should succeed or fail together. * * Calling sequence * ---------------- + * * - Allocate and initialize a `struct ref_transaction` by calling * `ref_transaction_begin()`. * - * - List intended ref updates by calling functions like - * `ref_transaction_update()` and `ref_transaction_create()`. - * - * - Call `ref_transaction_commit()` to execute the transaction. - * If this succeeds, the ref updates will have taken place and - * the transaction cannot be rolled back. - * - * - Instead of `ref_transaction_commit`, use - * `initial_ref_transaction_commit()` if the ref database is known - * to be empty (e.g. during clone). This is likely to be much - * faster. - * - * - At any time call `ref_transaction_free()` to discard the - * transaction and free associated resources. In particular, - * this rolls back the transaction if it has not been - * successfully committed. + * - Specify the intended ref updates by calling one or more of the + * following functions: + * - `ref_transaction_update()` + * - `ref_transaction_create()` + * - `ref_transaction_delete()` + * - `ref_transaction_verify()` + * + * - Then either: + * + * - Optionally call `ref_transaction_prepare()` to prepare the + * transaction. This locks all references, checks preconditions, + * etc. but doesn't finalize anything. If this step fails, the + * transaction has been closed and can only be freed. If this step + * succeeds, then `ref_transaction_commit()` is almost certain to + * succeed. However, you can still call `ref_transaction_abort()` + * if you decide not to commit the transaction after all. + * + * - Call `ref_transaction_commit()` to execute the transaction, + * make the changes permanent, and release all locks. If you + * haven't already called `ref_transaction_prepare()`, then + * `ref_transaction_commit()` calls it for you. + * + * Or + * + * - Call `initial_ref_transaction_commit()` if the ref database is + * known to be empty and have no other writers (e.g. during + * clone). This is likely to be much faster than + * `ref_transaction_commit()`. `ref_transaction_prepare()` should + * *not* be called before `initial_ref_transaction_commit()`. + * + * - Then finally, call `ref_transaction_free()` to free the + * `ref_transaction` data structure. + * + * At any time before calling `ref_transaction_commit()`, you can call + * `ref_transaction_abort()` to abort the transaction, rollback any + * locks, and free any associated resources (including the + * `ref_transaction` data structure). + * + * Putting it all together, a complete reference update looks like + * + * struct ref_transaction *transaction; + * struct strbuf err = STRBUF_INIT; + * int ret = 0; + * + * transaction = ref_store_transaction_begin(refs, &err); + * if (!transaction || + * ref_transaction_update(...) || + * ref_transaction_create(...) || + * ...etc... || + * ref_transaction_commit(transaction, &err)) { + * error("%s", err.buf); + * ret = -1; + * } + * ref_transaction_free(transaction); + * strbuf_release(&err); + * return ret; * * Error handling * -------------- @@ -183,8 +224,9 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **ref); * ------- * * Note that no locks are taken, and no refs are read, until - * `ref_transaction_commit` is called. So `ref_transaction_verify` - * won't report a verification failure until the commit is attempted. + * `ref_transaction_prepare()` or `ref_transaction_commit()` is + * called. So, for example, `ref_transaction_verify()` won't report a + * verification failure until the commit is attempted. */ struct ref_transaction; @@ -261,7 +303,10 @@ int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data); int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data); int for_each_ref_in_submodule(const char *submodule, const char *prefix, - each_ref_fn fn, void *cb_data); + each_ref_fn fn, void *cb_data); +int for_each_fullref_in_submodule(const char *submodule, const char *prefix, + each_ref_fn fn, void *cb_data, + unsigned int broken); int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data); int for_each_branch_ref_submodule(const char *submodule, @@ -331,7 +376,8 @@ int reflog_exists(const char *refname); * verify that the current value of the reference is old_sha1 before * deleting it. If old_sha1 is NULL, delete the reference if it * exists, regardless of its old value. It is an error for old_sha1 to - * be NULL_SHA1. flags is passed through to ref_transaction_delete(). + * be NULL_SHA1. msg and flags are passed through to + * ref_transaction_delete(). */ int refs_delete_ref(struct ref_store *refs, const char *msg, const char *refname, @@ -343,12 +389,13 @@ int delete_ref(const char *msg, const char *refname, /* * Delete the specified references. If there are any problems, emit * errors but attempt to keep going (i.e., the deletes are not done in - * an all-or-nothing transaction). flags is passed through to + * an all-or-nothing transaction). msg and flags are passed through to * ref_transaction_delete(). */ -int refs_delete_refs(struct ref_store *refs, struct string_list *refnames, - unsigned int flags); -int delete_refs(struct string_list *refnames, unsigned int flags); +int refs_delete_refs(struct ref_store *refs, const char *msg, + struct string_list *refnames, unsigned int flags); +int delete_refs(const char *msg, struct string_list *refnames, + unsigned int flags); /** Delete a reflog */ int refs_delete_reflog(struct ref_store *refs, const char *refname); @@ -427,6 +474,19 @@ struct ref_transaction *ref_transaction_begin(struct strbuf *err); * * refname -- the name of the reference to be affected. * + * new_sha1 -- the SHA-1 that should be set to be the new value of + * the reference. Some functions allow this parameter to be + * NULL, meaning that the reference is not changed, or + * null_sha1, meaning that the reference should be deleted. A + * copy of this value is made in the transaction. + * + * old_sha1 -- the SHA-1 value that the reference must have before + * the update. Some functions allow this parameter to be NULL, + * meaning that the old value of the reference is not checked, + * or null_sha1, meaning that the reference must not exist + * before the update. A copy of this value is made in the + * transaction. + * * flags -- flags affecting the update, passed to * update_ref_lock(). Can be REF_NODEREF, which means that * symbolic references should not be followed. @@ -508,20 +568,48 @@ int ref_transaction_verify(struct ref_transaction *transaction, unsigned int flags, struct strbuf *err); -/* - * Commit all of the changes that have been queued in transaction, as - * atomically as possible. - * - * Returns 0 for success, or one of the below error codes for errors. - */ /* Naming conflict (for example, the ref names A and A/B conflict). */ #define TRANSACTION_NAME_CONFLICT -1 /* All other errors. */ #define TRANSACTION_GENERIC_ERROR -2 + +/* + * Perform the preparatory stages of committing `transaction`. Acquire + * any needed locks, check preconditions, etc.; basically, do as much + * as possible to ensure that the transaction will be able to go + * through, stopping just short of making any irrevocable or + * user-visible changes. The updates that this function prepares can + * be finished up by calling `ref_transaction_commit()` or rolled back + * by calling `ref_transaction_abort()`. + * + * On success, return 0 and leave the transaction in "prepared" state. + * On failure, abort the transaction, write an error message to `err`, + * and return one of the `TRANSACTION_*` constants. + * + * Callers who don't need such fine-grained control over committing + * reference transactions should just call `ref_transaction_commit()`. + */ +int ref_transaction_prepare(struct ref_transaction *transaction, + struct strbuf *err); + +/* + * Commit all of the changes that have been queued in transaction, as + * atomically as possible. On success, return 0 and leave the + * transaction in "closed" state. On failure, roll back the + * transaction, write an error message to `err`, and return one of the + * `TRANSACTION_*` constants + */ int ref_transaction_commit(struct ref_transaction *transaction, struct strbuf *err); /* + * Abort `transaction`, which has been begun and possibly prepared, + * but not yet committed. + */ +int ref_transaction_abort(struct ref_transaction *transaction, + struct strbuf *err); + +/* * Like ref_transaction_commit(), but optimized for creating * references when originally initializing a repository (e.g., by "git * clone"). It writes the new references directly to packed-refs @@ -536,7 +624,7 @@ int initial_ref_transaction_commit(struct ref_transaction *transaction, struct strbuf *err); /* - * Free an existing transaction and all associated data. + * Free `*transaction` and all associated data. */ void ref_transaction_free(struct ref_transaction *transaction); |