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-rw-r--r--refs.h77
1 files changed, 59 insertions, 18 deletions
diff --git a/refs.h b/refs.h
index ec46acd..68c5770 100644
--- a/refs.h
+++ b/refs.h
@@ -10,6 +10,38 @@ struct ref_lock {
int force_write;
};
+/*
+ * A ref_transaction represents a collection of ref 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.
+ *
+ * - 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.
+ *
+ * Error handling
+ * --------------
+ *
+ * On error, transaction functions append a message about what
+ * went wrong to the 'err' argument. The message mentions what
+ * ref was being updated (if any) when the error occurred so it
+ * can be passed to 'die' or 'error' as-is.
+ *
+ * The message is appended to err without first clearing err.
+ * err will not be '\n' terminated.
+ */
struct ref_transaction;
/*
@@ -141,14 +173,17 @@ extern int is_branch(const char *refname);
extern int peel_ref(const char *refname, unsigned char *sha1);
/*
- * Locks a "refs/" ref returning the lock on success and NULL on failure.
- * On failure errno is set to something meaningful.
+ * Flags controlling lock_any_ref_for_update(), ref_transaction_update(),
+ * ref_transaction_create(), etc.
+ * REF_NODEREF: act on the ref directly, instead of dereferencing
+ * symbolic references.
+ *
+ * Flags >= 0x100 are reserved for internal use.
*/
-extern struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1);
-
-/** Locks any ref (for 'HEAD' type refs). */
#define REF_NODEREF 0x01
-/* errno is set to something meaningful on failure */
+/*
+ * This function sets errno to something meaningful on failure.
+ */
extern struct ref_lock *lock_any_ref_for_update(const char *refname,
const unsigned char *old_sha1,
int flags, int *type_p);
@@ -232,7 +267,7 @@ enum action_on_err {
* Begin a reference transaction. The reference transaction must
* be freed by calling ref_transaction_free().
*/
-struct ref_transaction *ref_transaction_begin(void);
+struct ref_transaction *ref_transaction_begin(struct strbuf *err);
/*
* The following functions add a reference check or update to a
@@ -250,7 +285,7 @@ struct ref_transaction *ref_transaction_begin(void);
* it must not have existed beforehand.
* Function returns 0 on success and non-zero on failure. A failure to update
* means that the transaction as a whole has failed and will need to be
- * rolled back. On failure the err buffer will be updated.
+ * rolled back.
*/
int ref_transaction_update(struct ref_transaction *transaction,
const char *refname,
@@ -264,28 +299,34 @@ int ref_transaction_update(struct ref_transaction *transaction,
* that the reference should have after the update; it must not be the
* null SHA-1. It is verified that the reference does not exist
* already.
+ * Function returns 0 on success and non-zero on failure. A failure to create
+ * means that the transaction as a whole has failed and will need to be
+ * rolled back.
*/
-void ref_transaction_create(struct ref_transaction *transaction,
- const char *refname,
- const unsigned char *new_sha1,
- int flags);
+int ref_transaction_create(struct ref_transaction *transaction,
+ const char *refname,
+ const unsigned char *new_sha1,
+ int flags,
+ struct strbuf *err);
/*
* Add a reference deletion to transaction. If have_old is true, then
* old_sha1 holds the value that the reference should have had before
* the update (which must not be the null SHA-1).
+ * Function returns 0 on success and non-zero on failure. A failure to delete
+ * means that the transaction as a whole has failed and will need to be
+ * rolled back.
*/
-void ref_transaction_delete(struct ref_transaction *transaction,
- const char *refname,
- const unsigned char *old_sha1,
- int flags, int have_old);
+int ref_transaction_delete(struct ref_transaction *transaction,
+ const char *refname,
+ const unsigned char *old_sha1,
+ int flags, int have_old,
+ struct strbuf *err);
/*
* Commit all of the changes that have been queued in transaction, as
* atomically as possible. Return a nonzero value if there is a
* problem.
- * If err is non-NULL we will add an error string to it to explain why
- * the transaction failed. The string does not end in newline.
*/
int ref_transaction_commit(struct ref_transaction *transaction,
const char *msg, struct strbuf *err);