Merge pull request #2448 from libgit2/cmn/reference-transaction

Introduce reference transactions

4 files changed, 128 insertions, 1 deletions

diff --git a/include/git2/reflog.h b/include/git2/reflog.h
index ac42a231c..c949a28f0 100644
--- a/include/git2/reflog.h
+++ b/include/git2/reflog.h
@@ -102,7 +102,7 @@ GIT_EXTERN(size_t) git_reflog_entrycount(git_reflog *reflog);
  * equal to 0 (zero) and less than `git_reflog_entrycount()`.
  * @return the entry; NULL if not found
  */
-GIT_EXTERN(const git_reflog_entry *) git_reflog_entry_byindex(git_reflog *reflog, size_t idx);
+GIT_EXTERN(const git_reflog_entry *) git_reflog_entry_byindex(const git_reflog *reflog, size_t idx);
 
 /**
  * Remove an entry from the reflog by its index
diff --git a/include/git2/sys/refdb_backend.h b/include/git2/sys/refdb_backend.h
index 3b216a287..d943e550f 100644
--- a/include/git2/sys/refdb_backend.h
+++ b/include/git2/sys/refdb_backend.h
@@ -153,6 +153,19 @@ struct git_refdb_backend {
 	 * Remove a reflog.
 	 */
 	int (*reflog_delete)(git_refdb_backend *backend, const char *name);
+
+	/**
+	 * Lock a reference. The opaque parameter will be passed to the unlock function
+	 */
+	int (*lock)(void **payload_out, git_refdb_backend *backend, const char *refname);
+
+	/**
+	 * Unlock a reference. Only one of target or symbolic_target
+	 * will be set. success indicates whether to update the
+	 * reference or discard the lock (if it's false)
+	 */
+	int (*unlock)(git_refdb_backend *backend, void *payload, int success, int update_reflog,
+		      const git_reference *ref, const git_signature *sig, const char *message);
 };
 
 #define GIT_REFDB_BACKEND_VERSION 1
diff --git a/include/git2/transaction.h b/include/git2/transaction.h
new file mode 100644
index 000000000..64abb0c69
--- /dev/null
+++ b/include/git2/transaction.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_transaction_h__
+#define INCLUDE_git_transaction_h__
+
+#include "common.h"
+GIT_BEGIN_DECL
+
+/**
+ * Create a new transaction object
+ *
+ * This does not lock anything, but sets up the transaction object to
+ * know from which repository to lock.
+ *
+ * @param out the resulting transaction
+ * @param repo the repository in which to lock
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_transaction_new(git_transaction **out, git_repository *repo);
+
+/**
+ * Lock a reference
+ *
+ * Lock the specified reference. This is the first step to updating a
+ * reference.
+ *
+ * @param tx the transaction
+ * @param refname the reference to lock
+ * @return 0 or an error message
+ */
+GIT_EXTERN(int) git_transaction_lock_ref(git_transaction *tx, const char *refname);
+
+/**
+ * Set the target of a reference
+ *
+ * Set the target of the specified reference. This reference must be
+ * locked.
+ *
+ * @param tx the transaction
+ * @param refname reference to update
+ * @param target target to set the reference to
+ * @param sig signature to use in the reflog; pass NULL to read the identity from the config
+ * @param msg message to use in the reflog
+ * @return 0, GIT_ENOTFOUND if the reference is not among the locked ones, or an error code
+ */
+GIT_EXTERN(int) git_transaction_set_target(git_transaction *tx, const char *refname, const git_oid *target, const git_signature *sig, const char *msg);
+
+/**
+ * Set the target of a reference
+ *
+ * Set the target of the specified reference. This reference must be
+ * locked.
+ *
+ * @param tx the transaction
+ * @param refname reference to update
+ * @param target target to set the reference to
+ * @param sig signature to use in the reflog; pass NULL to read the identity from the config
+ * @param msg message to use in the reflog
+ * @return 0, GIT_ENOTFOUND if the reference is not among the locked ones, or an error code
+ */
+GIT_EXTERN(int) git_transaction_set_symbolic_target(git_transaction *tx, const char *refname, const char *target, const git_signature *sig, const char *msg);
+
+/**
+ * Set the reflog of a reference
+ *
+ * Set the specified reference's reflog. If this is combined with
+ * setting the target, that update won't be written to the reflog.
+ *
+ * @param tx the transaction
+ * @param refname the reference whose reflog to set
+ * @param reflog the reflog as it should be written out
+ * @return 0, GIT_ENOTFOUND if the reference is not among the locked ones, or an error code
+ */
+GIT_EXTERN(int) git_transaction_set_reflog(git_transaction *tx, const char *refname, const git_reflog *reflog);
+
+/**
+ * Remove a reference
+ *
+ * @param tx the transaction
+ * @param refname the reference to remove
+ * @return 0, GIT_ENOTFOUND if the reference is not among the locked ones, or an error code
+ */
+GIT_EXTERN(int) git_transaction_remove(git_transaction *tx, const char *refname);
+
+/**
+ * Commit the changes from the transaction
+ *
+ * Perform the changes that have been queued. The updates will be made
+ * one by one, and the first failure will stop the processing.
+ *
+ * @param tx the transaction
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_transaction_commit(git_transaction *tx);
+
+/**
+ * Free the resources allocated by this transaction
+ *
+ * If any references remain locked, they will be unlocked without any
+ * changes made to them.
+ *
+ * @param tx the transaction
+ */
+GIT_EXTERN(void) git_transaction_free(git_transaction *tx);
+
+GIT_END_DECL
+#endif
diff --git a/include/git2/types.h b/include/git2/types.h
index 7ee7cc344..14b7071d2 100644
--- a/include/git2/types.h
+++ b/include/git2/types.h
@@ -171,6 +171,9 @@ typedef struct git_reference git_reference;
 /** Iterator for references */
 typedef struct git_reference_iterator  git_reference_iterator;
 
+/** Transactional interface to references */
+typedef struct git_transaction git_transaction;
+
 /** Merge heads, the input to merge */
 typedef struct git_merge_head git_merge_head;