[PATCH v2 3/9] refs: add new field in transaction for running transaction hook

[Jiang Xin <worldhello.net@gmail.com>]

From: Jiang Xin <zhiyou.jx@alibaba-inc.com>

Add a new field "hook_flags" in transaction, and only run the
"reference-transaction" hook if the specific flag is turned on.

The "reference-transaction" hook has three states: prepared, committed,
and aborted. To update a reference, git may create two seperate
transactions, one for loose reference and one for packed ref-store. This
may cause duplicate running of the hook for same references. The new
field "hook_flags" in the transaction can turn off running a specific
transaction. In some scenarios, we may only want to turn off certain
states of a transaction, such as "committed" and "aborted", but want to
turn on the "prepared" state of the hook to do some pre-checks, so the
"hook_flags" field has three bits to control running of the three states
of the hook.

By calling the "ref_store_transaction_begin()" function, all the flags
of the "hook_flags" field for the new initialized transaction will be
turned on. The new function "ref_store_transaction_begin_extended()"
will be used in later commits with a specific "hook_flags" field to
initialize a new transaction.

Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
---
 refs.c               | 25 +++++++++++++++++++++++--
 refs.h               |  3 +++
 refs/refs-internal.h |  8 ++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/refs.c b/refs.c
index 90bcb27168..48b69460e2 100644
--- a/refs.c
+++ b/refs.c
@@ -998,17 +998,27 @@ int read_ref_at(struct ref_store *refs, const char *refname,
 	return 1;
 }
 
-struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
-						    struct strbuf *err)
+struct ref_transaction *ref_store_transaction_begin_extended(struct ref_store *refs,
+							     unsigned int hook_flags,
+							     struct strbuf *err)
 {
 	struct ref_transaction *tr;
 	assert(err);
 
 	CALLOC_ARRAY(tr, 1);
 	tr->ref_store = refs;
+	tr->hook_flags = hook_flags;
 	return tr;
 }
 
+struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
+						    struct strbuf *err)
+{
+	return ref_store_transaction_begin_extended(refs,
+						    REF_TRANSACTION_RUN_ALL_HOOKS,
+						    err);
+}
+
 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 {
 	return ref_store_transaction_begin(get_main_ref_store(the_repository), err);
@@ -2074,6 +2084,17 @@ static int run_transaction_hook(struct ref_transaction *transaction,
 	const char *hook;
 	int ret = 0, i;
 
+	if (!strcmp(state, "prepared")) {
+		if (!(transaction->hook_flags & REF_TRANSACTION_RUN_PREPARED_HOOK))
+			return 0;
+	} else if (!strcmp(state, "committed")) {
+		if (!(transaction->hook_flags & REF_TRANSACTION_RUN_COMMITTED_HOOK))
+			return 0;
+	} else if (!strcmp(state, "aborted")) {
+		if (!(transaction->hook_flags & REF_TRANSACTION_RUN_ABORTED_HOOK))
+			return 0;
+	}
+
 	hook = find_hook("reference-transaction");
 	if (!hook)
 		return ret;
diff --git a/refs.h b/refs.h
index 47cb9edbaa..715127ab58 100644
--- a/refs.h
+++ b/refs.h
@@ -570,6 +570,9 @@ enum action_on_err {
  * Begin a reference transaction.  The reference transaction must
  * be freed by calling ref_transaction_free().
  */
+struct ref_transaction *ref_store_transaction_begin_extended(struct ref_store *refs,
+							     unsigned int hook_flags,
+							     struct strbuf *err);
 struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
 						    struct strbuf *err);
 struct ref_transaction *ref_transaction_begin(struct strbuf *err);
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 69f93b0e2a..5220d1980d 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -201,6 +201,13 @@ enum ref_transaction_state {
 	REF_TRANSACTION_CLOSED   = 2
 };
 
+#define REF_TRANSACTION_RUN_PREPARED_HOOK (1 << 0)
+#define REF_TRANSACTION_RUN_COMMITTED_HOOK (1 << 1)
+#define REF_TRANSACTION_RUN_ABORTED_HOOK (1 << 2)
+#define REF_TRANSACTION_RUN_ALL_HOOKS         \
+	(REF_TRANSACTION_RUN_PREPARED_HOOK  | \
+	 REF_TRANSACTION_RUN_COMMITTED_HOOK | \
+	 REF_TRANSACTION_RUN_ABORTED_HOOK)
 /*
  * Data structure for holding a reference transaction, which can
  * consist of checks and updates to multiple references, carried out
@@ -212,6 +219,7 @@ struct ref_transaction {
 	size_t alloc;
 	size_t nr;
 	enum ref_transaction_state state;
+	unsigned int hook_flags;
 	void *backend_data;
 };
 
-- 
2.36.1.25.gc87d5ad63a.dirty