[Tarantool-patches] [PATCH 2/2] fiber: use wakeup safely on self everywhere

[Vladislav Shpilevoy]

The previous commit made fiber_wakeup() safe to use on the current
fiber. Leverage the new behaviour everywhere in the source code to
remove all checks f != fiber() before fiber_wakeup(f) calls.

Follow-up #5292
---
 src/box/applier.cc  |  4 +---
 src/box/journal.c   |  6 ++++++
 src/box/journal.h   |  7 +++++++
 src/box/raft.c      | 14 +++-----------
 src/box/txn.c       |  6 ++----
 src/box/txn_limbo.c | 14 +-------------
 src/lib/swim/swim.c |  1 -
 7 files changed, 20 insertions(+), 32 deletions(-)

diff --git a/src/box/applier.cc b/src/box/applier.cc
index dc05c91d3..33181fdbf 100644
--- a/src/box/applier.cc
+++ b/src/box/applier.cc
@@ -792,9 +792,7 @@ apply_synchro_row_cb(struct journal_entry *entry)
 		txn_limbo_process(&txn_limbo, synchro_entry->req);
 		trigger_run(&replicaset.applier.on_wal_write, NULL);
 	}
-	/* The fiber is the same on final join. */
-	if (synchro_entry->owner != fiber())
-		fiber_wakeup(synchro_entry->owner);
+	fiber_wakeup(synchro_entry->owner);
 }
 
 /** Process a synchro request. */
diff --git a/src/box/journal.c b/src/box/journal.c
index 886a15139..df491610a 100644
--- a/src/box/journal.c
+++ b/src/box/journal.c
@@ -63,6 +63,12 @@ journal_entry_new(size_t n_rows, struct region *region,
 	return entry;
 }
 
+void
+journal_entry_fiber_wakeup_cb(struct journal_entry *entry)
+{
+	fiber_wakeup(entry->complete_data);
+}
+
 void
 journal_queue_wakeup(void)
 {
diff --git a/src/box/journal.h b/src/box/journal.h
index 8f3d56a61..4ab7e8afb 100644
--- a/src/box/journal.h
+++ b/src/box/journal.h
@@ -112,6 +112,13 @@ journal_entry_new(size_t n_rows, struct region *region,
 		  journal_write_async_f write_async_cb,
 		  void *complete_data);
 
+/**
+ * Treat complete_data like a fiber pointer and wake it up when journal write is
+ * done.
+ */
+void
+journal_entry_fiber_wakeup_cb(struct journal_entry *entry);
+
 struct journal_queue {
 	/** Maximal size of entries enqueued in journal (in bytes). */
 	int64_t max_size;
diff --git a/src/box/raft.c b/src/box/raft.c
index 47c869712..6b52c9876 100644
--- a/src/box/raft.c
+++ b/src/box/raft.c
@@ -155,8 +155,7 @@ box_raft_schedule_async(struct raft *raft)
 	 * adapted to this. Also don't wakeup the current fiber - it leads to
 	 * undefined behaviour.
 	 */
-	if ((box_raft_worker->flags & FIBER_IS_CANCELLABLE) != 0 &&
-	    fiber() != box_raft_worker)
+	if ((box_raft_worker->flags & FIBER_IS_CANCELLABLE) != 0)
 		fiber_wakeup(box_raft_worker);
 	box_raft_has_work = true;
 }
@@ -279,13 +278,6 @@ box_raft_broadcast(struct raft *raft, const struct raft_msg *msg)
 		relay_push_raft(replica->relay, &req);
 }
 
-/** Wakeup Raft state writer fiber waiting for WAL write end. */
-static void
-box_raft_write_cb(struct journal_entry *entry)
-{
-	fiber_wakeup(entry->complete_data);
-}
-
 static void
 box_raft_write(struct raft *raft, const struct raft_msg *msg)
 {
@@ -307,8 +299,8 @@ box_raft_write(struct raft *raft, const struct raft_msg *msg)
 
 	if (xrow_encode_raft(&row, region, &req) != 0)
 		goto fail;
-	journal_entry_create(entry, 1, xrow_approx_len(&row), box_raft_write_cb,
-			     fiber());
+	journal_entry_create(entry, 1, xrow_approx_len(&row),
+			     journal_entry_fiber_wakeup_cb, fiber());
 
 	/*
 	 * A non-cancelable fiber is considered non-wake-able, generally. Raft
diff --git a/src/box/txn.c b/src/box/txn.c
index 03b39e0de..07ab131a2 100644
--- a/src/box/txn.c
+++ b/src/box/txn.c
@@ -504,9 +504,7 @@ txn_free_or_wakeup(struct txn *txn)
 		txn_free(txn);
 	else {
 		txn_set_flags(txn, TXN_IS_DONE);
-		if (txn->fiber != fiber())
-			/* Wake a waiting fiber up. */
-			fiber_wakeup(txn->fiber);
+		fiber_wakeup(txn->fiber);
 	}
 }
 
@@ -578,7 +576,7 @@ txn_on_journal_write(struct journal_entry *entry)
 		txn_run_wal_write_triggers(txn);
 	if (!txn_has_flag(txn, TXN_WAIT_SYNC))
 		txn_complete_success(txn);
-	else if (txn->fiber != NULL && txn->fiber != fiber())
+	else if (txn->fiber != NULL)
 		fiber_wakeup(txn->fiber);
 finish:
 	fiber_set_txn(fiber(), NULL);
diff --git a/src/box/txn_limbo.c b/src/box/txn_limbo.c
index c22bd6665..5b23d1bb1 100644
--- a/src/box/txn_limbo.c
+++ b/src/box/txn_limbo.c
@@ -306,18 +306,6 @@ complete:
 	return 0;
 }
 
-/**
- * A callback for synchronous write: txn_limbo_write_synchro fiber
- * waiting to proceed once a record is written to WAL.
- */
-static void
-txn_limbo_write_cb(struct journal_entry *entry)
-{
-	assert(entry->complete_data != NULL);
-	if (fiber() != entry->complete_data)
-		fiber_wakeup(entry->complete_data);
-}
-
 static void
 txn_limbo_write_synchro(struct txn_limbo *limbo, uint16_t type, int64_t lsn,
 			uint64_t term)
@@ -346,7 +334,7 @@ txn_limbo_write_synchro(struct txn_limbo *limbo, uint16_t type, int64_t lsn,
 	xrow_encode_synchro(&row, body, &req);
 
 	journal_entry_create(entry, 1, xrow_approx_len(&row),
-			     txn_limbo_write_cb, fiber());
+			     journal_entry_fiber_wakeup_cb, fiber());
 
 	if (journal_write(entry) != 0 || entry->res < 0) {
 		diag_set(ClientError, ER_WAL_IO);
diff --git a/src/lib/swim/swim.c b/src/lib/swim/swim.c
index 1ecc90414..3955c3130 100644
--- a/src/lib/swim/swim.c
+++ b/src/lib/swim/swim.c
@@ -2219,7 +2219,6 @@ swim_kill_event_handler(struct swim *swim)
 	 * reused.
 	 */
 	swim->event_handler = NULL;
-	fiber_wakeup(f);
 	fiber_cancel(f);
 	fiber_join(f);
 }
-- 
2.24.3 (Apple Git-128)