[Tarantool-patches] [PATCH 9/9] box.ctl: rename clear_synchro_queue to promote

[Serge Petrenko via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

New function name will be `box.ctl.promote()`. It's much shorter and
closer to the function's now enriched functionality.

Old name `box.ctl.clear_synchro_queue()` remains in Lua for the sake of
backward compatibility.

Follow-up #5445
Closes #3055

@TarantoolBot document
Title: deprecate `box.ctl.clear_synchro_queue()` in favor of `box.ctl.promote()`

Replace all the mentions of `box.ctl.clear_synchro_queue()` with
`box.ctl.promote()` and add a note that `box.ctl.clear_synchro_queue()`
is a deprecated alias to `box.ctl.promote()`
---
 changelogs/unreleased/box-ctl-promote.md |  8 ++++++++
 src/box/box.cc                           | 20 ++++++++++----------
 src/box/box.h                            |  2 +-
 src/box/lua/ctl.c                        |  8 +++++---
 src/box/raft.c                           |  4 ++--
 5 files changed, 26 insertions(+), 16 deletions(-)
 create mode 100644 changelogs/unreleased/box-ctl-promote.md

diff --git a/changelogs/unreleased/box-ctl-promote.md b/changelogs/unreleased/box-ctl-promote.md
new file mode 100644
index 000000000..15f6fb206
--- /dev/null
+++ b/changelogs/unreleased/box-ctl-promote.md
@@ -0,0 +1,8 @@
+## feature/replication
+
+* Introduce `box.ctl.promote()` and the concept of manual elections (enabled
+  with `election_mode='manual'`). Once the instance is in `manual` election
+  mode, it acts like a `voter` most of the time, but may trigger elections and
+  become a leader, once `box.ctl.promote()` is called.
+  When `election_mode ~= 'manual'`, `box.ctl.promote()` replaces
+  `box.ctl.clear_synchro_queue()`, which is now deprecated (gh-3055).
diff --git a/src/box/box.cc b/src/box/box.cc
index 41d2ff0f8..40467805b 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1509,12 +1509,12 @@ box_wait_quorum(uint32_t lead_id, int64_t target_lsn, int quorum,
 }
 
 int
-box_clear_synchro_queue(bool try_wait)
+box_promote(bool try_wait)
 {
 	/* A guard to block multiple simultaneous function invocations. */
-	static bool in_clear_synchro_queue = false;
-	if (in_clear_synchro_queue) {
-		diag_set(ClientError, ER_UNSUPPORTED, "clear_synchro_queue",
+	static bool in_promote = false;
+	if (in_promote) {
+		diag_set(ClientError, ER_UNSUPPORTED, "promote",
 			 "simultaneous invocations");
 		return -1;
 	}
@@ -1564,7 +1564,7 @@ box_clear_synchro_queue(bool try_wait)
 	int64_t wait_lsn = txn_limbo.confirmed_lsn;
 	int rc = 0;
 	int quorum = replication_synchro_quorum;
-	in_clear_synchro_queue = true;
+	in_promote = true;
 
 	if (run_elections) {
 		/*
@@ -1581,13 +1581,13 @@ box_clear_synchro_queue(bool try_wait)
 		raft_cfg_is_candidate(box_raft(), false, false);
 		if (!box_raft()->is_enabled) {
 			diag_set(ClientError, ER_RAFT_DISABLED);
-			in_clear_synchro_queue = false;
+			in_promote = false;
 			return -1;
 		}
 		if (box_raft()->state != RAFT_STATE_LEADER) {
 			diag_set(ClientError, ER_INTERFERING_PROMOTE,
 				 box_raft()->leader);
-			in_clear_synchro_queue = false;
+			in_promote = false;
 			return -1;
 		}
 	}
@@ -1611,13 +1611,13 @@ box_clear_synchro_queue(bool try_wait)
 		if (former_leader_id != txn_limbo.owner_id) {
 			diag_set(ClientError, ER_INTERFERING_PROMOTE,
 				 txn_limbo.owner_id);
-			in_clear_synchro_queue = false;
+			in_promote = false;
 			return -1;
 		}
 	}
 
 	/*
-	 * clear_synchro_queue() is a no-op on the limbo owner, so all the rows
+	 * promote() is a no-op on the limbo owner, so all the rows
 	 * in the limbo must've come through the applier meaning they already
 	 * have an lsn assigned, even if their WAL write hasn't finished yet.
 	 */
@@ -1654,7 +1654,7 @@ promote:
 						req.lsn);
 		}
 	}
-	in_clear_synchro_queue = false;
+	in_promote = false;
 	return rc;
 }
 
diff --git a/src/box/box.h b/src/box/box.h
index e2321b9b0..89c6fe1a1 100644
--- a/src/box/box.h
+++ b/src/box/box.h
@@ -274,7 +274,7 @@ extern "C" {
 typedef struct tuple box_tuple_t;
 
 int
-box_clear_synchro_queue(bool try_wait);
+box_promote(bool try_wait);
 
 /* box_select is private and used only by FFI */
 API_EXPORT int
diff --git a/src/box/lua/ctl.c b/src/box/lua/ctl.c
index d039a059f..f06af8588 100644
--- a/src/box/lua/ctl.c
+++ b/src/box/lua/ctl.c
@@ -82,9 +82,9 @@ lbox_ctl_on_schema_init(struct lua_State *L)
 }
 
 static int
-lbox_ctl_clear_synchro_queue(struct lua_State *L)
+lbox_ctl_promote(struct lua_State *L)
 {
-	if (box_clear_synchro_queue(true) != 0)
+	if (box_promote(true) != 0)
 		return luaT_error(L);
 	return 0;
 }
@@ -124,7 +124,9 @@ static const struct luaL_Reg lbox_ctl_lib[] = {
 	{"wait_rw", lbox_ctl_wait_rw},
 	{"on_shutdown", lbox_ctl_on_shutdown},
 	{"on_schema_init", lbox_ctl_on_schema_init},
-	{"clear_synchro_queue", lbox_ctl_clear_synchro_queue},
+	{"promote", lbox_ctl_promote},
+	/* An old alias. */
+	{"clear_synchro_queue", lbox_ctl_promote},
 	{"is_recovery_finished", lbox_ctl_is_recovery_finished},
 	{"set_on_shutdown_timeout", lbox_ctl_set_on_shutdown_timeout},
 	{NULL, NULL}
diff --git a/src/box/raft.c b/src/box/raft.c
index 47d4fd56d..45baf5dd8 100644
--- a/src/box/raft.c
+++ b/src/box/raft.c
@@ -91,7 +91,7 @@ box_raft_update_synchro_queue(struct raft *raft)
 	 * If the node became a leader, it means it will ignore all records from
 	 * all the other nodes, and won't get late CONFIRM messages anyway. Can
 	 * clear the queue without waiting for confirmations.
-	 * It's alright that the user may have called clear_synchro_queue
+	 * It's alright that the user may have called promote
 	 * manually. In this case the call below will exit immediately and we'll
 	 * simply log a warning.
 	 */
@@ -100,7 +100,7 @@ box_raft_update_synchro_queue(struct raft *raft)
 		int rc = 0;
 		uint32_t errcode = 0;
 		do {
-			rc = box_clear_synchro_queue(false);
+			rc = box_promote(false);
 			if (rc != 0) {
 				struct error *err = diag_last_error(diag_get());
 				errcode = box_error_code(err);
-- 
2.24.3 (Apple Git-128)