lua: implement timeout for 'fiber:join'

Implement ability to pass timeout to 'fiber:join' function.
If timeout expired, join fails with 'timed out' error.

Closes #6203

@TarantoolBot document
Title: ability to set timeout for 'fiber:join' function was implemented
Implement ability to pass timeout to 'fiber:join' function.
If timeout expired, join fails with 'timed out' error.

changelogs/unreleased/gh-6203-implement-fiber-join-with-timeout.md

+## feature/core
+
+* Implement timeout for 'fiber:join' in lua (gh-6203).
\ No newline at end of file

src/lua/fiber.c

@@ -809,13 +809,20 @@ lbox_fiber_join(struct lua_State *L)
 
 	if (!(fiber->flags & FIBER_IS_JOINABLE))
 		luaL_error(L, "the fiber is not joinable");
-	fiber_join(fiber);
+	double timeout = TIMEOUT_INFINITY;
+	if (!lua_isnoneornil(L, 2)) {
+		if (!lua_isnumber(L, 2) ||
+		    (timeout = lua_tonumber(L, 2)) < .0) {
+			luaL_error(L, "fiber:join(timeout): bad arguments");
+		}
+	}
+	int rc = fiber_join_timeout(fiber, timeout);
 
 	if (child_L != NULL) {
 		coro_ref = lua_tointeger(child_L, -1);
 		lua_pop(child_L, 1);
 	}
-	if (fiber->f_ret != 0) {
+	if (rc != 0) {
 		/*
 		 * After fiber_join the error of fiber being joined was moved to
 		 * current fiber diag so we have to get it from there.

test/app/gh-6203-fiber-join-with-timeout.result

+fiber = require('fiber')
+---
+...
+timeout = 10
+---
+...
+function sleep(timeout) \
+    channel:get() \
+    fiber.sleep(timeout) \
+end
+---
+...
+channel = fiber.channel()
+---
+...
+f = fiber.create(sleep, timeout)
+---
+...
+f:set_joinable(true)
+---
+...
+channel:put(true)
+---
+- true
+...
+f:join(0.1) -- Join failed because of timeout
+---
+- false
+- timed out
+...
+timeout = 0.2
+---
+...
+f = fiber.create(sleep, timeout)
+---
+...
+f:set_joinable(true)
+---
+...
+channel:put(true)
+---
+- true
+...
+f:join("xxx") --error: 'fiber:join(timeout): bad arguments'
+---
+- error: 'fiber:join(timeout): bad arguments'
+...
+f:join(-1) --error: 'fiber:join(timeout): bad arguments'
+---
+- error: 'fiber:join(timeout): bad arguments'
+...

test/app/gh-6203-fiber-join-with-timeout.test.lua

+fiber = require('fiber')
+
+timeout = 10
+function sleep(timeout) \
+    channel:get() \
+    fiber.sleep(timeout) \
+end
+
+channel = fiber.channel()
+f = fiber.create(sleep, timeout)
+f:set_joinable(true)
+channel:put(true)
+f:join(0.1) -- Join failed because of timeout
+
+timeout = 0.2
+f = fiber.create(sleep, timeout)
+f:set_joinable(true)
+channel:put(true)
+f:join("xxx") --error: 'fiber:join(timeout): bad arguments'
+f:join(-1) --error: 'fiber:join(timeout): bad arguments'
+