replicaset_mode: allow api call in init state

In replicaset mode, the user can attempt to call public methods on the replica start.
For example, a single script is used for master and replica.

This patch allows you to call a public method in the INIT state without
interrupting the script by exiting with an obscure error.
It will only log an attempt to call a method from the check_state function,
which is present at the beginning of each public method.

Closes #216

CHANGELOG.md

@@ -5,6 +5,27 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+- In replicaset mode, the behavior of the public API is reduced to the same behavior
+  in all queue states, including INIT. Previously, in the INIT state, an ambiguous
+  error was thrown when trying to access a public method on a replica and the script
+  was interrupted by an error.
+
+  Old behavior (call `create_tube` on replica, queue is in INIT state):
+  ```
+  2023-09-04 14:01:11.000 [5990] main/103/replica.lua/box.load_cfg I> set 'read_only' configuration option to true
+  stack traceback:
+    /home/void/tmp/cluster/repl/queue/init.lua:44: in function '__index'
+    replica.lua:13: in main chunk
+  2023-09-04 14:01:11.004 [5990] main/105/checkpoint_daemon I> scheduled next checkpoint for Mon Sep  4 15:11:32 2023
+  2023-09-04 14:01:11.004 [5990] main utils.c:610 E> LuajitError: /home/void/tmp/cluster/repl/queue/init.lua:45: Please configure box.cfg{} in read/write mode first
+  ```
+  After this fix:
+  ```
+  2023-09-11 10:24:31.463 [19773] main/103/replica.lua abstract.lua:93 E> create_tube: queue is in INIT state
+  ```
+
 ## [1.3.2] - 2023-08-24
 
 ### Fixed

queue/init.lua

@@ -1,3 +1,4 @@
+local abstract = require('queue.abstract')
 local queue_state = require('queue.abstract.queue_state')
 local queue = nil
 
@@ -40,9 +41,18 @@ queue = setmetatable({
     state = queue_state.show,
     cfg = deferred_cfg,
     _VERSION = require('queue.version'),
-}, { __index = function()
-        print(debug.traceback())
-        error('Please configure box.cfg{} in read/write mode first')
+}, { __index = function(self, key)
+        -- In replicaset mode, the user can attempt to call public methods on the replica start.
+        -- For example, a single script is used for master and replica.
+        -- Each public method has a check on the state of the queue, so this forwarding is safe.
+        if deferred_opts['in_replicaset'] == true then
+            if abstract[key] ~= nil then
+                return abstract[key]
+            end
+        else
+            print(debug.traceback())
+            error('Please configure box.cfg{} in read/write mode first')
+        end
     end
 })
 

t/200-master-replica.t

@@ -24,7 +24,7 @@ local conn = {}
 test:plan(8)
 
 test:test('Check master-replica setup', function(test)
-    test:plan(8)
+    test:plan(9)
     local engine = os.getenv('ENGINE') or 'memtx'
     tnt.cluster.cfg{}
 
@@ -41,6 +41,8 @@ test:test('Check master-replica setup', function(test)
 
     -- Setup tube. Set ttr = 0.5 for sessions expire testing.
     conn:call('queue.cfg', {{ttr = 0.5, in_replicaset = true}})
+    test:isnil(conn:call('queue.create_tube', {'test', 'fifo'}),
+        'check api call in INIT state')
     queue.cfg{ttr = 0.5, in_replicaset = true}
     local tube = queue.create_tube('test', 'fifo', {engine = engine})
     test:ok(tube, 'test tube created')