driver: fix duplicate id error with mvvc on

Taking the maximum of the index is an implicit transactions, so it is
always done with 'read-confirmed' mvcc isolation level.
It can lead to errors when trying to make parallel 'put' calls with mvcc enabled.
It is hapenning because 'max' for several puts in parallel will be the same since
read confirmed isolation level makes visible all transactions that finished the commit.
To fix it we wrap it with box.begin/commit and set right isolation level.

Closes #207

queue/abstract/driver/fifo.lua

@@ -66,9 +66,36 @@ function method.normalize_task(self, task)
     return task
 end
 
+-- check if mvcc is enabled
+local function check_mvcc_state()
+    local cfg = box.cfg
+    if cfg['memtx_use_mvcc_engine'] == nil  or cfg['memtx_use_mvcc_engine'] == false then
+        return false
+    end
+
+    return true
+end
+
 -- put task in space
 function method.put(self, data, opts)
-    local max = self.space.index.task_id:max()
+    local max
+
+    -- taking the maximum of the index is an implicit transactions, so it is
+    -- always done with 'read-confirmed' mvcc isolation level.
+    -- It can lead to errors when trying to make parallel 'put' calls with mvcc enabled.
+    -- It is hapenning because 'max' for several puts in parallel will be the same since
+    -- read confirmed isolation level makes visible all transactions that finished the commit.
+    -- To fix it we wrap it with box.begin/commit and set right isolation level.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+    if check_mvcc_state() then
+        box.begin({txn_isolation = 'read-committed'})
+        max = self.space.index.task_id:max()
+        box.commit()
+    else
+        max = self.space.index.task_id:max()
+    end
+
     local id = max and max[1] + 1 or 0
     local task = self.space:insert{id, state.READY, data}
     self.on_task_change(task, 'put')

queue/abstract/driver/fifottl.lua

@@ -207,9 +207,36 @@ function method.normalize_task(self, task)
     return task and task:transform(3, 5)
 end
 
+-- check if mvcc is enabled
+local function check_mvcc_state()
+    local cfg = box.cfg
+    if cfg['memtx_use_mvcc_engine'] == nil  or cfg['memtx_use_mvcc_engine'] == false then
+        return false
+    end
+
+    return true
+end
+
 -- put task in space
 function method.put(self, data, opts)
-    local max = self.space.index.task_id:max()
+    local max
+
+    -- taking the maximum of the index is an implicit transactions, so it is
+    -- always done with 'read-confirmed' mvcc isolation level.
+    -- It can lead to errors when trying to make parallel 'put' calls with mvcc enabled.
+    -- It is hapenning because 'max' for several puts in parallel will be the same since
+    -- read confirmed isolation level makes visible all transactions that finished the commit.
+    -- To fix it we wrap it with box.begin/commit and set right isolation level.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+    if check_mvcc_state() then
+        box.begin({txn_isolation = 'read-committed'})
+        max = self.space.index.task_id:max()
+        box.commit()
+    else
+        max = self.space.index.task_id:max()
+    end
+
     local id = max and max[i_id] + 1 or 0
 
     local status

queue/abstract/driver/utube.lua

@@ -73,9 +73,36 @@ function method.normalize_task(self, task)
     return task and task:transform(3, 1)
 end
 
+-- check if mvcc is enabled
+local function check_mvcc_state()
+    local cfg = box.cfg
+    if cfg['memtx_use_mvcc_engine'] == nil  or cfg['memtx_use_mvcc_engine'] == false then
+        return false
+    end
+
+    return true
+end
+
 -- put task in space
 function method.put(self, data, opts)
-    local max = self.space.index.task_id:max()
+    local max
+
+    -- taking the maximum of the index is an implicit transactions, so it is
+    -- always done with 'read-confirmed' mvcc isolation level.
+    -- It can lead to errors when trying to make parallel 'put' calls with mvcc enabled.
+    -- It is hapenning because 'max' for several puts in parallel will be the same since
+    -- read confirmed isolation level makes visible all transactions that finished the commit.
+    -- To fix it we wrap it with box.begin/commit and set right isolation level.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+    if check_mvcc_state() then
+        box.begin({txn_isolation = 'read-committed'})
+        max = self.space.index.task_id:max()
+        box.commit()
+    else
+        max = self.space.index.task_id:max()
+    end
+
     local id = max and max[1] + 1 or 0
     local task = self.space:insert{id, state.READY, tostring(opts.utube), data}
     self.on_task_change(task, 'put')

queue/abstract/driver/utubettl.lua

@@ -215,9 +215,36 @@ function method.normalize_task(self, task)
     return task and task:transform(i_next_event, i_data - i_next_event)
 end
 
+-- check if mvcc is enabled
+local function check_mvcc_state()
+    local cfg = box.cfg
+    if cfg['memtx_use_mvcc_engine'] == nil  or cfg['memtx_use_mvcc_engine'] == false then
+        return false
+    end
+
+    return true
+end
+
 -- put task in space
 function method.put(self, data, opts)
-    local max = self.space.index.task_id:max()
+    local max
+
+    -- taking the maximum of the index is an implicit transactions, so it is
+    -- always done with 'read-confirmed' mvcc isolation level.
+    -- It can lead to errors when trying to make parallel 'put' calls with mvcc enabled.
+    -- It is hapenning because 'max' for several puts in parallel will be the same since
+    -- read confirmed isolation level makes visible all transactions that finished the commit.
+    -- To fix it we wrap it with box.begin/commit and set right isolation level.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+    if check_mvcc_state() then
+        box.begin({txn_isolation = 'read-committed'})
+        max = self.space.index.task_id:max()
+        box.commit()
+    else
+        max = self.space.index.task_id:max()
+    end
+
     local id = max and max[i_id] + 1 or 0
 
     local status

t/220-mvcc.t

@@ -0,0 +1,62 @@
+#!/usr/bin/env tarantool
+local qc = require('queue.compat')
+if not qc.check_version({2, 6, 1}) then
+    log.info('Tests skipped, tarantool version < 2.6.1')
+    return
+end
+local yaml  = require('yaml')
+local fiber = require('fiber')
+
+local test  = require('tap').test()
+test:plan(6)
+
+local queue = require('queue')
+local state = require('queue.abstract.state')
+
+local tnt   = require('t.tnt')
+tnt.cfg{memtx_use_mvcc_engine = true}
+
+local engine = 'memtx'
+
+test:ok(rawget(box, 'space'), 'box started')
+test:ok(queue, 'queue is loaded')
+
+local tube = queue.create_tube('test', 'fifo', { engine = engine })
+test:ok(tube, 'test tube created')
+test:is(tube.name, 'test', 'tube.name')
+test:is(tube.type, 'fifo', 'tube.type')
+
+test:test('concurent take', function(test)
+    test:plan(151)
+
+    local channel = fiber.channel(1000)
+    test:ok(channel, 'channel created')
+
+    local res = {}
+    for i = 1, 50 do
+        fiber.create(function(i)
+            local taken = tube:take(1)
+            test:ok(taken, 'Task was taken ' .. i)
+            table.insert(res, { taken })
+            channel:put(true)
+        end, i)
+    end
+
+    fiber.sleep(.1)
+    test:ok(tube:put(1), 'task 1 was put')
+
+    for i = 2, 50 do
+        fiber.create(function(i)
+            test:ok(tube:put(i), 'task ' .. i .. ' was put')
+        end, i)
+    end
+    fiber.sleep(.1)
+    for i = 1, 50 do
+        test:ok(channel:get(1 / i), 'take was done ' .. i)
+    end
+end)
+
+
+tnt.finish()
+os.exit(test:check() and 0 or 1)
+-- vim: set ft=lua: