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.
Current fix does not resolve that bug in situations when we already are in transaction
since it will open nested transactions.

Part of #207

queue/abstract/driver/fifo.lua

@@ -68,7 +68,27 @@ 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.
+    -- Current fix does not resolve that bug in situations when we already are in transaction
+    -- since it will open nested transactions.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+
+    if box.cfg.memtx_use_mvcc_engine and not box.is_in_txn() 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')
@@ -78,7 +98,7 @@ end
 -- take task
 function method.take(self)
     local task = self.space.index.status:min{state.READY}
-    if task ~= nil and task[2] == state.READY then
+    if task ~ nil and task[2] == state.READY then
         task = self.space:update(task[1], { { '=', 2, state.TAKEN } })
         self.on_task_change(task, 'take')
         return task

queue/abstract/driver/fifottl.lua

@@ -209,7 +209,27 @@ 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.
+    -- Current fix does not resolve that bug in situations when we already are in transaction
+    -- since it will open nested transactions.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+
+    if box.cfg.memtx_use_mvcc_engine and not box.is_in_txn() 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

@@ -75,7 +75,27 @@ 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.
+    -- Current fix does not resolve that bug in situations when we already are in transaction
+    -- since it will open nested transactions.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+
+    if box.cfg.memtx_use_mvcc_engine and not box.is_in_txn() 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

@@ -217,7 +217,27 @@ 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.
+    -- Current fix does not resolve that bug in situations when we already are in transaction
+    -- since it will open nested transactions.
+    -- See https://github.com/tarantool/queue/issues/207
+    -- See https://www.tarantool.io/ru/doc/latest/concepts/atomic/txn_mode_mvcc/
+
+    if box.cfg.memtx_use_mvcc_engine and not box.is_in_txn() 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 +1,63 @@
+#!/usr/bin/env tarantool
+local qc = require('queue.compat')
+local log   = require('log')
+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: