xorm/engine_group_policy.go
Lunny Xiao 109cb1a7d0 Add support Engine Group (#748)
* add support group engine

* revert code

* add NewGroup function

* add engine group policy

* rename file name

* modify policy interface

* remove Init function from policy interface

* refactor Group Policy

* rename and comments

* rename and bug fix for WeightRoundRobinPolicy

* modify Slave function

* modify Slave function and add LeastConnPolicy

* use original Engine and Session

* remove unused count variables

* fix bug on NewEngineGroup

* remove unused method

* improve range and refactor

* add some comments and refactor

* implement GroupPolicy of GroupPolicyHandler

* refactor

* simple code

* add tests support for EngineGroup & fix some bugs

* improve the NewEngineGroup interface

* change the default policy of engine group

* fix some tests
2017-10-16 15:28:13 +08:00

117 lines
2.6 KiB
Go

// Copyright 2017 The Xorm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package xorm
import (
"math/rand"
"sync"
"time"
)
// GroupPolicy is be used by chosing the current slave from slaves
type GroupPolicy interface {
Slave(*EngineGroup) *Engine
}
// GroupPolicyHandler should be used when a function is a GroupPolicy
type GroupPolicyHandler func(*EngineGroup) *Engine
// Slave implements the chosen of slaves
func (h GroupPolicyHandler) Slave(eg *EngineGroup) *Engine {
return h(eg)
}
// RandomPolicy implmentes randomly chose the slave of slaves
func RandomPolicy() GroupPolicyHandler {
var r = rand.New(rand.NewSource(time.Now().UnixNano()))
return func(g *EngineGroup) *Engine {
return g.Slaves()[r.Intn(len(g.Slaves()))]
}
}
// WeightRandomPolicy implmentes randomly chose the slave of slaves
func WeightRandomPolicy(weights []int) GroupPolicyHandler {
var rands = make([]int, 0, len(weights))
for i := 0; i < len(weights); i++ {
for n := 0; n < weights[i]; n++ {
rands = append(rands, i)
}
}
var r = rand.New(rand.NewSource(time.Now().UnixNano()))
return func(g *EngineGroup) *Engine {
var slaves = g.Slaves()
idx := rands[r.Intn(len(rands))]
if idx >= len(slaves) {
idx = len(slaves) - 1
}
return slaves[idx]
}
}
func RoundRobinPolicy() GroupPolicyHandler {
var pos = -1
var lock sync.Mutex
return func(g *EngineGroup) *Engine {
var slaves = g.Slaves()
lock.Lock()
defer lock.Unlock()
pos++
if pos >= len(slaves) {
pos = 0
}
return slaves[pos]
}
}
func WeightRoundRobinPolicy(weights []int) GroupPolicyHandler {
var rands = make([]int, 0, len(weights))
for i := 0; i < len(weights); i++ {
for n := 0; n < weights[i]; n++ {
rands = append(rands, i)
}
}
var pos = -1
var lock sync.Mutex
return func(g *EngineGroup) *Engine {
var slaves = g.Slaves()
lock.Lock()
defer lock.Unlock()
pos++
if pos >= len(rands) {
pos = 0
}
idx := rands[pos]
if idx >= len(slaves) {
idx = len(slaves) - 1
}
return slaves[idx]
}
}
// LeastConnPolicy implements GroupPolicy, every time will get the least connections slave
func LeastConnPolicy() GroupPolicyHandler {
return func(g *EngineGroup) *Engine {
var slaves = g.Slaves()
connections := 0
idx := 0
for i := 0; i < len(slaves); i++ {
openConnections := slaves[i].DB().Stats().OpenConnections
if i == 0 {
connections = openConnections
idx = i
} else if openConnections <= connections {
connections = openConnections
idx = i
}
}
return slaves[idx]
}
}