modules/sync: move sync objects to independent module

models/repo.go

 	"regexp"
 	"sort"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/Unknwon/cae/zip"
 	"github.com/gogits/gogs/modules/markdown"
 	"github.com/gogits/gogs/modules/process"
 	"github.com/gogits/gogs/modules/setting"
+	"github.com/gogits/gogs/modules/sync"
 )
 
 const (
 	_TPL_UPDATE_HOOK = "#!/usr/bin/env %s\n%s update $1 $2 $3 --config='%s'\n"
 )
 
+var repoWorkingPool = sync.NewSingleInstancePool()
+
 var (
 	ErrRepoFileNotExist  = errors.New("Repository file does not exist")
 	ErrRepoFileNotLoaded = errors.New("Repository file not loaded")
 		})
 }
 
-// statusPool represents a pool of status with true/false.
-type statusPool struct {
-	lock sync.RWMutex
-	pool map[string]bool
-}
-
-// Start sets value of given name to true in the pool.
-func (p *statusPool) Start(name string) {
-	p.lock.Lock()
-	defer p.lock.Unlock()
-
-	p.pool[name] = true
-}
-
-// Stop sets value of given name to false in the pool.
-func (p *statusPool) Stop(name string) {
-	p.lock.Lock()
-	defer p.lock.Unlock()
-
-	p.pool[name] = false
-}
-
-// IsRunning checks if value of given name is set to true in the pool.
-func (p *statusPool) IsRunning(name string) bool {
-	p.lock.RLock()
-	defer p.lock.RUnlock()
-
-	return p.pool[name]
-}
-
 // Prevent duplicate running tasks.
-var taskStatusPool = &statusPool{
-	pool: make(map[string]bool),
-}
+var taskStatusTable = sync.NewStatusTable()
 
 const (
 	_MIRROR_UPDATE = "mirror_update"
 
 // MirrorUpdate checks and updates mirror repositories.
 func MirrorUpdate() {
-	if taskStatusPool.IsRunning(_MIRROR_UPDATE) {
+	if taskStatusTable.IsRunning(_MIRROR_UPDATE) {
 		return
 	}
-	taskStatusPool.Start(_MIRROR_UPDATE)
-	defer taskStatusPool.Stop(_MIRROR_UPDATE)
+	taskStatusTable.Start(_MIRROR_UPDATE)
+	defer taskStatusTable.Stop(_MIRROR_UPDATE)
 
 	log.Trace("Doing: MirrorUpdate")
 
 
 // GitFsck calls 'git fsck' to check repository health.
 func GitFsck() {
-	if taskStatusPool.IsRunning(_GIT_FSCK) {
+	if taskStatusTable.IsRunning(_GIT_FSCK) {
 		return
 	}
-	taskStatusPool.Start(_GIT_FSCK)
-	defer taskStatusPool.Stop(_GIT_FSCK)
+	taskStatusTable.Start(_GIT_FSCK)
+	defer taskStatusTable.Stop(_GIT_FSCK)
 
 	log.Trace("Doing: GitFsck")
 
 }
 
 func CheckRepoStats() {
-	if taskStatusPool.IsRunning(_CHECK_REPOs) {
+	if taskStatusTable.IsRunning(_CHECK_REPOs) {
 		return
 	}
-	taskStatusPool.Start(_CHECK_REPOs)
-	defer taskStatusPool.Stop(_CHECK_REPOs)
+	taskStatusTable.Start(_CHECK_REPOs)
+	defer taskStatusTable.Stop(_CHECK_REPOs)
 
 	log.Trace("Doing: CheckRepoStats")
 
 // /_______  /\____ | |__||__|    \___  /   |__|____/\___  >
 //         \/      \/                 \/                 \/
 
-var repoWorkingPool = &workingPool{
-	pool:  make(map[string]*sync.Mutex),
-	count: make(map[string]int),
-}
-
 func (repo *Repository) LocalRepoPath() string {
 	return path.Join(setting.AppDataPath, "tmp/local-repo", com.ToStr(repo.ID))
 }

models/wiki.go

 	"path"
 	"path/filepath"
 	"strings"
-	"sync"
 
 	"github.com/Unknwon/com"
 
 	"github.com/gogits/git-module"
 
 	"github.com/gogits/gogs/modules/setting"
+	"github.com/gogits/gogs/modules/sync"
 )
 
-var wikiWorkingPool = &workingPool{
-	pool:  make(map[string]*sync.Mutex),
-	count: make(map[string]int),
-}
+var wikiWorkingPool = sync.NewSingleInstancePool()
 
 // ToWikiPageURL formats a string to corresponding wiki URL name.
 func ToWikiPageURL(name string) string {

models/working_pool.go

-// Copyright 2015 The Gogs Authors. All rights reserved.
-// Use of this source code is governed by a MIT-style
-// license that can be found in the LICENSE file.
-
-package models
-
-import (
-	"sync"
-)
-
-// workingPool represents a pool of working status which makes sure
-// that only one instance of same task is performing at a time.
-// However, different type of tasks can performing at the same time.
-type workingPool struct {
-	lock  sync.Mutex
-	pool  map[string]*sync.Mutex
-	count map[string]int
-}
-
-// CheckIn checks in a task and waits if others are running.
-func (p *workingPool) CheckIn(name string) {
-	p.lock.Lock()
-
-	lock, has := p.pool[name]
-	if !has {
-		lock = &sync.Mutex{}
-		p.pool[name] = lock
-	}
-	p.count[name]++
-
-	p.lock.Unlock()
-	lock.Lock()
-}
-
-// CheckOut checks out a task to let other tasks run.
-func (p *workingPool) CheckOut(name string) {
-	p.lock.Lock()
-	defer p.lock.Unlock()
-
-	p.pool[name].Unlock()
-	if p.count[name] == 1 {
-		delete(p.pool, name)
-		delete(p.count, name)
-	} else {
-		p.count[name]--
-	}
-}

modules/sync/single_instance_pool.go

+// Copyright 2016 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package sync
+
+import (
+	"sync"
+)
+
+// SingleInstancePool is a pool of non-identical instances
+// that only one instance with same identity is in the pool at a time.
+// In other words, only instances with different identities can exist
+// at the same time.
+//
+// This pool is particularly useful for performing tasks on same resource
+// on the file system in different goroutines.
+type SingleInstancePool struct {
+	lock sync.Mutex
+
+	// pool maintains locks for each instance in the pool.
+	pool map[string]*sync.Mutex
+
+	// count maintains the number of times an instance with same identity checks in
+	// to the pool, and should be reduced to 0 (removed from map) by checking out
+	// with same number of times.
+	count map[string]int
+}
+
+// NewSingleInstancePool initializes and returns a new SingleInstancePool object.
+func NewSingleInstancePool() *SingleInstancePool {
+	return &SingleInstancePool{
+		pool:  make(map[string]*sync.Mutex),
+		count: make(map[string]int),
+	}
+}
+
+// CheckIn checks in an instance to the pool and hangs while instance
+// with same indentity is using the lock.
+func (p *SingleInstancePool) CheckIn(identity string) {
+	p.lock.Lock()
+
+	lock, has := p.pool[identity]
+	if !has {
+		lock = &sync.Mutex{}
+		p.pool[identity] = lock
+	}
+	p.count[identity]++
+
+	p.lock.Unlock()
+	lock.Lock()
+}
+
+// CheckOut checks out an instance from the pool and releases the lock
+// to let other instances with same identity to grab the lock.
+func (p *SingleInstancePool) CheckOut(identity string) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.pool[identity].Unlock()
+	if p.count[identity] == 1 {
+		delete(p.pool, identity)
+		delete(p.count, identity)
+	} else {
+		p.count[identity]--
+	}
+}

modules/sync/status_pool.go

+// Copyright 2016 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package sync
+
+import (
+	"sync"
+)
+
+// StatusTable is a table maintains true/false values.
+//
+// This table is particularly useful for un/marking and checking values
+// in different goroutines.
+type StatusTable struct {
+	lock sync.RWMutex
+	pool map[string]bool
+}
+
+// NewStatusTable initializes and returns a new StatusTable object.
+func NewStatusTable() *StatusTable {
+	return &StatusTable{
+		pool: make(map[string]bool),
+	}
+}
+
+// Start sets value of given name to true in the pool.
+func (p *StatusTable) Start(name string) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.pool[name] = true
+}
+
+// Stop sets value of given name to false in the pool.
+func (p *StatusTable) Stop(name string) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.pool[name] = false
+}
+
+// IsRunning checks if value of given name is set to true in the pool.
+func (p *StatusTable) IsRunning(name string) bool {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	return p.pool[name]
+}