From c1ecb6c60a1acacf530e226b8043ca93d2fe4a07 Mon Sep 17 00:00:00 2001
From: Unknwon <u@gogs.io>
Date: Tue, 30 Aug 2016 15:50:30 -0700
Subject: [PATCH] modules/sync: add UniqueQueue

---
 models/pull.go               |  5 +--
 models/webhook.go            | 63 ++------------------------------
 modules/sync/unique_queue.go | 70 ++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 62 deletions(-)
 create mode 100644 modules/sync/unique_queue.go

diff --git a/models/pull.go b/models/pull.go
index 64b347554c..100d4db435 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -20,8 +20,11 @@ import (
 	"github.com/gogits/gogs/modules/log"
 	"github.com/gogits/gogs/modules/process"
 	"github.com/gogits/gogs/modules/setting"
+	"github.com/gogits/gogs/modules/sync"
 )
 
+var PullRequestQueue = sync.NewUniqueQueue(setting.Repository.PullRequestQueueLength)
+
 type PullRequestType int
 
 const (
@@ -537,8 +540,6 @@ func (pr *PullRequest) UpdateCols(cols ...string) error {
 	return err
 }
 
-var PullRequestQueue = NewUniqueQueue(setting.Repository.PullRequestQueueLength)
-
 // UpdatePatch generates and saves a new patch.
 func (pr *PullRequest) UpdatePatch() (err error) {
 	if err = pr.GetHeadRepo(); err != nil {
diff --git a/models/webhook.go b/models/webhook.go
index 2db0274115..528dd5e474 100644
--- a/models/webhook.go
+++ b/models/webhook.go
@@ -10,10 +10,8 @@ import (
 	"fmt"
 	"io/ioutil"
 	"strings"
-	"sync"
 	"time"
 
-	"github.com/Unknwon/com"
 	"github.com/go-xorm/xorm"
 	gouuid "github.com/satori/go.uuid"
 
@@ -22,8 +20,11 @@ import (
 	"github.com/gogits/gogs/modules/httplib"
 	"github.com/gogits/gogs/modules/log"
 	"github.com/gogits/gogs/modules/setting"
+	"github.com/gogits/gogs/modules/sync"
 )
 
+var HookQueue = sync.NewUniqueQueue(setting.Webhook.QueueLength)
+
 type HookContentType int
 
 const (
@@ -500,64 +501,6 @@ func PrepareWebhooks(repo *Repository, event HookEventType, p api.Payloader) err
 	return nil
 }
 
-// UniqueQueue represents a queue that guarantees only one instance of same ID is in the line.
-type UniqueQueue struct {
-	lock sync.Mutex
-	ids  map[string]bool
-
-	queue chan string
-}
-
-func (q *UniqueQueue) Queue() <-chan string {
-	return q.queue
-}
-
-func NewUniqueQueue(queueLength int) *UniqueQueue {
-	if queueLength <= 0 {
-		queueLength = 100
-	}
-
-	return &UniqueQueue{
-		ids:   make(map[string]bool),
-		queue: make(chan string, queueLength),
-	}
-}
-
-func (q *UniqueQueue) Remove(id interface{}) {
-	q.lock.Lock()
-	defer q.lock.Unlock()
-	delete(q.ids, com.ToStr(id))
-}
-
-func (q *UniqueQueue) AddFunc(id interface{}, fn func()) {
-	newid := com.ToStr(id)
-
-	if q.Exist(id) {
-		return
-	}
-
-	q.lock.Lock()
-	q.ids[newid] = true
-	if fn != nil {
-		fn()
-	}
-	q.lock.Unlock()
-	q.queue <- newid
-}
-
-func (q *UniqueQueue) Add(id interface{}) {
-	q.AddFunc(id, nil)
-}
-
-func (q *UniqueQueue) Exist(id interface{}) bool {
-	q.lock.Lock()
-	defer q.lock.Unlock()
-
-	return q.ids[com.ToStr(id)]
-}
-
-var HookQueue = NewUniqueQueue(setting.Webhook.QueueLength)
-
 func (t *HookTask) deliver() {
 	t.IsDelivered = true
 
diff --git a/modules/sync/unique_queue.go b/modules/sync/unique_queue.go
new file mode 100644
index 0000000000..3f3c1c8661
--- /dev/null
+++ b/modules/sync/unique_queue.go
@@ -0,0 +1,70 @@
+// 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 (
+	"github.com/Unknwon/com"
+)
+
+// UniqueQueue is a queue which guarantees only one instance of same
+// identity is in the line. Instances with same identity will be
+// discarded if there is already one in the line.
+//
+// This queue is particularly useful for preventing duplicated task
+// of same purpose.
+type UniqueQueue struct {
+	table *StatusTable
+	queue chan string
+}
+
+// NewUniqueQueue initializes and returns a new UniqueQueue object.
+func NewUniqueQueue(queueLength int) *UniqueQueue {
+	if queueLength <= 0 {
+		queueLength = 100
+	}
+
+	return &UniqueQueue{
+		table: NewStatusTable(),
+		queue: make(chan string, queueLength),
+	}
+}
+
+// Queue returns channel of queue for retrieving instances.
+func (q *UniqueQueue) Queue() <-chan string {
+	return q.queue
+}
+
+// Exist returns true if there is an instance with given indentity
+// exists in the queue.
+func (q *UniqueQueue) Exist(id interface{}) bool {
+	return q.table.IsRunning(com.ToStr(id))
+}
+
+// AddFunc adds new instance to the queue with a custom runnable function,
+// the queue is blocked until the function exits.
+func (q *UniqueQueue) AddFunc(id interface{}, fn func()) {
+	if q.Exist(id) {
+		return
+	}
+
+	idStr := com.ToStr(id)
+	q.table.lock.Lock()
+	q.table.pool[idStr] = true
+	if fn != nil {
+		fn()
+	}
+	q.table.lock.Unlock()
+	q.queue <- idStr
+}
+
+// Add adds new instance to the queue.
+func (q *UniqueQueue) Add(id interface{}) {
+	q.AddFunc(id, nil)
+}
+
+// Remove removes instance from the queue.
+func (q *UniqueQueue) Remove(id interface{}) {
+	q.table.Stop(com.ToStr(id))
+}