Add queue.go

README.md

@@ -37,3 +37,4 @@ THE SOFTWARE.
 * [Tim Cooper](https://github.com/bontibon) for [gumble](https://github.com/layeh/gumble).
 * [Ricardo Garcia](https://github.com/rg3) for [youtube-dl](https://github.com/rg3/youtube-dl).
 * [ScalingData](https://github.com/scalingdata) for [gcfg](https://github.com/scalingdata/gcfg).
+* [Hicham Bouabdallah](https://github.com/hishboy) for [Golang queue implementation](https://github.com/hishboy/gocommons/blob/master/lang/queue.go).

queue.go

@@ -0,0 +1,117 @@
+//
+//  queue.go
+//
+//  Created by Hicham Bouabdallah
+//  Copyright (c) 2012 SimpleRocket LLC
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the "Software"), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+
+package main
+
+import "sync"
+
+type queuenode struct {
+	data interface{}
+	next *queuenode
+}
+
+//	A go-routine safe FIFO (first in first out) data stucture.
+type Queue struct {
+	head  *queuenode
+	tail  *queuenode
+	count int
+	lock  *sync.Mutex
+}
+
+//	Creates a new pointer to a new queue.
+func NewQueue() *Queue {
+	q := &Queue{}
+	q.lock = &sync.Mutex{}
+	return q
+}
+
+//	Returns the number of elements in the queue (i.e. size/length)
+//	go-routine safe.
+func (q *Queue) Len() int {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+	return q.count
+}
+
+//	Pushes/inserts a value at the end/tail of the queue.
+//	Note: this function does mutate the queue.
+//	go-routine safe.
+func (q *Queue) Push(item interface{}) {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+
+	n := &queuenode{data: item}
+
+	if q.tail == nil {
+		q.tail = n
+		q.head = n
+	} else {
+		q.tail.next = n
+		q.tail = n
+	}
+	q.count++
+}
+
+//	Returns the value at the front of the queue.
+//	i.e. the oldest value in the queue.
+//	Note: this function does mutate the queue.
+//	go-routine safe.
+func (q *Queue) Poll() interface{} {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+
+	if q.head == nil {
+		return nil
+	}
+
+	n := q.head
+	q.head = n.next
+
+	if q.head == nil {
+		q.tail = nil
+	}
+	q.count--
+
+	return n.data
+}
+
+//	Returns a read value at the front of the queue.
+//	i.e. the oldest value in the queue.
+//	Note: this function does NOT mutate the queue.
+//	go-routine safe.
+func (q *Queue) Peek() interface{} {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+
+	n := q.head
+	if n == nil || n.data == nil {
+		return nil
+	}
+
+	return n.data
+}