Merge pull request #7 from Kikobeats/queue

perf: avoid array.shift, use a linked list

Author: Kikobeats

package.json

@@ -80,7 +80,7 @@
       "@commitlint/config-conventional"
     ],
     "rules": {
-      "body-max-length": [
+      "body-max-line-length": [
         0
       ]
     }

src/create.js

@@ -1,11 +1,39 @@
 'use strict'
 
+class Node {
+  constructor (data) {
+    this.data = data
+  }
+}
+
+class LinkedList {
+  enqueue (data) {
+    if (!this.head) {
+      this.head = new Node(data)
+    } else {
+      let current = this.head
+      while (current.next) {
+        current = current.next
+      }
+      current.next = new Node(data)
+    }
+  }
+
+  dequeue () {
+    if (!this.head) return
+    const data = this.head.data
+    this.head = this.head.next
+    return data
+  }
+}
+
 module.exports = (slots = 1) => {
-  const queue = []
+  const queue = new LinkedList()
 
   const release = () => {
     ++slots
-    if (queue.length > 0) queue.shift()()
+    const fn = queue.dequeue()
+    if (fn !== undefined) fn()
   }
 
   const acquire = resolve => {
@@ -15,9 +43,7 @@ module.exports = (slots = 1) => {
 
   const lock = () =>
     new Promise(resolve =>
-      lock.isLocked()
-        ? queue.push(acquire.bind(null, resolve))
-        : acquire(resolve)
+      lock.isLocked() ? queue.enqueue(() => acquire(resolve)) : acquire(resolve)
     )
 
   lock.isLocked = () => slots === 0