planning

node_modules/semaphore/lib/semaphore.js

@@ -0,0 +1,101 @@
+;(function(global) {
+
+'use strict';
+
+var nextTick = function (fn) { setTimeout(fn, 0); }
+if (typeof process != 'undefined' && process && typeof process.nextTick == 'function') {
+	// node.js and the like
+	nextTick = process.nextTick;
+}
+
+function semaphore(capacity) {
+	var semaphore = {
+		capacity: capacity || 1,
+		current: 0,
+		queue: [],
+		firstHere: false,
+
+		take: function() {
+			if (semaphore.firstHere === false) {
+        			semaphore.current++;
+        			semaphore.firstHere = true;
+        			var isFirst = 1;
+      			} else {
+        			var isFirst = 0;
+      			}
+			var item = { n: 1 };
+
+			if (typeof arguments[0] == 'function') {
+				item.task = arguments[0];
+			} else {
+				item.n = arguments[0];
+			}
+
+			if (arguments.length >= 2)  {
+				if (typeof arguments[1] == 'function') item.task = arguments[1];
+				else item.n = arguments[1];
+			}
+
+			var task = item.task;
+			item.task = function() { task(semaphore.leave); };
+
+			if (semaphore.current + item.n - isFirst > semaphore.capacity) {
+        			if (isFirst === 1) {
+        				semaphore.current--;
+        				semaphore.firstHere = false;
+        			}
+				return semaphore.queue.push(item);
+			}
+
+			semaphore.current += item.n - isFirst;
+			item.task(semaphore.leave);
+      			if (isFirst === 1) semaphore.firstHere = false;
+		},
+
+		leave: function(n) {
+			n = n || 1;
+
+			semaphore.current -= n;
+
+			if (!semaphore.queue.length) {
+				if (semaphore.current < 0) {
+					throw new Error('leave called too many times.');
+				}
+
+				return;
+			}
+
+			var item = semaphore.queue[0];
+
+			if (item.n + semaphore.current > semaphore.capacity) {
+				return;
+			}
+
+			semaphore.queue.shift();
+			semaphore.current += item.n;
+
+			nextTick(item.task);
+		},
+
+		available: function(n) {
+			n = n || 1;
+			return(semaphore.current + n <= semaphore.capacity);
+		}
+	};
+
+	return semaphore;
+};
+
+if (typeof exports === 'object') {
+    // node export
+    module.exports = semaphore;
+} else if (typeof define === 'function' && define.amd) {
+    // amd export
+    define(function () {
+        return semaphore;
+    });
+} else {
+    // browser global
+    global.semaphore = semaphore;
+}
+}(this));