基本雏型, 本地

node_modules/nedb/lib/executor.js

@@ -0,0 +1,77 @@
+/**
+ * Responsible for sequentially executing actions on the database
+ */
+
+var async = require('async')
+  ;
+
+function Executor () {
+  this.buffer = [];
+  this.ready = false;
+
+  // This queue will execute all commands, one-by-one in order
+  this.queue = async.queue(function (task, cb) {
+    var callback
+      , lastArg = task.arguments[task.arguments.length - 1]
+      , i, newArguments = []
+      ;
+
+    // task.arguments is an array-like object on which adding a new field doesn't work, so we transform it into a real array
+    for (i = 0; i < task.arguments.length; i += 1) { newArguments.push(task.arguments[i]); }
+
+    // Always tell the queue task is complete. Execute callback if any was given.
+    if (typeof lastArg === 'function') {
+      callback = function () {
+        if (typeof setImmediate === 'function') {
+           setImmediate(cb);
+        } else {
+          process.nextTick(cb);
+        }
+        lastArg.apply(null, arguments);
+      };
+
+      newArguments[newArguments.length - 1] = callback;
+    } else {
+      callback = function () { cb(); };
+      newArguments.push(callback);
+    }
+
+
+    task.fn.apply(task.this, newArguments);
+  }, 1);
+}
+
+
+/**
+ * If executor is ready, queue task (and process it immediately if executor was idle)
+ * If not, buffer task for later processing
+ * @param {Object} task
+ *                 task.this - Object to use as this
+ *                 task.fn - Function to execute
+ *                 task.arguments - Array of arguments
+ * @param {Boolean} forceQueuing Optional (defaults to false) force executor to queue task even if it is not ready
+ */
+Executor.prototype.push = function (task, forceQueuing) {
+  if (this.ready || forceQueuing) {
+    this.queue.push(task);
+  } else {
+    this.buffer.push(task);
+  }
+};
+
+
+/**
+ * Queue all tasks in buffer (in the same order they came in)
+ * Automatically sets executor as ready
+ */
+Executor.prototype.processBuffer = function () {
+  var i;
+  this.ready = true;
+  for (i = 0; i < this.buffer.length; i += 1) { this.queue.push(this.buffer[i]); }
+  this.buffer = [];
+};
+
+
+
+// Interface
+module.exports = Executor;