First Commit

node_modules/mongoose/lib/helpers/cursor/eachAsync.js

@@ -0,0 +1,107 @@
+'use strict';
+
+/*!
+ * Module dependencies.
+ */
+
+const utils = require('../../utils');
+
+/**
+ * Execute `fn` for every document in the cursor. If `fn` returns a promise,
+ * will wait for the promise to resolve before iterating on to the next one.
+ * Returns a promise that resolves when done.
+ *
+ * @param {Function} next the thunk to call to get the next document
+ * @param {Function} fn
+ * @param {Object} options
+ * @param {Function} [callback] executed when all docs have been processed
+ * @return {Promise}
+ * @api public
+ * @method eachAsync
+ */
+
+module.exports = function eachAsync(next, fn, options, callback) {
+  const parallel = options.parallel || 1;
+
+  const handleNextResult = function(doc, callback) {
+    const promise = fn(doc);
+    if (promise && typeof promise.then === 'function') {
+      promise.then(
+        function() { callback(null); },
+        function(error) { callback(error || new Error('`eachAsync()` promise rejected without error')); });
+    } else {
+      callback(null);
+    }
+  };
+
+  const iterate = function(callback) {
+    let drained = false;
+
+    const getAndRun = function(cb) {
+      _next(function(err, doc) {
+        if (err) return cb(err);
+        if (drained) {
+          return;
+        }
+        if (doc == null) {
+          drained = true;
+          return callback(null);
+        }
+        handleNextResult(doc, function(err) {
+          if (err) return cb(err);
+          // Make sure to clear the stack re: gh-4697
+          setTimeout(function() {
+            getAndRun(cb);
+          }, 0);
+        });
+      });
+    };
+
+    let error = null;
+    for (let i = 0; i < parallel; ++i) {
+      getAndRun(err => {
+        if (error != null) {
+          return;
+        }
+        if (err != null) {
+          error = err;
+          return callback(err);
+        }
+      });
+    }
+  };
+
+  const _nextQueue = [];
+  return utils.promiseOrCallback(callback, cb => {
+    iterate(cb);
+  });
+
+  // `next()` can only execute one at a time, so make sure we always execute
+  // `next()` in series, while still allowing multiple `fn()` instances to run
+  // in parallel.
+  function _next(cb) {
+    if (_nextQueue.length === 0) {
+      return next(_step(cb));
+    }
+    _nextQueue.push(cb);
+  }
+
+  function _step(cb) {
+    return function(err, doc) {
+      if (err != null) {
+        return cb(err);
+      }
+      cb(null, doc);
+
+      if (doc == null) {
+        return;
+      }
+
+      setTimeout(() => {
+        if (_nextQueue.length > 0) {
+          next(_step(_nextQueue.unshift()));
+        }
+      }, 0);
+    };
+  }
+};