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2019-11-28 20:40:02 +00:00
commit 1c78566f5b
2275 changed files with 272351 additions and 0 deletions
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+'use strict';
+
+/*!
+ * Module dependencies.
+ */
+
+var PromiseProvider = require('../../promise_provider');
+var async = require('async');
+
+/**
+ * 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) {
+  var Promise = PromiseProvider.get();
+  var parallel = options.parallel || 1;
+
+  var handleNextResult = function(doc, callback) {
+    var 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);
+    }
+  };
+
+  var iterate = function(callback) {
+    var drained = false;
+    var nextQueue = async.queue(function(task, cb) {
+      if (drained) return cb();
+      next(function(err, doc) {
+        if (err) return cb(err);
+        if (!doc) drained = true;
+        cb(null, doc);
+      });
+    }, 1);
+
+    var getAndRun = function(cb) {
+      nextQueue.push({}, function(err, doc) {
+        if (err) return cb(err);
+        if (!doc) return cb();
+        handleNextResult(doc, function(err) {
+          if (err) return cb(err);
+          // Make sure to clear the stack re: gh-4697
+          setTimeout(function() {
+            getAndRun(cb);
+          }, 0);
+        });
+      });
+    };
+
+    async.times(parallel, function(n, cb) {
+      getAndRun(cb);
+    }, callback);
+  };
+
+  return new Promise.ES6(function(resolve, reject) {
+    iterate(function(error) {
+      if (error) {
+        callback && callback(error);
+        return reject(error);
+      }
+      callback && callback(null);
+      return resolve();
+    });
+  });
+};