packager: extract BatchProcessor module

Reviewed By: davidaurelio

Differential Revision: D4449820

fbshipit-source-id: f54e6dd53ba4d211694e0bdc955af846d25778b8

react-packager/src/lib/BatchProcessor.js

@@ -0,0 +1,104 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+
+'use strict';
+
+const invariant = require('fbjs/lib/invariant');
+
+type ProcessBatch<TItem, TResult> = (
+  batch: Array<TItem>,
+  callback: (error?: Error, orderedResults?: Array<TResult>) => mixed,
+) => mixed;
+
+type BatchProcessorOptions = {
+  maximumDelayMs: number,
+  maximumItems: number,
+  concurrency: number,
+};
+
+/**
+ * We batch items together trying to minimize their processing, for example as
+ * network queries. For that we wait a small moment before processing a batch.
+ * We limit also the number of items we try to process in a single batch so that
+ * if we have many items pending in a short amount of time, we can start
+ * processing right away.
+ */
+class BatchProcessor<TItem, TResult> {
+
+  _options: BatchProcessorOptions;
+  _processBatch: ProcessBatch<TItem, TResult>;
+  _queue: Array<{
+    item: TItem,
+    callback: (error?: Error, result?: TResult) => mixed,
+  }>;
+  _timeoutHandle: ?number;
+  _currentProcessCount: number;
+
+  constructor(
+    options: BatchProcessorOptions,
+    processBatch: ProcessBatch<TItem, TResult>,
+  ) {
+    this._options = options;
+    this._processBatch = processBatch;
+    this._queue = [];
+    this._timeoutHandle = null;
+    this._currentProcessCount = 0;
+    (this: any)._processQueue = this._processQueue.bind(this);
+  }
+
+  _processQueue() {
+    this._timeoutHandle = null;
+    while (
+      this._queue.length > 0 &&
+      this._currentProcessCount < this._options.concurrency
+    ) {
+      this._currentProcessCount++;
+      const jobs = this._queue.splice(0, this._options.maximumItems);
+      const items = jobs.map(job => job.item);
+      this._processBatch(items, (error, results) => {
+        invariant(
+          results == null || results.length === items.length,
+          'Not enough results returned.',
+        );
+        for (let i = 0; i < items.length; ++i) {
+          jobs[i].callback(error, results && results[i]);
+        }
+        this._currentProcessCount--;
+        this._processQueueOnceReady();
+      });
+    }
+  }
+
+  _processQueueOnceReady() {
+    if (this._queue.length >= this._options.maximumItems) {
+      clearTimeout(this._timeoutHandle);
+      process.nextTick(this._processQueue);
+      return;
+    }
+    if (this._timeoutHandle == null) {
+      this._timeoutHandle = setTimeout(
+        this._processQueue,
+        this._options.maximumDelayMs,
+      );
+    }
+  }
+
+  queue(
+    item: TItem,
+    callback: (error?: Error, result?: TResult) => mixed,
+  ) {
+    this._queue.push({item, callback});
+    this._processQueueOnceReady();
+  }
+
+}
+
+module.exports = BatchProcessor;

react-packager/src/lib/GlobalTransformCache.js

@@ -11,9 +11,10 @@
 
 'use strict';
 
+const BatchProcessor = require('./BatchProcessor');
+
 const crypto = require('crypto');
 const imurmurhash = require('imurmurhash');
-const invariant = require('fbjs/lib/invariant');
 const jsonStableStringify = require('json-stable-stringify');
 const path = require('path');
 const request = require('request');
@@ -42,92 +43,6 @@ type FetchProps = {
 type FetchCallback = (error?: Error, result?: ?CachedResult) => mixed;
 type FetchURICallback = (error?: Error, resultURI?: ?string) => mixed;
 
-type ProcessBatch<TItem, TResult> = (
-  batch: Array<TItem>,
-  callback: (error?: Error, orderedResults?: Array<TResult>) => mixed,
-) => mixed;
-type BatchProcessorOptions = {
-  maximumDelayMs: number,
-  maximumItems: number,
-  concurrency: number,
-};
-
-/**
- * We batch keys together trying to make a smaller amount of queries. For that
- * we wait a small moment before starting to fetch. We limit also the number of
- * keys we try to fetch at once, so if we already have that many keys pending,
- * we can start fetching right away.
- */
-class BatchProcessor<TItem, TResult> {
-
-  _options: BatchProcessorOptions;
-  _processBatch: ProcessBatch<TItem, TResult>;
-  _queue: Array<{
-    item: TItem,
-    callback: (error?: Error, result?: TResult) => mixed,
-  }>;
-  _timeoutHandle: ?number;
-  _currentProcessCount: number;
-
-  constructor(
-    options: BatchProcessorOptions,
-    processBatch: ProcessBatch<TItem, TResult>,
-  ) {
-    this._options = options;
-    this._processBatch = processBatch;
-    this._queue = [];
-    this._timeoutHandle = null;
-    this._currentProcessCount = 0;
-    (this: any)._processQueue = this._processQueue.bind(this);
-  }
-
-  _processQueue() {
-    this._timeoutHandle = null;
-    while (
-      this._queue.length > 0 &&
-      this._currentProcessCount < this._options.concurrency
-    ) {
-      this._currentProcessCount++;
-      const jobs = this._queue.splice(0, this._options.maximumItems);
-      const items = jobs.map(job => job.item);
-      this._processBatch(items, (error, results) => {
-        invariant(
-          results == null || results.length === items.length,
-          'Not enough results returned.',
-        );
-        for (let i = 0; i < items.length; ++i) {
-          jobs[i].callback(error, results && results[i]);
-        }
-        this._currentProcessCount--;
-        this._processQueueOnceReady();
-      });
-    }
-  }
-
-  _processQueueOnceReady() {
-    if (this._queue.length >= this._options.maximumItems) {
-      clearTimeout(this._timeoutHandle);
-      process.nextTick(this._processQueue);
-      return;
-    }
-    if (this._timeoutHandle == null) {
-      this._timeoutHandle = setTimeout(
-        this._processQueue,
-        this._options.maximumDelayMs,
-      );
-    }
-  }
-
-  queue(
-    item: TItem,
-    callback: (error?: Error, result?: TResult) => mixed,
-  ) {
-    this._queue.push({item, callback});
-    this._processQueueOnceReady();
-  }
-
-}
-
 type URI = string;
 
 /**