HTML MessagePort as mojo::MessagePipeHandle

content/public/android/java/src/org/chromium/content/browser/PostMessageSender.java

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.content.browser;
-
-import java.util.ArrayDeque;
-
-/**
- * Sanity checks and sends post messages to web. Queues messages if necessary.
- */
-public class PostMessageSender implements AppWebMessagePortService.MessageChannelObserver {
-    /**
-     * The interface for message handler.
-     */
-    public static interface PostMessageSenderDelegate {
-        /*
-         * Posts a message to the destination frame for real. The unique message port
-         * id of any transferred port should be known at this time.
-         */
-        void postMessageToWeb(
-                String frameName, String message, String targetOrigin, int[] sentPortIds);
-
-        /*
-         * Whether the post message sender is ready to post messages.
-         */
-        boolean isPostMessageSenderReady();
-
-        /*
-         * Informs that all messages are posted and message queue is empty.
-         */
-        void onPostMessageQueueEmpty();
-    }
-    ;
-
-    // A struct to store Message parameters that are sent from App to Web.
-    private static class PostMessageParams {
-        public String frameName;
-        public String message;
-        public String targetOrigin;
-        public AppWebMessagePort[] sentPorts;
-
-        public PostMessageParams(String frameName, String message, String targetOrigin,
-                AppWebMessagePort[] sentPorts) {
-            this.frameName = frameName;
-            this.message = message;
-            this.targetOrigin = targetOrigin;
-            this.sentPorts = sentPorts;
-        }
-    }
-
-    private PostMessageSenderDelegate mDelegate;
-    private AppWebMessagePortService mService;
-
-    // If a message that is sent from android webview to web has a pending port (a port that
-    // is not internally created yet), this message, and any following messages will be
-    // queued until the transferred port becomes ready. This is necessary to prevent any
-    // reordering.
-    private ArrayDeque<PostMessageParams> mMessageQueue = new ArrayDeque<PostMessageParams>();
-
-    public PostMessageSender(PostMessageSenderDelegate delegate, AppWebMessagePortService service) {
-        mDelegate = delegate;
-        mService = service;
-    }
-
-    // TODO(sgurun) in code review it was found this was implemented wrongly
-    // as mMessageQueue.size() > 0. write a test to catch this.
-    public boolean isMessageQueueEmpty() {
-        return mMessageQueue.size() == 0;
-    }
-
-    // Return true if any sent port is pending.
-    private boolean anySentPortIsPending(AppWebMessagePort[] sentPorts) {
-        if (sentPorts != null) {
-            for (AppWebMessagePort port : sentPorts) {
-                if (!port.isReady()) {
-                    return true;
-                }
-            }
-        }
-        return false;
-    }
-
-    // A message to a frame is queued if:
-    // 1. Sender is not ready to post. When posting messages to frames, sender is always
-    // ready. However, when posting messages using message channels, sender may be in
-    // a pending state.
-    // 2. There are already queued messages
-    // 3. The message includes a port that is not ready yet.
-    private boolean shouldQueueMessage(AppWebMessagePort[] sentPorts) {
-        // if messages to frames are already in queue mode, simply queue it, no need to
-        // check ports.
-        if (mMessageQueue.size() > 0 || !mDelegate.isPostMessageSenderReady()) {
-            return true;
-        }
-        if (anySentPortIsPending(sentPorts)) {
-            return true;
-        }
-        return false;
-    }
-
-    private void postMessageToWeb(
-            String frameName, String message, String targetOrigin, AppWebMessagePort[] sentPorts) {
-        int[] portIds = null;
-        if (sentPorts != null) {
-            portIds = new int[sentPorts.length];
-            for (int i = 0; i < sentPorts.length; i++) {
-                portIds[i] = sentPorts[i].portId();
-            }
-            mService.removeSentPorts(portIds);
-        }
-        mDelegate.postMessageToWeb(frameName, message, targetOrigin, portIds);
-    }
-
-    /*
-     * Sanity checks the message and queues it if necessary. Posts the message to delegate
-     * when message can be sent.
-     */
-    public void postMessage(String frameName, String message, String targetOrigin,
-            AppWebMessagePort[] sentPorts) throws IllegalStateException {
-        // Sanity check all the ports that are being transferred.
-        if (sentPorts != null) {
-            for (AppWebMessagePort p : sentPorts) {
-                if (p.isClosed()) {
-                    throw new IllegalStateException("Closed port cannot be transfered");
-                }
-                if (p.isTransferred()) {
-                    throw new IllegalStateException("Port cannot be re-transferred");
-                }
-                if (p.isStarted()) {
-                    throw new IllegalStateException("Started port cannot be transferred");
-                }
-                p.setTransferred();
-            }
-        }
-        if (shouldQueueMessage(sentPorts)) {
-            mMessageQueue.add(new PostMessageParams(frameName, message, targetOrigin, sentPorts));
-        } else {
-            postMessageToWeb(frameName, message, targetOrigin, sentPorts);
-        }
-    }
-
-    /*
-     * Starts posting any messages that are queued.
-     */
-    public void onMessageChannelCreated() {
-        PostMessageParams msg;
-
-        if (!mDelegate.isPostMessageSenderReady()) {
-            return;
-        }
-
-        while ((msg = mMessageQueue.peek()) != null) {
-            // If there are still pending ports, message cannot be posted.
-            if (anySentPortIsPending(msg.sentPorts)) {
-                return;
-            }
-            mMessageQueue.remove();
-            postMessageToWeb(msg.frameName, msg.message, msg.targetOrigin, msg.sentPorts);
-        }
-        mDelegate.onPostMessageQueueEmpty();
-    }
-}