| // Copyright 2014 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. |
| |
| part of internal; |
| |
| // The MojoHandleWatcher sends a stream of events to application isolates that |
| // register Mojo handles with it. Application isolates make the following calls: |
| // |
| // add(handle, port, signals) - Instructs the MojoHandleWatcher isolate to add |
| // 'handle' to the set of handles it watches, and to notify the calling |
| // isolate only for the events specified by 'signals' using the send port |
| // 'port' |
| // |
| // remove(handle) - Instructs the MojoHandleWatcher isolate to remove 'handle' |
| // from the set of handles it watches. This allows the application isolate |
| // to, e.g., pause the stream of events. |
| // |
| // close(handle) - Notifies the HandleWatcherIsolate that a handle it is |
| // watching should be removed from its set and closed. |
| class MojoHandleWatcher { |
| // Control commands. |
| static const int ADD = 0; |
| static const int REMOVE = 1; |
| static const int CLOSE = 2; |
| static const int TIMER = 3; |
| static const int SHUTDOWN = 4; |
| |
| static const int kMojoHandleInvalid = 0; |
| static const int kDeadlineIndefinite = -1; |
| |
| static const int kMojoResultOk = 0; |
| static const int kMojoResultDeadlineExceeded = 4; |
| static const int kMojoResultFailedPrecondition = 9; |
| |
| static const int kMojoSignalsReadable = (1 << 0); |
| static const int kMojoSignalsWritable = (1 << 1); |
| static const int kMojoSignalsPeerClosed = (1 << 2); |
| static const int kMojoSignalsAll = |
| kMojoSignalsReadable | kMojoSignalsWritable | kMojoSignalsPeerClosed; |
| |
| static int _encodeCommand(int cmd, [int signals = 0]) => |
| (cmd << 3) | (signals & kMojoSignalsAll); |
| static int _decodeCommand(int cmd) { |
| assert(kMojoSignalsAll < 1 << 3); |
| return cmd >> 3; |
| } |
| static int _decodeSignals(int cmd) { |
| return cmd & kMojoSignalsAll; |
| } |
| |
| // The Mojo handle over which control messages are sent. |
| int _controlHandle; |
| |
| // Whether the handle watcher should shut down. |
| bool _shutdown; |
| |
| // The list of handles being watched. |
| List<int> _handles; |
| int _handleCount; |
| |
| // A port for each handle on which to send events back to the isolate that |
| // owns the handle. |
| List<SendPort> _ports; |
| |
| // The signals that we care about for each handle. |
| List<int> _signals; |
| |
| // A mapping from Mojo handles to their indices in _handles. |
| Map<int, int> _handleIndices; |
| |
| // Priority queue of timers registered with the watcher. |
| TimerQueue _timerQueue; |
| |
| MojoHandleWatcher(this._controlHandle) |
| : _shutdown = false, |
| _handles = new List<int>(), |
| _ports = new List<SendPort>(), |
| _signals = new List<int>(), |
| _handleIndices = new Map<int, int>(), |
| _handleCount = 1, |
| _timerQueue = new TimerQueue() { |
| // Setup control handle. |
| _handles.add(_controlHandle); |
| _ports.add(null); // There is no port for the control handle. |
| _signals.add(kMojoSignalsReadable); |
| _handleIndices[_controlHandle] = 0; |
| } |
| |
| static void _handleWatcherIsolate(int consumerHandle) { |
| MojoHandleWatcher watcher = new MojoHandleWatcher(consumerHandle); |
| while (!watcher._shutdown) { |
| int deadline = watcher._processTimerDeadlines(); |
| // mwmr[0]: result, mwmr[1]: index, mwmr[2]: list of signal states. |
| List mwmr = MojoHandleNatives.waitMany( |
| watcher._handles, watcher._signals, deadline); |
| if ((mwmr[0] == kMojoResultOk) && (mwmr[1] == 0)) { |
| watcher._handleControlMessage(); |
| } else if ((mwmr[0] == kMojoResultOk) && (mwmr[1] > 0)) { |
| int handle = watcher._handles[mwmr[1]]; |
| |
| // Route event. |
| watcher._routeEvent(mwmr[2][mwmr[1]][0], mwmr[1]); |
| // Remove the handle from the list. |
| watcher._removeHandle(handle); |
| } else if (mwmr[0] != kMojoResultDeadlineExceeded) { |
| // Some handle was closed, but not by us. |
| // Find it and close it on our side. |
| watcher._pruneClosedHandles(mwmr[2]); |
| } |
| } |
| } |
| |
| void _routeEvent(int satisfiedSignals, int idx) { |
| _ports[idx].send([_signals[idx], satisfiedSignals & _signals[idx]]); |
| } |
| |
| void _handleControlMessage() { |
| List result = MojoHandleWatcherNatives.recvControlData(_controlHandle); |
| // result[0] = mojo handle if any, or a timer deadline in milliseconds. |
| // result[1] = SendPort if any. |
| // result[2] = command << 2 | WRITABLE | READABLE |
| |
| var signals = _decodeSignals(result[2]); |
| int command = _decodeCommand(result[2]); |
| switch (command) { |
| case ADD: |
| _addHandle(result[0], result[1], signals); |
| break; |
| case REMOVE: |
| _removeHandle(result[0]); |
| break; |
| case CLOSE: |
| _close(result[0], result[1]); |
| break; |
| case TIMER: |
| _timer(result[1], result[0]); |
| break; |
| case SHUTDOWN: |
| _shutdownHandleWatcher(result[1]); |
| break; |
| default: |
| throw "Invalid Command: $command"; |
| break; |
| } |
| } |
| |
| void _addHandle(int mojoHandle, SendPort port, int signals) { |
| int idx = _handleIndices[mojoHandle]; |
| if (idx == null) { |
| _handles.add(mojoHandle); |
| _ports.add(port); |
| _signals.add(signals); |
| _handleIndices[mojoHandle] = _handleCount; |
| _handleCount++; |
| } else { |
| assert(_ports[idx] == port); |
| assert(_handles[idx] == mojoHandle); |
| _signals[idx] |= signals; |
| } |
| } |
| |
| void _removeHandle(int mojoHandle) { |
| int idx = _handleIndices[mojoHandle]; |
| if (idx == null) { |
| throw "Remove on a non-existent handle: idx = $idx."; |
| } |
| if (idx == 0) { |
| throw "The control handle (idx = 0) cannot be removed."; |
| } |
| // We don't use List.removeAt so that we know how to fix-up _handleIndices. |
| if (idx == _handleCount - 1) { |
| int handle = _handles[idx]; |
| _handleIndices[handle] = null; |
| _handles.removeLast(); |
| _signals.removeLast(); |
| _ports.removeLast(); |
| _handleCount--; |
| } else { |
| int last = _handleCount - 1; |
| _handleIndices[_handles[idx]] = null; |
| _handles[idx] = _handles[last]; |
| _signals[idx] = _signals[last]; |
| _ports[idx] = _ports[last]; |
| _handles.removeLast(); |
| _signals.removeLast(); |
| _ports.removeLast(); |
| _handleIndices[_handles[idx]] = idx; |
| _handleCount--; |
| } |
| } |
| |
| void _close(int mojoHandle, SendPort port, {bool pruning: false}) { |
| assert(!pruning || (port == null)); |
| int idx = _handleIndices[mojoHandle]; |
| if (idx == null) { |
| // An app isolate may request that the handle watcher close a handle that |
| // has already been pruned. This happens when the app isolate has not yet |
| // received the PEER_CLOSED event. The app isolate will not close the |
| // handle, so we must do so here. |
| MojoHandleNatives.close(mojoHandle); |
| if (port != null) port.send(null); // Notify that close is done. |
| return; |
| } |
| if (idx == 0) { |
| throw "The control handle (idx = 0) cannot be closed."; |
| } |
| MojoHandleNatives.close(_handles[idx]); |
| if (port != null) port.send(null); // Notify that close is done. |
| if (pruning) { |
| // If this handle is being pruned, notify the application isolate |
| // by sending MojoHandleSignals.PEER_CLOSED. |
| _ports[idx].send([_signals[idx], kMojoSignalsPeerClosed]); |
| } |
| _removeHandle(mojoHandle); |
| } |
| |
| // Returns the next timer deadline in units of microseconds from 'now'. |
| int _processTimerDeadlines() { |
| int now = (new DateTime.now()).millisecondsSinceEpoch; |
| while (_timerQueue.hasTimer && (now >= _timerQueue.currentTimeout)) { |
| _timerQueue.currentPort.send(null); |
| _timerQueue.removeCurrent(); |
| now = (new DateTime.now()).millisecondsSinceEpoch; |
| } |
| return _timerQueue.hasTimer |
| ? (_timerQueue.currentTimeout - now) * 1000 |
| : kDeadlineIndefinite; |
| } |
| |
| void _timer(SendPort port, int deadline) { |
| _timerQueue.updateTimer(port, deadline); |
| } |
| |
| void _pruneClosedHandles(List<List<int>> states) { |
| List<int> closed = new List(); |
| for (var i = 0; i < _handles.length; i++) { |
| if (states != null) { |
| int signals = states[i][0]; |
| if ((signals & kMojoSignalsPeerClosed) != 0) { |
| closed.add(_handles[i]); |
| } |
| } else { |
| List mwr = MojoHandleNatives.wait(_handles[i], kMojoSignalsAll, 0); |
| if ((mwr[0] != kMojoResultOk) && |
| (mwr[0] != kMojoResultDeadlineExceeded)) { |
| closed.add(_handles[i]); |
| } |
| } |
| } |
| for (var h in closed) { |
| _close(h, null, pruning: true); |
| } |
| // '_close' updated the '_handles' array, so at this point the '_handles' |
| // array and the caller's 'states' array are mismatched. |
| } |
| |
| void _shutdownHandleWatcher(SendPort shutdownSendPort) { |
| _shutdown = true; |
| MojoHandleNatives.close(_controlHandle); |
| shutdownSendPort.send(null); |
| } |
| |
| static int _sendControlData(int rawHandle, SendPort port, int data) { |
| int controlHandle = MojoHandleWatcherNatives.getControlHandle(); |
| if (controlHandle == kMojoHandleInvalid) { |
| return kMojoResultFailedPrecondition; |
| } |
| |
| var result = MojoHandleWatcherNatives.sendControlData( |
| controlHandle, rawHandle, port, data); |
| return result; |
| } |
| |
| // Starts up the MojoHandleWatcher isolate. Should be called only once |
| // per VM process. |
| static Future<Isolate> _start() { |
| // Make a control message pipe, |
| List pipeEndpoints = MojoMessagePipeNatives.MojoCreateMessagePipe(0); |
| assert(pipeEndpoints != null); |
| assert((pipeEndpoints is List) && (pipeEndpoints.length == 3)); |
| assert(pipeEndpoints[0] == kMojoResultOk); |
| |
| int consumerHandle = pipeEndpoints[1]; |
| int producerHandle = pipeEndpoints[2]; |
| |
| // Call setControlHandle with the other end. |
| assert(producerHandle != kMojoHandleInvalid); |
| MojoHandleWatcherNatives.setControlHandle(producerHandle); |
| |
| // Spawn the handle watcher isolate with the MojoHandleWatcher, |
| return Isolate.spawn(_handleWatcherIsolate, consumerHandle); |
| } |
| |
| // Causes the MojoHandleWatcher isolate to exit. Should be called only |
| // once per VM process. |
| static void _stop() { |
| // Create a port for notification that the handle watcher has shutdown. |
| var shutdownReceivePort = new ReceivePort(); |
| var shutdownSendPort = shutdownReceivePort.sendPort; |
| |
| // Send the shutdown command. |
| _sendControlData( |
| kMojoHandleInvalid, shutdownSendPort, _encodeCommand(SHUTDOWN)); |
| |
| // Close the control handle. |
| int controlHandle = MojoHandleWatcherNatives.getControlHandle(); |
| MojoHandleNatives.close(controlHandle); |
| |
| // Invalidate the control handle. |
| MojoHandleWatcherNatives.setControlHandle(kMojoHandleInvalid); |
| |
| // Wait for the handle watcher isolate to exit. |
| shutdownReceivePort.first.then((_) { |
| shutdownReceivePort.close(); |
| }); |
| } |
| |
| // If wait is true, returns a future that resolves only after the handle |
| // has actually been closed by the handle watcher. Otherwise, returns a |
| // future that resolves immediately. |
| static Future<int> close(int mojoHandle, {bool wait: false}) { |
| //assert(MojoHandle._removeUnclosedHandle(mojoHandle)); |
| if (!wait) { |
| return new Future.value( |
| _sendControlData(mojoHandle, null, _encodeCommand(CLOSE))); |
| } |
| int result; |
| var completer = new Completer(); |
| var rawPort = new RawReceivePort((_) { |
| completer.complete(result); |
| }); |
| result = |
| _sendControlData(mojoHandle, rawPort.sendPort, _encodeCommand(CLOSE)); |
| return completer.future.then((r) { |
| rawPort.close(); |
| return r; |
| }); |
| } |
| |
| static int add(int mojoHandle, SendPort port, int signals) { |
| return _sendControlData(mojoHandle, port, _encodeCommand(ADD, signals)); |
| } |
| |
| static int remove(int mojoHandle) { |
| return _sendControlData(mojoHandle, null, _encodeCommand(REMOVE)); |
| } |
| |
| static int timer(Object ignored, SendPort port, int deadline) { |
| // The deadline will be unwrapped before sending to the handle watcher. |
| return _sendControlData(deadline, port, _encodeCommand(TIMER)); |
| } |
| } |