| /* |
| * Copyright (C) 2019 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.wm; |
| |
| import java.io.File; |
| import java.io.FileOutputStream; |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| /** |
| * A ring buffer to store the {@code #size size} bytes of window trace data. |
| * The buffer operates on a trace entry level, that is, if the new trace data is larger than the |
| * available buffer space, the buffer will discard as many full trace entries as necessary to fit |
| * the new trace. |
| */ |
| class WindowTraceRingBuffer extends WindowTraceBuffer { |
| WindowTraceRingBuffer(int size, File traceFile) throws IOException { |
| super(size, traceFile); |
| } |
| |
| @Override |
| boolean canAdd(int protoLength) { |
| long availableSpace = getAvailableSpace(); |
| |
| while (availableSpace < protoLength) { |
| discardOldest(); |
| availableSpace = getAvailableSpace(); |
| } |
| |
| return true; |
| } |
| |
| @Override |
| void writeTraceToFile() throws IOException { |
| synchronized (mBufferLock) { |
| try (OutputStream os = new FileOutputStream(mTraceFile, true)) { |
| while (!mBuffer.isEmpty()) { |
| byte[] proto; |
| proto = mBuffer.poll(); |
| mBufferSize -= proto.length; |
| os.write(proto); |
| } |
| } |
| } |
| } |
| |
| private void discardOldest() { |
| byte[] item = mBuffer.poll(); |
| if (item == null) { |
| throw new IllegalStateException("No element to discard from buffer"); |
| } |
| mBufferSize -= item.length; |
| } |
| } |