| /* |
| * Copyright (C) 2013 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.accessorydisplay.common; |
| |
| import java.nio.ByteBuffer; |
| |
| /** |
| * Maintains a bounded pool of buffers. Attempts to acquire buffers beyond the maximum |
| * count will block until other buffers are released. |
| */ |
| final class BufferPool { |
| private final int mInitialBufferSize; |
| private final int mMaxBufferSize; |
| private final ByteBuffer[] mBuffers; |
| private int mAllocated; |
| private int mAvailable; |
| |
| public BufferPool(int initialBufferSize, int maxBufferSize, int maxBuffers) { |
| mInitialBufferSize = initialBufferSize; |
| mMaxBufferSize = maxBufferSize; |
| mBuffers = new ByteBuffer[maxBuffers]; |
| } |
| |
| public ByteBuffer acquire(int needed) { |
| synchronized (this) { |
| for (;;) { |
| if (mAvailable != 0) { |
| mAvailable -= 1; |
| return grow(mBuffers[mAvailable], needed); |
| } |
| |
| if (mAllocated < mBuffers.length) { |
| mAllocated += 1; |
| return ByteBuffer.allocate(chooseCapacity(mInitialBufferSize, needed)); |
| } |
| |
| try { |
| wait(); |
| } catch (InterruptedException ex) { |
| } |
| } |
| } |
| } |
| |
| public void release(ByteBuffer buffer) { |
| synchronized (this) { |
| buffer.clear(); |
| mBuffers[mAvailable++] = buffer; |
| notifyAll(); |
| } |
| } |
| |
| public ByteBuffer grow(ByteBuffer buffer, int needed) { |
| int capacity = buffer.capacity(); |
| if (capacity < needed) { |
| final ByteBuffer oldBuffer = buffer; |
| capacity = chooseCapacity(capacity, needed); |
| buffer = ByteBuffer.allocate(capacity); |
| oldBuffer.flip(); |
| buffer.put(oldBuffer); |
| } |
| return buffer; |
| } |
| |
| private int chooseCapacity(int capacity, int needed) { |
| while (capacity < needed) { |
| capacity *= 2; |
| } |
| if (capacity > mMaxBufferSize) { |
| if (needed > mMaxBufferSize) { |
| throw new IllegalArgumentException("Requested size " + needed |
| + " is larger than maximum buffer size " + mMaxBufferSize + "."); |
| } |
| capacity = mMaxBufferSize; |
| } |
| return capacity; |
| } |
| } |