1 files changed, 179 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/upstream/DefaultAllocator.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/upstream/DefaultAllocator.java
new file mode 100644
index 0000000000..b12efcbe4e
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/upstream/DefaultAllocator.java
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2016 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 org.mozilla.thirdparty.com.google.android.exoplayer2.upstream;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import java.util.Arrays;
+
+/**
+ * Default implementation of {@link Allocator}.
+ */
+public final class DefaultAllocator implements Allocator {
+
+  private static final int AVAILABLE_EXTRA_CAPACITY = 100;
+
+  private final boolean trimOnReset;
+  private final int individualAllocationSize;
+  private final byte[] initialAllocationBlock;
+  private final Allocation[] singleAllocationReleaseHolder;
+
+  private int targetBufferSize;
+  private int allocatedCount;
+  private int availableCount;
+  private Allocation[] availableAllocations;
+
+  /**
+   * Constructs an instance without creating any {@link Allocation}s up front.
+   *
+   * @param trimOnReset Whether memory is freed when the allocator is reset. Should be true unless
+   *     the allocator will be re-used by multiple player instances.
+   * @param individualAllocationSize The length of each individual {@link Allocation}.
+   */
+  public DefaultAllocator(boolean trimOnReset, int individualAllocationSize) {
+    this(trimOnReset, individualAllocationSize, 0);
+  }
+
+  /**
+   * Constructs an instance with some {@link Allocation}s created up front.
+   * <p>
+   * Note: {@link Allocation}s created up front will never be discarded by {@link #trim()}.
+   *
+   * @param trimOnReset Whether memory is freed when the allocator is reset. Should be true unless
+   *     the allocator will be re-used by multiple player instances.
+   * @param individualAllocationSize The length of each individual {@link Allocation}.
+   * @param initialAllocationCount The number of allocations to create up front.
+   */
+  public DefaultAllocator(boolean trimOnReset, int individualAllocationSize,
+      int initialAllocationCount) {
+    Assertions.checkArgument(individualAllocationSize > 0);
+    Assertions.checkArgument(initialAllocationCount >= 0);
+    this.trimOnReset = trimOnReset;
+    this.individualAllocationSize = individualAllocationSize;
+    this.availableCount = initialAllocationCount;
+    this.availableAllocations = new Allocation[initialAllocationCount + AVAILABLE_EXTRA_CAPACITY];
+    if (initialAllocationCount > 0) {
+      initialAllocationBlock = new byte[initialAllocationCount * individualAllocationSize];
+      for (int i = 0; i < initialAllocationCount; i++) {
+        int allocationOffset = i * individualAllocationSize;
+        availableAllocations[i] = new Allocation(initialAllocationBlock, allocationOffset);
+      }
+    } else {
+      initialAllocationBlock = null;
+    }
+    singleAllocationReleaseHolder = new Allocation[1];
+  }
+
+  public synchronized void reset() {
+    if (trimOnReset) {
+      setTargetBufferSize(0);
+    }
+  }
+
+  public synchronized void setTargetBufferSize(int targetBufferSize) {
+    boolean targetBufferSizeReduced = targetBufferSize < this.targetBufferSize;
+    this.targetBufferSize = targetBufferSize;
+    if (targetBufferSizeReduced) {
+      trim();
+    }
+  }
+
+  @Override
+  public synchronized Allocation allocate() {
+    allocatedCount++;
+    Allocation allocation;
+    if (availableCount > 0) {
+      allocation = availableAllocations[--availableCount];
+      availableAllocations[availableCount] = null;
+    } else {
+      allocation = new Allocation(new byte[individualAllocationSize], 0);
+    }
+    return allocation;
+  }
+
+  @Override
+  public synchronized void release(Allocation allocation) {
+    singleAllocationReleaseHolder[0] = allocation;
+    release(singleAllocationReleaseHolder);
+  }
+
+  @Override
+  public synchronized void release(Allocation[] allocations) {
+    if (availableCount + allocations.length >= availableAllocations.length) {
+      availableAllocations = Arrays.copyOf(availableAllocations,
+          Math.max(availableAllocations.length * 2, availableCount + allocations.length));
+    }
+    for (Allocation allocation : allocations) {
+      availableAllocations[availableCount++] = allocation;
+    }
+    allocatedCount -= allocations.length;
+    // Wake up threads waiting for the allocated size to drop.
+    notifyAll();
+  }
+
+  @Override
+  public synchronized void trim() {
+    int targetAllocationCount = Util.ceilDivide(targetBufferSize, individualAllocationSize);
+    int targetAvailableCount = Math.max(0, targetAllocationCount - allocatedCount);
+    if (targetAvailableCount >= availableCount) {
+      // We're already at or below the target.
+      return;
+    }
+
+    if (initialAllocationBlock != null) {
+      // Some allocations are backed by an initial block. We need to make sure that we hold onto all
+      // such allocations. Re-order the available allocations so that the ones backed by the initial
+      // block come first.
+      int lowIndex = 0;
+      int highIndex = availableCount - 1;
+      while (lowIndex <= highIndex) {
+        Allocation lowAllocation = availableAllocations[lowIndex];
+        if (lowAllocation.data == initialAllocationBlock) {
+          lowIndex++;
+        } else {
+          Allocation highAllocation = availableAllocations[highIndex];
+          if (highAllocation.data != initialAllocationBlock) {
+            highIndex--;
+          } else {
+            availableAllocations[lowIndex++] = highAllocation;
+            availableAllocations[highIndex--] = lowAllocation;
+          }
+        }
+      }
+      // lowIndex is the index of the first allocation not backed by an initial block.
+      targetAvailableCount = Math.max(targetAvailableCount, lowIndex);
+      if (targetAvailableCount >= availableCount) {
+        // We're already at or below the target.
+        return;
+      }
+    }
+
+    // Discard allocations beyond the target.
+    Arrays.fill(availableAllocations, targetAvailableCount, availableCount, null);
+    availableCount = targetAvailableCount;
+  }
+
+  @Override
+  public synchronized int getTotalBytesAllocated() {
+    return allocatedCount * individualAllocationSize;
+  }
+
+  @Override
+  public int getIndividualAllocationLength() {
+    return individualAllocationSize;
+  }
+
+}