memory-types/ashmem/src/main/java/com/facebook/imagepipeline/memory/AshmemMemoryChunk.java [128:167]:
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  public void copy(
      final int offset, final MemoryChunk other, final int otherOffset, final int count) {
    Preconditions.checkNotNull(other);
    // This implementation acquires locks on this and other objects and then delegates to
    // doCopy which does actual copy. In order to avoid deadlocks we have to establish some linear
    // order on all AshmemMemoryChunks and acquire locks according to this order. In order
    // to do that, we use unique ids.
    // So we have to address 3 cases:

    // Case 1: other buffer equals this buffer, id comparison
    if (other.getUniqueId() == getUniqueId()) {
      // we do not allow copying to the same address
      // lets log warning and not copy
      Log.w(
          TAG,
          "Copying from AshmemMemoryChunk "
              + Long.toHexString(getUniqueId())
              + " to AshmemMemoryChunk "
              + Long.toHexString(other.getUniqueId())
              + " which are the same ");
      Preconditions.checkArgument(false);
    }

    // Case 2: Other memory chunk id < this memory chunk id
    if (other.getUniqueId() < getUniqueId()) {
      synchronized (other) {
        synchronized (this) {
          doCopy(offset, other, otherOffset, count);
        }
      }
      return;
    }

    // Case 3: Other memory chunk id > this memory chunk id
    synchronized (this) {
      synchronized (other) {
        doCopy(offset, other, otherOffset, count);
      }
    }
  }
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memory-types/simple/src/main/java/com/facebook/imagepipeline/memory/BufferMemoryChunk.java [96:135]:
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  public void copy(
      final int offset, final MemoryChunk other, final int otherOffset, final int count) {
    Preconditions.checkNotNull(other);
    // This implementation acquires locks on this and other objects and then delegates to
    // doCopy which does actual copy. In order to avoid deadlocks we have to establish some linear
    // order on all BufferMemoryChunks and acquire locks according to this order. In order
    // to do that, we use unique ids.
    // So we have to address 3 cases:

    // Case 1: other buffer equals this buffer, id comparison
    if (other.getUniqueId() == getUniqueId()) {
      // we do not allow copying to the same address
      // lets log warning and not copy
      Log.w(
          TAG,
          "Copying from BufferMemoryChunk "
              + Long.toHexString(getUniqueId())
              + " to BufferMemoryChunk "
              + Long.toHexString(other.getUniqueId())
              + " which are the same ");
      Preconditions.checkArgument(false);
    }

    // Case 2: Other memory chunk id < this memory chunk id
    if (other.getUniqueId() < getUniqueId()) {
      synchronized (other) {
        synchronized (this) {
          doCopy(offset, other, otherOffset, count);
        }
      }
      return;
    }

    // Case 3: Other memory chunk id > this memory chunk id
    synchronized (this) {
      synchronized (other) {
        doCopy(offset, other, otherOffset, count);
      }
    }
  }
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