Motown in-proc streaming framework used to implement media services.

services/media/framework/allocator.cc

+// Copyright 2016 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.
+
+#include <cstdlib>
+
+#include "base/logging.h"
+#include "services/media/framework/allocator.h"
+
+namespace mojo {
+namespace media {
+
+namespace {
+
+class DefaultAllocator : public Allocator {
+ public:
+  // Allocator implementation.
+  void* AllocatePayloadBuffer(uint64_t size) override;
+
+  void ReleasePayloadBuffer(uint64_t size, void* buffer) override;
+};
+
+void* DefaultAllocator::AllocatePayloadBuffer(uint64_t size) {
+  DCHECK(size > 0);
+  return std::malloc(static_cast<size_t>(size));
+}
+
+void DefaultAllocator::ReleasePayloadBuffer(uint64_t size, void* buffer) {
+  DCHECK(size > 0);
+  DCHECK(buffer);
+  std::free(buffer);
+}
+
+class NullAllocator : public Allocator {
+ public:
+  // Allocator implementation.
+  void* AllocatePayloadBuffer(uint64_t size) override;
+
+  void ReleasePayloadBuffer(uint64_t size, void* buffer) override;
+};
+
+void* NullAllocator::AllocatePayloadBuffer(uint64_t size) {
+  NOTREACHED();
+  return nullptr;
+}
+
+void NullAllocator::ReleasePayloadBuffer(uint64_t size, void* buffer) {
+  DCHECK(size > 0);
+  DCHECK(buffer);

[johngro, 2016/01/28 19:14:54]

Given that allocate is NOTREACHED, shouldn't this be NOTREACHED as well?

Also, in order to assert that size > 0 here, we should do so as well in
AllocatePayloadBuffer.  That said, since we never give out a buffer anyway, is
there any real reason to assert anything about the size of the failed allocation
which is (for some reason) being released?

Finally, since the Null allocator never gives out an actual buffer (it always
returns nullptr), this should probably be DCHECK(!buffer) or DCHECK(buffer ==
nullptr).  It would be bit odd, but not unthinkable that someone is attempting
to return the failed allocation to the Null allocator; but if they attempt to do
so, the pointer they are "returning" had better be nullptr.

[dalesat, 2016/01/29 01:08:29]

NullAllocator is used when the packet packet payload didn't actually come from
an allocator. No one should call AllocatePayloadBuffer and ReleasePayloadBuffer
should do nothing. In retrospect, it would be simpler if Packet was OK not
having an allocator. I'll get rid of this.

[johngro, 2016/02/01 22:38:16]

Acknowledged.

+}
+
+static DefaultAllocator default_allocator;
+static NullAllocator null_allocator;

[johngro, 2016/01/28 19:14:55]

quick reminder, remember to make the Null allocator constexpr as well when you
take care of the Default allocator.

[dalesat, 2016/01/29 01:08:29]

Done.

+
+} // namespace
+
+// static
+Allocator* Allocator::GetDefault() {
+  return &default_allocator;
+}
+
+// static
+Allocator* Allocator::GetNull() {
+  return &null_allocator;
+}
+
+} // namespace media
+} // namespace mojo