Blimp: add packet-level DEFLATE compression using zlib.

blimp/net/compressed_packet_reader.h

+// 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.
+
+#ifndef BLIMP_NET_COMPRESSED_PACKET_READER_H_
+#define BLIMP_NET_COMPRESSED_PACKET_READER_H_
+
+#include "base/memory/weak_ptr.h"
+#include "blimp/net/blimp_net_export.h"
+#include "blimp/net/packet_reader.h"
+#include "net/base/completion_callback.h"
+#include "net/base/io_buffer.h"
+#include "third_party/zlib/zlib.h"
+
+namespace blimp {
+
+// Filter object which wraps a PacketReader, adding a DEFLATE decompression step
+// to received packets.
+// Details about the encoding format are available in the CompressedPacketWriter
+// header.
+class BLIMP_NET_EXPORT CompressedPacketReader : public PacketReader {
+ public:
+  // |source|: The source which from which compressed packets are read.
+  explicit CompressedPacketReader(scoped_ptr<PacketReader> source);
+
+  ~CompressedPacketReader() override;
+
+  // PacketReader implementation.
+  void ReadPacket(const scoped_refptr<net::GrowableIOBuffer>& decompressed_buf,
+                  const net::CompletionCallback& cb) override;
+
+ private:
+  // Called when source->ReadPacket() has completed.
+  // |buf|: The buffer which will receive decompressed data.
+  // |cb|: Callback which is triggered after decompression has finished.
+  // |result|: The result of the read operation.
+  void OnCompressedPacketReceived(
+      const scoped_refptr<net::GrowableIOBuffer> decompressed_buf,
+      const net::CompletionCallback& cb,
+      int result);
+
+  // Decompresses the contents of |compressed_buf_| to the buffer
+  // |decompressed|.
+  // |decompressed_size| is set to the size of the decompressed payload.
+  // On success, returns a >= 0 value indicating the size of the
+  // decompressed payload.
+  // On failure, returns a negative value indicating the error code
+  // (see net_errors.h).
+  int DecompressPacket(const scoped_refptr<net::GrowableIOBuffer>& decompressed,
+                       int size);
+
+  scoped_ptr<PacketReader> source_;
+  scoped_refptr<net::GrowableIOBuffer> compressed_buf_;
+  z_stream zlib_stream_{};

[Wez, 2016/03/29 21:38:38]

Is this valid syntax? Never seen this form before!

[Kevin M, 2016/03/29 23:48:23]

"brace-init", new in C++11. Empty braces imply default initialization, which
zero out the values in a POD struct.

[Wez, 2016/03/29 23:59:15]

Poo :( Looks like that language feature is currently on the banned list for
Chromium code.

[Kevin M, 2016/03/30 00:26:32]

Back to memset. :(

+
+  // Used to abandon pending ReadPacket() calls on teardown.
+  base::WeakPtrFactory<CompressedPacketReader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompressedPacketReader);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_COMPRESSED_PACKET_READER_H_