Tracing V2: Proto message and utils improvements.

components/tracing/core/proto_zero_message.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 COMPONENTS_TRACING_CORE_PROTO_ZERO_MESSAGE_H_
 #define COMPONENTS_TRACING_CORE_PROTO_ZERO_MESSAGE_H_
 
 #include <stdint.h>
 
 #include <type_traits>
 
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/template_util.h"
 #include "build/build_config.h"
+#include "components/tracing/core/proto_utils.h"
 #include "components/tracing/core/scattered_stream_writer.h"
 #include "components/tracing/tracing_export.h"
 
 namespace tracing {
 namespace v2 {
 
 class ProtoZeroMessageHandleBase;
 
 // Base class extended by the proto C++ stubs generated by the ProtoZero
 // compiler (see //components/tracing/tools/). This class provides the minimal
@@ skipping 26 matching lines @@
   void inc_size_already_written(size_t size) { size_already_written_ += size; }
 
 #if DCHECK_IS_ON()
   // Only for ProtoZeroMessageHandleBase.
   void set_handle(ProtoZeroMessageHandleBase* handle) { handle_ = handle; }
 #endif
 
  protected:
   ProtoZeroMessage();
 
-  void AppendVarIntU64(uint32_t field_id, uint64_t value);
-  void AppendVarIntU32(uint32_t field_id, uint32_t value);
-  void AppendFloat(uint32_t field_id, float value);
-  void AppendDouble(uint32_t field_id, double value);
+  // Proto types: uint64, uint32, int64, int32, bool, enum.
+  template <typename T>
+  void AppendVarInt(uint32_t field_id, T value) {
+    if (nested_message_)
+      EndNestedMessage();
+
+    uint8_t buffer[proto::kMaxSingilarFieldEncodedSize];
+    uint8_t* pos = buffer;
+
+    pos = proto::WriteVarInt(proto::MakeTagVarInt(field_id), pos);
+    // WriteVarInt treat signed values in two's complement form.

[petrcermak, 2016/08/09 09:55:53]

nit: s/treat/treats/. Also I think "writes" or "encodes" would be more
appropriate ("treats" is kind of ambiguous and "treat X in form Y" is a little
mystifying).

[kraynov, 2016/08/09 12:32:05]

Done.

+    pos = proto::WriteVarInt(value, pos);
+    WriteToStream(buffer, pos);
+  }
+
+  // Proto types: sint64, sint32.
+  template <typename T>
+  void AppendSignedVarInt(uint32_t field_id, T value) {
+    AppendVarInt(field_id, proto::ZigZagEncode(value));
+  }
+
+  // Proto types: fixed64, sfixed64, fixed32, sfixed32, double, float.
+  template <typename T>
+  void AppendFixed(uint32_t field_id, T value) {
+    if (nested_message_)
+      EndNestedMessage();
+
+    uint8_t buffer[proto::kMaxSingilarFieldEncodedSize];
+    uint8_t* pos = buffer;
+
+    pos = proto::WriteVarInt(proto::MakeTagFixed<T>(field_id), pos);
+    memcpy(pos, &value, sizeof(T));
+    pos += sizeof(T);
+    // TODO(kraynov) Optimize memcpy performance, see http://crbug.com/624311 .
+    WriteToStream(buffer, pos);
+  }
+
+  // TODO(kraynov) AppendTinyInt.

[petrcermak, 2016/08/09 09:55:53]

nit: missing colon "):". Also, please include the action in the TODO. Should it
be "Add AppendTinyInt" or "Implement AppendTinyInt"?

[kraynov, 2016/08/09 12:32:05]

Done.

   void AppendString(uint32_t field_id, const char* str);
   void AppendBytes(uint32_t field_id, const void* value, size_t size);
-  // TODO(kraynov): implement AppendVarIntS32/64(...) w/ zig-zag encoding.
 
   // Begins a nested message, using the static storage provided by the parent
   // class (see comment in |nested_messages_arena_|). The nested message ends
   // either when Finalize() is called or when any other Append* method is called
   // in the parent class.
   // The template argument T is supposed to be a stub class auto generated from
   // a .proto, hence a subclass of ProtoZeroMessage.
   template <class T>
   T* BeginNestedMessage(uint32_t field_id) {
     // This is to prevent subclasses (which should be autogenerated, though), to
@@ skipping 75 matching lines @@
   // DO NOT add any fields below |nested_messages_arena_|. The memory layout of
   // nested messages would overflow the storage allocated by the root message.
 
   DISALLOW_COPY_AND_ASSIGN(ProtoZeroMessage);
 };
 
 }  // namespace v2
 }  // namespace tracing
 
 #endif  // COMPONENTS_TRACING_CORE_PROTO_ZERO_MESSAGE_H_