Add 'flog' service implementation.

services/flog/flog_reader_impl.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 MOJO_SERVICES_FLOG_FLOG_READER_IMPL_H_
+#define MOJO_SERVICES_FLOG_FLOG_READER_IMPL_H_
+
+#include <limits>
+
+#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/services/flog/interfaces/flog.mojom.h"
+#include "services/flog/flog_service_impl.h"
+
+namespace mojo {
+namespace flog {
+
+// FlogReader implementation.
+class FlogReaderImpl : public FlogServiceImpl::Product<FlogReader>,
+                       public FlogReader,
+                       private FlogLogger {
+ public:
+  static std::shared_ptr<FlogReaderImpl> Create(
+      InterfaceRequest<FlogReader> request,
+      uint32_t log_id,
+      const std::string& label,
+      std::shared_ptr<FlogDirectory> directory,
+      FlogServiceImpl* owner);
+
+  ~FlogReaderImpl() override;
+
+  // FlogReader implementation.
+  void GetEntries(uint32_t start_index,
+                  uint32_t max_count,
+                  const GetEntriesCallback& callback) override;
+
+ private:
+  static const size_t kReadBufferSize = 16 * 1024;
+
+  FlogReaderImpl(InterfaceRequest<FlogReader> request,
+                 uint32_t log_id,
+                 const std::string& label,
+                 std::shared_ptr<FlogDirectory> directory,
+                 FlogServiceImpl* owner);
+
+  bool DiscardEntry();
+
+  FlogEntryPtr GetEntry();
+
+  // Reads data and returns the number of bytes read. |data_size| must be
+  // non-zero. |data| may be nullptr, in which case the data is discarded.
+  size_t ReadData(size_t data_size, void* data);
+
+  void FillReadBuffer(bool restart);
+
+  size_t read_buffer_bytes_remaining() {
+    return read_buffer_.size() - read_buffer_bytes_used_;
+  }
+
+  // Creates an entry with an uninitialized details field.
+  FlogEntryPtr CreateEntry(int64_t time_us, uint32_t channel_id);
+
+  // FlogLogger implementation (called by stub_).
+  void LogChannelCreation(int64_t time_us,
+                          uint32_t channel_id,
+                          const mojo::String& type_name) override;
+
+  void LogChannelMessage(int64_t time_us,
+                         uint32_t channel_id,
+                         mojo::Array<uint8_t> data) override;
+
+  void LogChannelDeletion(int64_t time_us, uint32_t channel_id) override;
+
+  uint32_t log_id_;
+  files::FilePtr file_;
+  uint32_t current_entry_index_ = 0;
+  std::vector<uint8_t> read_buffer_;
+  size_t read_buffer_bytes_used_;
+  bool fault_ = false;
+  FlogLoggerStub stub_;
+  FlogEntryPtr entry_;
+};
+
+}  // namespace flog
+}  // namespace mojo
+
+#endif  // MOJO_SERVICES_FLOG_FLOG_READER_IMPL_H_