Devirtualize SpeechRecognitionEngine

content/browser/speech/google_streaming_remote_engine.h

-// Copyright (c) 2012 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 CONTENT_BROWSER_SPEECH_GOOGLE_STREAMING_REMOTE_ENGINE_H_
-#define CONTENT_BROWSER_SPEECH_GOOGLE_STREAMING_REMOTE_ENGINE_H_
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/threading/non_thread_safe.h"
-#include "content/browser/speech/audio_encoder.h"
-#include "content/browser/speech/chunked_byte_buffer.h"
-#include "content/browser/speech/speech_recognition_engine.h"
-#include "content/common/content_export.h"
-#include "content/public/common/speech_recognition_error.h"
-#include "net/url_request/url_fetcher_delegate.h"
-
-namespace net {
-class URLRequestContextGetter;
-}
-
-namespace content {
-
-class AudioChunk;
-struct SpeechRecognitionError;
-struct SpeechRecognitionResult;
-
-// Implements a SpeechRecognitionEngine supporting continuous recognition by
-// means of interaction with Google streaming speech recognition webservice.
-// More in details, this class establishes two HTTP(S) connections with the
-// webservice, for each session, herein called "upstream" and "downstream".
-// Audio chunks are sent on the upstream by means of a chunked HTTP POST upload.
-// Recognition results are retrieved in a full-duplex fashion (i.e. while
-// pushing audio on the upstream) on the downstream by means of a chunked
-// HTTP GET request. Pairing between the two stream is handled through a
-// randomly generated key, unique for each request, which is passed in the
-// &pair= arg to both stream request URLs.
-// In the case of a regular session, the upstream is closed when the audio
-// capture ends (notified through a |AudioChunksEnded| call) and the downstream
-// waits for a corresponding server closure (eventually some late results can
-// come after closing the upstream).
-// Both stream are guaranteed to be closed when |EndRecognition| call is issued.
-class CONTENT_EXPORT GoogleStreamingRemoteEngine
-    : public NON_EXPORTED_BASE(SpeechRecognitionEngine),
-      public net::URLFetcherDelegate,
-      public NON_EXPORTED_BASE(base::NonThreadSafe) {
- public:
-  // Duration of each audio packet.
-  static const int kAudioPacketIntervalMs;
-
-  // IDs passed to URLFetcher::Create(). Used for testing.
-  static const int kUpstreamUrlFetcherIdForTesting;
-  static const int kDownstreamUrlFetcherIdForTesting;
-
-  explicit GoogleStreamingRemoteEngine(net::URLRequestContextGetter* context);
-  ~GoogleStreamingRemoteEngine() override;
-
-  // SpeechRecognitionEngine methods.
-  void SetConfig(const SpeechRecognitionEngineConfig& config) override;
-  void StartRecognition() override;
-  void EndRecognition() override;
-  void TakeAudioChunk(const AudioChunk& data) override;
-  void AudioChunksEnded() override;
-  bool IsRecognitionPending() const override;
-  int GetDesiredAudioChunkDurationMs() const override;
-
-  // net::URLFetcherDelegate methods.
-  void OnURLFetchComplete(const net::URLFetcher* source) override;
-  void OnURLFetchDownloadProgress(const net::URLFetcher* source,
-                                  int64_t current,
-                                  int64_t total) override;
-
- private:
-  // Response status codes from the speech recognition webservice.
-  static const int kWebserviceStatusNoError;
-  static const int kWebserviceStatusErrorNoMatch;
-
-  // Frame type for framed POST data. Do NOT change these. They must match
-  // values the server expects.
-  enum FrameType {
-    FRAME_PREAMBLE_AUDIO = 0,
-    FRAME_RECOGNITION_AUDIO = 1
-  };
-
-  // Data types for the internal Finite State Machine (FSM).
-  enum FSMState {
-    STATE_IDLE = 0,
-    STATE_BOTH_STREAMS_CONNECTED,
-    STATE_WAITING_DOWNSTREAM_RESULTS,
-    STATE_MAX_VALUE = STATE_WAITING_DOWNSTREAM_RESULTS
-  };
-
-  enum FSMEvent {
-    EVENT_END_RECOGNITION = 0,
-    EVENT_START_RECOGNITION,
-    EVENT_AUDIO_CHUNK,
-    EVENT_AUDIO_CHUNKS_ENDED,
-    EVENT_UPSTREAM_ERROR,
-    EVENT_DOWNSTREAM_ERROR,
-    EVENT_DOWNSTREAM_RESPONSE,
-    EVENT_DOWNSTREAM_CLOSED,
-    EVENT_MAX_VALUE = EVENT_DOWNSTREAM_CLOSED
-  };
-
-  struct FSMEventArgs {
-    explicit FSMEventArgs(FSMEvent event_value);
-    ~FSMEventArgs();
-
-    FSMEvent event;
-
-    // In case of EVENT_AUDIO_CHUNK, holds the chunk pushed by |TakeAudioChunk|.
-    scoped_refptr<const AudioChunk> audio_data;
-
-    // In case of EVENT_DOWNSTREAM_RESPONSE, hold the current chunk bytes.
-    std::unique_ptr<std::vector<uint8_t>> response;
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(FSMEventArgs);
-  };
-
-  // Invoked by both upstream and downstream URLFetcher callbacks to handle
-  // new chunk data, connection closed or errors notifications.
-  void DispatchHTTPResponse(const net::URLFetcher* source,
-                            bool end_of_response);
-
-  // Entry point for pushing any new external event into the recognizer FSM.
-  void DispatchEvent(const FSMEventArgs& event_args);
-
-  // Defines the behavior of the recognizer FSM, selecting the appropriate
-  // transition according to the current state and event.
-  FSMState ExecuteTransitionAndGetNextState(const FSMEventArgs& event_args);
-
-  // The methods below handle transitions of the recognizer FSM.
-  FSMState ConnectBothStreams(const FSMEventArgs& event_args);
-  FSMState TransmitAudioUpstream(const FSMEventArgs& event_args);
-  FSMState ProcessDownstreamResponse(const FSMEventArgs& event_args);
-  FSMState RaiseNoMatchErrorIfGotNoResults(const FSMEventArgs& event_args);
-  FSMState CloseUpstreamAndWaitForResults(const FSMEventArgs& event_args);
-  FSMState CloseDownstream(const FSMEventArgs& event_args);
-  FSMState AbortSilently(const FSMEventArgs& event_args);
-  FSMState AbortWithError(const FSMEventArgs& event_args);
-  FSMState Abort(SpeechRecognitionErrorCode error);
-  FSMState DoNothing(const FSMEventArgs& event_args);
-  FSMState NotFeasible(const FSMEventArgs& event_args);
-
-  std::string GetAcceptedLanguages() const;
-  std::string GenerateRequestKey() const;
-
-  // Upload a single chunk of audio data. Handles both unframed and framed
-  // upload formats, and uses the appropriate one.
-  void UploadAudioChunk(const std::string& data, FrameType type, bool is_final);
-
-  SpeechRecognitionEngineConfig config_;
-  std::unique_ptr<net::URLFetcher> upstream_fetcher_;
-  std::unique_ptr<net::URLFetcher> downstream_fetcher_;
-  scoped_refptr<net::URLRequestContextGetter> url_context_;
-  std::unique_ptr<AudioEncoder> encoder_;
-  std::unique_ptr<AudioEncoder> preamble_encoder_;
-  ChunkedByteBuffer chunked_byte_buffer_;
-  size_t previous_response_length_;
-  bool got_last_definitive_result_;
-  bool is_dispatching_event_;
-  bool use_framed_post_data_;
-  FSMState state_;
-
-  DISALLOW_COPY_AND_ASSIGN(GoogleStreamingRemoteEngine);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_SPEECH_GOOGLE_STREAMING_REMOTE_ENGINE_H_