Implement SpeechRecognizerImplAndroid

content/browser/speech/speech_recognizer_impl_android.cc

+// Copyright (c) 2013 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 "content/browser/speech/speech_recognizer_impl_android.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_array.h"
+#include "base/android/jni_string.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/bind.h"
+#include "base/utf_string_conversions.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/speech_recognition_event_listener.h"
+#include "content/public/browser/speech_recognition_manager.h"
+#include "content/public/browser/speech_recognition_session_config.h"
+#include "content/public/common/speech_recognition_grammar.h"
+#include "content/public/common/speech_recognition_result.h"
+#include "jni/SpeechRecognition_jni.h"
+
+using base::android::AppendJavaStringArrayToStringVector;
+using base::android::AttachCurrentThread;
+using base::android::GetApplicationContext;
+using base::android::JavaFloatArrayToFloatVector;
+
+namespace content {
+
+void SpeechRecognizerImplAndroid::Init(JNIEnv* env) {
+  RegisterNativesImpl(env);

[bulach, 2013/06/07 15:35:10]

as above, the way to do this is to expose a Register() methods, and add the call
in browser/android/browser_jni_registrar.cc..

[janx, 2013/06/10 16:51:18]

Fixed. Thanks for the explanation!

+}
+
+SpeechRecognizerImplAndroid::SpeechRecognizerImplAndroid(
+    SpeechRecognitionEventListener* listener,
+    int session_id)
+    : SpeechRecognizer(listener, session_id),
+      state_(STATE_IDLE) {
+}
+
+SpeechRecognizerImplAndroid::~SpeechRecognizerImplAndroid() { }
+
+void SpeechRecognizerImplAndroid::StartRecognition() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  listener_->OnRecognitionStart(session_id_);

[janx, 2013/06/07 12:43:58]

Primiano Tucci 2013/06/03 16:24:11
I'd like to have feedback by some other reviewer on this comment.
I think is a bit safer posting the OnRecognitionStart (and similar below), even
if the source and target threads are the same (IO), rather than calling the
callback method directly.
What I fear about calling callbacks synchronously is that you can end up in
unpleasant nested/reentrant call stacks.
For instance, imagine that for some reason the listener (i.e. the S.R. manager
in our case) has a code path that calls AbortRecognition in the
OnRecognitionStart event handler (e.g., in a error/not authorized code path).
In such a case you would end up having a call stack like this:
SRManager.Something()
 SRImplAndroid.StartRecognition()
  SRManager.OnRecognitionStart(...)
   SRImplAndroid.AbortRecognition()
    SRManager.OnRecognitionEnd()

I don't know if this particular example is possible with the current S.R.
manager implementation, but IMHO if some code path will change in future, a
nested call stack like the one depicted above could cause serious headaches.
Conversely, if you post call-backs on the same (IO) thread, you basically will
break any possiblity of nesting/reentrancy (at the price of a little higher
latency).


If you take a look to the current speech_recognizer_impl.cc implementation, all
the listener_->CallbackMethods() are always called inside the FSM, which by
design is always decoupled in a separate message loop task (read: all evolution
functions of the FSM are "posted").

What do you think?

+  SpeechRecognitionSessionConfig config_ =
+      SpeechRecognitionManager::GetInstance()->GetSessionConfig(session_id_);
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+      base::Bind(&content::SpeechRecognizerImplAndroid::StartRecognitionJNI,

[bulach, 2013/06/07 15:35:10]

ahn, right.. so there are two ways of doing this:
1. use "OnUIThread" suffix instead of "JNI".
2. since the code is simple enough, another pattern is to just test and post
back to itself..

...Foo() {
 if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, ... Foo);
    return;
 }
 DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 Java_..._Foo(...);
}

I don't have strong feelings either way, but there's a lot of boiler plate to
just separate the "OnUIThread", so perhaps it's simpler to keep in one function.

[janx, 2013/06/10 16:51:18]

I refactored most of them into single functions, except
StartRecognition{,OnUIThread} and OnRecognitionResults{,OnIOThread} because they
both need to perform operations on one thread and pass the result to the other
(respectively SpeechRecognitionManager::GetSessionConfig() on IO thread and
JavaFloatArrayToFloatVector on UI thread).

+                 this, config_.continuous, config_.interim_results));
+}
+
+void SpeechRecognizerImplAndroid::StartRecognitionJNI(bool continuous,
+                                                      bool interim_results) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  j_recognition_.Reset(Java_SpeechRecognition_createSpeechRecognition(
+      AttachCurrentThread(),

[bulach, 2013/06/07 15:35:10]

AttachCurrentThread is a bit expensive. common pattern is to extract in a local:
JNIEnv* env = AttachCurrentThread();

then use where needed.

[janx, 2013/06/10 16:51:18]

Done.

+      GetApplicationContext(),
+      reinterpret_cast<jint>(this)));
+  Java_SpeechRecognition_StartRecognition(AttachCurrentThread(),
+      j_recognition_.obj(), continuous, interim_results);
+}
+
+void SpeechRecognizerImplAndroid::AbortRecognition() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+      base::Bind(&content::SpeechRecognizerImplAndroid::AbortRecognitionJNI,
+                 this));
+  OnRecognitionError(SpeechRecognitionError(SPEECH_RECOGNITION_ERROR_ABORTED));
+}
+
+void SpeechRecognizerImplAndroid::AbortRecognitionJNI() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (!j_recognition_.is_null())
+    Java_SpeechRecognition_AbortRecognition(AttachCurrentThread(),
+                                             j_recognition_.obj());

[bulach, 2013/06/07 15:35:10]

nit: indent

[janx, 2013/06/10 16:51:18]

Done.

+}
+
+void SpeechRecognizerImplAndroid::StopAudioCapture() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+      base::Bind(&content::SpeechRecognizerImplAndroid::StopRecognitionJNI,
+                 this));
+}
+
+void SpeechRecognizerImplAndroid::StopRecognitionJNI() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (!j_recognition_.is_null())
+    Java_SpeechRecognition_StopRecognition(AttachCurrentThread(),
+                                           j_recognition_.obj());
+}
+
+bool SpeechRecognizerImplAndroid::IsActive() const {
+  return state_ != STATE_IDLE;
+}
+
+bool SpeechRecognizerImplAndroid::IsCapturingAudio() const {
+  return state_ == STATE_CAPTURING_AUDIO;
+}
+
+void SpeechRecognizerImplAndroid::OnAudioStartJNI(JNIEnv* env, jobject obj) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnAudioStart, this));
+}
+
+void SpeechRecognizerImplAndroid::OnAudioStart() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  state_ = STATE_CAPTURING_AUDIO;
+  listener_->OnAudioStart(session_id_);
+}
+
+void SpeechRecognizerImplAndroid::OnSoundStartJNI(JNIEnv* env, jobject obj) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnSoundStart, this));
+}
+
+void SpeechRecognizerImplAndroid::OnSoundStart() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  listener_->OnSoundStart(session_id_);
+}
+
+void SpeechRecognizerImplAndroid::OnSoundEndJNI(JNIEnv* env, jobject obj) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnSoundEnd, this));
+}
+
+void SpeechRecognizerImplAndroid::OnSoundEnd() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  listener_->OnSoundEnd(session_id_);
+}
+
+void SpeechRecognizerImplAndroid::OnAudioEndJNI(JNIEnv* env, jobject obj) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnAudioEnd, this));
+}
+
+void SpeechRecognizerImplAndroid::OnAudioEnd() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  state_ = STATE_AWAITING_FINAL_RESULT;
+  listener_->OnAudioEnd(session_id_);
+}
+
+void SpeechRecognizerImplAndroid::OnRecognitionResultsJNI(JNIEnv* env,
+    jobject obj, jobjectArray strings, jfloatArray floats,
+    jboolean provisional) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  std::vector<string16> options;
+  AppendJavaStringArrayToStringVector(env, strings, &options);
+  std::vector<float> scores(options.size(), 0.0);
+  if (floats != NULL)
+    JavaFloatArrayToFloatVector(env, floats, &scores);
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnRecognitionResults,
+                 this, options, scores, provisional));
+}
+
+void SpeechRecognizerImplAndroid::OnRecognitionResults(
+    std::vector<string16> options, std::vector<float> scores,
+    bool provisional) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  SpeechRecognitionResults results;
+  results.push_back(SpeechRecognitionResult());
+  SpeechRecognitionResult& result = results.back();
+  for (unsigned int i = 0; i < options.size(); i++) {
+    result.hypotheses.push_back(
+        SpeechRecognitionHypothesis(options[i],
+                                    static_cast<double>(scores[i])));
+  }
+  result.is_provisional = provisional;
+  listener_->OnRecognitionResults(session_id_, results);
+}
+
+void SpeechRecognizerImplAndroid::OnRecognitionErrorJNI(JNIEnv* env,
+    jobject obj, jint error) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  SpeechRecognitionErrorCode code;
+
+  // Translate Android speech recognition errors to Web Speech API errors.
+  // TODO(janx): Do this in SpeechRecognition.java instead.
+  switch(error) {
+    case 3: // ERROR_AUDIO
+      code = SPEECH_RECOGNITION_ERROR_AUDIO;
+      break;
+    case 5: // ERROR_CLIENT
+      code = SPEECH_RECOGNITION_ERROR_ABORTED;
+      break;
+    case 8: // ERROR_RECOGNIZER_BUSY
+    case 9: // ERROR_INSUFFICIENT_PERMISSIONS
+      code = SPEECH_RECOGNITION_ERROR_NOT_ALLOWED;
+      break;
+    case 1: // ERROR_NETWORK_TIMEOUT
+    case 2: // ERROR_NETWORK
+    case 4: // ERROR_SERVER
+      code = SPEECH_RECOGNITION_ERROR_NETWORK;
+      break;
+    case 7: // ERROR_NO_MATCH
+      code = SPEECH_RECOGNITION_ERROR_NO_MATCH;
+      break;
+    case 6: // ERROR_SPEECH_TIMEOUT
+      code = SPEECH_RECOGNITION_ERROR_NO_SPEECH;
+      break;
+    default:
+      NOTREACHED();
+      return;
+  }
+
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnRecognitionError, this,
+                 SpeechRecognitionError(code)));
+}
+
+void SpeechRecognizerImplAndroid::OnRecognitionError(
+    SpeechRecognitionError error) {
+  listener_->OnRecognitionError(session_id_, error);
+}
+
+void SpeechRecognizerImplAndroid::OnRecognitionEndJNI(JNIEnv* env,
+    jobject obj) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognizerImplAndroid::OnRecognitionEnd, this));
+}
+
+void SpeechRecognizerImplAndroid::OnRecognitionEnd() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  state_ = STATE_IDLE;
+  listener_->OnRecognitionEnd(session_id_);
+}
+
+}  // namespace content