Refactoring WebRTC Java/JNI audio recording in C++ and Java.

This is a big refactoring of the existing C++/JNI/Java support for audio recording in native WebRTC:

- Removes unused code and old WEBRTC logging macros
- Now uses optimal sample rate and buffer size in Java AudioRecord (used hard-coded sample rate before)
- Makes code more inline with the implementation in Chrome
- Adds helper methods for JNI handling to improve readability
- Changes the threading model (high-prio audio thread now lives in Java-land and C++ only works as proxy)
- Adds basic thread checks
- Removes all locks in C++ land
- Removes all locks in Java
- Improves construction/destruction
- Additional cleanup

Tested using AppRTCDemo and WebRTCDemo APKs on N6, N5, N7, Samsung Galaxy S4 and
Samsung Galaxy S4 mini (which uses 44.1kHz as native sample rate).

BUG=NONE
R=magjed@webrtc.org, perkj@webrtc.org, pthatcher@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/33969004

Cr-Commit-Position: refs/heads/master@{#8325}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8325 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/utility/source/helpers_android.cc

@@ -8,27 +8,89 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include "webrtc/base/checks.h"
 #include "webrtc/modules/utility/interface/helpers_android.h"
 
+#include <android/log.h>
 #include <assert.h>
+#include <pthread.h>
 #include <stddef.h>
+#include <unistd.h>
+
+#define TAG "HelpersAndroid"
+#define ALOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)
 
 namespace webrtc {
 
+JNIEnv* GetEnv(JavaVM* jvm) {
+  void* env = NULL;
+  jint status = jvm->GetEnv(&env, JNI_VERSION_1_6);
+  CHECK(((env != NULL) && (status == JNI_OK)) ||
+        ((env == NULL) && (status == JNI_EDETACHED)))
+      << "Unexpected GetEnv return: " << status << ":" << env;
+  return reinterpret_cast<JNIEnv*>(env);
+}
+
+jmethodID GetMethodID (
+    JNIEnv* jni, jclass c, const std::string& name, const char* signature) {
+  jmethodID m = jni->GetMethodID(c, name.c_str(), signature);
+  CHECK_EXCEPTION(jni) << "Error during GetMethodID: " << name << ", "
+                       << signature;
+  CHECK(m) << name << ", " << signature;
+  return m;
+}
+
+jclass FindClass(JNIEnv* jni, const std::string& name) {
+  jclass c = jni->FindClass(name.c_str());
+  CHECK_EXCEPTION(jni) << "Error during FindClass: " << name;
+  CHECK(c) << name;
+  return c;
+}
+
+jobject NewGlobalRef(JNIEnv* jni, jobject o) {
+  jobject ret = jni->NewGlobalRef(o);
+  CHECK_EXCEPTION(jni) << "Error during NewGlobalRef";
+  CHECK(ret);
+  return ret;
+}
+
+void DeleteGlobalRef(JNIEnv* jni, jobject o) {
+  jni->DeleteGlobalRef(o);
+  CHECK_EXCEPTION(jni) << "Error during DeleteGlobalRef";
+}
+
+std::string GetThreadId() {
+  char buf[21];  // Big enough to hold a kuint64max plus terminating NULL.
+  int thread_id = gettid();
+  CHECK_LT(snprintf(buf, sizeof(buf), "%i", thread_id),
+      static_cast<int>(sizeof(buf))) << "Thread id is bigger than uint64??";
+  return std::string(buf);
+}
+
+std::string GetThreadInfo() {
+  return "@[tid=" + GetThreadId() + "]";
+}
+
 AttachThreadScoped::AttachThreadScoped(JavaVM* jvm)
     : attached_(false), jvm_(jvm), env_(NULL) {
-  jint ret_val = jvm->GetEnv(reinterpret_cast<void**>(&env_), JNI_VERSION_1_4);
-  if (ret_val == JNI_EDETACHED) {
-    // Attach the thread to the Java VM.
-    ret_val = jvm_->AttachCurrentThread(&env_, NULL);
-    attached_ = ret_val == JNI_OK;
-    assert(attached_);
+  env_ = GetEnv(jvm);
+  if (!env_) {
+    // Adding debug log here so we can track down potential leaks and figure
+    // out why we sometimes see "Native thread exiting without having called
+    // DetachCurrentThread" in logcat outputs.
+    ALOGD("Attaching thread to JVM%s", GetThreadInfo().c_str());
+    jint res = jvm->AttachCurrentThread(&env_, NULL);
+    attached_ = (res == JNI_OK);
+    CHECK(attached_) << "AttachCurrentThread failed: " << res;
   }
 }
 
 AttachThreadScoped::~AttachThreadScoped() {
-  if (attached_ && (jvm_->DetachCurrentThread() < 0)) {
-    assert(false);
+  if (attached_) {
+    ALOGD("Detaching thread from JVM%s", GetThreadInfo().c_str());
+    jint res = jvm_->DetachCurrentThread();
+    CHECK(res == JNI_OK) << "DetachCurrentThread failed: " << res;
+    CHECK(!GetEnv(jvm_));
   }
 }