Fix race condition in NetworkChangeNotifier on Android.

net/android/network_change_notifier_android.cc

Index: net/android/network_change_notifier_android.cc
diff --git a/net/android/network_change_notifier_android.cc b/net/android/network_change_notifier_android.cc
index 66aacaf1a8edc68402fe0ff6aeaa0313415a1989..f055af971db4a41bf54e6d386da5c2dc4a2d873e 100644
--- a/net/android/network_change_notifier_android.cc
+++ b/net/android/network_change_notifier_android.cc
@@ -4,33 +4,72 @@
 
 #include "net/android/network_change_notifier_android.h"
 
-#include "base/logging.h"
 #include "base/android/jni_android.h"
+#include "base/logging.h"
 #include "jni/NetworkChangeNotifier_jni.h"
 
 namespace net {
 
-NetworkChangeNotifierAndroid::NetworkChangeNotifierAndroid() {
-  JNIEnv* env = base::android::AttachCurrentThread();
-  java_network_change_notifier_.Reset(
-      Java_NetworkChangeNotifier_createInstance(
-          env,
-          base::android::GetApplicationContext(),
-          reinterpret_cast<jint>(this)));
+namespace {
+
+// Returns whether the provided connection type is known.
+bool CheckConnectionType(int connection_type) {
+  switch (connection_type) {
+    case NetworkChangeNotifier::CONNECTION_UNKNOWN:
+    case NetworkChangeNotifier::CONNECTION_ETHERNET:
+    case NetworkChangeNotifier::CONNECTION_WIFI:
+    case NetworkChangeNotifier::CONNECTION_2G:
+    case NetworkChangeNotifier::CONNECTION_3G:
+    case NetworkChangeNotifier::CONNECTION_4G:
+    case NetworkChangeNotifier::CONNECTION_NONE:
+      return true;
+    default:
+      NOTREACHED() << "Unknown connection type received: " << connection_type;
+      return false;
+  }
 }
 
+}  // namespace
+
 NetworkChangeNotifierAndroid::~NetworkChangeNotifierAndroid() {
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_NetworkChangeNotifier_destroyInstance(env);
-  java_network_change_notifier_.Reset();
 }
 
 void NetworkChangeNotifierAndroid::NotifyObserversOfConnectionTypeChange(
     JNIEnv* env,
-    jobject obj) {
+    jobject obj,
+    jint new_connection_type) {
+  int connection_type = CheckConnectionType(new_connection_type) ?
+      new_connection_type : CONNECTION_UNKNOWN;

[gone, 2012/09/20 21:52:01]

Just saw this when rebasing my patch; this overloads the CONNECTION_UNKNOWN
type.  CONNECTION_UNKNOWN implies that there is a network connection, but that
we don't know what kind it is.  Is this intentional?

[szym, 2012/09/20 21:54:19]

I believe so. CONNECTION_NONE is used to indicate we are offline. Paul?

+  SetConnectionType(connection_type);
   NetworkChangeNotifier::NotifyObserversOfConnectionTypeChange();
 }
 
+jint NetworkChangeNotifierAndroid::GetConnectionType(JNIEnv* env, jobject obj) {
+  return GetCurrentConnectionType();
+}
+
+// static
+bool NetworkChangeNotifierAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+NetworkChangeNotifierAndroid::NetworkChangeNotifierAndroid() {
+  SetConnectionType(CONNECTION_UNKNOWN);
+  JNIEnv* env = base::android::AttachCurrentThread();
+  java_network_change_notifier_.Reset(
+      Java_NetworkChangeNotifier_createInstance(
+          env,
+          base::android::GetApplicationContext(),
+          reinterpret_cast<jint>(this)));
+}
+
+void NetworkChangeNotifierAndroid::SetConnectionType(int connection_type) {
+  base::AutoLock auto_lock(lock_);
+  connection_type_ = connection_type;
+}
+
 void NetworkChangeNotifierAndroid::ForceConnectivityState(bool state) {
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_NetworkChangeNotifier_forceConnectivityState(env, state);
@@ -38,36 +77,8 @@ void NetworkChangeNotifierAndroid::ForceConnectivityState(bool state) {
 
 NetworkChangeNotifier::ConnectionType
     NetworkChangeNotifierAndroid::GetCurrentConnectionType() const {
-  JNIEnv* env = base::android::AttachCurrentThread();
-
-  // Pull the connection type from the Java-side then convert it to a
-  // native-side NetworkChangeNotifier::ConnectionType.
-  jint connection_type = Java_NetworkChangeNotifier_connectionType(
-      env, java_network_change_notifier_.obj());
-  switch (connection_type) {
-    case CONNECTION_UNKNOWN:
-      return CONNECTION_UNKNOWN;
-    case CONNECTION_ETHERNET:
-      return CONNECTION_ETHERNET;
-    case CONNECTION_WIFI:
-      return CONNECTION_WIFI;
-    case CONNECTION_2G:
-      return CONNECTION_2G;
-    case CONNECTION_3G:
-      return CONNECTION_3G;
-    case CONNECTION_4G:
-      return CONNECTION_4G;
-    case CONNECTION_NONE:
-      return CONNECTION_NONE;
-    default:
-      NOTREACHED() << "Unknown connection type received: " << connection_type;
-      return CONNECTION_NONE;
-  }
-}
-
-// static
-bool NetworkChangeNotifierAndroid::Register(JNIEnv* env) {
-  return RegisterNativesImpl(env);
+  base::AutoLock auto_lock(lock_);
+  return static_cast<NetworkChangeNotifier::ConnectionType>(connection_type_);
 }
 
 }  // namespace net