Fix JNI for warning about failure to unlink DeathRecipients

We now (a) use the right Class getName() method, and (b) look it
up once at setup time rather than doing that lookup every time we
want to emit the warning.  Verified to work properly and no longer
crash or throw or otherwise complain.

Change-Id: If0767f8845588ba7f34bac21474f4e2ad5c111d6

1 files changed, 22 insertions, 16 deletions

diff --git a/core/jni/android_util_Binder.cpp b/core/jni/android_util_Binder.cpp
index 4cf4afa..494a2b3 100644
--- a/core/jni/android_util_Binder.cpp
+++ b/core/jni/android_util_Binder.cpp
@@ -119,6 +119,11 @@ static struct binderproxy_offsets_t
 
 } gBinderProxyOffsets;
 
+static struct class_offsets_t
+{
+    jmethodID mGetName;
+} gClassOffsets;
+
 // ----------------------------------------------------------------------------
 
 static struct parcel_offsets_t
@@ -452,22 +457,18 @@ public:
             // Okay, something is wrong -- we have a hard reference to a live death
             // recipient on the VM side, but the list is being torn down.
             JNIEnv* env = javavm_to_jnienv(mVM);
-            ScopedLocalRef<jclass> classRef(env, env->GetObjectClass(mObject));
-            jmethodID getnameMethod = env->GetMethodID(classRef.get(),
-                    "getName", "()Ljava/lang/String;");
-            if (getnameMethod) {
-                ScopedLocalRef<jstring> nameRef(env,
-                        (jstring) env->CallObjectMethod(classRef.get(), getnameMethod));
-                ScopedUtfChars nameUtf(env, nameRef.get());
-                if (nameUtf.c_str() != NULL) {
-                    LOGW("BinderProxy is being destroyed but the application did not call "
-                            "unlinkToDeath to unlink all of its death recipients beforehand.  "
-                            "Releasing leaked death recipient: %s", nameUtf.c_str());
-                } else {
-                    LOGW("BinderProxy being destroyed; unable to get DR object name");
-                    env->ExceptionClear();
-                }
-            } else LOGW("BinderProxy being destroyed; unable to find DR class getName");
+            ScopedLocalRef<jclass> objClassRef(env, env->GetObjectClass(mObject));
+            ScopedLocalRef<jstring> nameRef(env,
+                    (jstring) env->CallObjectMethod(objClassRef.get(), gClassOffsets.mGetName));
+            ScopedUtfChars nameUtf(env, nameRef.get());
+            if (nameUtf.c_str() != NULL) {
+                LOGW("BinderProxy is being destroyed but the application did not call "
+                        "unlinkToDeath to unlink all of its death recipients beforehand.  "
+                        "Releasing leaked death recipient: %s", nameUtf.c_str());
+            } else {
+                LOGW("BinderProxy being destroyed; unable to get DR object name");
+                env->ExceptionClear();
+            }
         }
     }
 
@@ -1230,6 +1231,11 @@ static int int_register_android_os_BinderProxy(JNIEnv* env)
         = env->GetFieldID(clazz, "mOrgue", "I");
     assert(gBinderProxyOffsets.mOrgue);
 
+    clazz = env->FindClass("java/lang/Class");
+    LOG_FATAL_IF(clazz == NULL, "Unable to find java.lang.Class");
+    gClassOffsets.mGetName = env->GetMethodID(clazz, "getName", "()Ljava/lang/String;");
+    assert(gClassOffsets.mGetName);
+
     return AndroidRuntime::registerNativeMethods(
         env, kBinderProxyPathName,
         gBinderProxyMethods, NELEM(gBinderProxyMethods));