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POJava method is not invoked when calling it from native pthread
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I need a simple Java service which starts at system boot and uses shared library with some functional which uses POSIX threads. While implementing JNI interface I faced with a some problem which doesn't allow me to make a Java method call from native code. GetMethodID() returns not NULL so I suppose it is doing well. Also there is no any suspicious errors which can help. So I added a lot of output to log and prepared a simple java test for that. (all the code is listed below, but project can be found in <a href="https://github.com/YaMike/JavaServiceTest" rel="nofollow">this repository at github</a> as well). List of the files of the project: Service: <ul> <li>TestService.java </li> <li>TestController.java</li> <li>TestListener.java</li> <li>TestNative.java <<-- java method is here</li> </ul> Native code: <ul> <li>layer-jni.c <<-- native call is here</li> </ul> Other: <ul> <li>Android.mk</li> <li>Application.mk</li> <li>AndroidManifest.xml</li> </ul> All files are listed below. I tried the following logic in test service: 1.Service is started: TestService.java: <pre class="lang-java prettyprint-override"><code>package com.example.testservice; import java.lang.String; import android.app.Notification; import android.app.PendingIntent; import android.app.Service; import android.content.Intent; import android.os.Handler; import android.os.HandlerThread; import android.os.IBinder; import android.os.Looper; import android.os.Message; import android.util.Log; import android.widget.Toast; public class TestService extends Service { private Looper mServiceLooper; private ServiceHandler mServiceHandler; private TestController testCtrl = null; private static final String TAG = "TestService"; private final class ServiceHandler extends Handler { public ServiceHandler(Looper looper) { super(looper); } @Override public void handleMessage(Message msg) { Log.e(TAG, msg.toString()); Log.e(TAG, "IT WORKS"); } } @Override public IBinder onBind(Intent intent) { return null; } public void onDestroy() { Toast.makeText(this, "Test service stopped", Toast.LENGTH_LONG).show(); Log.d(TAG, "Test has been stopped"); } @Override public void onCreate() { super.onCreate(); Log.i(TAG, "onCreate"); HandlerThread thread = new HandlerThread("ServiceStartArguments", android.os.Process.THREAD_PRIORITY_BACKGROUND); thread.start(); mServiceLooper = thread.getLooper(); mServiceHandler = new ServiceHandler(mServiceLooper); } @Override public void onStart(Intent intent, int startid) { if (testCtrl != null) { Log.d(TAG, "Service already running."); return; } Log.d(TAG, "Starting test controller"); testCtrl = new TestController(); Log.d(TAG, "Test controller has started"); } } </code></pre> 2.It creates TestController class (where most of the logic must be) which creates TestNative class. interface TestListener.java: <pre class="lang-java prettyprint-override"><code>package com.example.testservice; public interface TestListener { public void stringJavaMethod(String regStr); } </code></pre> TestController.java: <pre class="lang-java prettyprint-override"><code>package com.example.testservice; import android.util.Log; public class TestController implements TestListener { private static final String TAG = "TestController"; private TestNative mTestNative = null; TestController() { Log.d(TAG, "Starting test native"); mTestNative = new TestNative(this); } @Override public void stringJavaMethod(String regStr) { Log.d(TAG, "Callback called!!!!\n"); Log.e(TAG, regStr); } </code></pre> } TestNative.java: <pre class="lang-java prettyprint-override"><code>package com.example.testservice; import android.os.Handler; import android.util.Log; public class TestNative implements TestListener { static { System.loadLibrary("log"); System.loadLibrary("layer-jni"); } private static final String TAG = "TestNative"; private Handler mHandler; private TestListener mDelegate; TestNative(TestListener t) { mDelegate = t; mHandler = new Handler(); startAthread(); } @Override public void stringJavaMethod(final String regStr) { Log.d(TAG, "IT WORKS?" + regStr); mHandler.post(new Runnable() { public void run() { Log.e(TAG, "CALLED!\n"); mDelegate.stringJavaMethod(regStr); } }); } /* native interface */ public static native void startAthread(); } </code></pre> 3.TestNative class asks native library to start working via startAthread() method. 4.Native code stores JVM, makes a global reference for calling object and starts a thread. 5.Thread attaches himself to JVM and gets a new JNIEnv* pointer. Then it looks for Java method ID using global object link which was obtained at step#4 and then it tries to call this method periodically. The only native source is layer-jni.c: <pre><code>#include "logcat.h" #include "layer-jni.h" #include <jni.h> #include <string.h> #include <pthread.h> #include <unistd.h> #include <time.h> #include <stdio.h> #include <stdlib.h> #include <android/asset_manager.h> #include <android/asset_manager_jni.h> JavaVM *jvm = NULL; /* removed jObj UPD3 */ // jobject jObj; /* added see UPD2 */ jclass jCls; /******************/ static int run = 0; static pthread_t t; /* jobject -> jclass */ void callVoidMethodString(JNIEnv *env, jclass jcl, jmethodID jmid, const char *str); JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *ajvm, void *dummy) { return JNI_VERSION_1_6; } void *thread_func(void *dummy) { run = 1; JNIEnv *env = NULL; if (JNI_EDETACHED == (*jvm)->GetEnv(jvm, (void**)&env, JNI_VERSION_1_6)) { if ( 0 != (*jvm)->AttachCurrentThread(jvm, &env, NULL)) { DBG_INFO("Cannot attach JNIEnv!\n"); } } /* UPD2 - jObj -> jCls */ jmethodID jmid = (*env)->GetMethodID(env, jCls, "stringJavaMethod", "(Ljava/lang/String;)V"); if (!jmid) { DBG_ERR("Cannot find java method...Terminating\n"); return NULL; } while(run) { struct timespec ts = {.tv_sec = 1, .tv_nsec = 0 }; nanosleep(&ts, NULL); DBG_INFO("Trying to call method\n"); callVoidMethodString(env, jCls, jmid, "***** Native2Java call works! *****\n"); } (*jvm)->DetachCurrentThread(jvm); return NULL; } JNIEXPORT void JNICALL Java_com_example_testservice_TestNative_startAthread( JNIEnv* env, jobject thiz) { DBG_INFO("enter startAthread()\n"); if (JNI_OK != (*env)->GetJavaVM(env, &jvm)) { DBG_ERR("Cannot access Java VM! Terminating call.\n"); return; } DBG_INFO("Caching class tc...\n"); /* Updated: jObj replaced with jCls */ jCls = thiz; jobject globalRef = (*env)->NewGlobalRef(env, jCls); (*env)->DeleteLocalRef(env, jCls); jCls = globalRef; if (NULL == jCls) { DBG_ERR("Cannot cache class TronNative!\n"); return; } /* UPD3: removed block below */ /* Added see UPD2 */ /*DBG_INFO("Caching class TestNative...\n"); *jclass clazz = (*env)->FindClass(env, "com/example/testservice/TestNative"); *if ((*env)->ExceptionCheck(env) == JNI_TRUE){ * (*env)->ExceptionDescribe(env); * DBG_ERR("Exception while looking for TestNative class.\n"); * return; *} *jCls = (jclass)(*env)->NewGlobalRef(env, clazz); * *if ((*env)->ExceptionCheck(env) == JNI_TRUE){ * (*env)->ExceptionDescribe(env); * DBG_ERR("Exception while trying to globalize TestNative class.\n"); * return; *} *(*env)->DeleteLocalRef(env, clazz); */ /*****************/ if (pthread_create(&t, NULL, thread_func, NULL)) { DBG_ERR("Cannot create thread!\n"); } } static unsigned call_count = 0; /* jobject -> jclass */ void callVoidMethodString(JNIEnv *env, jclass jcl, jmethodID jmid, const char *str) { jstring jstr = (*env)->NewStringUTF(env, str); char calls_str[50] = {0}; sprintf(calls_str, "calls:%u\n", call_count++); (*env)->CallVoidMethod(env, jcl, jmid, jstr); if ((*env)->ExceptionCheck(env)) { DBG_ERR("There is some exceptional situation!\n"); (*env)->ExceptionDescribe(env); (*env)->ExceptionClear(env); } (*env)->DeleteLocalRef(env, jstr); DBG_INFO(calls_str); } </code></pre> 6.As a result java method "public void stringJavaMethod(final String regStr)" is not invoked while CallVoidMethod() in native code is called. No any errors and no method call... Log output I get while starting test service: <pre><code>11-12 14:05:05.396: I/GAV2(18672): Thread[GAThread,5,main]: No campaign data found. 11-12 14:05:05.586: I/Autostart(16419): Starting service... 11-12 14:05:05.586: D/dalvikvm(18934): Late-enabling CheckJNI 11-12 14:05:05.586: I/ActivityManager(441): Start proc com.example.testservice for service com.example.testservice/.TestService: pid=18934 uid=10097 gids={50097, 3003, 1028} 11-12 14:05:05.606: D/dalvikvm(18934): Debugger has detached; object registry had 1 entries 11-12 14:05:05.696: D/dalvikvm(441): GC_EXPLICIT freed 1485K, 39% free 16961K/27776K, paused 3ms+7ms, total 89ms 11-12 14:05:05.736: I/TestService(18934): onCreate 11-12 14:05:05.736: D/TestService(18934): Starting test controller 11-12 14:05:05.736: D/TestController(18934): Starting test native 11-12 14:05:05.736: D/dalvikvm(18934): No JNI_OnLoad found in /system/lib/liblog.so 0x420e0a08, skipping init 11-12 14:05:05.736: D/dalvikvm(18934): Trying to load lib /data/app-lib/com.example.testservice-1/liblayer-jni.so 0x420e0a08 11-12 14:05:05.736: D/dalvikvm(18934): Added shared lib /data/app-lib/com.example.testservice-1/liblayer-jni.so 0x420e0a08 11-12 14:05:05.736: I/JNITestService(18934): enter startAthread() 11-12 14:05:05.736: I/JNITestService(18934): Caching class tc... 11-12 14:05:05.736: D/TestService(18934): Test controller has started 11-12 14:05:06.736: I/JNITestService(18934): Trying to call method 11-12 14:05:06.736: I/JNITestService(18934): calls:0 11-12 14:05:07.736: I/JNITestService(18934): Trying to call method 11-12 14:05:07.736: I/JNITestService(18934): calls:1 ...etc </code></pre> Thus there are no any messages from Java code about call from native code and no java method invocation. And that's the problem. As a result I planned to see a string " Native2Java call works! \n" in the log which is passed as parameter to JNI call. Listing of Android.mk: <pre><code>LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) ANDROID_NDK := /home/michael/Downloads/android-ndk-r8e LOCAL_MODULE := layer-jni LOCAL_SRC_FILES := layer-jni.c LOCAL_LDLIBS := -llog TARGET_ARCH_ABI := armeabi-v7a include $(BUILD_SHARED_LIBRARY) </code></pre> Application.mk: <pre><code>APP_ABI := armeabi-v7a APP_PLATFORM := android-9 #APP_CPPFLAGS := -D__GXX_EXPERIMENTAL_CXX0X__ -std=gnu++11 STLPORT_FORCE_REBUILD := true APP_STL := stlport_shared </code></pre> AndroidManifest.xml: <pre class="lang-xml prettyprint-override"><code><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.testservice" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="17" /> <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"></uses-permission> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> <uses-permission android:name="android.permission.INTERNET"/> <uses-permission android:name="android.permission.RECORD_AUDIO"/> <uses-permission android:name="android.permission.USE_SIP"/> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name"> <service android:name=".TestService" android:exported="true"> <intent-filter> <action android:name="com.example.testservice.TestService"> </action> </intent-filter> </service> <receiver android:name=".autostart"> <intent-filter> <action android:name="android.intent.action.BOOT_COMPLETED"> </action> </intent-filter> </receiver> </application> </manifest> </code></pre> I highly appreciate if somebody can help me with an advice or ideas what I have to check/to fix in my logic. UPD: If I change Java method to static, GetMethodID() to GetStaticMethodID() and CallVoidMethod() to CallStaticVoidMethod() it starts working: <pre><code>11-12 17:44:27.406: D/TestNative(21444): IT WORKS?***** Native2Java call works! ***** 11-12 17:44:27.406: I/JNITestService(21444): calls:38 11-12 17:44:28.406: I/JNITestService(21444): Trying to call method 11-12 17:44:28.406: D/TestNative(21444): IT WORKS?***** Native2Java call works! ***** 11-12 17:44:28.406: I/JNITestService(21444): calls:39 11-12 17:44:29.426: I/JNITestService(21444): Trying to call method </code></pre> Still don't know the reason why non-static member is not working... UPD2: Fixed call GetMethodID() - replace jObj with jCls. If jCls is obtained via FindClass() then result remains the same (no call, no error). If jCls is obtained via GetObjectClass() instead of FindClass() - then exception occured while trying to get method id using this new jCls: <pre><code>11-12 18:17:59.926: D/TestService(22540): Test controller has started 11-12 18:17:59.926: E/JNITestService(22540): Cannot find java method...Terminating 11-12 18:17:59.926: W/dalvikvm(22540): threadid=12: thread exiting with uncaught exception (group=0x4198b700) 11-12 18:17:59.926: E/AndroidRuntime(22540): FATAL EXCEPTION: Thread-6532 11-12 18:17:59.926: E/AndroidRuntime(22540): java.lang.NoSuchMethodError: no method with name='stringJavaMethod' signature='(Ljava/lang/String;)V' in class Ljava/lang/Class; 11-12 18:17:59.926: E/AndroidRuntime(22540): at dalvik.system.NativeStart.run(Native Method) </code></pre> UPD3: Remove jObj, only jCls is used now. And parameter of startAthread has been fixed. But still no error, no call (non-static method, static version of method is working).
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Java method is not invoked when calling it from native pthread
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