使用JVM TI技术实现JVM监控
在JAVA单元测试中，需要监控单元测试的覆盖率，记录JAVA代码的执行过程，或者是需要动态插装字节码的应用程序中(例如AOP/IOC技术, 动态插装字节码的技术我将在下一篇的博客中介绍)，我们可以使用JVM TI接口进行监控，本程序介绍一种监控JAVA代码的方法,注意：本程序不适合代码量很大的项目，会严重影响程序性能，如果需要开发高性能的监控代码，请参考我的另一篇博客
#include "stdafx.h"
#include <jni.h>
#include <jni_md.h>
#include "windows.h"
#include <jvmti.h>
#include <string>
#include <cstring>
#include <iostream>
#include <list>
#include <map>
#include <set>
#include <stdlib.h>
#include <jni_md.h>
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}
typedef jint (WINAPI *_CreateJavaVM)(JavaVM **, void **, void *);
static jvmtiEnv *gb_jvmti = NULL;
static jvmtiCapabilities gb_capa;
static jrawMonitorID gb_lock;
static void enter_critical_section(jvmtiEnv *jvmti)
{
jvmtiError error;
error = jvmti->RawMonitorEnter(gb_lock);
}
static void exit_critical_section(jvmtiEnv *jvmti)
{
jvmtiError error;
error = jvmti->RawMonitorExit(gb_lock);
}
static void JNICALL callbackException(jvmtiEnv *jvmti_env, JNIEnv* env, jthread thr, jmethodID method, jlocation location, jobject exception, jmethodID catch_method, jlocation catch_location)
{
enter_critical_section(gb_jvmti);
{
char *name,*sig,*gsig;
jvmtiError error = gb_jvmti->GetMethodName(method, &name, &sig, &gsig);
if (error != JVMTI_ERROR_NONE)
{
printf("ERROR:GetMethodName!\n");
return;
}
printf("In Agent: Got an exception from Method: %s\n" ,name );
// if(strcmp(name,"main")==0)
// {
// }
}
exit_critical_section(gb_jvmti);
}
JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved)
{
jvmtiError error;
jvmtiEventCallbacks callbacks;
jint result = jvm->GetEnv((void **) &gb_jvmti, JVMTI_VERSION_1_0);
if(result != JNI_OK || gb_jvmti==NULL)
{
printf("ERROR: Unable to access JVMTI!");
return JNI_ERR;
}
memset(&gb_capa,0,sizeof(jvmtiCapabilities));
gb_capa.can_signal_thread = 1;
gb_capa.can_get_owned_monitor_info = 1;
gb_capa.can_generate_method_entry_events = 1;
gb_capa.can_generate_exception_events = 1;
gb_capa.can_generate_vm_object_alloc_events = 1;
gb_capa.can_tag_objects = 1;
//error = gb_jvmti->AddCapabilities(&gb_capa);
/* if(error != JVMTI_ERROR_NONE)
{
printf("ERROR: Can't get JVMTI capabilities");
return JNI_ERR;
}*/
jclass *classes;
jint count;
error = gb_jvmti->GetLoadedClasses(&count, &classes);
if (error) {
printf("ERROR: JVMTI GetLoadedClasses failed!\n");
}
for (int i = 0; i < count; i++) {
char *sig;
gb_jvmti->GetClassSignature(classes[i], &sig, NULL);
if(strcmp(sig,"com/test/VMAttacher")>0)
{
printf("cls sig=%s\n", sig);
}
}
memset(&callbacks,0,sizeof(jvmtiEventCallbacks));
callbacks.Exception = &callbackException;
error = gb_jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
if(error != JVMTI_ERROR_NONE)
{
printf("ERROR: Can't set jvmti callback!");
return JNI_ERR;
}
error = gb_jvmti->CreateRawMonitor("agent data", &gb_lock);
if(error != JVMTI_ERROR_NONE)
{
printf("ERROR: Can't create raw monitor!");
return JNI_ERR;
}
// error = gb_jvmti->SetEventNotificationMode(JVMTI_ENABLE,JVMTI_EVENT_VM_INIT, (jthread)NULL);
error = gb_jvmti->SetEventNotificationMode(JVMTI_ENABLE,JVMTI_EVENT_EXCEPTION, (jthread)NULL);
return JNI_OK;
}
JNIEXPORT void JNICALL Agent_OnUnload(JavaVM *vm)
{
//
}
将以上代码编译DLL控件后，再使用javapath或者javalib参数指定该DLL控件作为JAVA Agent启动即可