| /* |
| * Copyright (c) 2004, 2015, Oracle and/or its affiliates. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * - Neither the name of Oracle nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /* |
| * This source code is provided to illustrate the usage of a given feature |
| * or technique and has been deliberately simplified. Additional steps |
| * required for a production-quality application, such as security checks, |
| * input validation and proper error handling, might not be present in |
| * this sample code. |
| */ |
| |
| |
| /* Example of using JVMTI_EVENT_GARBAGE_COLLECTION_START and |
| * JVMTI_EVENT_GARBAGE_COLLECTION_FINISH events. |
| */ |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include "jni.h" |
| #include "jvmti.h" |
| |
| /* For stdout_message(), fatal_error(), and check_jvmti_error() */ |
| #include "agent_util.h" |
| |
| /* Global static data */ |
| static jvmtiEnv *jvmti; |
| static int gc_count; |
| static jrawMonitorID lock; |
| |
| /* Worker thread that waits for garbage collections */ |
| static void JNICALL |
| worker(jvmtiEnv* jvmti, JNIEnv* jni, void *p) |
| { |
| jvmtiError err; |
| |
| stdout_message("GC worker started...\n"); |
| |
| for (;;) { |
| err = (*jvmti)->RawMonitorEnter(jvmti, lock); |
| check_jvmti_error(jvmti, err, "raw monitor enter"); |
| while (gc_count == 0) { |
| err = (*jvmti)->RawMonitorWait(jvmti, lock, 0); |
| if (err != JVMTI_ERROR_NONE) { |
| err = (*jvmti)->RawMonitorExit(jvmti, lock); |
| check_jvmti_error(jvmti, err, "raw monitor wait"); |
| return; |
| } |
| } |
| gc_count = 0; |
| |
| err = (*jvmti)->RawMonitorExit(jvmti, lock); |
| check_jvmti_error(jvmti, err, "raw monitor exit"); |
| |
| /* Perform arbitrary JVMTI/JNI work here to do post-GC cleanup */ |
| stdout_message("post-GarbageCollectionFinish actions...\n"); |
| } |
| } |
| |
| /* Creates a new jthread */ |
| static jthread |
| alloc_thread(JNIEnv *env) |
| { |
| jclass thrClass; |
| jmethodID cid; |
| jthread res; |
| |
| thrClass = (*env)->FindClass(env, "java/lang/Thread"); |
| if ( thrClass == NULL ) { |
| fatal_error("Cannot find Thread class\n"); |
| } |
| cid = (*env)->GetMethodID(env, thrClass, "<init>", "()V"); |
| if ( cid == NULL ) { |
| fatal_error("Cannot find Thread constructor method\n"); |
| } |
| res = (*env)->NewObject(env, thrClass, cid); |
| if ( res == NULL ) { |
| fatal_error("Cannot create new Thread object\n"); |
| } |
| return res; |
| } |
| |
| /* Callback for JVMTI_EVENT_VM_INIT */ |
| static void JNICALL |
| vm_init(jvmtiEnv *jvmti, JNIEnv *env, jthread thread) |
| { |
| jvmtiError err; |
| |
| stdout_message("VMInit...\n"); |
| |
| err = (*jvmti)->RunAgentThread(jvmti, alloc_thread(env), &worker, NULL, |
| JVMTI_THREAD_MAX_PRIORITY); |
| check_jvmti_error(jvmti, err, "running agent thread"); |
| } |
| |
| /* Callback for JVMTI_EVENT_GARBAGE_COLLECTION_START */ |
| static void JNICALL |
| gc_start(jvmtiEnv* jvmti_env) |
| { |
| stdout_message("GarbageCollectionStart...\n"); |
| } |
| |
| /* Callback for JVMTI_EVENT_GARBAGE_COLLECTION_FINISH */ |
| static void JNICALL |
| gc_finish(jvmtiEnv* jvmti_env) |
| { |
| jvmtiError err; |
| |
| stdout_message("GarbageCollectionFinish...\n"); |
| |
| err = (*jvmti)->RawMonitorEnter(jvmti, lock); |
| check_jvmti_error(jvmti, err, "raw monitor enter"); |
| gc_count++; |
| err = (*jvmti)->RawMonitorNotify(jvmti, lock); |
| check_jvmti_error(jvmti, err, "raw monitor notify"); |
| err = (*jvmti)->RawMonitorExit(jvmti, lock); |
| check_jvmti_error(jvmti, err, "raw monitor exit"); |
| } |
| |
| /* Agent_OnLoad() is called first, we prepare for a VM_INIT event here. */ |
| JNIEXPORT jint JNICALL |
| DEF_Agent_OnLoad(JavaVM *vm, char *options, void *reserved) |
| { |
| jint rc; |
| jvmtiError err; |
| jvmtiCapabilities capabilities; |
| jvmtiEventCallbacks callbacks; |
| |
| /* Get JVMTI environment */ |
| rc = (*vm)->GetEnv(vm, (void **)&jvmti, JVMTI_VERSION); |
| if (rc != JNI_OK) { |
| fatal_error("ERROR: Unable to create jvmtiEnv, rc=%d\n", rc); |
| return -1; |
| } |
| |
| /* Get/Add JVMTI capabilities */ |
| (void)memset(&capabilities, 0, sizeof(capabilities)); |
| capabilities.can_generate_garbage_collection_events = 1; |
| err = (*jvmti)->AddCapabilities(jvmti, &capabilities); |
| check_jvmti_error(jvmti, err, "add capabilities"); |
| |
| /* Set callbacks and enable event notifications */ |
| memset(&callbacks, 0, sizeof(callbacks)); |
| callbacks.VMInit = &vm_init; |
| callbacks.GarbageCollectionStart = &gc_start; |
| callbacks.GarbageCollectionFinish = &gc_finish; |
| err = (*jvmti)->SetEventCallbacks(jvmti, &callbacks, sizeof(callbacks)); |
| check_jvmti_error(jvmti, err, "set event callbacks"); |
| err = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, |
| JVMTI_EVENT_VM_INIT, NULL); |
| check_jvmti_error(jvmti, err, "set event notification"); |
| err = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, |
| JVMTI_EVENT_GARBAGE_COLLECTION_START, NULL); |
| check_jvmti_error(jvmti, err, "set event notification"); |
| err = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, |
| JVMTI_EVENT_GARBAGE_COLLECTION_FINISH, NULL); |
| check_jvmti_error(jvmti, err, "set event notification"); |
| |
| /* Create the necessary raw monitor */ |
| err = (*jvmti)->CreateRawMonitor(jvmti, "lock", &lock); |
| check_jvmti_error(jvmti, err, "create raw monitor"); |
| return 0; |
| } |
| |
| /* Agent_OnUnload() is called last */ |
| JNIEXPORT void JNICALL |
| DEF_Agent_OnUnload(JavaVM *vm) |
| { |
| } |