130 lines
4.1 KiB
C++
130 lines
4.1 KiB
C++
/*
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* Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
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* Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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#include <atomic>
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#include <jvmti.h>
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#include <jni.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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static jvmtiEnv *_jvmti;
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static JavaVM *_jvm;
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#define BUFFER_SIZE 100000
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static std::atomic<jmethodID> ring_buffer[BUFFER_SIZE];
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void get_method_details(jmethodID method) {
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jclass method_class;
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char *class_name = nullptr;
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if (_jvmti->GetMethodDeclaringClass(method, &method_class) == JVMTI_ERROR_NONE) {
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if (_jvmti->GetClassSignature(method_class, &class_name, nullptr) == JVMTI_ERROR_NONE) {
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_jvmti->Deallocate((unsigned char *)class_name);
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}
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}
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}
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void* read_ringbuffer(void* arg) {
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JNIEnv *env;
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_jvm->AttachCurrentThreadAsDaemon((void **)&env, nullptr);
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for (;;) {
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jmethodID id = ring_buffer[rand() % BUFFER_SIZE].load(std::memory_order_relaxed);
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if (id != (jmethodID)0) {
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get_method_details(id);
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}
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}
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return nullptr;
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}
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static void JNICALL ClassPrepareCallback(jvmtiEnv *jvmti_env,
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JNIEnv *jni_env,
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jthread thread,
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jclass klass) {
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static bool reader_created = false;
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static int ring_buffer_idx = 0;
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char *class_name = nullptr;
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if (jvmti_env->GetClassSignature(klass, &class_name, nullptr) != JVMTI_ERROR_NONE) {
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return;
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}
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// We only care MyClass and only one thread loads it
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bool is_my_class = strcmp(class_name, "LMyClass;") == 0;
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jvmti_env->Deallocate((unsigned char *)class_name);
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if (!is_my_class) {
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return;
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}
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if (!reader_created) {
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pthread_t tid;
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pthread_create(&tid, nullptr, read_ringbuffer, nullptr);
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reader_created = true;
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}
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jint method_count;
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jmethodID *methods;
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if (jvmti_env->GetClassMethods(klass, &method_count, &methods) == JVMTI_ERROR_NONE) {
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ring_buffer[ring_buffer_idx++].store(methods[0], std::memory_order_relaxed);
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ring_buffer_idx = ring_buffer_idx % BUFFER_SIZE;
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jvmti_env->Deallocate((unsigned char *)methods);
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}
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}
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JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {
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for (int i = 0; i < BUFFER_SIZE; i++) {
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ring_buffer[i].store(0, std::memory_order_relaxed);
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}
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jvmtiEventCallbacks callbacks;
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jvmtiError error;
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_jvm = jvm;
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if (jvm->GetEnv((void **)&_jvmti, JVMTI_VERSION_1_0) != JNI_OK) {
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fprintf(stderr, "Unable to access JVMTI!\n");
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return JNI_ERR;
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}
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// Set up the event callbacks
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memset(&callbacks, 0, sizeof(callbacks));
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callbacks.ClassPrepare = &ClassPrepareCallback;
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// Register the callbacks
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error = _jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
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if (error != JVMTI_ERROR_NONE) {
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fprintf(stderr, "Error setting event callbacks: %d\n", error);
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return JNI_ERR;
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}
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// Enable the ClassPrepare event
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error = _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_PREPARE, nullptr);
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if (error != JVMTI_ERROR_NONE) {
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fprintf(stderr, "Error enabling ClassPrepare event: %d\n", error);
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return JNI_ERR;
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}
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return JNI_OK;
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}
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