1 /*
2 * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 #include <stdio.h>
25 #include <string.h>
26 #include <jni.h>
27 #include <jvmti.h>
28
29 #include "jvmti_common.hpp"
30 #include "jvmti_thread.hpp"
31
32
33 extern "C" {
34
35 /* ========================================================================== */
36
37 /* scaffold objects */
38 static JNIEnv *jni = nullptr;
39 static jvmtiEnv *jvmti = nullptr;
40 static jlong timeout = 0;
41
42 /* test objects */
43 static jthread expected_thread = nullptr;
44 static jobject expected_object = nullptr;
45 static volatile int eventsCount = 0;
46
47 /* ========================================================================== */
48
49 void JNICALL
50 MonitorContendedEnter(jvmtiEnv *jvmti, JNIEnv *jni, jthread thr, jobject obj) {
51
52 LOG("MonitorContendedEnter event:\n\tthread: %p, object: %p, expected object: %p\n",thr, obj, expected_object);
53
54 print_thread_info(jvmti, jni, thr);
55
56 if (expected_thread == nullptr) {
57 jni->FatalError("expected_thread is null.");
58 }
59
60 if (expected_object == nullptr) {
61 jni->FatalError("expected_object is null.");
62 }
63
64 /* check if event is for tested thread and for tested object */
65 if (jni->IsSameObject(expected_thread, thr) &&
66 jni->IsSameObject(expected_object, obj)) {
67 eventsCount++;
68 LOG("Increasing eventCount to %d\n", eventsCount);
69 }
70 }
71
72 /* ========================================================================== */
73
74 static int prepare() {
75 jvmtiError err = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_MONITOR_CONTENDED_ENTER, nullptr);
76 if (err != JVMTI_ERROR_NONE) {
77 jni->FatalError("Error enabling JVMTI_EVENT_MONITOR_CONTENDED_ENTER.");
78 }
79 return JNI_TRUE;
80 }
81
82 static int clean() {
83 LOG("Disabling events\n");
84 /* disable MonitorContendedEnter event */
85 jvmtiError err = jvmti->SetEventNotificationMode(JVMTI_DISABLE, JVMTI_EVENT_MONITOR_CONTENDED_ENTER, nullptr);
86 if (err != JVMTI_ERROR_NONE) {
87 set_agent_fail_status();
88 }
89 return JNI_TRUE;
90 }
91
92 /* agent algorithm
93 */
94 static void JNICALL
95 agentProc(jvmtiEnv *jvmti, JNIEnv *agentJNI, void *arg) {
96 jni = agentJNI;
97
98 /* wait for initial sync */
99 if (!agent_wait_for_sync(timeout)) {
100 return;
101 }
102
103 if (!prepare()) {
104 set_agent_fail_status();
105 return;
106 }
107
108 /* clear events count */
109 eventsCount = 0;
110
111 /* resume debugee to catch MonitorContendedEnter event */
112 if (!((agent_resume_sync() == JNI_TRUE) && (agent_wait_for_sync(timeout) == JNI_TRUE))) {
113 return;
114 }
115 LOG("Number of MonitorContendedEnter events: %d\n", eventsCount);
116
117 if (eventsCount == 0) {
118 COMPLAIN("No any MonitorContendedEnter event\n");
119 set_agent_fail_status();
120 }
121
122 if (!clean()) {
123 set_agent_fail_status();
124 return;
125 }
126
127 /* resume debugee after last sync */
128 if (!agent_resume_sync())
129 return;
130 }
131
132 jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {
133 jvmtiCapabilities caps;
134 jvmtiEventCallbacks callbacks;
135 jvmtiError err;
136 jint res;
137
138 timeout = 60000;
139 LOG("Timeout: %d msc\n", (int) timeout);
140
141 res = jvm->GetEnv((void **) &jvmti, JVMTI_VERSION_1_1);
142 if (res != JNI_OK || jvmti == nullptr) {
143 LOG("Wrong result of a valid call to GetEnv!\n");
144 return JNI_ERR;
145 }
146
147 err = init_agent_data(jvmti, &agent_data);
148 if (err != JVMTI_ERROR_NONE) {
149 return JNI_ERR;
150 }
151
152 memset(&caps, 0, sizeof(jvmtiCapabilities));
153 caps.can_generate_monitor_events = 1;
154 caps.can_support_virtual_threads = 1;
155
156 err = jvmti->AddCapabilities(&caps);
157 if (err != JVMTI_ERROR_NONE) {
158 LOG("(AddCapabilities) unexpected error: %s (%d)\n", TranslateError(err), err);
159 return JNI_ERR;
160 }
161
162 err = jvmti->GetCapabilities(&caps);
163 if (err != JVMTI_ERROR_NONE) {
164 LOG("(GetCapabilities) unexpected error: %s (%d)\n", TranslateError(err), err);
165 return JNI_ERR;
166 }
167
168 if (!caps.can_generate_monitor_events) {
169 return JNI_ERR;
170 }
171
172 memset(&callbacks, 0, sizeof(callbacks));
173 callbacks.MonitorContendedEnter = &MonitorContendedEnter;
174 err = jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
175 if (err != JVMTI_ERROR_NONE) {
176 return JNI_ERR;
177 }
178
179 /* register agent proc and arg */
180 set_agent_proc(agentProc, nullptr);
181
182 return JNI_OK;
183 }
184
185 JNIEXPORT jint JNICALL Java_mcontenter01_getEventCount(JNIEnv *jni, jobject obj) {
186 return eventsCount;
187 }
188
189 JNIEXPORT void JNICALL Java_mcontenter01_setExpected(JNIEnv *jni, jobject clz, jobject obj, jobject thread) {
190 LOG("Remembering global reference for monitor object is %p\n", obj);
191 /* make object accessible for a long time */
192 expected_object = jni->NewGlobalRef(obj);
193 if (expected_object == nullptr) {
194 jni->FatalError("Error saving global reference to monitor.\n");
195 }
196
197 /* make thread accessable for a long time */
198 expected_thread = jni->NewGlobalRef(thread);
199 if (thread == nullptr) {
200 jni->FatalError("Error saving global reference to thread.\n");
201 }
202
203 return;
204 }
205
206 JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {
207 return Agent_Initialize(jvm, options, reserved);
208 }
209
210 JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM *jvm, char *options, void *reserved) {
211 return Agent_Initialize(jvm, options, reserved);
212 }
213 }