1 /*
2 * Copyright (c) 2015, 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 package org.graalvm.compiler.debug;
24
25 import java.util.ArrayList;
26 import java.util.Collection;
27 import java.util.Collections;
28 import java.util.List;
29 import java.util.stream.Collectors;
30
31 import org.graalvm.compiler.options.Option;
32 import org.graalvm.compiler.options.OptionValue;
33
34 /**
35 * Facility for fingerprinting execution.
36 */
37 public class Fingerprint implements AutoCloseable {
38
39 public static class Options {
40 @Option(help = "Enables execution fingerprinting.")//
41 public static final OptionValue<Boolean> UseFingerprinting = new OptionValue<>(false);
42
43 @Option(help = "Limit number of events shown in fingerprinting error message.")//
44 public static final OptionValue<Integer> FingerprintErrorEventTailLength = new OptionValue<>(50);
45
46 @Option(help = "Fingerprinting event at which to execute breakpointable code.")//
47 public static final OptionValue<Integer> FingerprintingBreakpointEvent = new OptionValue<>(-1);
48 }
49
50 /**
51 * Determines whether fingerprinting is enabled.
52 */
53 public static final boolean ENABLED = Options.UseFingerprinting.getValue();
54
55 private static final ThreadLocal<Fingerprint> current = ENABLED ? new ThreadLocal<>() : null;
56
57 private final List<String> events;
58 private int index;
59
60 /**
61 * Creates an object to record a fingerprint.
62 */
63 public Fingerprint() {
64 events = new ArrayList<>();
65 index = -1;
66 }
67
68 /**
69 * Creates an object to verify execution matches a given fingerprint.
70 *
71 * @param toVerifyAgainst the fingerprint events to verify against
72 */
73 public Fingerprint(List<String> toVerifyAgainst) {
74 this.events = toVerifyAgainst;
75 index = 0;
76 }
77
78 /**
79 * Creates an object to verify execution matches a given fingerprint.
80 *
81 * @param toVerifyAgainst the fingerprint to verify against
82 */
83 public Fingerprint(Fingerprint toVerifyAgainst) {
84 this(toVerifyAgainst.events);
85 }
86
87 public Collection<String> getEvents() {
88 return Collections.unmodifiableCollection(events);
89 }
90
91 /**
92 * Starts fingerprint recording or verification for the current thread. At most one fingerprint
93 * object can be active for any thread.
94 */
95 public Fingerprint open() {
96 if (ENABLED) {
97 assert current.get() == null;
98 current.set(this);
99 return this;
100 }
101 return null;
102 }
103
104 /**
105 * Finishes fingerprint recording or verification for the current thread.
106 */
107 @Override
108 public void close() {
109 if (ENABLED) {
110 assert current.get() == this;
111 current.set(null);
112 }
113 }
114
115 private static final int BREAKPOINT_EVENT = Options.FingerprintingBreakpointEvent.getValue();
116
117 /**
118 * Submits an execution event for the purpose of recording or verifying a fingerprint. This must
119 * only be called if {@link #ENABLED} is {@code true}.
120 */
121 public static void submit(String format, Object... args) {
122 assert ENABLED : "fingerprinting must be enabled (-Dgraal." + Options.UseFingerprinting.getName() + "=true)";
123 Fingerprint fingerprint = current.get();
124 if (fingerprint != null) {
125 int eventId = fingerprint.nextEventId();
126 if (eventId == BREAKPOINT_EVENT) {
127 // Set IDE breakpoint on the following line and set the relevant
128 // system property to debug a fingerprint verification error.
129 System.console();
130 }
131 fingerprint.event(String.format(eventId + ": " + format, args));
132 }
133 }
134
135 private int nextEventId() {
136 return index == -1 ? events.size() : index;
137 }
138
139 private static final int MAX_EVENT_TAIL_IN_ERROR_MESSAGE = Options.FingerprintErrorEventTailLength.getValue();
140
141 private String tail() {
142 int start = Math.max(index - MAX_EVENT_TAIL_IN_ERROR_MESSAGE, 0);
143 return events.subList(start, index).stream().collect(Collectors.joining(String.format("%n")));
144 }
145
146 private void event(String entry) {
147 if (index == -1) {
148 events.add(entry);
149 } else {
150 if (index > events.size()) {
151 throw new InternalError(String.format("%s%nOriginal fingerprint limit reached", tail()));
152 }
153 String l = events.get(index);
154 if (!l.equals(entry)) {
155 throw new InternalError(String.format("%s%nFingerprint differs at event %d%nexpected: %s%n actual: %s", tail(), index, l, entry));
156 }
157 index++;
158 }
159 }
160 }