| /* |
| * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package java.lang; |
| |
| import jdk.internal.reflect.CallerSensitive; |
| |
| import java.util.*; |
| import java.util.function.Consumer; |
| import java.util.function.Function; |
| import java.util.function.Predicate; |
| import java.util.stream.Stream; |
| |
| /** |
| * A stack walker. |
| * |
| * <p> The {@link StackWalker#walk walk} method opens a sequential stream |
| * of {@link StackFrame StackFrame}s for the current thread and then applies |
| * the given function to walk the {@code StackFrame} stream. |
| * The stream reports stack frame elements in order, from the top most frame |
| * that represents the execution point at which the stack was generated to |
| * the bottom most frame. |
| * The {@code StackFrame} stream is closed when the {@code walk} method returns. |
| * If an attempt is made to reuse the closed stream, |
| * {@code IllegalStateException} will be thrown. |
| * |
| * <p> The {@linkplain Option <em>stack walking options</em>} of a |
| * {@code StackWalker} determines the information of |
| * {@link StackFrame StackFrame} objects to be returned. |
| * By default, stack frames of the reflection API and implementation |
| * classes are {@linkplain Option#SHOW_HIDDEN_FRAMES hidden} |
| * and {@code StackFrame}s have the class name and method name |
| * available but not the {@link StackFrame#getDeclaringClass() Class reference}. |
| * |
| * <p> {@code StackWalker} is thread-safe. Multiple threads can share |
| * a single {@code StackWalker} object to traverse its own stack. |
| * A permission check is performed when a {@code StackWalker} is created, |
| * according to the options it requests. |
| * No further permission check is done at stack walking time. |
| * |
| * @apiNote |
| * Examples |
| * |
| * <p>1. To find the first caller filtering a known list of implementation class: |
| * <pre>{@code |
| * StackWalker walker = StackWalker.getInstance(Option.RETAIN_CLASS_REFERENCE); |
| * Optional<Class<?>> callerClass = walker.walk(s -> |
| * s.map(StackFrame::getDeclaringClass) |
| * .filter(interestingClasses::contains) |
| * .findFirst()); |
| * }</pre> |
| * |
| * <p>2. To snapshot the top 10 stack frames of the current thread, |
| * <pre>{@code |
| * List<StackFrame> stack = StackWalker.getInstance().walk(s -> |
| * s.limit(10).collect(Collectors.toList())); |
| * }</pre> |
| * |
| * Unless otherwise noted, passing a {@code null} argument to a |
| * constructor or method in this {@code StackWalker} class |
| * will cause a {@link NullPointerException NullPointerException} |
| * to be thrown. |
| * |
| * @since 9 |
| */ |
| public final class StackWalker { |
| /** |
| * A {@code StackFrame} object represents a method invocation returned by |
| * {@link StackWalker}. |
| * |
| * <p> The {@link #getDeclaringClass()} method may be unsupported as determined |
| * by the {@linkplain Option stack walking options} of a {@linkplain |
| * StackWalker stack walker}. |
| * |
| * @since 9 |
| * @jvms 2.6 |
| */ |
| public static interface StackFrame { |
| /** |
| * Gets the <a href="ClassLoader.html#name">binary name</a> |
| * of the declaring class of the method represented by this stack frame. |
| * |
| * @return the binary name of the declaring class of the method |
| * represented by this stack frame |
| * |
| * @jls 13.1 The Form of a Binary |
| */ |
| public String getClassName(); |
| |
| /** |
| * Gets the name of the method represented by this stack frame. |
| * @return the name of the method represented by this stack frame |
| */ |
| public String getMethodName(); |
| |
| /** |
| * Gets the declaring {@code Class} for the method represented by |
| * this stack frame. |
| * |
| * @return the declaring {@code Class} of the method represented by |
| * this stack frame |
| * |
| * @throws UnsupportedOperationException if this {@code StackWalker} |
| * is not configured with {@link Option#RETAIN_CLASS_REFERENCE |
| * Option.RETAIN_CLASS_REFERENCE}. |
| */ |
| public Class<?> getDeclaringClass(); |
| |
| /** |
| * Returns the index to the code array of the {@code Code} attribute |
| * containing the execution point represented by this stack frame. |
| * The code array gives the actual bytes of Java Virtual Machine code |
| * that implement the method. |
| * |
| * @return the index to the code array of the {@code Code} attribute |
| * containing the execution point represented by this stack frame, |
| * or a negative number if the method is native. |
| * |
| * @jvms 4.7.3 The {@code Code} Attribute |
| */ |
| public int getByteCodeIndex(); |
| |
| /** |
| * Returns the name of the source file containing the execution point |
| * represented by this stack frame. Generally, this corresponds |
| * to the {@code SourceFile} attribute of the relevant {@code class} |
| * file as defined by <cite>The Java Virtual Machine Specification</cite>. |
| * In some systems, the name may refer to some source code unit |
| * other than a file, such as an entry in a source repository. |
| * |
| * @return the name of the file containing the execution point |
| * represented by this stack frame, or {@code null} if |
| * this information is unavailable. |
| * |
| * @jvms 4.7.10 The {@code SourceFile} Attribute |
| */ |
| public String getFileName(); |
| |
| /** |
| * Returns the line number of the source line containing the execution |
| * point represented by this stack frame. Generally, this is |
| * derived from the {@code LineNumberTable} attribute of the relevant |
| * {@code class} file as defined by <cite>The Java Virtual Machine |
| * Specification</cite>. |
| * |
| * @return the line number of the source line containing the execution |
| * point represented by this stack frame, or a negative number if |
| * this information is unavailable. |
| * |
| * @jvms 4.7.12 The {@code LineNumberTable} Attribute |
| */ |
| public int getLineNumber(); |
| |
| /** |
| * Returns {@code true} if the method containing the execution point |
| * represented by this stack frame is a native method. |
| * |
| * @return {@code true} if the method containing the execution point |
| * represented by this stack frame is a native method. |
| */ |
| public boolean isNativeMethod(); |
| |
| /** |
| * Gets a {@code StackTraceElement} for this stack frame. |
| * |
| * @return {@code StackTraceElement} for this stack frame. |
| */ |
| public StackTraceElement toStackTraceElement(); |
| } |
| |
| /** |
| * Stack walker option to configure the {@linkplain StackFrame stack frame} |
| * information obtained by a {@code StackWalker}. |
| * |
| * @since 9 |
| */ |
| public enum Option { |
| /** |
| * Retains {@code Class} object in {@code StackFrame}s |
| * walked by this {@code StackWalker}. |
| * |
| * <p> A {@code StackWalker} configured with this option will support |
| * {@link StackWalker#getCallerClass()} and |
| * {@link StackFrame#getDeclaringClass() StackFrame.getDeclaringClass()}. |
| */ |
| RETAIN_CLASS_REFERENCE, |
| /** |
| * Shows all reflection frames. |
| * |
| * <p>By default, reflection frames are hidden. A {@code StackWalker} |
| * configured with this {@code SHOW_REFLECT_FRAMES} option |
| * will show all reflection frames that |
| * include {@link java.lang.reflect.Method#invoke} and |
| * {@link java.lang.reflect.Constructor#newInstance(Object...)} |
| * and their reflection implementation classes. |
| * |
| * <p>The {@link #SHOW_HIDDEN_FRAMES} option can also be used to show all |
| * reflection frames and it will also show other hidden frames that |
| * are implementation-specific. |
| * |
| * @apiNote |
| * This option includes the stack frames representing the invocation of |
| * {@code Method} and {@code Constructor}. Any utility methods that |
| * are equivalent to calling {@code Method.invoke} or |
| * {@code Constructor.newInstance} such as {@code Class.newInstance} |
| * are not filtered or controlled by any stack walking option. |
| */ |
| SHOW_REFLECT_FRAMES, |
| /** |
| * Shows all hidden frames. |
| * |
| * <p>A Java Virtual Machine implementation may hide implementation |
| * specific frames in addition to {@linkplain #SHOW_REFLECT_FRAMES |
| * reflection frames}. A {@code StackWalker} with this {@code SHOW_HIDDEN_FRAMES} |
| * option will show all hidden frames (including reflection frames). |
| */ |
| SHOW_HIDDEN_FRAMES; |
| } |
| |
| enum ExtendedOption { |
| /** |
| * Obtain monitors, locals and operands. |
| */ |
| LOCALS_AND_OPERANDS |
| }; |
| |
| static final EnumSet<Option> DEFAULT_EMPTY_OPTION = EnumSet.noneOf(Option.class); |
| |
| private final static StackWalker DEFAULT_WALKER = |
| new StackWalker(DEFAULT_EMPTY_OPTION); |
| |
| private final Set<Option> options; |
| private final ExtendedOption extendedOption; |
| private final int estimateDepth; |
| |
| /** |
| * Returns a {@code StackWalker} instance. |
| * |
| * <p> This {@code StackWalker} is configured to skip all |
| * {@linkplain Option#SHOW_HIDDEN_FRAMES hidden frames} and |
| * no {@linkplain Option#RETAIN_CLASS_REFERENCE class reference} is retained. |
| * |
| * @return a {@code StackWalker} configured to skip all |
| * {@linkplain Option#SHOW_HIDDEN_FRAMES hidden frames} and |
| * no {@linkplain Option#RETAIN_CLASS_REFERENCE class reference} is retained. |
| * |
| */ |
| public static StackWalker getInstance() { |
| // no permission check needed |
| return DEFAULT_WALKER; |
| } |
| |
| /** |
| * Returns a {@code StackWalker} instance with the given option specifying |
| * the stack frame information it can access. |
| * |
| * <p> |
| * If a security manager is present and the given {@code option} is |
| * {@link Option#RETAIN_CLASS_REFERENCE Option.RETAIN_CLASS_REFERENCE}, |
| * it calls its {@link SecurityManager#checkPermission checkPermission} |
| * method for {@code RuntimePermission("getStackWalkerWithClassReference")}. |
| * |
| * @param option {@link Option stack walking option} |
| * |
| * @return a {@code StackWalker} configured with the given option |
| * |
| * @throws SecurityException if a security manager exists and its |
| * {@code checkPermission} method denies access. |
| */ |
| public static StackWalker getInstance(Option option) { |
| return getInstance(EnumSet.of(Objects.requireNonNull(option))); |
| } |
| |
| /** |
| * Returns a {@code StackWalker} instance with the given {@code options} specifying |
| * the stack frame information it can access. If the given {@code options} |
| * is empty, this {@code StackWalker} is configured to skip all |
| * {@linkplain Option#SHOW_HIDDEN_FRAMES hidden frames} and no |
| * {@linkplain Option#RETAIN_CLASS_REFERENCE class reference} is retained. |
| * |
| * <p> |
| * If a security manager is present and the given {@code options} contains |
| * {@link Option#RETAIN_CLASS_REFERENCE Option.RETAIN_CLASS_REFERENCE}, |
| * it calls its {@link SecurityManager#checkPermission checkPermission} |
| * method for {@code RuntimePermission("getStackWalkerWithClassReference")}. |
| * |
| * @param options {@link Option stack walking option} |
| * |
| * @return a {@code StackWalker} configured with the given options |
| * |
| * @throws SecurityException if a security manager exists and its |
| * {@code checkPermission} method denies access. |
| */ |
| public static StackWalker getInstance(Set<Option> options) { |
| if (options.isEmpty()) { |
| return DEFAULT_WALKER; |
| } |
| |
| EnumSet<Option> optionSet = toEnumSet(options); |
| checkPermission(optionSet); |
| return new StackWalker(optionSet); |
| } |
| |
| /** |
| * Returns a {@code StackWalker} instance with the given {@code options} specifying |
| * the stack frame information it can access. If the given {@code options} |
| * is empty, this {@code StackWalker} is configured to skip all |
| * {@linkplain Option#SHOW_HIDDEN_FRAMES hidden frames} and no |
| * {@linkplain Option#RETAIN_CLASS_REFERENCE class reference} is retained. |
| * |
| * <p> |
| * If a security manager is present and the given {@code options} contains |
| * {@link Option#RETAIN_CLASS_REFERENCE Option.RETAIN_CLASS_REFERENCE}, |
| * it calls its {@link SecurityManager#checkPermission checkPermission} |
| * method for {@code RuntimePermission("getStackWalkerWithClassReference")}. |
| * |
| * <p> |
| * The {@code estimateDepth} specifies the estimate number of stack frames |
| * this {@code StackWalker} will traverse that the {@code StackWalker} could |
| * use as a hint for the buffer size. |
| * |
| * @param options {@link Option stack walking options} |
| * @param estimateDepth Estimate number of stack frames to be traversed. |
| * |
| * @return a {@code StackWalker} configured with the given options |
| * |
| * @throws IllegalArgumentException if {@code estimateDepth <= 0} |
| * @throws SecurityException if a security manager exists and its |
| * {@code checkPermission} method denies access. |
| */ |
| public static StackWalker getInstance(Set<Option> options, int estimateDepth) { |
| if (estimateDepth <= 0) { |
| throw new IllegalArgumentException("estimateDepth must be > 0"); |
| } |
| EnumSet<Option> optionSet = toEnumSet(options); |
| checkPermission(optionSet); |
| return new StackWalker(optionSet, estimateDepth); |
| } |
| |
| // ----- private constructors ------ |
| private StackWalker(EnumSet<Option> options) { |
| this(options, 0, null); |
| } |
| private StackWalker(EnumSet<Option> options, int estimateDepth) { |
| this(options, estimateDepth, null); |
| } |
| private StackWalker(EnumSet<Option> options, int estimateDepth, ExtendedOption extendedOption) { |
| this.options = options; |
| this.estimateDepth = estimateDepth; |
| this.extendedOption = extendedOption; |
| } |
| |
| private static void checkPermission(Set<Option> options) { |
| Objects.requireNonNull(options); |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| if (options.contains(Option.RETAIN_CLASS_REFERENCE)) { |
| sm.checkPermission(new RuntimePermission("getStackWalkerWithClassReference")); |
| } |
| } |
| } |
| |
| /* |
| * Returns a defensive copy |
| */ |
| private static EnumSet<Option> toEnumSet(Set<Option> options) { |
| Objects.requireNonNull(options); |
| if (options.isEmpty()) { |
| return DEFAULT_EMPTY_OPTION; |
| } else { |
| return EnumSet.copyOf(options); |
| } |
| } |
| |
| /** |
| * Applies the given function to the stream of {@code StackFrame}s |
| * for the current thread, traversing from the top frame of the stack, |
| * which is the method calling this {@code walk} method. |
| * |
| * <p>The {@code StackFrame} stream will be closed when |
| * this method returns. When a closed {@code Stream<StackFrame>} object |
| * is reused, {@code IllegalStateException} will be thrown. |
| * |
| * @apiNote |
| * For example, to find the first 10 calling frames, first skipping those frames |
| * whose declaring class is in package {@code com.foo}: |
| * <blockquote> |
| * <pre>{@code |
| * List<StackFrame> frames = StackWalker.getInstance().walk(s -> |
| * s.dropWhile(f -> f.getClassName().startsWith("com.foo.")) |
| * .limit(10) |
| * .collect(Collectors.toList())); |
| * }</pre></blockquote> |
| * |
| * <p>This method takes a {@code Function} accepting a {@code Stream<StackFrame>}, |
| * rather than returning a {@code Stream<StackFrame>} and allowing the |
| * caller to directly manipulate the stream. The Java virtual machine is |
| * free to reorganize a thread's control stack, for example, via |
| * deoptimization. By taking a {@code Function} parameter, this method |
| * allows access to stack frames through a stable view of a thread's control |
| * stack. |
| * |
| * <p>Parallel execution is effectively disabled and stream pipeline |
| * execution will only occur on the current thread. |
| * |
| * @implNote The implementation stabilizes the stack by anchoring a frame |
| * specific to the stack walking and ensures that the stack walking is |
| * performed above the anchored frame. When the stream object is closed or |
| * being reused, {@code IllegalStateException} will be thrown. |
| * |
| * @param function a function that takes a stream of |
| * {@linkplain StackFrame stack frames} and returns a result. |
| * @param <T> The type of the result of applying the function to the |
| * stream of {@linkplain StackFrame stack frame}. |
| * |
| * @return the result of applying the function to the stream of |
| * {@linkplain StackFrame stack frame}. |
| */ |
| @CallerSensitive |
| public <T> T walk(Function<? super Stream<StackFrame>, ? extends T> function) { |
| // Returning a Stream<StackFrame> would be unsafe, as the stream could |
| // be used to access the stack frames in an uncontrolled manner. For |
| // example, a caller might pass a Spliterator of stack frames after one |
| // or more frames had been traversed. There is no robust way to detect |
| // whether the execution point when |
| // Spliterator.tryAdvance(java.util.function.Consumer<? super T>) is |
| // invoked is the exact same execution point where the stack frame |
| // traversal is expected to resume. |
| |
| Objects.requireNonNull(function); |
| return StackStreamFactory.makeStackTraverser(this, function) |
| .walk(); |
| } |
| |
| /** |
| * Performs the given action on each element of {@code StackFrame} stream |
| * of the current thread, traversing from the top frame of the stack, |
| * which is the method calling this {@code forEach} method. |
| * |
| * <p> This method is equivalent to calling |
| * <blockquote> |
| * {@code walk(s -> { s.forEach(action); return null; });} |
| * </blockquote> |
| * |
| * @param action an action to be performed on each {@code StackFrame} |
| * of the stack of the current thread |
| */ |
| @CallerSensitive |
| public void forEach(Consumer<? super StackFrame> action) { |
| Objects.requireNonNull(action); |
| StackStreamFactory.makeStackTraverser(this, s -> { |
| s.forEach(action); |
| return null; |
| }).walk(); |
| } |
| |
| /** |
| * Gets the {@code Class} object of the caller who invoked the method |
| * that invoked {@code getCallerClass}. |
| * |
| * <p> This method filters {@linkplain Option#SHOW_REFLECT_FRAMES reflection |
| * frames}, {@link java.lang.invoke.MethodHandle}, and |
| * {@linkplain Option#SHOW_HIDDEN_FRAMES hidden frames} regardless of the |
| * {@link Option#SHOW_REFLECT_FRAMES SHOW_REFLECT_FRAMES} |
| * and {@link Option#SHOW_HIDDEN_FRAMES SHOW_HIDDEN_FRAMES} options |
| * this {@code StackWalker} has been configured with. |
| * |
| * <p> This method should be called when a caller frame is present. If |
| * it is called from the bottom most frame on the stack, |
| * {@code IllegalCallerException} will be thrown. |
| * |
| * <p> This method throws {@code UnsupportedOperationException} |
| * if this {@code StackWalker} is not configured with the |
| * {@link Option#RETAIN_CLASS_REFERENCE RETAIN_CLASS_REFERENCE} option. |
| * |
| * @apiNote |
| * For example, {@code Util::getResourceBundle} loads a resource bundle |
| * on behalf of the caller. It invokes {@code getCallerClass} to identify |
| * the class whose method called {@code Util::getResourceBundle}. |
| * Then, it obtains the class loader of that class, and uses |
| * the class loader to load the resource bundle. The caller class |
| * in this example is {@code MyTool}. |
| * |
| * <pre>{@code |
| * class Util { |
| * private final StackWalker walker = StackWalker.getInstance(Option.RETAIN_CLASS_REFERENCE); |
| * public ResourceBundle getResourceBundle(String bundleName) { |
| * Class<?> caller = walker.getCallerClass(); |
| * return ResourceBundle.getBundle(bundleName, Locale.getDefault(), caller.getClassLoader()); |
| * } |
| * } |
| * |
| * class MyTool { |
| * private final Util util = new Util(); |
| * private void init() { |
| * ResourceBundle rb = util.getResourceBundle("mybundle"); |
| * } |
| * } |
| * }</pre> |
| * |
| * An equivalent way to find the caller class using the |
| * {@link StackWalker#walk walk} method is as follows |
| * (filtering the reflection frames, {@code MethodHandle} and hidden frames |
| * not shown below): |
| * <pre>{@code |
| * Optional<Class<?>> caller = walker.walk(s -> |
| * s.map(StackFrame::getDeclaringClass) |
| * .skip(2) |
| * .findFirst()); |
| * }</pre> |
| * |
| * When the {@code getCallerClass} method is called from a method that |
| * is the bottom most frame on the stack, |
| * for example, {@code static public void main} method launched by the |
| * {@code java} launcher, or a method invoked from a JNI attached thread, |
| * {@code IllegalCallerException} is thrown. |
| * |
| * @return {@code Class} object of the caller's caller invoking this method. |
| * |
| * @throws UnsupportedOperationException if this {@code StackWalker} |
| * is not configured with {@link Option#RETAIN_CLASS_REFERENCE |
| * Option.RETAIN_CLASS_REFERENCE}. |
| * @throws IllegalCallerException if there is no caller frame, i.e. |
| * when this {@code getCallerClass} method is called from a method |
| * which is the last frame on the stack. |
| */ |
| @CallerSensitive |
| public Class<?> getCallerClass() { |
| if (!options.contains(Option.RETAIN_CLASS_REFERENCE)) { |
| throw new UnsupportedOperationException("This stack walker " + |
| "does not have RETAIN_CLASS_REFERENCE access"); |
| } |
| |
| return StackStreamFactory.makeCallerFinder(this).findCaller(); |
| } |
| |
| // ---- package access ---- |
| |
| static StackWalker newInstance(Set<Option> options, ExtendedOption extendedOption) { |
| EnumSet<Option> optionSet = toEnumSet(options); |
| checkPermission(optionSet); |
| return new StackWalker(optionSet, 0, extendedOption); |
| } |
| |
| int estimateDepth() { |
| return estimateDepth; |
| } |
| |
| boolean hasOption(Option option) { |
| return options.contains(option); |
| } |
| |
| boolean hasLocalsOperandsOption() { |
| return extendedOption == ExtendedOption.LOCALS_AND_OPERANDS; |
| } |
| |
| void ensureAccessEnabled(Option access) { |
| if (!hasOption(access)) { |
| throw new UnsupportedOperationException("No access to " + access + |
| ": " + options.toString()); |
| } |
| } |
| } |