org.lwjgl.system.StackWalkUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of org.lwjgl.lwjgl Show documentation
LWJGL OSGi bundle (Core LWJGL bundle)
The newest version!
/*
 * Copyright LWJGL. All rights reserved.
 * License terms: https://www.lwjgl.org/license
 */
package org.lwjgl.system;

import javax.annotation.*;
import java.util.*;

/**
 * Stack-walking utilities.
 *
 * On Java 9 these methods are implemented using {@code java.lang.StackWalker}, which has much lower overhead.
 */
final class StackWalkUtil {

    private StackWalkUtil() {
    }

    static StackTraceElement[] stackWalkArray(Object[] a) {
        return (StackTraceElement[])a;
    }

    static Object stackWalkGetMethod(Class after) {
        StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();

        for (int i = 3; i < stackTrace.length; i++) {
            if (!stackTrace[i].getClassName().startsWith(after.getName())) {
                return stackTrace[i];
            }
        }

        throw new IllegalStateException();
    }

    private static boolean isSameMethod(StackTraceElement a, StackTraceElement b) {
        return isSameMethod(a, b, b.getMethodName());
    }

    private static boolean isSameMethod(StackTraceElement a, StackTraceElement b, String methodName) {
        return a.getMethodName().equals(methodName) &&
               a.getClassName().equals(b.getClassName()) &&
               a.getFileName().equals(b.getFileName());
    }

    private static boolean isAutoCloseable(StackTraceElement element, StackTraceElement pushed) {
        // Java 9 try-with-resources: synthetic $closeResource
        if (isSameMethod(element, pushed, "$closeResource")) {
            return true;
        }

        // Kotlin T.use: kotlin.AutoCloseable::closeFinally
        if ("closeFinally".equals(element.getMethodName()) && "AutoCloseable.kt".equals(element.getFileName())) {
            return true;
        }

        return false;
    }

    @Nullable
    static Object stackWalkCheckPop(Class after, Object pushedObj) {
        StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();

        for (int i = 3; i < stackTrace.length; i++) {
            StackTraceElement element = stackTrace[i];
            if (element.getClassName().startsWith(after.getName())) {
                continue;
            }

            StackTraceElement pushed = (StackTraceElement)pushedObj;
            if (isSameMethod(element, pushed)) {
                return null;
            }

            if (isAutoCloseable(element, pushed) && i + 1 < stackTrace.length) {
                // Some runtimes use a separate method to call AutoCloseable::close in try-with-resources blocks.
                // That method suppresses any exceptions thrown by close if necessary.
                // When that happens, the pop is 1 level deeper than expected.
                element = stackTrace[i + 1];
                if (isSameMethod(pushed, stackTrace[i + 1])) {
                    return null;
                }
            }

            return element;
        }

        throw new IllegalStateException();
    }

    static Object[] stackWalkGetTrace() {
        StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();

        int i = 3;
        for (; i < stackTrace.length; i++) {
            if (!stackTrace[i].getClassName().startsWith("org.lwjgl.system.Memory")) {
                break;
            }
        }

        return Arrays.copyOfRange(stackTrace, i, stackTrace.length);
    }

}