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Inspect and record the execution of Java for use with App Land
package com.appland.appmap.transform;
import java.io.ByteArrayInputStream;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.reflections.Reflections;
import org.reflections.scanners.SubTypesScanner;
import org.reflections.util.ClasspathHelper;
import org.reflections.util.ConfigurationBuilder;
import org.reflections.util.FilterBuilder;
import org.tinylog.TaggedLogger;
import com.appland.appmap.config.AppMapConfig;
import com.appland.appmap.config.Properties;
import com.appland.appmap.output.v1.NoSourceAvailableException;
import com.appland.appmap.transform.annotations.AnnotationUtil;
import com.appland.appmap.transform.annotations.AnnotationUtil.AnnotatedBehavior;
import com.appland.appmap.transform.annotations.AnnotationUtil.AnnotatedClass;
import com.appland.appmap.transform.annotations.AppMapInstrumented;
import com.appland.appmap.transform.annotations.Hook;
import com.appland.appmap.transform.annotations.HookFactory;
import com.appland.appmap.transform.annotations.HookSite;
import com.appland.appmap.transform.annotations.HookValidationException;
import com.appland.appmap.util.AppMapClassPool;
import com.appland.appmap.util.Logger;
import javassist.ClassPool;
import javassist.CtBehavior;
import javassist.CtClass;
import javassist.Modifier;
import javassist.NotFoundException;
import javassist.bytecode.AnnotationsAttribute;
import javassist.bytecode.ClassFile;
import javassist.bytecode.ConstPool;
import javassist.bytecode.annotation.Annotation;
/**
* The ClassFileTransformer is responsible for loading and caching hooks during {@link com.appland.appmap.Agent}
* statup. The {@link ClassFileTransformer#transform} method is used by the Instrumentation API to
* modify class bytecode at load time. When a class is loaded, this class will attempt to apply
* hooks to each behavior declared by that class.
*/
public class ClassFileTransformer implements java.lang.instrument.ClassFileTransformer {
private static final TaggedLogger logger = AppMapConfig.getLogger(null);
private static String tracePrefix = Properties.DebugClassPrefix;
private static final String PROCESS_PACKAGE = "com.appland.appmap.process";
private final String name;
private final List unkeyedHooks = new ArrayList<>();
private final Map> keyedHooks = new HashMap<>();
private HookFactory hookFactory;
private Hook[] sortedUnkeyedHooks = null;
private Map allKeyedHooks = null;
// These stats are only intended to give a sense of how much work was done by
// the transformers. It's not neccessary that they be absolutely correct, so
// access to them isn't synchronized.
private static final List instances = new ArrayList<>();
private long classesExamined = 0;
private long methodsHooked = 0;
private long methodsExamined = 0;
private HashMap packagesHooked = new HashMap<>();
private HashMap packagesIgnored = new HashMap<>();
private long classesIgnored = 0;
/**
* Default constructor. Caches hooks for future class transforms.
*/
public ClassFileTransformer(String name, HookFactory hookFactory) {
super();
this.name = name;
this.hookFactory = hookFactory;
Reflections reflections = new Reflections(new ConfigurationBuilder()
.setUrls(ClasspathHelper.forPackage(PROCESS_PACKAGE))
.setScanners(new SubTypesScanner(false))
.filterInputsBy(new FilterBuilder().includePackage(PROCESS_PACKAGE)));
ClassPool classPool = AppMapClassPool.acquire(Thread.currentThread().getContextClassLoader());
try {
for (Class classType : reflections.getSubTypesOf(Object.class)) {
try {
CtClass ctClass = classPool.get(classType.getName());
processClass(ctClass);
ctClass.detach();
} catch (NotFoundException e) {
logger.debug(e);
}
}
resolveHooks();
} finally {
AppMapClassPool.release();
instances.add(this);
}
}
private void resolveHooks() {
// @formatter:off
Function, Hook[]> sorter = s -> s.sorted(
Comparator.comparingInt(Hook::getPosition)
)
.toArray(Hook[]::new);
sortedUnkeyedHooks = sorter.apply(unkeyedHooks.stream());
allKeyedHooks = keyedHooks
.entrySet()
.stream()
.collect(Collectors.toMap(
Map.Entry::getKey,
e -> sorter.apply(
Stream.of(
e.getValue(),
unkeyedHooks
)
.flatMap(Collection::stream)))
);
// @formatter:on
}
private void addHook(Hook hook) {
if (hook == null) {
return;
}
String key = hook.getKey();
logger.trace("{}: {}", key, hook);
if (key == null) {
unkeyedHooks.add(hook);
} else {
List matchingKeyedHooks = keyedHooks.computeIfAbsent(key, k -> new ArrayList<>());
matchingKeyedHooks.add(hook);
}
}
private Hook[] getHooks(String methodId) {
Hook[] methodHooks = allKeyedHooks.get(methodId);
return methodHooks != null ? methodHooks : sortedUnkeyedHooks;
}
private void processClass(CtClass ctClass) {
boolean traceClass = tracePrefix == null || ctClass.getName().startsWith(tracePrefix);
if (traceClass) {
logger.trace(() -> ctClass.getName());
}
for (CtBehavior behavior : ctClass.getDeclaredBehaviors()) {
if (traceClass) {
logger.trace(() -> behavior.getLongName());
}
Hook hook = hookFactory.from(behavior);
if (hook == null) {
if (traceClass) {
logger.trace("{}, no hooks", () -> behavior.getLongName());
}
continue;
}
ctClass.defrost();
try {
hook.validate();
} catch (HookValidationException e) {
logger.debug(e, "failed to validate hook");
continue;
}
this.addHook(hook);
if (traceClass) {
logger.trace("registered hook {}", hook);
}
}
}
private boolean applyHooks(CtBehavior behavior) {
boolean traceClass = tracePrefix == null || behavior.getDeclaringClass().getName().startsWith(tracePrefix);
try {
List hookSites = getHookSites(behavior);
if (hookSites == null) {
if (traceClass) {
logger.trace("no hook sites");
}
return false;
}
Hook.apply(behavior, hookSites);
if (logger.isDebugEnabled()) {
for (HookSite hookSite : hookSites) {
final Hook hook = hookSite.getHook();
String className = behavior.getDeclaringClass().getName();
if (tracePrefix != null && !className.startsWith(tracePrefix)) {
continue;
}
if (traceClass) {
logger.trace("hooked {}.{}{} on ({},{}) with {}",
className,
behavior.getName(),
behavior.getMethodInfo().getDescriptor(),
hook.getMethodEvent().getEventString(),
hook.getPosition(),
hook);
}
}
}
return true;
} catch (NoSourceAvailableException e) {
Logger.println(e);
}
return false;
}
public List getHookSites(CtBehavior behavior) {
List hookSites = null;
Map hookContext = new HashMap<>();
// Put this behavior's annotations in the context so they'll be available
// when the hooks are prepared.
AnnotatedBehavior ab = new AnnotatedBehavior(behavior);
AnnotationsAttribute attr = ab.get();
Set behaviorAnnotations = null;
if (attr != null) {
behaviorAnnotations = new HashSet<>();
Annotation[] annotations = attr.getAnnotations();
for (Annotation a : annotations) {
behaviorAnnotations.add(a.getTypeName());
}
}
hookContext.put(Hook.ANNOTATIONS, behaviorAnnotations);
for (Hook hook : getHooks(behavior.getName())) {
HookSite hookSite = hook.prepare(behavior, hookContext);
if (hookSite == null) {
continue;
}
if (hookSites == null) {
hookSites = new ArrayList<>();
}
hookSites.add(hookSite);
}
return hookSites;
}
@Override
public byte[] transform(ClassLoader loader,
String className,
Class redefiningClass,
ProtectionDomain domain,
byte[] bytes) throws IllegalClassFormatException {
classesExamined++;
AppMapClassPool.acquire(loader);
try {
// Anonymous classes created by sun.misc.Unsafe.defineAnonymousClass don't
// have names.
if (className == null) {
return null;
}
className = className.replace('/', '.');
if (className.startsWith("com.appland")
&& !className.startsWith("com.appland.appmap.test.fixture")) {
return null;
}
boolean traceClass = tracePrefix == null || className.startsWith(tracePrefix);
CtClass ctClass;
try {
ClassPool classPool = AppMapClassPool.get();
if (traceClass) {
logger.debug("className: {}", className);
}
ctClass = classPool.makeClass(new ByteArrayInputStream(bytes));
} catch (RuntimeException e) {
// The class is frozen
// We can defrost it and apply our changes, though in practice I've observed this to be
// unstable. Particularly, exceptions thrown from the Groovy runtime due to missing methods.
// There's likely a way to do this safely, but further investigation is needed.
//
// ctClass = classPool.get(className.replace('/', '.'));
// ctClass.defrost();
//
// For now, just skip this class
logger.warn(e, "makeClass failed");
return null;
}
if (ctClass.isInterface()) {
if (traceClass) {
logger.trace("{} is an interface", className);
}
return null;
}
boolean hookApplied = false;
for (CtBehavior behavior : ctClass.getDeclaredBehaviors()) {
if (traceClass) {
logger.trace("behavior: {}", behavior.getLongName());
}
if ((behavior.getModifiers() & Modifier.ABSTRACT) != 0) {
if (traceClass) {
logger.trace("abstract method");
}
continue;
}
methodsExamined++;
if (this.applyHooks(behavior)) {
hookApplied = true;
methodsHooked++;
}
}
if (hookApplied) {
// One or more of the methods in the the class were marked as needing to
// be instrumented. Mark the class so the bytebuddy transformer will
// know it needs to be instrumented.
ClassFile classFile = ctClass.getClassFile();
ConstPool constPool = classFile.getConstPool();
Annotation annot = new Annotation(AppMapInstrumented.class.getName(), constPool);
AnnotationUtil.setAnnotation(new AnnotatedClass(ctClass), annot);
if (traceClass) {
logger.trace("hooks applied to {}", className);
}
if (logger.isDebugEnabled()) {
packagesHooked.compute(ctClass.getPackageName(), (k, v) -> v == null ? 1 : v + 1);
}
return ctClass.toBytecode();
}
classesIgnored++;
if (logger.isDebugEnabled()) {
packagesIgnored.compute(ctClass.getPackageName(), (k, v) -> v == null ? 1 : v + 1);
}
if (traceClass) {
logger.trace("no hooks applied to {}, methods: {}", ctClass::getName,
() -> Arrays.stream(ctClass.getDeclaredBehaviors())
.map(CtBehavior::getName).collect(Collectors.joining(",")));
}
} catch (Throwable t) {
// Don't allow this exception to propagate out of this method, because it will
// be swallowed
// by sun.instrument.TransformerManager.
logger.warn(t);
} finally {
AppMapClassPool.release();
}
return null;
}
public static void logStatistics() {
instances.forEach(cft -> {
logger.info("+++ {} +++", cft.name);
logger.info("classes examined: {}", cft.classesExamined);
logger.info("classes ignored: {}", cft.classesIgnored);
logger.info("methods examined: {}", cft.methodsExamined);
logger.info("methods instrumented: {}", cft.methodsHooked);
logger.debug("{} packages hooked:\n{}", () -> cft.packagesHooked.size(),
() -> collectPkgs(cft.packagesHooked));
logger.debug("{} packages ignored:\n{}", () -> cft.packagesIgnored.size(),
() -> collectPkgs(cft.packagesIgnored));
logger.info("=== {} ===", cft.name);
});
}
@SuppressWarnings("unchecked")
private static String collectPkgs(HashMap p) {
HashMap pkgs = (HashMap)p.clone();
return pkgs.entrySet().stream()
.sorted(Map.Entry.comparingByValue().reversed())
.map(entry -> entry.getKey() + ": " + entry.getValue())
.collect(Collectors.joining("\n"));
}
}