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Merged
merged 1 commit into from
Oct 10, 2025
Merged

Add specific type for matching class-loaders by their indexed key #19

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31 changes: 15 additions & 16 deletions utils/src/main/java/datadog/instrument/utils/ClassInfoCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -8,16 +8,15 @@

import java.util.Arrays;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.IntPredicate;

/**
* Shares class information from multiple classloaders in a single cache.
*
* <p>Information is indexed by class-name, with an optional class-loader filter. When multiple
* <p>Information is indexed by class-name, with an optional class-loader matcher. When multiple
* classes are defined with the same name, only one has its information cached at any given time.
* The class-loader can then be used to check information is for the correct class.
*
* @see ClassLoaderIndex#getClassLoaderKeyId
* @see ClassLoaderIndex#getClassLoaderKeyId(ClassLoader)
*/
public final class ClassInfoCache<T> {

Expand Down Expand Up @@ -72,7 +71,7 @@ public void share(String className, T info) {
}

/**
* Finds information for the given class-name, under the given class-loader.
* Finds information for the given class-name, scoped to the given class-loader.
*
* @param className the class-name
* @param cl the class-loader
Expand All @@ -83,18 +82,18 @@ public T find(CharSequence className, ClassLoader cl) {
}

/**
* Shares information for the given class-name, under the given class-loader.
* Shares information for the given class-name, scoped to the given class-loader.
*
* @param className the class-name
* @param info the information to share under the class-name and class-loader
* @param cl limit the information to this class-loader
* @param cl scope the information to this class-loader
*/
public void share(String className, T info, ClassLoader cl) {
share(className, info, ClassLoaderIndex.getClassLoaderKeyId(cl));
}

/**
* Finds information for the given class-name, under the given class-loader key.
* Finds information for the given class-name, scoped to the given class-loader key.
*
* @param className the class-name
* @param classLoaderKeyId the class-loader's key-id
Expand All @@ -113,7 +112,7 @@ public T find(CharSequence className, int classLoaderKeyId) {
SharedInfo existing = shared[slot];
if (existing != null) {
if (existing.className.contentEquals(className)) {
// filter on class-loader, -1 on either side matches all
// match on class-loader key, -1 on either side matches all
if ((classLoaderKeyId ^ existing.classLoaderKeyId) <= 0) {
// use global TICKS as a substitute for access time
// TICKS is only incremented in 'share' for performance reasons
Expand All @@ -134,15 +133,15 @@ public T find(CharSequence className, int classLoaderKeyId) {
}

/**
* Finds information for the given class-name, filtered by class-loader key.
* Finds information for the given class-name, scoped to class-loaders with matching keys.
*
* @param className the class-name
* @param classLoaderKeyFilter the filter for the class-loader key
* @return information shared under the class-name and filtered class-loader
* @param classLoaderKeyMatcher matcher of class-loader keys
* @return information shared under the class-name and matching class-loader
* @see ClassLoaderIndex#getClassLoaderKeyId(ClassLoader)
*/
@SuppressWarnings("unchecked")
public T find(CharSequence className, IntPredicate classLoaderKeyFilter) {
public T find(CharSequence className, ClassLoaderKeyMatcher classLoaderKeyMatcher) {
final int hash = className.hashCode();
final SharedInfo[] shared = this.shared;
final int slotMask = this.slotMask;
Expand All @@ -153,9 +152,9 @@ public T find(CharSequence className, IntPredicate classLoaderKeyFilter) {
SharedInfo existing = shared[slot];
if (existing != null) {
if (existing.className.contentEquals(className)) {
// apply filter to class-loader key, -1 always matches
// apply custom matcher to class-loader key, -1 always matches
if (existing.classLoaderKeyId < 0
|| classLoaderKeyFilter.test(existing.classLoaderKeyId)) {
|| classLoaderKeyMatcher.test(existing.classLoaderKeyId)) {
// use global TICKS as a substitute for access time
// TICKS is only incremented in 'share' for performance reasons
existing.accessed = TICKS.get();
Expand All @@ -175,11 +174,11 @@ public T find(CharSequence className, IntPredicate classLoaderKeyFilter) {
}

/**
* Shares information for the given class-name, under the given class-loader key.
* Shares information for the given class-name, scoped to the given class-loader key.
*
* @param className the class-name
* @param info the information to share under the class-name and class-loader
* @param classLoaderKeyId limit the information to this class-loader key-id
* @param classLoaderKeyId scope the information to this class-loader key-id
* @see ClassLoaderIndex#getClassLoaderKeyId(ClassLoader)
*/
@SuppressWarnings("StatementWithEmptyBody")
Expand Down
25 changes: 25 additions & 0 deletions utils/src/main/java/datadog/instrument/utils/ClassLoaderKeyMatcher.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
/*
* Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
* This product includes software developed at Datadog (https://www.datadoghq.com/).
* Copyright 2025-Present Datadog, Inc.
*/

package datadog.instrument.utils;

/**
* Matcher used to partition class-loaders by their indexed key-id.
*
* @see ClassLoaderIndex#getClassLoaderKeyId(ClassLoader)
* @see ClassInfoCache#find(CharSequence, ClassLoaderKeyMatcher)
*/
@FunctionalInterface
public interface ClassLoaderKeyMatcher {

/**
* Evaluates this matcher against the given class-loader key-id.
*
* @param classLoaderKeyId the class-loader key-id
* @return {@code true} if the key-id matched; otherwise {@code false}
*/
boolean test(int classLoaderKeyId);
}
47 changes: 23 additions & 24 deletions utils/src/test/java/datadog/instrument/utils/ClassInfoCacheTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@

import java.util.HashSet;
import java.util.Set;
import java.util.function.IntPredicate;
import org.junit.jupiter.api.Test;

class ClassInfoCacheTest {
Expand All @@ -20,10 +19,10 @@ void basicOperation() {
ClassLoader myCL = newCL();
ClassLoader notMyCL = newCL();

int myCLKey = ClassLoaderIndex.getClassLoaderKeyId(myCL);
int myCLKeyId = ClassLoaderIndex.getClassLoaderKeyId(myCL);

IntPredicate myCLFilter = sameCLKey(myCLKey);
IntPredicate notMyCLFilter = myCLFilter.negate();
ClassLoaderKeyMatcher matchMyCL = sameCLKey(myCLKeyId);
ClassLoaderKeyMatcher dontMatchMyCL = keyId -> !matchMyCL.test(keyId);

assertNull(cache.find("example.test.MyGlobalClass"));
assertNull(cache.find("example.test.MyLocalClass"));
Expand All @@ -37,13 +36,13 @@ void basicOperation() {
assertNull(cache.find("example.test.MyLocalClass", notMyCL));
assertNull(cache.find("example.test.NotMyClass", notMyCL));

assertNull(cache.find("example.test.MyGlobalClass", myCLFilter));
assertNull(cache.find("example.test.MyLocalClass", myCLFilter));
assertNull(cache.find("example.test.NotMyClass", myCLFilter));
assertNull(cache.find("example.test.MyGlobalClass", matchMyCL));
assertNull(cache.find("example.test.MyLocalClass", matchMyCL));
assertNull(cache.find("example.test.NotMyClass", matchMyCL));

assertNull(cache.find("example.test.MyGlobalClass", notMyCLFilter));
assertNull(cache.find("example.test.MyLocalClass", notMyCLFilter));
assertNull(cache.find("example.test.NotMyClass", notMyCLFilter));
assertNull(cache.find("example.test.MyGlobalClass", dontMatchMyCL));
assertNull(cache.find("example.test.MyLocalClass", dontMatchMyCL));
assertNull(cache.find("example.test.NotMyClass", dontMatchMyCL));

cache.share("example.test.MyGlobalClass", "my global data");
cache.share("example.test.MyLocalClass", "my local data", myCL);
Expand All @@ -60,13 +59,13 @@ void basicOperation() {
assertNull(cache.find("example.test.MyLocalClass", notMyCL));
assertNull(cache.find("example.test.NotMyClass", notMyCL));

assertEquals("my global data", cache.find("example.test.MyGlobalClass", myCLFilter));
assertEquals("my local data", cache.find("example.test.MyLocalClass", myCLFilter));
assertNull(cache.find("example.test.NotMyClass", myCLFilter));
assertEquals("my global data", cache.find("example.test.MyGlobalClass", matchMyCL));
assertEquals("my local data", cache.find("example.test.MyLocalClass", matchMyCL));
assertNull(cache.find("example.test.NotMyClass", matchMyCL));

assertEquals("my global data", cache.find("example.test.MyGlobalClass", notMyCLFilter));
assertNull(cache.find("example.test.MyLocalClass", notMyCLFilter));
assertNull(cache.find("example.test.NotMyClass", notMyCLFilter));
assertEquals("my global data", cache.find("example.test.MyGlobalClass", dontMatchMyCL));
assertNull(cache.find("example.test.MyLocalClass", dontMatchMyCL));
assertNull(cache.find("example.test.NotMyClass", dontMatchMyCL));

cache.clear();

Expand All @@ -82,13 +81,13 @@ void basicOperation() {
assertNull(cache.find("example.test.MyLocalClass", notMyCL));
assertNull(cache.find("example.test.NotMyClass", notMyCL));

assertNull(cache.find("example.test.MyGlobalClass", myCLFilter));
assertNull(cache.find("example.test.MyLocalClass", myCLFilter));
assertNull(cache.find("example.test.NotMyClass", myCLFilter));
assertNull(cache.find("example.test.MyGlobalClass", matchMyCL));
assertNull(cache.find("example.test.MyLocalClass", matchMyCL));
assertNull(cache.find("example.test.NotMyClass", matchMyCL));

assertNull(cache.find("example.test.MyGlobalClass", notMyCLFilter));
assertNull(cache.find("example.test.MyLocalClass", notMyCLFilter));
assertNull(cache.find("example.test.NotMyClass", notMyCLFilter));
assertNull(cache.find("example.test.MyGlobalClass", dontMatchMyCL));
assertNull(cache.find("example.test.MyLocalClass", dontMatchMyCL));
assertNull(cache.find("example.test.NotMyClass", dontMatchMyCL));
}

@Test
Expand Down Expand Up @@ -151,8 +150,8 @@ void overflow() {
}
}

private static IntPredicate sameCLKey(int clKey) {
return k -> k == clKey;
private static ClassLoaderKeyMatcher sameCLKey(int expectedKeyId) {
return keyId -> keyId == expectedKeyId;
}

private static ClassLoader newCL() {
Expand Down