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Muzzle match only once in each class loader #4543

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merged 4 commits into from
Nov 1, 2021
Merged

Muzzle match only once in each class loader #4543

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00b262c
Muzzle match only once in each class loader
laurit Oct 29, 2021
d621760
Move muzzle matcher caching from ReferenceMatcher to InstrumentationM…
laurit Oct 29, 2021
fb09a9e
Update comment as caching was moved to a different method
laurit Oct 29, 2021
bb1c762
Fix comment
laurit Oct 29, 2021
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14 changes: 9 additions & 5 deletions ...va/io/opentelemetry/javaagent/tooling/instrumentation/InstrumentationModuleInstaller.java
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
import static net.bytebuddy.matcher.ElementMatchers.named;
import static net.bytebuddy.matcher.ElementMatchers.not;

import io.opentelemetry.instrumentation.api.caching.Cache;
import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
import io.opentelemetry.javaagent.tooling.HelperInjector;
Expand Down Expand Up @@ -124,6 +125,7 @@ AgentBuilder install(
private static class MuzzleMatcher implements AgentBuilder.RawMatcher {
private final InstrumentationModule instrumentationModule;
private final AtomicBoolean initialized = new AtomicBoolean(false);
private final Cache<ClassLoader, Boolean> matchCache = Cache.builder().setWeakKeys().build();
private volatile ReferenceMatcher referenceMatcher;

private MuzzleMatcher(InstrumentationModule instrumentationModule) {
Expand All @@ -137,10 +139,14 @@ public boolean matches(
JavaModule module,
Class<?> classBeingRedefined,
ProtectionDomain protectionDomain) {
ReferenceMatcher muzzle = getReferenceMatcher();
if (classLoader == BOOTSTRAP_LOADER) {
classLoader = Utils.getBootstrapProxy();
}
return matchCache.computeIfAbsent(classLoader, this::doesMatch);
}

private boolean doesMatch(ClassLoader classLoader) {
ReferenceMatcher muzzle = getReferenceMatcher();
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boolean isMatch = muzzle.matches(classLoader);

if (!isMatch) {
Expand Down Expand Up @@ -168,10 +174,8 @@ public boolean matches(
return isMatch;
}

// ReferenceMatcher internally caches the muzzle check results per classloader, that's why we
// keep its instance in a field
// it is lazily created to avoid unnecessarily loading the muzzle references from the module
// during the agent setup
// ReferenceMatcher is lazily created to avoid unnecessarily loading the muzzle references from
// the module during the agent setup
private ReferenceMatcher getReferenceMatcher() {
if (initialized.compareAndSet(false, true)) {
referenceMatcher = ReferenceMatcher.of(instrumentationModule);
Expand Down
18 changes: 6 additions & 12 deletions muzzle/src/main/java/io/opentelemetry/javaagent/tooling/muzzle/ReferenceMatcher.java
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@
import static java.util.Collections.emptyList;
import static java.util.Collections.singletonList;

import io.opentelemetry.instrumentation.api.caching.Cache;
import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
import io.opentelemetry.javaagent.tooling.muzzle.references.ClassRef;
import io.opentelemetry.javaagent.tooling.muzzle.references.FieldRef;
Expand All @@ -31,7 +30,6 @@
/** Matches a set of references against a classloader. */
public final class ReferenceMatcher {

private final Cache<ClassLoader, Boolean> mismatchCache = Cache.builder().setWeakKeys().build();
private final Map<String, ClassRef> references;
private final Set<String> helperClassNames;
private final HelperClassPredicate helperClassPredicate;
Expand All @@ -53,18 +51,14 @@ public static ReferenceMatcher of(InstrumentationModule instrumentationModule) {
}

/**
* Matcher used by ByteBuddy. Fails fast and only caches empty results, or complete results
* Matcher used by ByteBuddy. Caller is expected to cache the result if this method is called
* multiple times for given class loader.
*
* @param userClassLoader Classloader to validate against (cannot be {@code null}, must pass
* "bootstrap proxy" instead of bootstrap class loader)
* @param loader Classloader to validate against (cannot be {@code null}, must pass "bootstrap
* proxy" instead of bootstrap class loader)
* @return true if all references match the classpath of loader
*/
public boolean matches(ClassLoader userClassLoader) {
return mismatchCache.computeIfAbsent(userClassLoader, this::doesMatch);
}

// loader cannot be null, must pass "bootstrap proxy" instead of bootstrap class loader
private boolean doesMatch(ClassLoader loader) {
public boolean matches(ClassLoader loader) {
TypePool typePool = createTypePool(loader);
for (ClassRef reference : references.values()) {
if (!checkMatch(reference, typePool, loader).isEmpty()) {
Expand All @@ -75,7 +69,7 @@ private boolean doesMatch(ClassLoader loader) {
}

/**
* Loads the full list of mismatches. Used in debug contexts only
* Loads the full list of mismatches. Used in debug contexts only.
*
* @param loader Classloader to validate against (cannot be {@code null}, must pass "bootstrap *
* proxy" instead of bootstrap class loader)
Expand Down