Reduce footprint of SourceFile tracking

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java

@@ -9,31 +9,32 @@
 import com.datadog.debugger.instrumentation.InstrumentationResult;
 import com.datadog.debugger.probe.ProbeDefinition;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 public class ClassesToRetransformFinder {
  private static final Logger LOGGER = LoggerFactory.getLogger(ClassesToRetransformFinder.class);
+ private static final Pattern COMMA_PATTERN = Pattern.compile(",");
 
- private final ConcurrentMap<String, List<String>> classNamesBySourceFile =
- new ConcurrentHashMap<>();
+ private final ConcurrentMap<String, String> classNamesBySourceFile = new ConcurrentHashMap<>();
 
  public void register(String sourceFile, String className) {
  // store only the class name that are different from SourceFile name
  // (Inner or non-public Top-Level classes)
  classNamesBySourceFile.compute(
  sourceFile,
- (key, list) -> {
- if (list == null) {
- list = new ArrayList<>();
+ (key, classNames) -> {
+ if (classNames == null) {
+ return className;
  }
- list.add(className);
- return list;
+ return classNames + "," + className;
  });
  }
 
@@ -89,13 +90,11 @@ Trie getAllChangedClasses(ConfigurationComparer comparer) {
 
  private void processAdditionalClasses(String sourceFile, Trie changedClasses) {
  sourceFile = stripPackagePath(sourceFile);
- // need to clone the list to avoid concurrent modification during iteration
- List<String> additionalClasses =
- classNamesBySourceFile.computeIfPresent(
- sourceFile, (k, classNames) -> new ArrayList<>(classNames));
- if (additionalClasses == null) {
+ String classNames = classNamesBySourceFile.get(sourceFile);
+ if (classNames == null) {
  return;
  }
+ List<String> additionalClasses = Arrays.asList(COMMA_PATTERN.split(classNames));
  for (String additionalClass : additionalClasses) {
  additionalClass = normalizeFilePath(additionalClass);
  changedClasses.insert(reverseStr(additionalClass));

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/InnerHelper.java

@@ -3,4 +3,6 @@
 public class InnerHelper {
 
  public static class MyInner {}
+
+ public static class MySecondInner {}
 }

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/SourceFileTrackingTransformerTest.java

@@ -58,12 +58,22 @@ void transformInner() throws IllegalClassFormatException {
  null,
  null,
  getClassFileBytes(InnerHelper.MyInner.class));
+ sourceFileTrackingTransformer.transform(
+ null,
+ getInternalName(InnerHelper.MySecondInner.class),
+ null,
+ null,
+ getClassFileBytes(InnerHelper.MySecondInner.class));
  changedClasses =
  finder.getAllLoadedChangedClasses(
- new Class[] {InnerHelper.class, InnerHelper.MyInner.class}, comparer);
- assertEquals(2, changedClasses.size());
+ new Class[] {
+ InnerHelper.class, InnerHelper.MyInner.class, InnerHelper.MySecondInner.class
+ },
+ comparer);
+ assertEquals(3, changedClasses.size());
  assertEquals(InnerHelper.class, changedClasses.get(0));
  assertEquals(InnerHelper.MyInner.class, changedClasses.get(1));
+ assertEquals(InnerHelper.MySecondInner.class, changedClasses.get(2));
  }
 
  private ConfigurationComparer createComparer(String sourceFile) {