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⚡ Bolt: Parallelize source JAR resolution #112

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⚡ Bolt: Parallelize source JAR resolution #112

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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## 2024-05-23 - [Parallel Stream Safety]
**Learning:** Switching to `parallelStream` requires careful audit of all shared mutable state, even in test helpers. I learned that `GraphMemoizator` was using a non-thread-safe `HashMap`, and `SourcesLocatorTest`'s `FakeOpener` also used `HashMap`.
**Action:** Always check thread-safety of underlying data structures when introducing parallel streams, including abstract classes and test doubles.
12 changes: 3 additions & 9 deletions resolver/src/main/java/net/evendanan/bazel/mvn/merger/GraphMemoizator.java
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@@ -1,25 +1,19 @@
package net.evendanan.bazel.mvn.merger;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.annotation.Nonnull;

public abstract class GraphMemoizator<T> {
private final Map<String, T> cache = new HashMap<>();
private final Map<String, T> cache = new ConcurrentHashMap<>();

@Nonnull
protected abstract T calculate(@Nonnull T original);

@Nonnull
public T map(@Nonnull T original) {
final String key = getKeyForObject(original);
if (cache.containsKey(key)) {
return cache.get(key);
} else {
final T revised = calculate(original);
cache.put(key, revised);
return revised;
}
return cache.computeIfAbsent(key, k -> calculate(original));
}

protected abstract String getKeyForObject(final T object);
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6 changes: 3 additions & 3 deletions resolver/src/main/java/net/evendanan/bazel/mvn/merger/SourcesJarLocator.java
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Expand Up @@ -5,9 +5,9 @@
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collection;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;
import javax.annotation.Nonnull;
import net.evendanan.bazel.mvn.api.DependencyTools;
Expand All @@ -18,7 +18,7 @@ public class SourcesJarLocator {
private static final String SOURCES_CLASSIFIER = "sources";

private final ConnectionFactory mConnectionFactory;
private final Map<String, String> mURLCache = new HashMap<>();
private final Map<String, String> mURLCache = new ConcurrentHashMap<>();

public SourcesJarLocator() {
this(url -> (HttpURLConnection) url.openConnection());
Expand All @@ -31,7 +31,7 @@ public SourcesJarLocator() {

private static Collection<Dependency> fillSourcesAttribute(
Collection<Dependency> dependencies, DependencyMemoizator memoizator) {
return dependencies.stream().map(memoizator::map).collect(Collectors.toList());
return dependencies.parallelStream().map(memoizator::map).collect(Collectors.toList());
}

public Collection<Dependency> fillSourcesAttribute(Collection<Dependency> dependencies) {
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5 changes: 3 additions & 2 deletions resolver/src/test/java/net/evendanan/bazel/mvn/merger/SourcesLocatorTest.java
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Expand Up @@ -151,8 +151,9 @@ public void testOnlyQueriesURIOnce() throws Exception {
private static class FakeOpener
implements net.evendanan.bazel.mvn.merger.SourcesJarLocator.ConnectionFactory {

private final Map<URL, Integer> buildsCounter = new HashMap<>();
private final Map<URL, HttpURLConnection> returnedConnections = new HashMap<>();
private final Map<URL, Integer> buildsCounter = new java.util.concurrent.ConcurrentHashMap<>();
private final Map<URL, HttpURLConnection> returnedConnections =
new java.util.concurrent.ConcurrentHashMap<>();

private boolean openFailure = false;

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