Make MavenArtifactDownloader use an expiring cache to prevent redundant/overloading lookups.

Seems to solve it randomly failing.
Small hack to attach gradle API source to eclipse workspace.

Author: LexManos

build.gradle

@@ -6,6 +6,7 @@ plugins {
 
 apply plugin: 'java'
 apply plugin: 'maven-publish'
+apply plugin: 'eclipse'
 
 group = 'net.minecraftforge.gradle'
 version = gitVersion()
@@ -47,6 +48,11 @@ repositories {
     maven { url = 'http://files.minecraftforge.net/maven' }
 }
 
+wrapper {
+    gradleVersion = '4.9'
+    distributionType = Wrapper.DistributionType.ALL
+}
+
 dependencies {
     commonImplementation gradleApi()
     commonImplementation 'com.cloudbees:diff4j:1.2'
@@ -69,6 +75,21 @@ dependencies {
     userdevImplementation sourceSets.common.output
 }
 
+//Gradle doesn't add it's own source when doing the API. So lets hack it in!
+import org.gradle.plugins.ide.eclipse.model.*
+import org.gradle.plugins.ide.eclipse.model.internal.*
+project.extensions.eclipse.classpath.file.whenMerged { Classpath cp ->
+    def gradleSrc = gradle.gradleHomeDir.absolutePath.replace(File.separator, '/') + '/src/'
+    cp.entries.each { entry ->
+        if ((entry in AbstractLibrary) && entry.library.file.name.startsWith('gradle-')) {
+            def type = (entry.library.file.name =~ "^gradle(-(.*))?-(${gradle.gradleVersion})")[0][2]
+            if (type == 'api') type = 'core-api' //Gradle name is different for cores
+            if (type == '') type = 'core'
+            entry.sourcePath = new FileReferenceFactory().fromPath(gradleSrc + type)
+        }
+    }
+}
+
 publishing {
     publications {
         mavenJava(MavenPublication) {

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,5 @@
-#Wed Aug 01 17:10:49 CEST 2018
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.9-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.9-all.zip

src/common/java/net/minecraftforge/gradle/common/util/MavenArtifactDownloader.java

@@ -4,53 +4,62 @@
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.ExternalModuleDependency;
 import org.gradle.api.artifacts.ModuleVersionIdentifier;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
 
 import java.io.File;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Set;
-import java.util.WeakHashMap;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 
 public class MavenArtifactDownloader {
+    private static final Cache<String, File> CACHE = CacheBuilder.newBuilder()
+            .expireAfterWrite(5, TimeUnit.MINUTES)
+            .build();
 
-    private static final Map<Project, Integer> COUNTERS = new WeakHashMap<>();
-    private static final Map<String, Set<File>> CACHE = new HashMap<>();
     private static final Map<String, String> VERSIONS = new HashMap<>();
 
-    public static Set<File> download(Project project, String artifact) {
-        return download(project, artifact, false);
-    }
-    public static Set<File> download(Project project, String artifact, boolean changing) {
-        Set<File> ret = CACHE.get(artifact);
-        if (ret == null) {
-            String name = "mavenDownloader_" + artifact.replace(":", "/");
-            synchronized(project) {
-                name += COUNTERS.getOrDefault(project, 0);
-                COUNTERS.compute(project, (proj, prev) -> (prev != null ? prev : 0) + 1);
+    private static File _download(Project project, String artifact, boolean changing) {
+        File ret = null;
+        try {
+            ret = CACHE.get(artifact, () -> gradleDownload(project, artifact, changing));
+            if (ret != null && !ret.exists()) {
+                CACHE.invalidate(artifact);
+                ret = CACHE.get(artifact, () -> gradleDownload(project, artifact, changing));
             }
-            Configuration cfg = project.getConfigurations().create(name);
-            ExternalModuleDependency dependency = (ExternalModuleDependency)project.getDependencies().create(artifact);
-            dependency.setChanging(changing);
-            cfg.getDependencies().add(dependency);
-            cfg.resolutionStrategy(strat -> {
-                strat.cacheChangingModulesFor(5, TimeUnit.MINUTES);
-                strat.cacheDynamicVersionsFor(5, TimeUnit.MINUTES);
-            });
-            ret = cfg.resolve();
+        } catch (ExecutionException e) {
+            e.printStackTrace();
+        }
+        return ret;
+    }
 
-            Artifact mine = Artifact.from(artifact);
-            cfg.getResolvedConfiguration().getResolvedArtifacts().forEach(art -> {
-                ModuleVersionIdentifier resolved = art.getModuleVersion().getId();
-                if (resolved.getGroup().equals(mine.getGroup()) && resolved.getName().equals(mine.getName())) {
-                    if ((mine.getClassifier() == null && art.getClassifier() == null) || mine.getClassifier().equals(art.getClassifier()))
-                        VERSIONS.put(artifact, resolved.getVersion());
-                }
-            });
+    private static File gradleDownload(Project project, String artifact, boolean changing) {
+        String name = "mavenDownloader_" + artifact.replace(":", "/");
 
-            project.getConfigurations().remove(cfg);
-            //CACHE.put(artifact, ret); //Daemons break this
-        }
+        //TODO: Bypass gradle's crap?
+        //List<ArtifactRepository> repos = project.getRepositories();
+
+        Configuration cfg = project.getConfigurations().create(name);
+        ExternalModuleDependency dependency = (ExternalModuleDependency)project.getDependencies().create(artifact);
+        dependency.setChanging(changing);
+        cfg.getDependencies().add(dependency);
+        cfg.resolutionStrategy(strat -> {
+            strat.cacheChangingModulesFor(5, TimeUnit.MINUTES);
+            strat.cacheDynamicVersionsFor(5, TimeUnit.MINUTES);
+        });
+        File ret = cfg.resolve().iterator().next(); //We only want the first, not transitive
+
+        Artifact mine = Artifact.from(artifact);
+        cfg.getResolvedConfiguration().getResolvedArtifacts().forEach(art -> {
+            ModuleVersionIdentifier resolved = art.getModuleVersion().getId();
+            if (resolved.getGroup().equals(mine.getGroup()) && resolved.getName().equals(mine.getName())) {
+                if ((mine.getClassifier() == null && art.getClassifier() == null) || mine.getClassifier().equals(art.getClassifier()))
+                    VERSIONS.put(artifact, resolved.getVersion());
+            }
+        });
+
+        project.getConfigurations().remove(cfg);
         return ret;
     }
 
@@ -59,12 +68,11 @@ public static File single(Project project, String artifact) {
     }
 
     public static File single(Project project, String artifact, boolean changing) {
-        Set<File> ret = download(project, artifact, changing);
-        return ret == null ? null : ret.iterator().next();
+        return _download(project, artifact, changing);
     }
 
     public static String getVersion(Project project, String artifact) {
-        download(project, artifact);
+        single(project, artifact);
         return VERSIONS.get(artifact);
     }
 }

src/mcp/java/net/minecraftforge/gradle/mcp/function/ListLibrariesFunction.java

@@ -30,8 +30,7 @@ public File execute(MCPEnvironment environment) {
             Set<File> files = new HashSet<>();
             for (JsonElement libElement : json.getAsJsonArray("libraries")) {
                 JsonObject library = libElement.getAsJsonObject();
-                Set<File> libFiles = MavenArtifactDownloader.download(environment.project, library.get("name").getAsString());
-                files.addAll(libFiles);
+                files.add(MavenArtifactDownloader.single(environment.project, library.get("name").getAsString()));
             }
 
             // Write the list