feat: Add isolating classloader for sharing across projects

Closes GH-55

src/main/java/net/kyori/mammoth/IsolatingClassLoader.java

@@ -0,0 +1,86 @@
+/*
+ * This file is part of mammoth, licensed under the MIT License.
+ *
+ * Copyright (c) 2024 KyoriPowered
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package net.kyori.mammoth;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Iterator;
+import java.util.Set;
+import org.gradle.api.file.FileCollection;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A factory for classloaders that will load classes from themselves rather than its parent where possible.
+ *
+ * <p>This can be used to create isolated environments for working with Gradle plugins, or providing an alternative to workers.</p>
+ *
+ * <p>The returned loader from any of these factory methods will be registered as parallel capable.</p>
+ *
+ * @since 1.4.0
+ */
+public final class IsolatingClassLoader {
+  private IsolatingClassLoader() {
+  }
+
+  /**
+   * Create a new loader based on a provided set of URLs.
+   *
+   * @param parent the parent loader
+   * @param urls the urls
+   * @return the newly created loader
+   * @since 1.4.0
+   */
+  public static @NotNull URLClassLoader isolatingClassLoader(final @Nullable ClassLoader parent, final @NotNull URL @NotNull... urls) {
+    return new IsolatingClassLoaderImpl(urls, parent);
+  }
+
+  /**
+   * Create a new loader based on a provided file collection.
+   *
+   * @param parent the parent loader
+   * @param files the file collection
+   * @return the newly created loader
+   * @since 1.4.0
+   */
+  public static @NotNull URLClassLoader isolatingClassLoader(final @Nullable ClassLoader parent, final @NotNull FileCollection files) {
+    final Set<File> unwrapped = files.getFiles();
+    final URL[] urls = new URL[unwrapped.size()];
+    final Iterator<File> it = files.iterator();
+    int idx = 0;
+    File file;
+    while (it.hasNext()) {
+      file = it.next();
+      try {
+        urls[idx++] = file.toURI().toURL();
+      } catch (final MalformedURLException ex) {
+        throw new IllegalArgumentException("Unable to include file " + file + " in classpath");
+      }
+    }
+
+    return new IsolatingClassLoaderImpl(urls, parent);
+  }
+}

src/main/java/net/kyori/mammoth/IsolatingClassLoaderImpl.java

@@ -0,0 +1,114 @@
+/*
+ * This file is part of mammoth, licensed under the MIT License.
+ *
+ * Copyright (c) 2024 KyoriPowered
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package net.kyori.mammoth;
+
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Enumeration;
+import java.util.NoSuchElementException;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+final class IsolatingClassLoaderImpl extends URLClassLoader {
+  static {
+    ClassLoader.registerAsParallelCapable();
+  }
+
+  private final ClassLoader parent;
+
+  // todo: maybe add transformer function (UnaryOperator<byte[]>)? just for fun
+  // todo: add a filter
+  IsolatingClassLoaderImpl(final URL[] urls, final ClassLoader parent) {
+    super(urls, parent);
+    this.parent = parent;
+  }
+
+  @Override
+  protected @Nullable Class<?> loadClass(final @NotNull String name, final boolean resolve) throws ClassNotFoundException {
+    synchronized (this.getClassLoadingLock(name)) {
+      Class<?> result = this.findLoadedClass(name);
+      if (result == null) {
+        try {
+          result = this.findClass(name);
+        } catch (final ClassNotFoundException ex) {
+          // ignore, delegate to parent
+        }
+      }
+
+      if (result == null) {
+        return super.loadClass(name, resolve);
+      }
+
+      if (resolve) {
+        this.resolveClass(result);
+      }
+      return result;
+    }
+  }
+
+  @Override
+  public @Nullable URL getResource(final String name) {
+    @Nullable URL result = this.findResource(name);
+    if (result == null) {
+      result = super.getResource(name);
+    }
+    return result;
+  }
+
+  @Override
+  public @NotNull Enumeration<URL> getResources(final String name) throws IOException {
+    return new Enumeration<URL>() {
+      @Nullable Enumeration<URL> active = IsolatingClassLoaderImpl.this.findResources(name);
+      @Nullable Enumeration<URL> staged = IsolatingClassLoaderImpl.this.parent == null
+        ? ClassLoader.getSystemClassLoader().getResources(name)
+        : IsolatingClassLoaderImpl.this.parent.getResources(name);
+
+      private @Nullable Enumeration<URL> nextComponent() {
+        if (this.active == null) {
+          return null;
+        } else if (!this.active.hasMoreElements()) {
+          this.active = this.staged;
+          this.staged = null;
+        }
+        return this.active;
+      }
+
+      @Override
+      public boolean hasMoreElements() {
+        final @Nullable Enumeration<URL> component = this.nextComponent();
+        return component != null && component.hasMoreElements();
+      }
+
+      @Override
+      public @NotNull URL nextElement() {
+        final @Nullable Enumeration<URL> component = this.nextComponent();
+        if (component == null) {
+          throw new NoSuchElementException();
+        }
+        return component.nextElement();
+      }
+    };
+  }
+}