Implement SPI to allow swapping out JIMFS at runtime (part of #311)

java-compiler-testing/src/main/java/io/github/ascopes/jct/workspaces/RamFileSystemProvider.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2022 - 2023, the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.github.ascopes.jct.workspaces;
+
+import io.github.ascopes.jct.workspaces.impl.DefaultFileSystemProviderImpl;
+import java.nio.file.FileSystem;
+import java.util.ServiceLoader;
+import org.apiguardian.api.API;
+import org.apiguardian.api.API.Status;
+
+/**
+ * Service provider interface for a RAM-based file system provider.
+ *
+ * <p>This enables swapping out the default RAM file system implementation with a custom
+ * implementation by using Java's {@link ServiceLoader} mechanism.
+ *
+ * @author Ashley Scopes
+ * @since 0.0.1 (0.0.1-M9)
+ */
+@API(since = "0.0.1", status = Status.STABLE)
+public interface RamFileSystemProvider {
+
+  /**
+   * Create the new file system.
+   *
+   * @param name the file system name to use.
+   * @return the file system object.
+   */
+  FileSystem createFileSystem(String name);
+
+  /**
+   * Get the service provider implementation to use.
+   *
+   * @return the first service provider implementation, or a default implementation if not provided.
+   */
+  static RamFileSystemProvider getInstance() {
+    return ServiceLoader
+        .load(RamFileSystemProvider.class)
+        .findFirst()
+        .orElseGet(DefaultFileSystemProviderImpl::getInstance);
+  }
+}

java-compiler-testing/src/main/java/io/github/ascopes/jct/workspaces/impl/DefaultFileSystemProviderImpl.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2022 - 2023, the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.github.ascopes.jct.workspaces.impl;
+
+import com.google.common.jimfs.Configuration;
+import com.google.common.jimfs.Feature;
+import com.google.common.jimfs.Jimfs;
+import com.google.common.jimfs.PathType;
+import io.github.ascopes.jct.workspaces.RamFileSystemProvider;
+import java.nio.file.FileSystem;
+import org.apiguardian.api.API;
+import org.apiguardian.api.API.Status;
+
+/**
+ * RAM file system provider that uses JIMFS as the underlying file system implementation.
+ *
+ * @author Ashley Scopes
+ * @since 0.0.1 (0.0.1-M9)
+ */
+@API(since = "0.0.1", status = Status.INTERNAL)
+public final class DefaultFileSystemProviderImpl implements RamFileSystemProvider {
+
+  private static final DefaultFileSystemProviderImpl INSTANCE = new DefaultFileSystemProviderImpl();
+
+  /**
+   * Get the singleton instance of this provider.
+   *
+   * @return the singleton instance.
+   */
+  public static DefaultFileSystemProviderImpl getInstance() {
+    return INSTANCE;
+  }
+
+  private DefaultFileSystemProviderImpl() {
+    // Singleton object.
+  }
+
+  @Override
+  public FileSystem createFileSystem(String name) {
+    var config = Configuration
+        .builder(PathType.unix())
+        .setSupportedFeatures(Feature.LINKS, Feature.SYMBOLIC_LINKS, Feature.FILE_CHANNEL)
+        .setAttributeViews("basic", "posix")
+        .setRoots("/")
+        .setWorkingDirectory("/")
+        .setPathEqualityUsesCanonicalForm(true)
+        .build();
+
+    return Jimfs.newFileSystem(config);
+  }
+}

java-compiler-testing/src/main/java/io/github/ascopes/jct/workspaces/impl/RamDirectoryImpl.java

@@ -18,10 +18,7 @@
 import static io.github.ascopes.jct.utils.FileUtils.assertValidRootName;
 import static io.github.ascopes.jct.utils.IoExceptionUtils.uncheckedIo;
 
-import com.google.common.jimfs.Configuration;
-import com.google.common.jimfs.Feature;
-import com.google.common.jimfs.Jimfs;
-import com.google.common.jimfs.PathType;
+import io.github.ascopes.jct.workspaces.RamFileSystemProvider;
 import java.io.IOException;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
@@ -95,16 +92,7 @@ public static RamDirectoryImpl newRamDirectory(String name) {
 
     assertValidRootName(name);
 
-    var config = Configuration
-        .builder(PathType.unix())
-        .setSupportedFeatures(Feature.LINKS, Feature.SYMBOLIC_LINKS, Feature.FILE_CHANNEL)
-        .setAttributeViews("basic", "posix")
-        .setRoots("/")
-        .setWorkingDirectory("/")
-        .setPathEqualityUsesCanonicalForm(true)
-        .build();
-
-    var fileSystem = Jimfs.newFileSystem(config);
+    var fileSystem = RamFileSystemProvider.getInstance().createFileSystem(name);
     var path = fileSystem.getRootDirectories().iterator().next().resolve(name);
 
     // Ensure the base directory exists.

java-compiler-testing/src/main/java/module-info.java

@@ -13,6 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+import io.github.ascopes.jct.workspaces.RamFileSystemProvider;
+
 /**
  * A framework for performing exhaustive integration testing against Java compilers in modern Java
  * libraries, with a focus on full JPMS support.
@@ -116,6 +119,12 @@
   exports io.github.ascopes.jct.repr;
   exports io.github.ascopes.jct.workspaces;
 
+  ///////////////////////////////////
+  /// SERVICE PROVIDER INTERFACES ///
+  ///////////////////////////////////
+
+  uses RamFileSystemProvider;
+
   //////////////////////////////////////////////////////
   /// EXPOSURE OF INTERNALS TO THE TESTING NAMESPACE ///
   //////////////////////////////////////////////////////