Make plugin-maven use local config files if possible

plugin-maven/CHANGES.md

@@ -5,6 +5,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Fixed
 * Shared library used by the nodejs-based steps used to be extracted into the user home directory, but now it is extracted into a temporary directory and deleted on VM shutdown. ([#586](https://github.com/diffplug/spotless/pull/586))
+* If you specified a config file for a formatter, it used to be needlessly copied to a randomly-named file in the build folder.  This could cause performance to suffer, especially for [large multi-project builds that use eclipse](https://github.com/diffplug/spotless/issues/559). ([#572](https://github.com/diffplug/spotless/pull/572))
+  * Note: if you are extracting config files from resource jars, we still have bad performance for this case, see [#559](https://github.com/diffplug/spotless/issues/559) for details.
 
 ## [1.31.1] - 2020-05-21
 ### Fixed

plugin-maven/src/main/java/com/diffplug/spotless/maven/FileLocator.java

@@ -39,12 +39,20 @@ public FileLocator(ResourceManager resourceManager, File baseDir, File buildDir)
 		this.buildDir = Objects.requireNonNull(buildDir);
 	}
 
-	/** Asserts that the given path is a file, then copies it with a new random name into the build folder. */
+	/**
+	 * If the given path is a local file returns it as such unchanged,
+	 * otherwise extracts the given resource to a randomly-named file in the build folder.
+	 */
 	public File locateFile(String path) {
 		if (isNullOrEmpty(path)) {
 			return null;
 		}
 
+		File localFile = new File(path);
+		if (localFile.exists() && localFile.isFile()) {
+			return localFile;
+		}
+
 		String outputFile = tmpOutputFileName(path);
 		try {
 			return resourceManager.getResourceAsFile(path, outputFile);
@@ -60,20 +68,6 @@ private static String tmpOutputFileName(String path) {
 		return TMP_RESOURCE_FILE_PREFIX + UUID.randomUUID() + '.' + extension;
 	}
 
-	/** Asserts that the given path exists as a file or folder. */
-	public File locateLocal(String path) {
-		if (isNullOrEmpty(path)) {
-			return null;
-		}
-
-		File exists = new File(path);
-		if (exists.exists()) {
-			return exists;
-		}
-
-		throw new RuntimeException("Unable to locate file with path: " + path);
-	}
-
 	public File getBaseDir() {
 		return baseDir;
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/generic/Prettier.java

@@ -61,12 +61,12 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 			}
 		}
 
-		File npm = npmExecutable != null ? stepConfig.getFileLocator().locateLocal(npmExecutable) : null;
+		File npm = npmExecutable != null ? stepConfig.getFileLocator().locateFile(npmExecutable) : null;
 
 		// process config file or inline config
 		File configFileHandler;
 		if (this.configFile != null) {
-			configFileHandler = stepConfig.getFileLocator().locateLocal(this.configFile);
+			configFileHandler = stepConfig.getFileLocator().locateFile(this.configFile);
 		} else {
 			configFileHandler = null;
 		}

plugin-maven/src/main/java/com/diffplug/spotless/maven/typescript/Tsfmt.java

@@ -70,7 +70,7 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 			devDependencies.put("tslint", tslintVersion);
 		}
 
-		File npm = npmExecutable != null ? stepConfig.getFileLocator().locateLocal(npmExecutable) : null;
+		File npm = npmExecutable != null ? stepConfig.getFileLocator().locateFile(npmExecutable) : null;
 
 		TypedTsFmtConfigFile configFile;
 		Map<String, Object> configInline;
@@ -84,13 +84,13 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 			}
 			configInline = null;
 			if (this.tsconfigFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSCONFIG, stepConfig.getFileLocator().locateLocal(tsconfigFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSCONFIG, stepConfig.getFileLocator().locateFile(tsconfigFile));
 			} else if (this.tsfmtFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSFMT, stepConfig.getFileLocator().locateLocal(tsfmtFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSFMT, stepConfig.getFileLocator().locateFile(tsfmtFile));
 			} else if (this.tslintFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSLINT, stepConfig.getFileLocator().locateLocal(tslintFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSLINT, stepConfig.getFileLocator().locateFile(tslintFile));
 			} else if (this.vscodeFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.VSCODE, stepConfig.getFileLocator().locateLocal(vscodeFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.VSCODE, stepConfig.getFileLocator().locateFile(vscodeFile));
 			} else {
 				throw new Error("Programming error: the xors did not match the cases");
 			}