1162: add unique suffix reflecting package.json content

Author: simschla

lib/src/main/java/com/diffplug/spotless/npm/NodeServerLayout.java

@@ -29,8 +29,8 @@ class NodeServerLayout {
 	private final File serveJsFile;
 	private final File npmrcFile;
 
-	NodeServerLayout(File buildDir, String stepName) {
-		this.nodeModulesDir = new File(buildDir, "spotless-node-modules-" + stepName);
+	NodeServerLayout(File buildDir, String stepName, String stepSuffix) {
+		this.nodeModulesDir = new File(buildDir, String.format("spotless-node-modules-%s-%s", stepName, stepSuffix));
 		this.packageJsonFile = new File(nodeModulesDir, "package.json");
 		this.serveJsFile = new File(nodeModulesDir, "serve.js");
 		this.npmrcFile = new File(nodeModulesDir, ".npmrc");

lib/src/main/java/com/diffplug/spotless/npm/NpmFormatterStepStateBase.java

@@ -56,7 +56,14 @@ protected NpmFormatterStepStateBase(String stepName, NpmConfig npmConfig, NpmFor
 		this.stepName = requireNonNull(stepName);
 		this.npmConfig = requireNonNull(npmConfig);
 		this.locations = locations;
-		this.nodeServerLayout = new NodeServerLayout(locations.buildDir(), stepName);
+		String stateSuffix = stateSuffix();
+		logger.info("Creating {} with name {} and state suffix {}", this.getClass().getSimpleName(), stepName, stateSuffix);
+		this.nodeServerLayout = new NodeServerLayout(locations.buildDir(), stepName, stateSuffix);
+	}
+
+	protected String stateSuffix() {
+		String packageJsonContent = npmConfig.getPackageJsonContent();
+		return NpmResourceHelper.md5(packageJsonContent);
 	}
 
 	protected void prepareNodeServerLayout() throws IOException {

lib/src/main/java/com/diffplug/spotless/npm/NpmResourceHelper.java

@@ -21,6 +21,7 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.StandardCopyOption;
+import java.security.MessageDigest;
 import java.time.Duration;
 import java.util.Arrays;
 import java.util.Objects;
@@ -122,4 +123,20 @@ static File copyFileToDirAtSubpath(File file, File targetDir, String relativePat
 			throw ThrowingEx.asRuntime(e);
 		}
 	}
+
+	static String md5(File file) {
+		return md5(readUtf8StringFromFile(file));
+	}
+
+	static String md5(String fileContent) {
+		MessageDigest md = ThrowingEx.get(() -> MessageDigest.getInstance("MD5"));
+		md.update(fileContent.getBytes(StandardCharsets.UTF_8));
+		byte[] digest = md.digest();
+		// convert byte array digest to hex string
+		StringBuilder sb = new StringBuilder();
+		for (byte b : digest) {
+			sb.append(String.format("%02x", b & 0xff));
+		}
+		return sb.toString();
+	}
 }