eclipse language server, handle directory corruption

customization-base/src/main/java/com/azure/autorest/customization/implementation/ls/EclipseLanguageServerFacade.java

@@ -8,8 +8,10 @@
 import org.apache.tools.tar.TarInputStream;
 import org.slf4j.Logger;
 
+import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.UncheckedIOException;
 import java.net.URI;
@@ -20,11 +22,12 @@
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.TimeUnit;
 import java.util.zip.GZIPInputStream;
 
 public class EclipseLanguageServerFacade {
     private static final String DOWNLOAD_BASE_URL
-        = "https://www.eclipse.org/downloads/download.php?file=/jdtls/milestones/";
+            = "https://www.eclipse.org/downloads/download.php?file=/jdtls/milestones/";
 
     private final Process server;
 
@@ -34,8 +37,8 @@ public EclipseLanguageServerFacade(String pathToLanguageServerPlugin, Logger log
             int javaVersion = Runtime.version().feature();
 
             Path languageServerPath = (pathToLanguageServerPlugin == null)
-                ? getLanguageServerDirectory(javaVersion, logger)
-                : Paths.get(pathToLanguageServerPlugin).resolve("jdt-language-server");
+                    ? getLanguageServerDirectory(javaVersion, logger, false)
+                    : Paths.get(pathToLanguageServerPlugin).resolve("jdt-language-server");
 
             List<String> command = new ArrayList<>();
             command.add("java");
@@ -72,18 +75,55 @@ public EclipseLanguageServerFacade(String pathToLanguageServerPlugin, Logger log
                 command.add("./config_linux");
             }
 
-            logger.info("Starting Eclipse JDT language server at {}", languageServerPath);
-            server = new ProcessBuilder(command).redirectOutput(ProcessBuilder.Redirect.PIPE)
+            Process server = startServer(command, languageServerPath, logger);
+            if (!server.isAlive()) {
+                if (pathToLanguageServerPlugin == null) {
+                    // If user didn't specify language server path, we do a clean re-download.
+                    logger
+                            .warn("Eclipse language server failed to start. The folder may be corrupted. Try re-download.");
+                    server = startServer(command, getLanguageServerDirectory(javaVersion, logger, true), logger);
+                    if (!server.isAlive()) {
+                        // if server failed to start anyway, throw with server output.
+                        throw new RuntimeException(String.format(
+                                "Eclipse language server failed to start, error output:\n %s", readServerOutput(server)));
+                    }
+                } else {
+                    // if user specify the language server path, we just throw with server output.
+                    throw new RuntimeException(String.format(
+                            "Eclipse language server failed to start, error output:\n %s", readServerOutput(server)));
+                }
+            }
+            this.server = server;
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private String readServerOutput(Process server) throws IOException {
+        if (server.getInputStream() == null) {
+            return null;
+        }
+        StringBuilder stringBuilder = new StringBuilder();
+        try (BufferedReader reader = new BufferedReader(new InputStreamReader(server.getInputStream()))) {
+            reader.lines().forEachOrdered(line -> stringBuilder.append(line).append("\n"));
+        }
+        return stringBuilder.toString();
+    }
+
+    private Process startServer(List<String> command, Path languageServerPath, Logger logger) throws Exception {
+        logger.info("Starting Eclipse JDT language server at {}", languageServerPath);
+        final Process server;
+        server = new ProcessBuilder(command).redirectOutput(ProcessBuilder.Redirect.PIPE)
                 .redirectInput(ProcessBuilder.Redirect.PIPE)
                 .redirectErrorStream(true)
                 .directory(languageServerPath.toFile())
                 .start();
-        } catch (Exception e) {
-            throw new RuntimeException(e);
-        }
+        server.waitFor(1, TimeUnit.SECONDS);
+        return server;
     }
 
-    private static Path getLanguageServerDirectory(int javaVersion, Logger logger) throws IOException {
+    private static Path getLanguageServerDirectory(int javaVersion, Logger logger, boolean forceReDownload)
+            throws IOException {
         Path tmp = Paths.get(System.getProperty("java.io.tmpdir"));
         Path autorestLanguageServer = tmp.resolve("autorest-java-language-server");
 
@@ -93,21 +133,24 @@ private static Path getLanguageServerDirectory(int javaVersion, Logger logger) t
             // Eclipse JDT language server version 1.12.0 is the last version that supports Java 11, which is
             // autorest.java's baseline.
             downloadUrl
-                = URI.create(DOWNLOAD_BASE_URL + "1.12.0/jdt-language-server-1.12.0-202206011637.tar.gz").toURL();
+                    = URI.create(DOWNLOAD_BASE_URL + "1.12.0/jdt-language-server-1.12.0-202206011637.tar.gz").toURL();
             languageServerPath = autorestLanguageServer.resolve("1.12.0");
         } else {
             // Eclipse JDT language server version 1.39.0 is the latest version that supports Java 17.
             // In the future this else statement may need to be replaced with an else if as newer versions of
             // Eclipse JDT language server may baseline on Java 21 (or later).
             downloadUrl
-                = URI.create(DOWNLOAD_BASE_URL + "1.39.0/jdt-language-server-1.39.0-202408291433.tar.gz").toURL();
+                    = URI.create(DOWNLOAD_BASE_URL + "1.39.0/jdt-language-server-1.39.0-202408291433.tar.gz").toURL();
             languageServerPath = autorestLanguageServer.resolve("1.39.0");
         }
 
         Path languageServer = languageServerPath.resolve("jdt-language-server");
-        if (!Files.exists(languageServerPath) || !Files.exists(languageServer)) {
-            Files.createDirectories(languageServerPath);
+
+        if (!Files.exists(languageServer) || forceReDownload) {
+            Files.createDirectories(languageServer);
             Path zipPath = languageServerPath.resolve("jdt-language-server.tar.gz");
+            Files.deleteIfExists(zipPath);
+
             logger.info("Downloading Eclipse JDT language server from {} to {}", downloadUrl, zipPath);
             try (InputStream in = downloadUrl.openStream()) {
                 Files.copy(in, zipPath);
@@ -123,13 +166,15 @@ private static Path getLanguageServerDirectory(int javaVersion, Logger logger) t
     private static Path unzipLanguageServer(Path zipPath) throws IOException {
         try (TarInputStream tar = new TarInputStream(new GZIPInputStream(Files.newInputStream(zipPath)))) {
             Path languageServerDirectory = zipPath.getParent().resolve("jdt-language-server");
-            Files.createDirectory(languageServerDirectory);
             TarEntry entry;
             while ((entry = tar.getNextEntry()) != null) {
                 if (entry.isDirectory()) {
                     Files.createDirectories(languageServerDirectory.resolve(entry.getName()));
                 } else {
-                    Files.copy(tar, languageServerDirectory.resolve(entry.getName()));
+                    Path entryPath = languageServerDirectory.resolve(entry.getName());
+                    // In case of corrupted folder, delete before create.
+                    Files.deleteIfExists(entryPath);
+                    Files.copy(tar, entryPath);
                 }
             }