improvement: Retry with coursier jar if anything fails

packages/metals-languageclient/src/__tests__/setupCoursier.test.ts

@@ -50,7 +50,8 @@ describe("setupCoursier", () => {
       "17",
       tmpDir,
       process.cwd(),
-      new LogOutputChannel()
+      new LogOutputChannel(),
+      false
     );
     expect(fs.existsSync(coursier)).toBeTruthy;
     expect(fs.existsSync(javaHome)).toBeTruthy;

packages/metals-languageclient/src/setupCoursier.ts

@@ -19,7 +19,8 @@ export async function setupCoursier(
   javaVersion: JavaVersion,
   coursierFetchPath: string,
   extensionPath: string,
-  output: OutputChannel
+  output: OutputChannel,
+  forceCoursierJar: boolean
 ): Promise<{ coursier: string; javaHome: string }> {
   const handleOutput = (out: Buffer) => {
     const msg = out.toString().trim();
@@ -75,7 +76,12 @@ export async function setupCoursier(
     return ((await getJavaPath).stdout as string).trim();
   };
 
-  var coursier = await resolveCoursier();
+  var coursier: string | undefined;
+  if (forceCoursierJar) {
+    coursier = undefined;
+  } else {
+    coursier = await resolveCoursier();
+  }
   output.appendLine(`Using coursier located at ${coursier}`);
 
   var javaHome = await getJavaHome(javaVersion, output);

packages/metals-vscode/src/extension.ts

@@ -207,7 +207,8 @@
 async function fetchAndLaunchMetals(
   context: ExtensionContext,
   serverVersion: string,
-  javaVersion: JavaVersion
+  javaVersion: JavaVersion,
+  forceCoursierJar = false
 ) {
   outputChannel.appendLine(`Metals version: ${serverVersion}`);
 
@@ -228,9 +229,24 @@
     javaVersion,
     metalsDirPath,
     context.extensionPath,
-    outputChannel
+    outputChannel,
+    forceCoursierJar
   );
 
+  const canRetryWithJar =
+    javaHome && !coursier.endsWith(".jar") && !forceCoursierJar;
+
+  function retry(error: any): Promise<any> {
+    if (canRetryWithJar) {
+      outputChannel.appendLine(
+        "Trying again with the embedded coursier. This might take longer."
+      );
+      return fetchAndLaunchMetals(context, serverVersion, javaVersion, true);
+    } else {
+      return Promise.reject(error);
+    }
+  }
+
   const javaConfig = getJavaConfig({
     workspaceRoot: workspace.workspaceFolders
       ? workspace.workspaceFolders[0]?.uri.fsPath
@@ -262,15 +278,15 @@
           serverProperties,
           javaConfig,
           serverVersion
-        ).catch((reason) => {
+        ).catch((reason): Promise<any> => {
           outputChannel.appendLine(
             "Launching Metals failed with the following:"
           );
           outputChannel.appendLine(reason.message);
           outputChannel.appendLine(
             debugInformation(serverVersion, serverProperties, javaConfig)
           );
-          throw reason;
+          return retry(reason);
         });
       },
       (reason) => {
@@ -283,30 +299,34 @@
             debugInformation(serverVersion, serverProperties, javaConfig)
           );
         }
-        const msg = (() => {
-          const proxy =
-            `See https://scalameta.org/metals/docs/editors/vscode/#http-proxy for instructions ` +
-            `if you are using an HTTP proxy.`;
-          if (process.env.FLATPAK_SANDBOX_DIR) {
-            return (
-              `Failed to download Metals. It seems you are running Visual Studio Code inside the ` +
-              `Flatpak sandbox, which is known to interfere with the download of Metals. ` +
-              `Please, try running Visual Studio Code without Flatpak.`
-            );
-          } else {
-            return (
-              `Failed to download Metals, make sure you have an internet connection, ` +
-              `the Metals version '${serverVersion}'. ` +
-              proxy
-            );
-          }
-        })();
-        outputChannel.show();
-        window.showErrorMessage(msg, openSettingsAction).then((choice) => {
-          if (choice === openSettingsAction) {
-            commands.executeCommand(workbenchCommands.openSettings);
-          }
-        });
+        if (canRetryWithJar) {
+          return retry(reason);
+        } else {
+          const msg = (() => {
+            const proxy =
+              `See https://scalameta.org/metals/docs/editors/vscode/#http-proxy for instructions ` +
+              `if you are using an HTTP proxy.`;
+            if (process.env.FLATPAK_SANDBOX_DIR) {
+              return (
+                `Failed to download Metals. It seems you are running Visual Studio Code inside the ` +
+                `Flatpak sandbox, which is known to interfere with the download of Metals. ` +
+                `Please, try running Visual Studio Code without Flatpak.`
+              );
+            } else {
+              return (
+                `Failed to download Metals, make sure you have an internet connection, ` +
+                `the Metals version '${serverVersion}'. ` +
+                proxy
+              );
+            }
+          })();
+          outputChannel.show();
+          window.showErrorMessage(msg, openSettingsAction).then((choice) => {
+            if (choice === openSettingsAction) {
+              commands.executeCommand(workbenchCommands.openSettings);
+            }
+          });
+        }
       }
     );
 }