feature/add-gradle-init

src/participation/cloning.service.ts

@@ -8,6 +8,8 @@ import * as path from "path";
 import { retrieveVcsAccessToken } from "../artemis/authentication.client";
 import { getWorkspaceFolder, theiaEnv } from "../theia/theia";
 import { addVcsTokenToUrl } from "@shared/models/participation.model";
+import { ProgrammingExercise, ProgrammingLanguage } from "@shared/models/exercise.model";
+import { warmupGradleDaemon } from "./gradle.service";
 
 export async function cloneUserRepo(repoUrl: string, username: string) {
   // get folder to clone repo into
@@ -48,6 +50,13 @@ export async function cloneUserRepo(repoUrl: string, username: string) {
   const cloneUrlWithToken = new URL(addVcsTokenToUrl(repoUrl, username, vcsToken));
   const clonePath = await cloneByGivenURL(cloneUrlWithToken, destinationPath);
 
+  // Pre-warm Gradle in the background so the student's first build is faster.
+  // The depth (off/daemon/deps/full) is controlled by the GRADLE_PREWARM env var.
+  const exercise = getState().displayedExercise;
+  if ((exercise as ProgrammingExercise)?.programmingLanguage === ProgrammingLanguage.JAVA) {
+    warmupGradleDaemon(clonePath, theiaEnv.GRADLE_PREWARM);
+  }
+
   if (!theiaEnv.THEIA_FLAG) {
     // Prompt the user to open the cloned folder in a new workspace
     const openIn = await vscode.window.showInformationMessage(

src/participation/gradle.service.ts

@@ -0,0 +1,59 @@
+import { spawn } from "child_process";
+import * as fs from "fs";
+import * as path from "path";
+import { GradlePrewarmLevel } from "../theia/env-strategy";
+
+/**
+ * Gradle invocation per prewarm level. Each higher level warms one more phase of
+ * the student's first build during session startup (see the prewarming levels L1-L4):
+ *  - "daemon" (L1): start the Gradle daemon so it is warm and reused.
+ *  - "deps"   (L3): additionally configure the build and resolve/download dependencies.
+ *  - "full"   (L4): additionally compile, leaving the first build near-instant.
+ * "off" disables prewarming and is handled before this map is used.
+ */
+const PREWARM_ARGS: Record<Exclude<GradlePrewarmLevel, "off">, string[]> = {
+  daemon: ["--daemon", "help"],
+  deps: ["--daemon", "dependencies"],
+  full: ["--daemon", "build", "-x", "test"],
+};
+
+/**
+ * Pre-warms the Gradle build in the background after cloning a repository, so the
+ * student's first build can skip the phases warmed here. Runs detached and never
+ * blocks the caller.
+ *
+ * Silently skips if:
+ * - Prewarming is disabled (`level` is "off")
+ * - Running on Windows (not a supported environment)
+ * - The project does not contain a `gradlew` file (not a Gradle project)
+ */
+export function warmupGradleDaemon(
+  projectPath: string,
+  level: GradlePrewarmLevel = "daemon",
+): void {
+  if (level === "off" || process.platform === "win32") {
+    return;
+  }
+
+  const gradlewPath = path.join(projectPath, "gradlew");
+  if (!fs.existsSync(gradlewPath)) {
+    return;
+  }
+
+  try {
+    fs.chmodSync(gradlewPath, 0o755);
+
+    const child = spawn("./gradlew", PREWARM_ARGS[level], {
+      cwd: projectPath,
+      detached: true,
+      stdio: "ignore",
+    });
+    // Detached failures surface asynchronously via the 'error' event, not the throw below.
+    child.on("error", (error) => {
+      console.warn(`Gradle prewarm (${level}) failed to start: ${error.message}`);
+    });
+    child.unref();
+  } catch (error: any) {
+    console.warn(`Gradle prewarm (${level}) failed: ${error.message}`);
+  }
+}

src/theia/env-strategy.ts

@@ -1,13 +1,24 @@
 import * as vscode from "vscode";
 import { exec } from "child_process";
 
+/**
+ * Controls how much of the first Gradle build is warmed up in the background at
+ * session startup (see the prewarming levels L1-L4):
+ *  - "off":    no prewarming.
+ *  - "daemon": start the Gradle daemon so it is warm and reused (L1).
+ *  - "deps":   also configure the build and resolve/download dependencies (L3).
+ *  - "full":   also compile, leaving the student's first build near-instant (L4).
+ */
+export type GradlePrewarmLevel = "off" | "daemon" | "deps" | "full";
+
 export type TheiaEnv = {
   THEIA_FLAG: boolean;
   ARTEMIS_TOKEN: string | undefined;
   ARTEMIS_URL: string | undefined;
   GIT_URI: URL | undefined;
   GIT_USER: string | undefined;
   GIT_MAIL: string | undefined;
+  GRADLE_PREWARM: GradlePrewarmLevel;
 };
 
 const ENV_KEYS = [
@@ -17,8 +28,28 @@ const ENV_KEYS = [
   "GIT_URI",
   "GIT_USER",
   "GIT_MAIL",
+  "GRADLE_PREWARM",
 ] as const satisfies Array<string>;
 
+/**
+ * Default prewarm level when the environment variable is unset. Warming the
+ * daemon is cheap and benefits every Gradle session, so it is the safe default.
+ */
+export const DEFAULT_GRADLE_PREWARM: GradlePrewarmLevel = "daemon";
+
+function parseGradlePrewarm(value: string | undefined): GradlePrewarmLevel {
+  const level = value?.trim().toLowerCase();
+  if (level === "off" || level === "daemon" || level === "deps" || level === "full") {
+    return level;
+  }
+  if (level) {
+    console.warn(
+      `Unknown GRADLE_PREWARM value "${value}", falling back to "${DEFAULT_GRADLE_PREWARM}"`,
+    );
+  }
+  return DEFAULT_GRADLE_PREWARM;
+}
+
 export interface TheiaEnvStrategy {
   load(): Promise<TheiaEnv>;
 }
@@ -32,6 +63,7 @@ function parseTheiaEnv(env: Record<string, string | undefined>): TheiaEnv {
     GIT_URI: gitUriString ? new URL(gitUriString) : undefined,
     GIT_USER: env["GIT_USER"],
     GIT_MAIL: env["GIT_MAIL"],
+    GRADLE_PREWARM: parseGradlePrewarm(env["GRADLE_PREWARM"]),
   };
 }
 

src/theia/theia.ts

@@ -2,7 +2,7 @@ import * as vscode from "vscode";
 import simpleGit, { GitConfigScope } from "simple-git";
 import { hostname } from "os";
 import { cloneByGivenURL } from "../participation/cloning.service";
-import { createTheiaEnvStrategy, TheiaEnv } from "./env-strategy";
+import { createTheiaEnvStrategy, DEFAULT_GRADLE_PREWARM, TheiaEnv } from "./env-strategy";
 
 // Mutable theiaEnv that gets populated after loading
 export let theiaEnv: TheiaEnv = {
@@ -12,6 +12,7 @@ export let theiaEnv: TheiaEnv = {
   GIT_URI: undefined,
   GIT_USER: undefined,
   GIT_MAIL: undefined,
+  GRADLE_PREWARM: DEFAULT_GRADLE_PREWARM,
 };
 
 /**