cache result of getVersions

This enables zig.install to work even if ziglang.org is down.

Author: Vexu

src/zigSetup.ts

@@ -71,35 +71,18 @@ async function findClosestSatisfyingZigVersion(
     version: semver.SemVer,
 ): Promise<semver.SemVer> {
     if (version.prerelease.length !== 0) return version;
-    const cacheKey = `zig-satisfying-version-${version.raw}`;
 
-    try {
-        // We can't just return `version` because `0.12.0` should return `0.12.1`.
-        const availableVersions = (await getVersions()).map((item) => item.version);
-        const selectedVersion = semver.maxSatisfying(availableVersions, `^${version.toString()}`);
-        await context.globalState.update(cacheKey, selectedVersion ? selectedVersion.raw : undefined);
-        return selectedVersion ?? version;
-    } catch {
-        const selectedVersion = context.globalState.get<string | null>(cacheKey, null);
-        return selectedVersion ? new semver.SemVer(selectedVersion) : version;
-    }
+    // We can't just return `version` because `0.12.0` should return `0.12.1`.
+    const availableVersions = (await getVersions(context)).map((item) => item.version);
+    const selectedVersion = semver.maxSatisfying(availableVersions, `^${version.toString()}`);
+    return selectedVersion ?? version;
 }
 
 async function getLatestTaggedZigVersion(context: vscode.ExtensionContext): Promise<semver.SemVer | null> {
-    const cacheKey = "zig-latest-tagged";
-    try {
-        const zigVersion = await getVersions();
-        const latestTagged = zigVersion.find((item) => item.version.prerelease.length === 0);
-        const result = latestTagged?.version ?? null;
-        await context.globalState.update(cacheKey, latestTagged?.version.raw);
-        return result;
-    } catch {
-        const latestTagged = context.globalState.get<string | null>(cacheKey, null);
-        if (latestTagged) {
-            return new semver.SemVer(latestTagged);
-        }
-        return null;
-    }
+    const zigVersion = await getVersions(context);
+    const latestTagged = zigVersion.find((item) => item.version.prerelease.length === 0);
+    const result = latestTagged?.version ?? null;
+    return result;
 }
 
 /**
@@ -108,13 +91,29 @@ async function getLatestTaggedZigVersion(context: vscode.ExtensionContext): Prom
  *
  * Throws an exception when no network connection is available.
  */
-async function getVersions(): Promise<zigUtil.ZigVersion[]> {
-    const [zigIndexJson, machIndexJson] = await Promise.all(
-        ["https://ziglang.org/download/index.json", "https://pkg.machengine.org/zig/index.json"].map(async (url) => {
-            const response = await fetch(url);
-            return response.json() as Promise<zigUtil.VersionIndex>;
-        }),
-    );
+async function getVersions(context: vscode.ExtensionContext): Promise<zigUtil.ZigVersion[]> {
+    const cacheKey = "zig-versions-list";
+    let zigIndexJson, machIndexJson;
+    try {
+        [zigIndexJson, machIndexJson] = await Promise.all(
+            ["https://ziglang.org/download/index.json", "https://pkg.machengine.org/zig/index.json"].map(
+                async (url) => {
+                    const response = await fetch(url);
+                    return response.json() as Promise<zigUtil.VersionIndex>;
+                },
+            ),
+        );
+    } catch (error) {
+        const cached = context.globalState.get<zigUtil.ZigVersion[]>(cacheKey);
+        if (cached !== undefined) {
+            for (const version of cached) {
+                // Must be instanceof SemVer
+                version.version = new semver.SemVer(version.version.raw);
+            }
+            return cached;
+        }
+        throw error;
+    }
     const indexJson = { ...machIndexJson, ...zigIndexJson };
 
     const result: zigUtil.ZigVersion[] = [];
@@ -140,6 +139,7 @@ async function getVersions(): Promise<zigUtil.ZigVersion[]> {
         );
     }
     sortVersions(result);
+    await context.globalState.update(cacheKey, result);
     return result;
 }
 
@@ -182,7 +182,7 @@ async function selectVersionAndInstall(context: vscode.ExtensionContext) {
     }));
 
     try {
-        const onlineVersions = await getVersions();
+        const onlineVersions = await getVersions(context);
         outer: for (const onlineVersion of onlineVersions) {
             for (const version of versions) {
                 if (semver.eq(version.version, onlineVersion.version)) {
@@ -591,7 +591,7 @@ async function getMirrors(context: vscode.ExtensionContext): Promise<vscode.Uri[
                 timestamp: new Date().getTime(),
                 mirrors: mirrorList,
             };
-            context.globalState.update(key, cached);
+            await context.globalState.update(key, cached);
         } catch {
             // Cannot fetch mirrors, rely on cache.
         }