Fix redis race condition

apps/api/src/server.ts

@@ -126,22 +126,19 @@ export const app = new Elysia()
             .group("/sync", (app) =>
                 app
                     // Sync status
-                    .get("/", async ({ }) => await productSyncer.getState())
+                    .get("/", async ({ }) => ({
+                        state: await productSyncer.getState(),
+                        isRunning: await productSyncer.isRunning()
+                    }))
                     // Full sync
                     .post("/", async ({ }) => {
-                        const syncState = await productSyncer.getState();
+                        if (!await productSyncer.sync())
-                        if (syncState.isSyncing)
                             throw status(409, "Sync already in progress");
-
-                        await productSyncer.sync();
                     })
                     // Per-product sync
                     .post("/:printfulProductId", async ({ params }) => {
-                        const syncState = await productSyncer.getState();
+                        if (!await productSyncer.sync(params.printfulProductId))
-                        if (syncState.isSyncing)
                             throw status(409, "Sync already in progress");
-
-                        await productSyncer.sync(params.printfulProductId);
                     }, { params: z.object({ printfulProductId: z.coerce.number() }) }),
             )
             .get("/:printfulProductId", async ({ params }) => {

apps/portal/src/routes/commerce/+page.svelte

@@ -6,21 +6,22 @@
     const { data } = $props();
 
     const synchronizer = $state({
-        isSyncing: false,
+        isRunning: false,
-        syncingIds: [] as number[],
+        printfulProductIds: [] as number[],
         poll: async function () {
             const res = (await (
                 await fetch(`${PUBLIC_API_URL}/products/sync`)
             ).json()) as any;
             if (res.data) {
-                synchronizer.isSyncing = res.data.isSyncing;
+                synchronizer.isRunning = res.data.isRunning;
-                synchronizer.syncingIds = res.data.syncingIds;
+                synchronizer.printfulProductIds =
+                    res.data.state.printfulProductIds;
             }
         },
         startPolling: () => {
             const intervalId = setInterval(async () => {
                 await synchronizer.poll();
-                if (!synchronizer.isSyncing) clearInterval(intervalId);
+                if (!synchronizer.isRunning) clearInterval(intervalId);
             }, 100);
         },
         syncAll: async () => {
@@ -40,7 +41,7 @@
 
     onMount(async () => {
         await synchronizer.poll();
-        if (synchronizer.isSyncing) {
+        if (synchronizer.isRunning) {
             synchronizer.startPolling();
         }
     });
@@ -59,11 +60,11 @@
     <p>Loading...</p>
 {:then printfulProducts}
     <button
-        disabled={synchronizer.isSyncing}
+        disabled={synchronizer.isRunning}
         onclick={() => synchronizer.syncAll()}
         class="btn btn-xl mb-5"
     >
-        {#if synchronizer.isSyncing}
+        {#if synchronizer.isRunning}
             Syncing...
         {:else}
             Sync all
@@ -98,7 +99,7 @@
                         >
                         <td>
                             {#await isProductSynced(printfulProduct) then isSynced}
-                                {#if synchronizer.syncingIds.includes(printfulProduct.id)}
+                                {#if synchronizer.printfulProductIds.includes(printfulProduct.id)}
                                     <div class="badge badge-warning">
                                         Syncing...
                                     </div>
@@ -115,7 +116,7 @@
                         </td>
                         <td>
                             <button
-                                disabled={synchronizer.isSyncing}
+                                disabled={synchronizer.isRunning}
                                 onclick={() =>
                                     synchronizer.sync(printfulProduct.id)}
                                 class="btn"

packages/commerce/src/sync.ts

@@ -7,7 +7,7 @@ import pino from "pino";
 
 const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
 
-type MainProduct = {
+type MetaPrintfulProduct = {
     name: string;
     externalId: string;
     colors: Set<string>;
@@ -18,8 +18,7 @@ type MainProduct = {
 };
 
 type SyncState = {
-    isSyncing: boolean;
+    printfulProductIds: number[];
-    syncingIds: number[];
 };
 
 export class ProductSyncer {
@@ -33,14 +32,15 @@ export class ProductSyncer {
         this.log = (log ?? pino({ level: "silent" })).child({ component: "ProductSyncer" });
     }
 
-    async sync(printfulProductId?: number) {
+    async sync(printfulProductId?: number): Promise<boolean> {
-        const syncStart = Date.now();
+        const canRun = await this.run();
+        if (!canRun) return false;
+
         try {
+            const syncStart = Date.now();
             if (printfulProductId) this.log.info({ printfulProductId }, "sync started");
             else this.log.info("sync started");
 
-            await this.setState({ isSyncing: true, syncingIds: [] });
-
             this.log.debug("populating webflow products");
             const webflowProducts: Webflow.Products.ProductAndSkus[] = await this.webflow.Products.list({ forceAll: true });
 
@@ -59,7 +59,7 @@ export class ProductSyncer {
             }
 
             this.log.info({ count: printfulProducts.length }, "generating meta printful products");
-            const metaPrintfulProducts: MainProduct[] = [];
+            const metaPrintfulProducts: MetaPrintfulProduct[] = [];
             for (const printfulProduct of printfulProducts) {
                 const mainProductName = this.getMainProductName(
                     printfulProduct.name,
@@ -93,8 +93,7 @@ export class ProductSyncer {
             for (const metaPrintfulProduct of metaPrintfulProducts) {
                 this.log.info({ name: metaPrintfulProduct.name }, "syncing meta printful product");
                 await this.setState({
-                    isSyncing: true,
+                    printfulProductIds: metaPrintfulProduct.variants.map(
-                    syncingIds: metaPrintfulProduct.variants.map(
                         (v) => v.product.sync_product.id,
                     ),
                 });
@@ -291,22 +290,13 @@ export class ProductSyncer {
             this.log.info({ durationMs: Date.now() - syncStart }, "sync complete");
         } finally {
             try {
-                await this.setState({ isSyncing: false, syncingIds: [] });
+                await redis.del("commerce:sync:lock");
+                await redis.del("commerce:sync:state");
             } catch {
                 this.log.error("failed to reset sync state");
             }
         }
-    }
+        return true;
-
-    async setState(state: SyncState) {
-        await redis.set("commerce:sync:state", JSON.stringify(state));
-        await redis.expire("commerce:sync:state", 1800);
-    }
-
-    async getState(): Promise<SyncState> {
-        const val = await redis.get("commerce:sync:state");
-        if (val) return JSON.parse(val);
-        return { isSyncing: false, syncingIds: [] };
     }
 
     findColorInProductName(productName: string): string {
@@ -322,4 +312,22 @@ export class ProductSyncer {
             return productName;
         }
     }
+
+    async isRunning(): Promise<boolean> {
+        return !!await redis.get("commerce:sync:lock");
+    }
+
+    async getState(): Promise<SyncState> {
+        const val = await redis.get("commerce:sync:state");
+        if (val) return JSON.parse(val);
+        return { printfulProductIds: [] };
+    }
+
+    private async setState(state: SyncState) {
+        await redis.set("commerce:sync:state", JSON.stringify(state), "EX", 1800);
+    }
+
+    private async run(): Promise<boolean> {
+        return !!await redis.set("commerce:sync:lock", "1", "NX", "EX", "1800");
+    }
 }