optimize: add image cache

packages/widgets-core/src/datasource/api.ts

@@ -27,6 +27,11 @@ export default async function executeApiDatasource (config: ApiDatasourceConfig,
     throw new HttpRequestError(response, await response.json());
   }
 
+  if (!ctx.httpResponses) {
+    ctx.httpResponses = [];
+  }
+  ctx.httpResponses.push(response);
+
   const data = await response.json();
 
   return jp.query(data, config.parser.extract);

packages/widgets-types/index.d.ts

@@ -6,6 +6,10 @@ export interface WidgetBaseContext<P extends Record<string, any> = Record<string
   parameters: P;
 
   getTimeParams (): { zone: string, period: string };
+
+  // For collect response info to calculate cache
+  // See: https://github.com/pingcap/ossinsight-next/issues/47
+  httpResponses?: Response[];
 }
 
 export interface LinkedDataContext {

web/app/widgets/[vendor]/[name]/thumbnail.png/route.ts

@@ -1,3 +1,4 @@
+import { computeExpired } from '@/app/widgets/[vendor]/[name]/thumbnail.png/utils';
 import config from '@/site.config';
 import { apiEvent, autoParams, serverSendGaMeasurementEvent } from '@/utils/ga';
 import { resolveImageSizeConfig } from '@/utils/siteConfig';
@@ -56,7 +57,11 @@ export async function GET (request: NextRequest, { params: { vendor, name: param
     ...autoParams('widget_param_', parameters),
   }, request)]);
 
-  const data = await datasource(createWidgetBaseContext('server', parameters));
+  const ctx = createWidgetBaseContext('server', parameters);
+  const data = await datasource(ctx);
+  const expires = computeExpired(ctx)
+    // If no expires header exists in request context, set the cache to 3 minutes
+    ?? new Date(Date.now() + 1000 * 60 * 3);
 
   const colorScheme = request.nextUrl.searchParams.get('color_scheme') ?? 'dark';
 
@@ -121,9 +126,12 @@ export async function GET (request: NextRequest, { params: { vendor, name: param
   return new NextResponse(canvas.toBuffer('image/png'), {
     headers: {
       'Content-Type': 'image/png',
+      ...(expires && {
+        'Expires': expires.toUTCString(),
+        'Cache-Control': 'public',
+      }),
     },
   });
 }
 
 export const dynamic = 'force-dynamic';
-export const fetchCache = 'force-cache';

web/app/widgets/[vendor]/[name]/thumbnail.png/utils.ts

@@ -0,0 +1,30 @@
+import { WidgetBaseContext } from '@ossinsight/widgets-types';
+
+const DAYS = 1000 * 60 * 60 * 24;
+
+/**
+ * Get `Expires` fields from all responses. If any response was empty, returns null.
+ * @param ctx
+ * @param maxDays set the max expires days.
+ */
+export function computeExpired (ctx: WidgetBaseContext, maxDays = 1) {
+  if (ctx.httpResponses?.length === 0) {
+    return null;
+  }
+
+  return ctx.httpResponses?.reduce((date: Date | null, response) => {
+    const e = response.headers.get('Expires');
+    if (e) {
+      const newDate = new Date(e);
+      if (date) {
+        if (newDate < date) {
+          return newDate;
+        } else {
+          return date;
+        }
+      }
+      return null;
+    }
+    return null;
+  }, new Date(Date.now() + maxDays * DAYS));
+}