cache snapshot response

Author: seanlim

package.json

@@ -40,6 +40,7 @@
     "form-data": "^4.0.0",
     "is-uuid": "^1.0.2",
     "knex": "^0.95.4",
+    "memory-cache": "^0.2.0",
     "moment-timezone": "^0.5.33",
     "node-telegram-bot-api": "^0.53.0",
     "pg": "^8.6.0",

src/api/handlers/snapshots.ts

@@ -1,14 +1,27 @@
 import getLatestSnapshot from "../../db/queries/getLatestSnapshot";
 import type { Context } from "../context";
 import type { Handler } from "./types";
+import cache from "memory-cache";
 
 export const get: Handler = (ctx: Context) => async (req, res) => {
   const { id } = req.params;
+  let snapshot;
 
-  const snapshot =
-    id === "latest"
-      ? await getLatestSnapshot(ctx.db)
-      : await ctx.db("snapshots").where({ id }).first();
+  const cached = cache.get(id);
+
+  if (cached !== null) {
+    snapshot = cached;
+  } else {
+    snapshot =
+      id === "latest"
+        ? await getLatestSnapshot(ctx.db)
+        : await ctx.db("snapshots").where({ id }).first();
+
+    cache.put(id, snapshot, 120000, () => {
+      // purge after 2 minutes
+      cache.clear();
+    });
+  }
 
   res.json({
     data: snapshot,

yarn.lock

@@ -2042,6 +2042,11 @@ [email protected]:
   resolved "https://registry.yarnpkg.com/media-typer/-/media-typer-0.3.0.tgz#8710d7af0aa626f8fffa1ce00168545263255748"
   integrity sha1-hxDXrwqmJvj/+hzgAWhUUmMlV0g=
 
+memory-cache@^0.2.0:
+  version "0.2.0"
+  resolved "https://registry.yarnpkg.com/memory-cache/-/memory-cache-0.2.0.tgz#7890b01d52c00c8ebc9d533e1f8eb17e3034871a"
+  integrity sha1-eJCwHVLADI68nVM+H46xfjA0hxo=
+
 [email protected]:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/merge-descriptors/-/merge-descriptors-1.0.1.tgz#b00aaa556dd8b44568150ec9d1b953f3f90cbb61"