Backporting a bunch of optimizations from db-only branch

web/syscalls/datastore.proxy.ts

@@ -1,15 +1,48 @@
+import { KvQuery } from "$sb/types.ts";
+import { LimitedMap } from "../../common/limited_map.ts";
 import type { SysCallMapping } from "../../plugos/system.ts";
 import type { Client } from "../client.ts";
-import { proxySyscalls } from "./util.ts";
+import { proxySyscall, proxySyscalls } from "./util.ts";
 
 export function dataStoreProxySyscalls(client: Client): SysCallMapping {
-  return proxySyscalls(client, [
+  const syscalls = proxySyscalls(client, [
     "datastore.delete",
     "datastore.set",
     "datastore.batchSet",
     "datastore.batchDelete",
     "datastore.batchGet",
     "datastore.get",
-    "datastore.query",
   ]);
+  // Add a cache for datastore.query
+  const queryCache = new LimitedMap<any>(5);
+  syscalls["datastore.query"] = async (ctx, query: KvQuery) => {
+    let cacheKey: string | undefined;
+    const cacheSecs = query.cacheSecs;
+    // Should we do caching?
+    if (cacheSecs) {
+      // Remove the cacheSecs from the query
+      query = { ...query, cacheSecs: undefined };
+      cacheKey = JSON.stringify(query);
+      const cachedResult = queryCache.get(cacheKey);
+      if (cachedResult) {
+        // Let's use the cached result
+        return cachedResult;
+      }
+    }
+
+    const result = await proxySyscall(
+      ctx,
+      client.httpSpacePrimitives,
+      "datastore.query",
+      [
+        query,
+      ],
+    );
+    if (cacheKey) {
+      // Store in the cache
+      queryCache.set(cacheKey, result, cacheSecs! * 1000);
+    }
+    return result;
+  };
+  return syscalls;
 }