Refactoring work to support multi-tenancy and multiple storage, database backends (#598)

* Backend infrastructure
* New backend configuration work
* Factor out KV prefixing
* Don't put assets in the manifest cache
* Removed fancy authentication stuff
* Documentation updates

plugos/lib/kv_primitives.ts

@@ -9,4 +9,48 @@ export interface KvPrimitives {
   batchSet(entries: KV[]): Promise<void>;
   batchDelete(keys: KvKey[]): Promise<void>;
   query(options: KvQueryOptions): AsyncIterableIterator<KV>;
+  close(): void;
+}
+
+/**
+ * Turns any KvPrimitives into a KvPrimitives that automatically prefixes all keys (and removes them again when reading)
+ */
+export class PrefixedKvPrimitives implements KvPrimitives {
+  constructor(private wrapped: KvPrimitives, private prefix: KvKey) {
+  }
+
+  batchGet(keys: KvKey[]): Promise<any[]> {
+    return this.wrapped.batchGet(keys.map((key) => this.applyPrefix(key)));
+  }
+
+  batchSet(entries: KV[]): Promise<void> {
+    return this.wrapped.batchSet(
+      entries.map(({ key, value }) => ({ key: this.applyPrefix(key), value })),
+    );
+  }
+
+  batchDelete(keys: KvKey[]): Promise<void> {
+    return this.wrapped.batchDelete(keys.map((key) => this.applyPrefix(key)));
+  }
+
+  async *query(options: KvQueryOptions): AsyncIterableIterator<KV> {
+    for await (
+      const result of this.wrapped.query({
+        prefix: this.applyPrefix(options.prefix),
+      })
+    ) {
+      yield { key: this.stripPrefix(result.key), value: result.value };
+    }
+  }
+  close(): void {
+    this.wrapped.close();
+  }
+
+  private applyPrefix(key?: KvKey): KvKey {
+    return [...this.prefix, ...(key ? key : [])];
+  }
+
+  private stripPrefix(key: KvKey): KvKey {
+    return key.slice(this.prefix.length);
+  }
 }