feat: implement maxDepth for azure-storage-blob

Implements native `maxDepth` for the `azure-storage-blob` driver by
using hierarchical fetches.

src/drivers/azure-storage-blob.ts

@@ -36,6 +36,47 @@ export interface AzureStorageBlobOptions {
 
 const DRIVER_NAME = "azure-storage-blob";
 
+async function getKeysByDepth(
+  client: ContainerClient,
+  maxDepth: number
+): Promise<string[]> {
+  const queue: Array<{ depth: number; name: string }> = [];
+  let current: { depth: number; name: string } | undefined = {
+    name: "",
+    depth: 0,
+  };
+  const keys: string[] = [];
+
+  do {
+    const iterator = client
+      .listBlobsByHierarchy(":", {
+        prefix: current.name,
+      })
+      .byPage({ maxPageSize: 1000 });
+
+    for await (const result of iterator) {
+      const { blobPrefixes, blobItems } = result.segment;
+
+      if (blobPrefixes && current.depth < maxDepth) {
+        for (const childPrefix of blobPrefixes) {
+          queue.push({
+            name: childPrefix.name,
+            depth: current.depth + 1,
+          });
+        }
+      }
+
+      for (const item of blobItems) {
+        keys.push(item.name);
+      }
+    }
+
+    current = queue.pop();
+  } while (current !== undefined);
+
+  return keys;
+}
+
 export default defineDriver((opts: AzureStorageBlobOptions) => {
   let containerClient: ContainerClient;
   const getContainerClient = () => {
@@ -81,6 +122,9 @@ export default defineDriver((opts: AzureStorageBlobOptions) => {
   return {
     name: DRIVER_NAME,
     options: opts,
+    flags: {
+      maxDepth: true,
+    },
     getInstance: getContainerClient,
     async hasItem(key) {
       return await getContainerClient().getBlockBlobClient(key).exists();
@@ -108,7 +152,11 @@ export default defineDriver((opts: AzureStorageBlobOptions) => {
     async removeItem(key) {
       await getContainerClient().getBlockBlobClient(key).delete();
     },
-    async getKeys() {
+    async getKeys(_base, opts) {
+      if (opts?.maxDepth !== undefined) {
+        return getKeysByDepth(getContainerClient(), opts.maxDepth);
+      }
+
       const iterator = getContainerClient()
         .listBlobsFlat()
         .byPage({ maxPageSize: 1000 });

test/drivers/azure-storage-blob.test.ts

@@ -1,8 +1,17 @@
-import { describe, beforeAll, afterAll } from "vitest";
+import {
+  describe,
+  beforeAll,
+  afterAll,
+  it,
+  expect,
+  vi,
+  afterEach,
+} from "vitest";
 import driver from "../../src/drivers/azure-storage-blob";
 import { testDriver } from "./utils";
 import { BlobServiceClient } from "@azure/storage-blob";
 import { ChildProcess, exec } from "node:child_process";
+import { ContainerClient } from "@azure/storage-blob";
 
 describe.skip("drivers: azure-storage-blob", () => {
   let azuriteProcess: ChildProcess;
@@ -17,10 +26,65 @@ describe.skip("drivers: azure-storage-blob", () => {
   afterAll(() => {
     azuriteProcess.kill(9);
   });
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
   testDriver({
     driver: driver({
       connectionString: "UseDevelopmentStorage=true",
       accountName: "local",
     }),
+    additionalTests(ctx) {
+      it("natively supports depth in getKeys", async () => {
+        const spy = vi.spyOn(ContainerClient.prototype, "listBlobsByHierarchy");
+
+        await ctx.storage.setItem("depth-test/key0", "boop");
+        await ctx.storage.setItem("depth-test/depth0/key1", "boop");
+        await ctx.storage.setItem("depth-test/depth0/depth1/key2", "boop");
+        await ctx.storage.setItem("depth-test/depth0/depth1/key3", "boop");
+
+        expect(
+          (
+            await ctx.driver.getKeys('', {
+              maxDepth: 1,
+            })
+          ).sort()
+        ).toMatchObject(["depth-test:key0"]);
+
+        // assert that the underlying blob storage was only called upto 1 depth
+        // to confirm the native filtering was used
+        expect(spy).toHaveBeenCalledTimes(2);
+        expect(spy).toHaveBeenCalledWith(":", {
+          // azure actually mutates `options` and sets `prefix` to
+          // `undefined` even though we pass it in as `""`. it seems this
+          // assertion works by reference, so we see the mutated value
+          prefix: undefined,
+        });
+        expect(spy).toHaveBeenCalledWith(":", {
+          prefix: "depth-test:",
+        });
+
+        spy.mockClear();
+
+        expect(
+          (
+            await ctx.driver.getKeys('', {
+              maxDepth: 2,
+            })
+          ).sort()
+        ).toMatchObject(["depth-test:depth0:key1", "depth-test:key0"]);
+
+        expect(spy).toHaveBeenCalledTimes(3);
+        expect(spy).toHaveBeenCalledWith(":", {
+          prefix: undefined,
+        });
+        expect(spy).toHaveBeenCalledWith(":", {
+          prefix: "depth-test:",
+        });
+        expect(spy).toHaveBeenCalledWith(":", {
+          prefix: "depth-test:depth0:",
+        });
+      });
+    },
   });
 });

test/drivers/utils.ts

@@ -196,6 +196,7 @@ export function testDriver(opts: TestOptions) {
   }
 
   it("removeItem", async () => {
+    await ctx.storage.setItem("s1:a", "test_data");
     await ctx.storage.removeItem("s1:a", false);
     expect(await ctx.storage.hasItem("s1:a")).toBe(false);
     expect(await ctx.storage.getItem("s1:a")).toBe(null);