Version counters

.changeset/grumpy-penguins-lick.md

@@ -0,0 +1,6 @@
+---
+"@zarrita/storage": patch
+"@zarrita/core": patch
+---
+
+Use a counter to prioritize v2/v3 when opening.

packages/core/src/open.ts

@@ -13,6 +13,25 @@ import {
 	v2_to_v3_group_metadata,
 } from "./util.js";
 
+function create_version_counter() {
+	let version_counts = new WeakMap<Readable, { v2: number; v3: number }>();
+	function get_counts(store: Readable) {
+		let counts = version_counts.get(store) ?? { v2: 0, v3: 0 };
+		version_counts.set(store, counts);
+		return counts;
+	}
+	return {
+		increment(store: Readable, version: "v2" | "v3") {
+			get_counts(store)[version] += 1;
+		},
+		version_max(store: Readable): "v2" | "v3" {
+			let counts = get_counts(store);
+			return counts.v3 > counts.v2 ? "v3" : "v2";
+		},
+	};
+}
+let VERSION_COUNTER = create_version_counter();
+
 async function load_attrs(
 	location: Location<Readable>,
 ): Promise<Attributes> {
@@ -43,6 +62,7 @@ async function open_v2<Store extends Readable>(
 	let loc = "store" in location ? location : new Location(location);
 	let attrs = {};
 	if (options.attrs ?? true) attrs = await load_attrs(loc);
+	VERSION_COUNTER.increment(loc.store, "v2");
 	if (options.kind === "array") return open_array_v2(loc, attrs);
 	if (options.kind === "group") return open_group_v2(loc, attrs);
 	return open_array_v2(loc, attrs).catch((err) => {
@@ -130,6 +150,7 @@ async function open_v3<Store extends Readable>(
 ): Promise<Array<DataType, Store> | Group<Store>> {
 	let loc = "store" in location ? location : new Location(location);
 	let node = await _open_v3(loc);
+	VERSION_COUNTER.increment(loc.store, "v3");
 	if (options.kind === undefined) return node;
 	if (options.kind === "array" && node instanceof Array) return node;
 	if (options.kind === "group" && node instanceof Group) return node;
@@ -159,9 +180,16 @@ export async function open<Store extends Readable>(
 	location: Location<Store> | Store,
 	options: { kind?: "array" | "group" } = {},
 ): Promise<Array<DataType, Store> | Group<Store>> {
-	return open_v3(location, options as any).catch((err) => {
+	const store = "store" in location ? location.store : location;
+	const version_max = VERSION_COUNTER.version_max(store);
+	// Use the open function for the version with the most successful opens.
+	// Note that here we use the dot syntax to access the open functions
+	// because this enables us to use vi.spyOn during testing.
+	let open_primary = version_max === "v2" ? open.v2 : open.v3;
+	let open_secondary = version_max === "v2" ? open.v3 : open.v2;
+	return open_primary(location, options as any).catch((err) => {
 		if (err instanceof NodeNotFoundError) {
-			return open_v2(location, options as any);
+			return open_secondary(location, options as any);
 		}
 		throw err;
 	});

packages/storage/__tests__/fetch.test.ts

@@ -1,10 +1,13 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
 
+import { open, root } from "@zarrita/core";
+
 import FetchStore from "../src/fetch.js";
 
 // `vitest --api` exposes the port 51204
 // ref: https://vitest.dev/config/#api
 let href = "http://localhost:51204/fixtures/v3/data.zarr";
+let href_v2 = "http://localhost:51204/fixtures/v2/data.zarr";
 
 describe("FetchStore", () => {
 	afterEach(() => {
@@ -138,4 +141,20 @@ describe("FetchStore", () => {
 			'"tributes\\": {}, \\"zarr_format\\": 3, \\"node_type\\": \\"gro"',
 		);
 	});
+
+	it("prioritizes v2 over v3 based on count of successful opens by version", async () => {
+		let storeRoot = root(new FetchStore(href_v2));
+
+		const v2_spy = vi.spyOn(open, "v2");
+		const v3_spy = vi.spyOn(open, "v3");
+
+		let arr1 = await open(storeRoot.resolve("1d.chunked.i2"), {
+			kind: "array",
+		});
+		let arr2 = await open(storeRoot.resolve("1d.chunked.ragged.i2"), {
+			kind: "array",
+		});
+		expect(v2_spy).toHaveBeenCalledTimes(2);
+		expect(v3_spy).toHaveBeenCalledTimes(0);
+	});
 });

packages/storage/package.json

@@ -21,6 +21,9 @@
 		"reference-spec-reader": "^0.2.0",
 		"unzipit": "^1.3.6"
 	},
+	"devDependencies": {
+		"@zarrita/core": "workspace:^"
+	},
 	"publishConfig": {
 		"main": "dist/src/index.js",
 		"exports": {