Implement D1Database using D1JS and D1 API (#480)

Previously, Miniflare had its own implementations of `BetaDatabase`
and `Statement`. These were subtly different to the implementations
in the D1 Wrangler shim D1JS, causing behaviour mismatches.

This change switches the implementation to use the shim, with
Miniflare implementing the underlying D1 HTTP API instead. We'll
need to do this anyway when adding D1 support to Miniflare 3 using
`workerd`.

Specific changes:
- Throw when calling `D1PreparedStatement#run()` with statements that
  return data, closes #441
- Fix response envelope format, closes #442 and
  cloudflare/workers-sdk#2504
- Fix binding/return of `BLOB`-typed values, closes
  cloudflare/workers-sdk#2527
- Fix `D1Database#raw()` return, closes cloudflare/workers-sdk#2238
  (already fixed in #474)
- Add support for `D1Database#dump()`
- Run `D1Database#{batch,exec}()` statements in implicit transaction
- Only run first statement when calling
  `D1PreparedStatement#{first,run,all,raw}()`

packages/core/src/standards/http.ts

@@ -752,7 +752,7 @@ class MiniflareDispatcher extends Dispatcher {
 }
 
 export async function fetch(
-  this: Dispatcher | void,
+  this: Dispatcher | unknown,
   input: RequestInfo,
   init?: RequestInit
 ): Promise<Response> {

packages/d1/src/api.ts

@@ -0,0 +1,204 @@
+import crypto from "crypto";
+import fs from "fs/promises";
+import os from "os";
+import path from "path";
+import { performance } from "perf_hooks";
+import { Request, RequestInfo, RequestInit, Response } from "@miniflare/core";
+import type { SqliteDB } from "@miniflare/shared";
+import type { Statement as SqliteStatement } from "better-sqlite3";
+import splitSqlQuery from "./splitter";
+
+// query
+interface SingleQuery {
+  sql: string;
+  params?: any[] | null;
+}
+
+// response
+interface ErrorResponse {
+  error: string;
+  success: false;
+  served_by: string;
+}
+interface ResponseMeta {
+  duration: number;
+  last_row_id: number | null;
+  changes: number | null;
+  served_by: string;
+  internal_stats: null;
+}
+interface SuccessResponse {
+  results: any;
+  duration: number;
+  lastRowId: number | null;
+  changes: number | null;
+  success: true;
+  served_by: string;
+  meta: ResponseMeta | null;
+}
+
+const served_by = "miniflare.db";
+
+function ok(results: any, start: number): SuccessResponse {
+  const duration = performance.now() - start;
+  return {
+    results,
+    duration,
+    // These are all `null`ed out in D1
+    lastRowId: null,
+    changes: null,
+    success: true,
+    served_by,
+    meta: {
+      duration,
+      last_row_id: null,
+      changes: null,
+      served_by,
+      internal_stats: null,
+    },
+  };
+}
+function err(error: any): ErrorResponse {
+  return {
+    error: String(error),
+    success: false,
+    served_by,
+  };
+}
+
+type QueryRunner = (query: SingleQuery) => SuccessResponse;
+
+function normaliseParams(params: SingleQuery["params"]): any[] {
+  return (params ?? []).map((param) =>
+    // If `param` is an array, assume it's a byte array
+    Array.isArray(param) ? new Uint8Array(param) : param
+  );
+}
+function normaliseResults(rows: any[]): any[] {
+  return rows.map((row) =>
+    Object.fromEntries(
+      Object.entries(row).map(([key, value]) => [
+        key,
+        // If `value` is an array, convert it to a regular numeric array
+        value instanceof Buffer ? Array.from(value) : value,
+      ])
+    )
+  );
+}
+
+const DOESNT_RETURN_DATA_MESSAGE =
+  "The columns() method is only for statements that return data";
+const EXECUTE_RETURNS_DATA_MESSAGE =
+  "SQL execute error: Execute returned results - did you mean to call query?";
+function returnsData(stmt: SqliteStatement): boolean {
+  try {
+    stmt.columns();
+    return true;
+  } catch (e) {
+    // `columns()` fails on statements that don't return data
+    if (e instanceof TypeError && e.message === DOESNT_RETURN_DATA_MESSAGE) {
+      return false;
+    }
+    throw e;
+  }
+}
+
+export class D1DatabaseAPI {
+  constructor(private readonly db: SqliteDB) {}
+
+  #query: QueryRunner = (query) => {
+    const start = performance.now();
+    // D1 only respects the first statement
+    const sql = splitSqlQuery(query.sql)[0];
+    const stmt = this.db.prepare(sql);
+    const params = normaliseParams(query.params);
+    let results: any[];
+    if (returnsData(stmt)) {
+      results = stmt.all(params);
+    } else {
+      // `/query` does support queries that don't return data,
+      // returning `[]` instead of `null`
+      stmt.run(params);
+      results = [];
+    }
+    return ok(normaliseResults(results), start);
+  };
+
+  #execute: QueryRunner = (query) => {
+    const start = performance.now();
+    // D1 only respects the first statement
+    const sql = splitSqlQuery(query.sql)[0];
+    const stmt = this.db.prepare(sql);
+    // `/execute` only supports queries that don't return data
+    if (returnsData(stmt)) throw new Error(EXECUTE_RETURNS_DATA_MESSAGE);
+    const params = normaliseParams(query.params);
+    stmt.run(params);
+    return ok(null, start);
+  };
+
+  async #handleQueryExecute(
+    request: Request,
+    runner: QueryRunner
+  ): Promise<Response> {
+    // `D1Database#batch()` will call `/query` with an array of queries
+    const query = await request.json<SingleQuery | SingleQuery[]>();
+    let results: SuccessResponse | SuccessResponse[];
+    if (Array.isArray(query)) {
+      // Run batches in an implicit transaction. Note we have to use savepoints
+      // here as the SQLite transaction stack may not be empty if we're running
+      // inside the Miniflare testing environment, and nesting regular
+      // transactions is not permitted.
+      const savepointName = `MINIFLARE_D1_BATCH_${Date.now()}_${Math.floor(
+        Math.random() * Number.MAX_SAFE_INTEGER
+      )}`;
+      this.db.exec(`SAVEPOINT ${savepointName};`); // BEGIN TRANSACTION;
+      try {
+        results = query.map(runner);
+        this.db.exec(`RELEASE ${savepointName};`); // COMMIT;
+      } catch (e) {
+        this.db.exec(`ROLLBACK TO ${savepointName};`); // ROLLBACK;
+        this.db.exec(`RELEASE ${savepointName};`);
+        throw e;
+      }
+    } else {
+      results = runner(query);
+    }
+    return Response.json(results);
+  }
+
+  async #handleDump(): Promise<Response> {
+    // `better-sqlite3` requires us to back up to a file, so create a temp one
+    const random = crypto.randomBytes(8).toString("hex");
+    const tmpPath = path.join(os.tmpdir(), `miniflare-d1-dump-${random}.db`);
+    await this.db.backup(tmpPath);
+    const buffer = await fs.readFile(tmpPath);
+    // Delete file in the background, ignore errors as they don't really matter
+    void fs.unlink(tmpPath).catch(() => {});
+    return new Response(buffer, {
+      headers: { "Content-Type": "application/octet-stream" },
+    });
+  }
+
+  async fetch(input: RequestInfo, init?: RequestInit) {
+    // `D1Database` may call fetch with a relative URL, so resolve it, making
+    // sure to only construct a `new URL()` once.
+    if (typeof input === "string") input = new URL(input, "http://localhost");
+    const request = new Request(input, init);
+    if (!(input instanceof URL)) input = new URL(request.url);
+    const pathname = input.pathname;
+
+    if (request.method !== "POST") return new Response(null, { status: 405 });
+    try {
+      if (pathname === "/query") {
+        return await this.#handleQueryExecute(request, this.#query);
+      } else if (pathname === "/execute") {
+        return await this.#handleQueryExecute(request, this.#execute);
+      } else if (pathname === "/dump") {
+        return await this.#handleDump();
+      }
+    } catch (e) {
+      return Response.json(err(e));
+    }
+    return new Response(null, { status: 404 });
+  }
+}