feat(core): support AbortSignal in readFile (#10943)

cli/dts/lib.deno.ns.d.ts

@@ -861,6 +861,15 @@ declare namespace Deno {
     mode?: number;
   }
 
+  export interface ReadFileOptions {
+    /**
+     * An abort signal to allow cancellation of the file read operation.
+     * If the signal becomes aborted the readFile operation will be stopped
+     * and the promise returned will be rejected with an AbortError.
+     */
+    signal?: AbortSignal;
+  }
+
   /**
    *
    *  Check if a given resource id (`rid`) is a TTY.
@@ -1385,7 +1394,10 @@ declare namespace Deno {
    * ```
    *
    * Requires `allow-read` permission. */
-  export function readTextFile(path: string | URL): Promise<string>;
+  export function readTextFile(
+    path: string | URL,
+    options?: ReadFileOptions,
+  ): Promise<string>;
 
   /** Synchronously reads and returns the entire contents of a file as an array
    * of bytes. `TextDecoder` can be used to transform the bytes to string if
@@ -1411,7 +1423,10 @@ declare namespace Deno {
    * ```
    *
    * Requires `allow-read` permission. */
-  export function readFile(path: string | URL): Promise<Uint8Array>;
+  export function readFile(
+    path: string | URL,
+    options?: ReadFileOptions,
+  ): Promise<Uint8Array>;
 
   /** A FileInfo describes a file and is returned by `stat`, `lstat`,
    * `statSync`, `lstatSync`. */

cli/tests/unit/read_file_test.ts

@@ -95,3 +95,25 @@ unitTest(
     assertEquals(resourcesBefore, Deno.resources());
   },
 );
+
+unitTest(
+  { perms: { read: true } },
+  async function readFileWithAbortSignal(): Promise<void> {
+    const ac = new AbortController();
+    queueMicrotask(() => ac.abort());
+    await assertThrowsAsync(async () => {
+      await Deno.readFile("cli/tests/fixture.json", { signal: ac.signal });
+    });
+  },
+);
+
+unitTest(
+  { perms: { read: true } },
+  async function readTextileWithAbortSignal(): Promise<void> {
+    const ac = new AbortController();
+    queueMicrotask(() => ac.abort());
+    await assertThrowsAsync(async () => {
+      await Deno.readTextFile("cli/tests/fixture.json", { signal: ac.signal });
+    });
+  },
+);

runtime/js/12_io.js

@@ -110,9 +110,12 @@
   const READ_PER_ITER = 32 * 1024;
 
   async function readAll(r) {
+    return await readAllInner(r);
+  }
+  async function readAllInner(r, options) {
     const buffers = [];
-
-    while (true) {
+    const signal = options?.signal ?? null;
+    while (!signal?.aborted) {
       const buf = new Uint8Array(READ_PER_ITER);
       const read = await r.read(buf);
       if (typeof read == "number") {
@@ -121,6 +124,9 @@
         break;
       }
     }
+    if (signal?.aborted) {
+      throw new DOMException("The read operation was aborted.", "AbortError");
+    }
 
     let totalLen = 0;
     for (const buf of buffers) {
@@ -177,6 +183,7 @@
     write,
     writeSync,
     readAll,
+    readAllInner,
     readAllSync,
   };
 })(this);

runtime/js/40_read_file.js

@@ -4,7 +4,7 @@
 ((window) => {
   const core = window.Deno.core;
   const { open, openSync } = window.__bootstrap.files;
-  const { readAll, readAllSync } = window.__bootstrap.io;
+  const { readAllInner, readAllSync } = window.__bootstrap.io;
 
   function readFileSync(path) {
     const file = openSync(path);
@@ -16,10 +16,10 @@
     }
   }
 
-  async function readFile(path) {
+  async function readFile(path, options) {
     const file = await open(path);
     try {
-      const contents = await readAll(file);
+      const contents = await readAllInner(file, options);
       return contents;
     } finally {
       file.close();
@@ -36,10 +36,10 @@
     }
   }
 
-  async function readTextFile(path) {
+  async function readTextFile(path, options) {
     const file = await open(path);
     try {
-      const contents = await readAll(file);
+      const contents = await readAllInner(file, options);
       return core.decode(contents);
     } finally {
       file.close();