feat(unstable): add Deno.fdatasyncSync and fdatasync (#6403)

cli/js/deno_unstable.ts

@@ -5,7 +5,7 @@
 export { umask } from "./ops/fs/umask.ts";
 export { linkSync, link } from "./ops/fs/link.ts";
 export { fstatSync, fstat } from "./ops/fs/stat.ts";
-export { fsyncSync, fsync } from "./ops/fs/sync.ts";
+export { fdatasyncSync, fdatasync, fsyncSync, fsync } from "./ops/fs/sync.ts";
 export { symlinkSync, symlink } from "./ops/fs/symlink.ts";
 export { loadavg, osRelease, hostname } from "./ops/os.ts";
 export { openPlugin } from "./ops/plugins.ts";

cli/js/lib.deno.unstable.d.ts

@@ -1119,6 +1119,28 @@ declare namespace Deno {
    */
   export function ftruncate(rid: number, len?: number): Promise<void>;
 
+  /* **UNSTABLE**: New API, yet to be vetted.
+   * Synchronously flushes any pending data operations of the given file stream to disk.
+   *  ```ts
+   * const file = Deno.openSync("my_file.txt", { read: true, write: true, create: true });
+   * Deno.writeSync(file.rid, new TextEncoder().encode("Hello World"));
+   * Deno.fdatasyncSync(file.rid);
+   * console.log(new TextDecoder().decode(Deno.readFileSync("my_file.txt"))); // Hello World
+   * ```
+   */
+  export function fdatasyncSync(rid: number): void;
+
+  /** **UNSTABLE**: New API, yet to be vetted.
+   * Flushes any pending data operations of the given file stream to disk.
+   *  ```ts
+   * const file = await Deno.open("my_file.txt", { read: true, write: true, create: true });
+   * await Deno.write(file.rid, new TextEncoder().encode("Hello World"));
+   * await Deno.fdatasync(file.rid);
+   * console.log(new TextDecoder().decode(await Deno.readFile("my_file.txt"))); // Hello World
+   * ```
+   */
+  export function fdatasync(rid: number): Promise<void>;
+
   /** **UNSTABLE**: New API, yet to be vetted.
    * Synchronously flushes any pending data and metadata operations of the given file stream to disk.
    *  ```ts

cli/js/ops/fs/sync.ts

@@ -1,6 +1,14 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { sendSync, sendAsync } from "../dispatch_json.ts";
 
+export function fdatasyncSync(rid: number): void {
+  sendSync("op_fdatasync", { rid });
+}
+
+export async function fdatasync(rid: number): Promise<void> {
+  await sendAsync("op_fdatasync", { rid });
+}
+
 export function fsyncSync(rid: number): void {
   sendSync("op_fsync", { rid });
 }

cli/ops/fs.rs

@@ -22,6 +22,7 @@ use rand::{thread_rng, Rng};
 pub fn init(i: &mut CoreIsolate, s: &State) {
   i.register_op("op_open", s.stateful_json_op2(op_open));
   i.register_op("op_seek", s.stateful_json_op2(op_seek));
+  i.register_op("op_fdatasync", s.stateful_json_op2(op_fdatasync));
   i.register_op("op_fsync", s.stateful_json_op2(op_fsync));
   i.register_op("op_fstat", s.stateful_json_op2(op_fstat));
   i.register_op("op_umask", s.stateful_json_op(op_umask));
@@ -207,6 +208,50 @@ fn op_seek(
   }
 }
 
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct FdatasyncArgs {
+  promise_id: Option<u64>,
+  rid: i32,
+}
+
+fn op_fdatasync(
+  isolate_state: &mut CoreIsolateState,
+  state: &State,
+  args: Value,
+  _zero_copy: &mut [ZeroCopyBuf],
+) -> Result<JsonOp, OpError> {
+  state.check_unstable("Deno.fdatasync");
+  let args: FdatasyncArgs = serde_json::from_value(args)?;
+  let rid = args.rid as u32;
+
+  let resource_table = isolate_state.resource_table.clone();
+  let is_sync = args.promise_id.is_none();
+
+  if is_sync {
+    let mut resource_table = resource_table.borrow_mut();
+    std_file_resource(&mut resource_table, rid, |r| match r {
+      Ok(std_file) => std_file.sync_data().map_err(OpError::from),
+      Err(_) => Err(OpError::type_error(
+        "cannot sync this type of resource".to_string(),
+      )),
+    })?;
+    Ok(JsonOp::Sync(json!({})))
+  } else {
+    let fut = async move {
+      let mut resource_table = resource_table.borrow_mut();
+      std_file_resource(&mut resource_table, rid, |r| match r {
+        Ok(std_file) => std_file.sync_data().map_err(OpError::from),
+        Err(_) => Err(OpError::type_error(
+          "cannot sync this type of resource".to_string(),
+        )),
+      })?;
+      Ok(json!({}))
+    };
+    Ok(JsonOp::Async(fut.boxed_local()))
+  }
+}
+
 #[derive(Deserialize)]
 #[serde(rename_all = "camelCase")]
 struct FsyncArgs {

cli/tests/unit/sync_test.ts

@@ -1,6 +1,42 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { unitTest, assertEquals } from "./test_util.ts";
 
+unitTest(
+  { perms: { read: true, write: true } },
+  function fdatasyncSyncSuccess(): void {
+    const filename = Deno.makeTempDirSync() + "/test_fdatasyncSync.txt";
+    const file = Deno.openSync(filename, {
+      read: true,
+      write: true,
+      create: true,
+    });
+    const data = new Uint8Array(64);
+    Deno.writeSync(file.rid, data);
+    Deno.fdatasyncSync(file.rid);
+    assertEquals(Deno.readFileSync(filename), data);
+    Deno.close(file.rid);
+    Deno.removeSync(filename);
+  }
+);
+
+unitTest(
+  { perms: { read: true, write: true } },
+  async function fdatasyncSuccess(): Promise<void> {
+    const filename = (await Deno.makeTempDir()) + "/test_fdatasync.txt";
+    const file = await Deno.open(filename, {
+      read: true,
+      write: true,
+      create: true,
+    });
+    const data = new Uint8Array(64);
+    await Deno.write(file.rid, data);
+    await Deno.fdatasync(file.rid);
+    assertEquals(await Deno.readFile(filename), data);
+    Deno.close(file.rid);
+    await Deno.remove(filename);
+  }
+);
+
 unitTest(
   { perms: { read: true, write: true } },
   function fsyncSyncSuccess(): void {