feat: add public close methods

Add method to close transport and writer.

Before there was no public way to close the transport/reader/writer created by attach
for a socket, and the connection would hold the node process open.

For example, this script would not exit (without an explicit process.exit(0))
```
attach({ socket: pathToNvimSocket })
```

This change adds .close to transport and NeovimClient which ends the writer.
The other side of the connection should then close the reader which triggers detach and the
cleanup code.

I added asyncDispose methods for folks using modern javascript runtimes that support explicit
resource management:

```
await using client = attach({ socket: pathToNvimSocket })
```

Other wise you can call close
```
try {
  const client = attach({ socket: pathToNvimSocket })
} finally {
  await client.close()
}
```

Author: everett1992

packages/neovim/src/api/client.ts

@@ -6,6 +6,7 @@ import { Transport } from '../utils/transport';
 import { VimValue } from '../types/VimValue';
 import { Neovim } from './Neovim';
 import { Buffer } from './Buffer';
+import { ASYNC_DISPOSE_SYMBOL } from '../utils/util';
 
 const REGEX_BUF_EVENT = /nvim_buf_(.*)_event/;
 
@@ -249,4 +250,15 @@ export class NeovimClient extends Neovim {
 
     return false;
   }
+
+  async close(): Promise<void> {
+    await this.transport.close()
+  }
+
+  /**
+   * @see close
+   */
+  async [ASYNC_DISPOSE_SYMBOL](): Promise<void> {
+    await this.close();
+  }
 }

packages/neovim/src/utils/transport.test.ts

@@ -1,5 +1,5 @@
 import { EventEmitter } from 'node:events';
-import { Readable, Writable } from 'node:stream';
+import { PassThrough, Readable, Writable } from 'node:stream';
 import * as msgpack from '@msgpack/msgpack';
 import expect from 'expect';
 import { attach } from '../attach/attach';
@@ -17,8 +17,8 @@ describe('transport', () => {
     });
 
     // Create fake reader/writer and send a (broken) message.
-    const fakeReader = new Readable({ read() {} });
-    const fakeWriter = new Writable({ write() {} });
+    const fakeReader = new Readable({ read() { } });
+    const fakeWriter = new Writable({ write() { } });
 
     const nvim = attach({ reader: fakeReader, writer: fakeWriter });
     void nvim; // eslint-disable-line no-void
@@ -27,4 +27,17 @@ describe('transport', () => {
     const msg = msgpack.encode(invalidPayload);
     fakeReader.push(Buffer.from(msg.buffer, msg.byteOffset, msg.byteLength));
   });
+
+  it('closes transport and cleans up pending requests', async () => {
+    const socket = new PassThrough()
+
+    const nvim = attach({ reader: socket, writer: socket });
+
+    // Close the transport
+    const closePromise = nvim.close();
+
+    // Verify close promise resolves
+    await expect(closePromise).resolves.toBeUndefined();
+  });
 });
+

packages/neovim/src/utils/transport.ts

@@ -7,6 +7,7 @@ import { inspect } from 'node:util';
 
 import { encode, decode, ExtensionCodec, decodeMultiStream } from '@msgpack/msgpack';
 import { Metadata } from '../api/types';
+import { ASYNC_DISPOSE_SYMBOL } from './util';
 
 export let exportsForTesting: any; // eslint-disable-line import/no-mutable-exports
 // .mocharc.js sets NODE_ENV=test.
@@ -88,7 +89,7 @@ class Transport extends EventEmitter {
     this.reader = reader;
     this.client = client;
 
-    this.reader.on('end', () => {
+    this.reader.once('end', () => {
       this.emit('detach');
     });
 
@@ -179,6 +180,25 @@ class Transport extends EventEmitter {
       this.writer.write(this.encodeToBuffer([1, 0, 'Invalid message type', null]));
     }
   }
+
+  /**
+   * Close the transport.
+   *
+   * Ends the writer, the other end of the connection should close our reader which cleans up
+   * remaining resources.
+   */
+  async close(): Promise<void> {
+    return new Promise((resolve) => {
+      this.writer.end(resolve)
+    });
+  }
+
+  /**
+   * @see close
+   */
+  async [ASYNC_DISPOSE_SYMBOL](): Promise<void> {
+    await this.close();
+  }
 }
 
 export { Transport };

packages/neovim/src/utils/util.ts

@@ -41,3 +41,9 @@ export function partialClone(
 
   return clonedObj;
 }
+
+/**
+ * Polyfill for Symbol.asyncDispose if not available in the runtime.
+ * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/asyncDispose
+ */
+export const ASYNC_DISPOSE_SYMBOL = Symbol.asyncDispose ?? Symbol.for('Symbol.asyncDispose');