WriteHandle

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

An interface for a writable Handle

Order of operations is guaranteed, except for writeImplBlocking; writeImplBlocking() will immediately try to write to the handle.

Interface Synopsis

namespace HH\Lib\IO;

interface WriteHandle implements Handle {...}

Public Methods

• ->writeAllAsync(string $bytes, ?int $timeout_ns = NULL): Awaitable<void>
  Write all of the requested data
• ->writeAllowPartialSuccessAsync(string $bytes, ?int $timeout_ns = NULL): Awaitable<int>
  Write data, waiting if necessary

Protected Methods

• ->writeImpl(string $bytes): int
  An immediate unordered write