MemoryHandle

:::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. :::

Read from/write to an in-memory buffer

This class is intended for use in unit tests.

Interface Synopsis

namespace HH\Lib\IO;

final class MemoryHandle implements CloseableSeekableReadWriteHandle {...}

Public Methods

• ->__construct(string $buffer = '', MemoryHandleWriteMode $writeMode = MemoryHandleWriteMode::OVERWRITE)
• ->appendToBuffer(string $data): void
  Append data to the internal buffer, preserving position
• ->close(): void
• ->closeWhenDisposed(): \IDisposable
• ->getBuffer(): string
• ->readAllowPartialSuccessAsync(?int $max_bytes = NULL, ?int $_timeout_nanos = NULL): Awaitable<string>
• ->readImpl(?int $max_bytes = NULL): string
• ->reset(string $data = ''): void
  Set the internal buffer and reset position to the beginning of the file
• ->seek(int $pos): void
• ->tell(): int
• ->writeAllowPartialSuccessAsync(string $data, ?int $timeout_nanos = NULL): Awaitable<int>

Public Methods (HH\Lib\IO\WriteHandle)

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

Public Methods (HH\Lib\IO\ReadHandle)

• ->readAllAsync(?int $max_bytes = NULL, ?int $timeout_ns = NULL): Awaitable<string>
  Read until there is no more data to read
• ->readFixedSizeAsync(int $size, ?int $timeout_ns = NULL): Awaitable<string>
  Read a fixed amount of data

Protected Methods

• ->writeImpl(string $data): int