`phasync\Util\StringBuffer` class

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Documentation

A high performance string buffer for buffering streaming data that can be parsed efficiently. Designed for protocol parsing in servers (HTTP, FastCGI, WebSocket) where you need to read fixed-size frames from a byte stream.

For safe coroutine-to-coroutine communication, use Channels instead.

To prevent readers from waiting forever if the writer crashes, use the deadman switch feature:

phasync::go(function() use ($sb, $socket) {
    $deadman = $sb->getDeadmanSwitch();
    while ($data = fread($socket, 8192)) {
        $sb->write($data);
    }
    $sb->end(); // Always end properly - deadman is just a safety net
});

If the writer exits without calling end(), the deadman switch triggers and any blocking read will throw DeadmanException. Buffered data can still be read before the exception is thrown.

Inheritance

Implements: phasync\SelectableInterface

Uses Traits: phasync\DeadmanSwitchTrait

Constants (1)

Name	Value
`BUFFER_WASTE_LIMIT`	`4096`

Properties (9)

protected SplDoublyLinkedList $queue

Contains the chunks of binary data appended or prepended

protected string $buffer

Contains unread bytes, for situations where data was consumed

protected int $length

The length of the unread bytes buffer

protected int $offset

The read offset in the unread bytes buffer, to reduce the number

private int $totalRead

The total number of bytes that have been read from the string

private int $totalWritten

The total number of bytes that have been written to the buffer.

private bool $ended

Has the end of data been signalled?

private bool $failed

True if the writer terminated unexpectedly (deadman switch triggered).

private ?WeakReference $deadmanSwitch

Weak reference to the deadman switch, allowing it to be GC'd

Methods (15)

public `__construct()`

Create a new StringBuffer instance.

public `await()`

Wait until the buffer has data available to read or has been ended.

public `isReady()`

Check if a read operation would not block.

public `isEmpty()`

Returns true if there is no data currently available to read.

public `write()`

Write data to the buffer

public `read()`

Read up to $maxLength bytes from the buffer.

public `readFromResource()`

Asynchronously read data from the stream resource into the

public `end()`

Signal the equivalent of an end of file. No further writes

protected `deadmanSwitchTriggered()`

Called when the deadman switch is triggered.

public `eof()`

True if the end of file has been reached.

public `readFixed()`

Read a fixed number of bytes from the buffer, and return null

public `writeToResource()`

Data that enters the buffer will be written asynchronously to the

public `unread()`

Prepend data to the buffer.

protected `fill()`

Function that grows the string buffer until it can be

public `getDeadmanSwitch()`

Get a deadman switch for this object.

Source

src/Util/StringBuffer.php:33-377