Diviner Arcanist Tech Docs ArcanistHgClientChannel

final class ArcanistHgClientChannel
Arcanist Technical Documentation ()

Channel to a Mercurial "cmdserver" client. For a detailed description of the "cmdserver" protocol, see ArcanistHgServerChannel. This channel implements the other half of the protocol: it decodes messages from the client and encodes messages from the server.

Because the proxy server speaks the exact same protocol that Mercurial does and fully decodes both sides of the protocol, we need this half of the decode/encode to talk to clients. Without it, we wouldn't be able to determine when a client request had completed and was ready for transmission to the Mercurial server.

(Technically, we could get away without re-encoding messages from the server, but the serialization is not complicated and having a general implementation of encoded/decode for both the client and server dialects seemed useful.)

Tasks

Reading and Writing

public function read() — Read a message from the channel, if a message is available.
public function write($message) — Write a message to the channel.
public function addMessage($message) — Add a message to the queue. While you normally do not need to do this, you can use it to inject out-of-band messages.

Waiting for Activity

public static function waitForAny($channels, $options) — Wait for any activity on a list of channels. Convenience wrapper around @{method:waitForActivity}.
public static function waitForActivity($reads, $writes, $options) — Wait (using select()) for channels to become ready for reads or writes. This method blocks until some channel is ready to be updated.
public function waitForMessage() — Wait for a message, blocking until one is available.

Responding to Activity

public function update()

Channel Implementation

public function setName($name) — Set a channel name. This is primarily intended to allow you to debug channel code more easily, by naming channels something meaningful.
public function getName() — Get the channel name, as set by @{method:setName}.
public function isOpen()
public function closeWriteChannel()
public function isOpenForReading()
public function isOpenForWriting()
protected function readBytes($length)
protected function writeBytes($bytes)
protected function getReadSockets()
protected function getWriteSockets()
public function setReadBufferSize($size)
public function isReadBufferEmpty()
public function isWriteBufferEmpty()
public function getWriteBufferSize()
public function flush()

Protocol Implementation

protected function encodeMessage($argv) — Encode a message for transmission to the client. The message should be a pair with the channel name and the a block of data, like this:
protected function decodeStream($data) — Decode a message received from the client. The message looks like this:

Other Methods

public function __get($name)
public function __set($name, $value)
public function current()
public function key()
public function next()
public function rewind()
public function valid()
private function throwOnAttemptedIteration()
public function getPhobjectClassConstant($key, $byte_limit) — Read the value of a class constant.
public function __construct($channel)
protected function didConstruct()
protected function getUnderlyingChannel()
private function throwOnRawByteOperations()

Methods

public function __get($name)
Inherited

This method is not documented.

Parameters

$name

Return

wild

public function __set($name, $value)
Inherited

This method is not documented.

Parameters

	$name
	$value

Return

wild

public function current()
Inherited

This method is not documented.

Return

wild

public function key()
Inherited

This method is not documented.

Return

wild

public function next()
Inherited

This method is not documented.

Return

wild

public function rewind()
Inherited

This method is not documented.

Return

wild

public function valid()
Inherited

This method is not documented.

Return

wild

private function throwOnAttemptedIteration()
Inherited

This method is not documented.

Return

wild

public function getPhobjectClassConstant($key, $byte_limit)
Inherited

Phobject

Read the value of a class constant.

This is the same as just typing self::CONSTANTNAME, but throws a more useful message if the constant is not defined and allows the constant to be limited to a maximum length.

Parameters

string	$key	Name of the constant.
int\|null	$byte_limit	Maximum number of bytes permitted in the value.

Return

string

Value of the constant.

public function __construct($channel)
Inherited

This method is not documented.

Return

this	//Implicit.//

public function read()
Inherited

PhutilChannel

Read from the channel. A channel defines the format of data that is read from it, so this method may return strings, objects, or anything else.

The default implementation returns bytes.

PhutilProtocolChannel

Read a message from the channel, if a message is available.

Return

wild	A message, or null if no message is available.

public function write($message)
Inherited

PhutilChannel

Write to the channel. A channel defines what data format it accepts, so this method may take strings, objects, or anything else.

The default implementation accepts bytes.

PhutilProtocolChannel

Write a message to the channel.

Parameters

wild

$bytes

Data to write to the channel, normally bytes.

Return

this

public static function waitForAny($channels, $options)
Inherited

PhutilChannel

Wait for any activity on a list of channels. Convenience wrapper around waitForActivity().

Parameters

list<PhutilChannel>	$channels	A list of channels to wait for.
dict	$options	Options, see above.

Return

void

public static function waitForActivity($reads, $writes, $options)
Inherited

PhutilChannel

Wait (using select()) for channels to become ready for reads or writes. This method blocks until some channel is ready to be updated.

It does not provide a way to determine which channels are ready to be updated. The expectation is that you'll just update every channel. This might change eventually.

Available options are:

'read' (list<stream>) Additional streams to select for read.
'write' (list<stream>) Additional streams to select for write.
'except' (list<stream>) Additional streams to select for except.
'timeout' (float) Select timeout, defaults to 1.

NOTE: Extra streams must be streams, not sockets, because this method uses stream_select(), not socket_select().

Parameters

list<PhutilChannel>	$reads	List of channels to wait for reads on.
list<PhutilChannel>	$writes	List of channels to wait for writes on.
array	$options

Return

void

public function update()
Inherited

PhutilChannel

Updates the channel, filling input buffers and flushing output buffers. Returns false if the channel has closed.

Return

bool	True if the channel is still open.

public function setName($name)
Inherited

PhutilChannel

Set a channel name. This is primarily intended to allow you to debug channel code more easily, by naming channels something meaningful.

Parameters

string

$name

Channel name.

Return

this

public function getName()
Inherited

PhutilChannel

Get the channel name, as set by setName().

Return

string

Name of the channel.

public function isOpen()
Inherited

PhutilChannel

Test if the channel is open: active, can be read from and written to, etc.

Return

bool	True if the channel is open.

public function closeWriteChannel()
Inherited

PhutilChannel

Close the channel for writing.

Return

void

public function isOpenForReading()
Inherited

PhutilChannel

Test if the channel is open for reading.

Return

bool	True if the channel is open for reading.

public function isOpenForWriting()
Inherited

PhutilChannel

Test if the channel is open for writing.

Return

bool	True if the channel is open for writing.

protected function readBytes($length)
Inherited

PhutilChannel

Read from the channel's underlying I/O.

Parameters

int

$length

Maximum number of bytes to read.

Return

string

Bytes, if available.

protected function writeBytes($bytes)
Inherited

PhutilChannel

Write to the channel's underlying I/O.

Parameters

string

$bytes

Bytes to write.

Return

int	Number of bytes written.

protected function getReadSockets()
Inherited

PhutilChannel

Get sockets to select for reading.

Return

list<stream>

Read sockets.

protected function getWriteSockets()
Inherited

PhutilChannel

Get sockets to select for writing.

Return

list<stream>

Write sockets.

public function setReadBufferSize($size)
Inherited

PhutilChannel

Set the maximum size of the channel's read buffer. Reads will artificially block once the buffer reaches this size until the in-process buffer is consumed.

Parameters

int|null

$size

Maximum read buffer size, or `null` for a limitless buffer.

Return

this

public function isReadBufferEmpty()
Inherited

PhutilChannel

Test state of the read buffer.

Return

bool	True if the read buffer is empty.

public function isWriteBufferEmpty()
Inherited

PhutilChannel

Test state of the write buffer.

Return

bool	True if the write buffer is empty.

public function getWriteBufferSize()
Inherited

PhutilChannel

Get the number of bytes we're currently waiting to write.

Return

int	Number of waiting bytes.

public function flush()
Inherited

PhutilChannel

Wait for any buffered writes to complete. This is a blocking call. When the call returns, the write buffer will be empty.

Return

wild

protected function didConstruct()
Inherited

This method is not documented.

Return

wild

protected function getUnderlyingChannel()
Inherited

This method is not documented.

Return

wild

private function throwOnRawByteOperations()
Inherited

This method is not documented.

Return

wild

public function addMessage($message)
Inherited

PhutilProtocolChannel

Add a message to the queue. While you normally do not need to do this, you can use it to inject out-of-band messages.

Parameters

wild

$message

Some message.

Return

this

protected function encodeMessage($argv)

PhutilProtocolChannel

Encode a message for transmission.

ArcanistHgClientChannel

Encode a message for transmission to the client. The message should be a pair with the channel name and the a block of data, like this:

array('o', '<some data...>');

We encode it like this:

o
1234                # Length, as a 4-byte unsigned long.
<data: 1234 bytes>

For a detailed description of the cmdserver protocol, see ArcanistHgServerChannel.

Parameters

wild

$message

Some message.

Return

string

Encoded string for transmission to the client.

protected function decodeStream($data)

PhutilProtocolChannel

Decode bytes from the underlying channel into zero or more complete messages. The messages should be returned.

This method is called as data is available. It will receive incoming data only once, and must buffer any data which represents only part of a message. Once a complete message is received, it can return the message and discard that part of the buffer.

Generally, a protocol channel should maintain a read buffer, implement a parser in this method, and store parser state on the object to be able to process incoming data in small chunks.

ArcanistHgClientChannel

Decode a message received from the client. The message looks like this:

runcommand\n
8                   # Length, as a 4-byte unsigned long.
log\0
-l\0
5

We decode it into a list in PHP, which looks like this:

array(
  'runcommand',
  'log',
  '-l',
  '5',
);

Parameters

string

$data

One or more bytes from the underlying channel.

Return

list<list<string>>

Zero or more complete commands.

public function waitForMessage()
Inherited

PhutilProtocolChannel

Wait for a message, blocking until one is available.

Return

wild	A message.

Defined: src/hgdaemon/ArcanistHgClientChannel.php:22
Extends: PhobjectPhutilChannelPhutilChannelChannelPhutilProtocolChannel

final class ArcanistHgClientChannelArcanist Technical Documentation ()

Tasks

Reading and Writing

Waiting for Activity

Responding to Activity

Channel Implementation

Protocol Implementation

Other Methods

Methods

public function __get($name)Inherited

public function __set($name, $value)Inherited

public function current()Inherited

public function key()Inherited

public function next()Inherited

public function rewind()Inherited

public function valid()Inherited

private function throwOnAttemptedIteration()Inherited

public function getPhobjectClassConstant($key, $byte_limit)Inherited

public function __construct($channel)Inherited

public function read()Inherited

public function write($message)Inherited

public static function waitForAny($channels, $options)Inherited

public static function waitForActivity($reads, $writes, $options)Inherited

public function update()Inherited

public function setName($name)Inherited

public function getName()Inherited

public function isOpen()Inherited

public function closeWriteChannel()Inherited

public function isOpenForReading()Inherited

public function isOpenForWriting()Inherited

protected function readBytes($length)Inherited

protected function writeBytes($bytes)Inherited

protected function getReadSockets()Inherited

protected function getWriteSockets()Inherited

public function setReadBufferSize($size)Inherited

public function isReadBufferEmpty()Inherited

public function isWriteBufferEmpty()Inherited

public function getWriteBufferSize()Inherited

public function flush()Inherited

protected function didConstruct()Inherited

protected function getUnderlyingChannel()Inherited

private function throwOnRawByteOperations()Inherited

public function addMessage($message)Inherited

protected function encodeMessage($argv)

protected function decodeStream($data)

public function waitForMessage()Inherited

final class ArcanistHgClientChannel
Arcanist Technical Documentation ()

public function __get($name)
Inherited

public function __set($name, $value)
Inherited

public function current()
Inherited

public function key()
Inherited

public function next()
Inherited

public function rewind()
Inherited

public function valid()
Inherited

private function throwOnAttemptedIteration()
Inherited

public function getPhobjectClassConstant($key, $byte_limit)
Inherited

public function __construct($channel)
Inherited

public function read()
Inherited

public function write($message)
Inherited

public static function waitForAny($channels, $options)
Inherited

public static function waitForActivity($reads, $writes, $options)
Inherited

public function update()
Inherited

public function setName($name)
Inherited

public function getName()
Inherited

public function isOpen()
Inherited

public function closeWriteChannel()
Inherited

public function isOpenForReading()
Inherited

public function isOpenForWriting()
Inherited

protected function readBytes($length)
Inherited

protected function writeBytes($bytes)
Inherited

protected function getReadSockets()
Inherited

protected function getWriteSockets()
Inherited

public function setReadBufferSize($size)
Inherited

public function isReadBufferEmpty()
Inherited

public function isWriteBufferEmpty()
Inherited

public function getWriteBufferSize()
Inherited

public function flush()
Inherited

protected function didConstruct()
Inherited

protected function getUnderlyingChannel()
Inherited

private function throwOnRawByteOperations()
Inherited

public function addMessage($message)
Inherited

public function waitForMessage()
Inherited