Class for implementing a serial queue channel in memory. More...

#include <qchannel.h>

Inheritance diagram for PQueueChannel:

Collaboration diagram for PQueueChannel:

Public Member Functions
Construction
	PQueueChannel (PINDEX queueSize=0)
	Create a new queue channel with the specified maximum size. More...

	~PQueueChannel ()
	Delete queue and release memory used. More...

Overrides from class PChannel
virtual PString	GetName () const
	Get the platform and I/O channel type name of the channel. More...

virtual PBoolean	Read (void *buf, PINDEX len)
	Low level read from the file channel. More...

virtual PBoolean	Write (const void *buf, PINDEX len)
	Low level write to the file channel. More...

virtual PBoolean	Close ()
	Close the file channel. More...

Queue manipulation functions
virtual PBoolean	Open (PINDEX queueSize)
	Open a queue, allocating the queueSize bytes. More...

PINDEX	GetSize () const
	Get the queue size. More...

PINDEX	GetLength () const
	Get the current queue length. More...

Public Member Functions inherited from PChannel
PBoolean	SetErrorValues (Errors errorCode, int osError, ErrorGroup group=LastGeneralError)
	Set error values to those specified. More...

virtual Comparison	Compare (const PObject &obj) const
	Get the relative rank of the two strings. More...

virtual PINDEX	HashFunction () const
	Calculate a hash value for use in sets and dictionaries. More...

virtual PBoolean	IsOpen () const
	Determine if the channel is currently open. More...

virtual P_INT_PTR	GetHandle () const
	Get the integer operating system handle for the channel. More...

FILE *	FDOpen (const char *mode)
	Re-open the device using the stdio library. More...

virtual PChannel *	GetBaseReadChannel () const
	Get the base channel of channel indirection using PIndirectChannel. More...

virtual PChannel *	GetBaseWriteChannel () const
	Get the base channel of channel indirection using PIndirectChannel. More...

virtual bool	CloseBaseReadChannel ()
	Close the base channel of channel indirection using PIndirectChannel. More...

virtual bool	CloseBaseWriteChannel ()
	Close the base channel of channel indirection using PIndirectChannel. More...

void	SetReadTimeout (const PTimeInterval &time)
	Set the timeout for read operations. More...

PTimeInterval	GetReadTimeout () const
	Get the timeout for read operations. More...

virtual PINDEX	GetLastReadCount () const
	Get the number of bytes read by the last Read() call. More...

virtual PINDEX	SetLastReadCount (PINDEX count)

virtual int	ReadChar ()
	Read a single character from the channel. More...

PBoolean	ReadBlock (void *buf, PINDEX len)
	Read len bytes into the buffer from the channel. More...

PString	ReadString (PINDEX len)
	Read `len` character into a string from the channel. More...

void	SetWriteTimeout (const PTimeInterval &time)
	Set the timeout for write operations to complete. More...

PTimeInterval	GetWriteTimeout () const
	Get the timeout for write operations to complete. More...

virtual PBoolean	Write (const void buf, PINDEX len, const void )
	Low level write to the channel with marker. More...

virtual PINDEX	GetLastWriteCount () const
	Get the number of bytes written by the last Write() call. More...

virtual PINDEX	SetLastWriteCount (PINDEX count)

PBoolean	WriteChar (int c)
	Write a single character to the channel. More...

PBoolean	WriteString (const PString &str)
	Write a string to the channel. More...

	~PChannel ()
	Close down the channel. More...

Errors	GetErrorCode (ErrorGroup group=NumErrorGroups) const
	Get normalised error code. More...

int	GetErrorNumber (ErrorGroup group=NumErrorGroups) const
	Get OS errro code. More...

virtual PString	GetErrorText (ErrorGroup group=NumErrorGroups) const
	Get error message description. More...

virtual bool	ReadAsync (AsyncContext &context)
	Begin an asynchronous read from channel. More...

virtual void	OnReadComplete (AsyncContext &context)
	User callback function for when a `ReadAsync()` call has completed or timed out. More...

virtual bool	WriteAsync (AsyncContext &context)
	Begin an asynchronous write from channel. More...

virtual void	OnWriteComplete (AsyncContext &context)
	User callback function for when a WriteAsync() call has completed or timed out. More...

virtual PBoolean	Shutdown (ShutdownValue option)
	Close one or both of the data streams associated with a channel. More...

virtual bool	SetLocalEcho (bool localEcho)
	Set local echo mode. More...

virtual bool	FlowControl (const void *flowData)
	Flow Control information Pass data to the channel for flowControl determination. More...

PBoolean	SetBufferSize (PINDEX newSize)
	Set the iostream buffer size for reads and writes. More...

PBoolean	SendCommandString (const PString &command)
	Send a command meta-string. More...

void	AbortCommandString ()
	Abort a command string that is in progress. More...

Public Member Functions inherited from PObject
__inline unsigned	GetTraceContextIdentifier () const
	Get PTRACE context identifier. More...

__inline void	SetTraceContextIdentifier (unsigned id)

__inline void	SetTraceContextIdentifier (const PObject &obj)

__inline void	SetTraceContextIdentifier (const PObject *obj)

__inline void	CopyTraceContextIdentifier (PObject &obj) const

__inline void	CopyTraceContextIdentifier (PObject *obj) const

virtual	~PObject ()

__inline const char *	GetClass () const

__inline bool	IsClass (const char *name) const

__inline const PObject *	PTraceObjectInstance () const

virtual PObject *	Clone () const
	Create a copy of the class on the heap. More...

template<class CLS >
CLS *	CloneAs () const
	As for Clone() but converts to specified type. More...

virtual Comparison	CompareObjectMemoryDirect (const PObject &obj) const
	Determine the byte wise comparison of two objects. More...

bool	operator== (const PObject &obj) const
	Compare the two objects. More...

bool	operator!= (const PObject &obj) const
	Compare the two objects. More...

bool	operator< (const PObject &obj) const
	Compare the two objects. More...

bool	operator> (const PObject &obj) const
	Compare the two objects. More...

bool	operator<= (const PObject &obj) const
	Compare the two objects. More...

bool	operator>= (const PObject &obj) const
	Compare the two objects. More...

virtual void	PrintOn (ostream &strm) const
	Output the contents of the object to the stream. More...

virtual void	ReadFrom (istream &strm)
	Input the contents of the object from the stream. More...

Protected Member Functions
	PDECLARE_MUTEX (mutex)

Protected Member Functions inherited from PChannel
	PChannel (const PChannel &)

PChannel &	operator= (const PChannel &)

virtual PBoolean	ConvertOSError (P_INT_PTR libcReturnValue, ErrorGroup group=LastGeneralError)
	Convert an operating system error into platform independent error. More...

int	ReadCharWithTimeout (PTimeInterval &timeout)
	Read a character with specified timeout. More...

PBoolean	ReceiveCommandString (int nextChar, const PString &reply, PINDEX &pos, PINDEX start)

bool	CheckNotOpen ()

virtual int	os_errno () const

PBoolean	PXSetIOBlock (PXBlockType type, const PTimeInterval &timeout)

P_INT_PTR	GetOSHandleAsInt () const

int	PXClose ()

	PDECLARE_MUTEX (px_threadMutex)

	PDECLARE_MUTEX (px_writeMutex)

	PChannel ()
	Create the channel. More...

Protected Member Functions inherited from PObject
	PObject ()
	Constructor for PObject, made protected so cannot ever create one on its own. More...

Protected Attributes
BYTE *	queueBuffer

PINDEX	queueSize

PINDEX	queueLength

PINDEX	enqueuePos

PINDEX	dequeuePos

PSyncPoint	unempty

PSyncPoint	unfull

Protected Attributes inherited from PChannel
PTimeInterval	readTimeout
	Timeout for read operations. More...

PTimeInterval	writeTimeout
	Timeout for write operations. More...

atomic< P_INT_PTR >	os_handle
	The operating system file handle return by standard open() function. More...

PThreadLocalStorage< Status >	m_status [NumErrorGroups+1]

PXBlockType	px_lastBlockType

PThread *	px_readThread

PThread *	px_writeThread

PThread *	px_selectThread [3]

PCriticalSection	px_selectMutex [3]

Protected Attributes inherited from PObject
unsigned	m_traceContextIdentifier

Additional Inherited Members
Public Types inherited from PChannel
enum	PXBlockType { PXReadBlock, PXWriteBlock, PXAcceptBlock, PXConnectBlock }

enum	Errors { NoError, NotFound, FileExists, DiskFull, AccessDenied, DeviceInUse, BadParameter, NoMemory, NotOpen, Timeout, Interrupted, BufferTooSmall, Miscellaneous, ProtocolFailure, Unavailable, NumNormalisedErrors }
	Normalised error codes. More...

enum	ErrorGroup { LastReadError, LastWriteError, LastGeneralError, NumErrorGroups }
	Error groups. More...

typedef PNotifierTemplate < PChannel::AsyncContext & >	AsyncNotifier

enum	ShutdownValue { ShutdownRead = 0, ShutdownWrite = 1, ShutdownReadAndWrite = 2 }

Public Types inherited from PObject
enum	Comparison { LessThan = -1, EqualTo = 0, GreaterThan = 1 }
	Result of the comparison operation performed by the `Compare()` function. More...

Static Public Member Functions inherited from PChannel
static PString	GetErrorText (Errors lastError, int osError=0)
	Get error message description. More...

Static Public Member Functions inherited from PObject
static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject *from)

static __inline void	CopyTraceContextIdentifier (PObject *to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject to, const PObject from)

static __inline const char *	Class ()

static __inline const PObject *	PTraceObjectInstance (const char *)

static __inline const PObject *	PTraceObjectInstance (const PObject *obj)

template<typename T >
static Comparison	Compare2 (T v1, T v2)
	Compare two types, returning Comparison type. More...

static Comparison	InternalCompareObjectMemoryDirect (const PObject obj1, const PObject obj2, PINDEX size)
	Internal function caled from CompareObjectMemoryDirect() More...

Detailed Description

Class for implementing a serial queue channel in memory.

This implements a simple memory based First In First Out queue. Data written to an instance of the class may be read from the same instance at some later time.

The queue will block the read for the Read Timeout if the queue is empty. Similarly a write will be clocked for Write Timeout if the queue is full.

If there is any data to be read then it returns immediately with those bytes, so you must check the GetLastReadCount() to determine the actual number of bytes read and not rely on the count being passed into the read function.

Constructor & Destructor Documentation

PQueueChannel::PQueueChannel ( PINDEX queueSize = 0 )

Create a new queue channel with the specified maximum size.

Parameters

queueSize Queue size

PQueueChannel::~PQueueChannel ( )

Delete queue and release memory used.

Member Function Documentation

virtual PBoolean PQueueChannel::Close ( )

virtual

Close the file channel.

Returns: true if close was OK.

Reimplemented from PChannel.

PINDEX PQueueChannel::GetLength ( ) const

inline

Get the current queue length.

virtual PString PQueueChannel::GetName ( ) const

inlinevirtual

Get the platform and I/O channel type name of the channel.

For example, it would return the filename in PFile type channels.

Returns: the name of the channel.

Implements PChannel.

PINDEX PQueueChannel::GetSize ( ) const

inline

Get the queue size.

virtual PBoolean PQueueChannel::Open ( PINDEX queueSize )

virtual

Open a queue, allocating the queueSize bytes.

Parameters

queueSize Queue size

PQueueChannel::PDECLARE_MUTEX ( mutex )

protected

virtual PBoolean PQueueChannel::Read	(	void *	buf,
		PINDEX	len
	)

virtual

Low level read from the file channel.

The read timeout is ignored for file I/O. The GetLastReadCount() function returns the actual number of bytes read.

The GetErrorCode() function should be consulted after Read() returns false to determine what caused the failure.

Returns: true indicates that at least one character was read from the channel. false means no bytes were read due to timeout or some other I/O error.

Parameters

buf	Pointer to a block of memory to receive the read bytes.
len	Maximum number of bytes to read into the buffer.

Reimplemented from PChannel.

virtual PBoolean PQueueChannel::Write	(	const void *	buf,
		PINDEX	len
	)

virtual

Low level write to the file channel.

The write timeout is ignored for file I/O. The GetLastWriteCount() function returns the actual number of bytes written.

The GetErrorCode() function should be consulted after Write() returns false to determine what caused the failure.

Returns: true if at least len bytes were written to the channel.

Parameters

buf	Pointer to a block of memory to write.
len	Number of bytes to write.

Reimplemented from PChannel.

Member Data Documentation

PINDEX PQueueChannel::dequeuePos

protected

PINDEX PQueueChannel::enqueuePos

protected

BYTE* PQueueChannel::queueBuffer

protected

PINDEX PQueueChannel::queueLength

protected

PINDEX PQueueChannel::queueSize

protected

PSyncPoint PQueueChannel::unempty

protected

PSyncPoint PQueueChannel::unfull

protected

The documentation for this class was generated from the following file:

qchannel.h

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation