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PChannel Class Reference

#include <channel.h>

Inheritance diagram for PChannel:

PObject PConsoleChannel PFile PIndirectChannel PPipeChannel PQueueChannel PSerialChannel PSocket PSoundChannel PVideoChannel

List of all members.

Detailed Description

Abstract class defining I/O channel semantics. An I/O channel can be a serial port, pipe, network socket or even just a simple file. Anything that requires opening and closing then reading and/or writing from.

A descendent would typically have constructors and an Open()# function which enables access to the I/O channel it represents. The Read()# and Write()# functions would then be overridden to the platform and I/O specific mechanisms required.

The general model for a channel is that the channel accepts and/or supplies a stream of bytes. The access to the stream of bytes is via a set of functions that allow certain types of transfer. These include direct transfers, buffered transfers (via iostream) or asynchronous transfers.

The model also has the fundamental state of the channel being { open} or { closed}. A channel instance that is closed contains sufficient information to describe the channel but does not allocate or lock any system resources. An open channel allocates or locks the particular system resource. The act of opening a channel is a key event that may fail. In this case the channel remains closed and error values are set.

Definition at line 277 of file channel.h.

Comparison functions

enum  Comparison { LessThan = -1, EqualTo = 0, GreaterThan = 1 }
virtual Comparison CompareObjectMemoryDirect (const PObject &obj) const
bool operator!= (const PObject &obj) const
bool operator< (const PObject &obj) const
bool operator<= (const PObject &obj) const
bool operator== (const PObject &obj) const
bool operator> (const PObject &obj) const
bool operator>= (const PObject &obj) const

Error functions

enum  ErrorGroup { LastReadError, LastWriteError, LastGeneralError, NumErrorGroups }
enum  Errors {
  NoError, NotFound, FileExists, DiskFull,
  AccessDenied, DeviceInUse, BadParameter, NoMemory,
  NotOpen, Timeout, Interrupted, BufferTooSmall,
  Miscellaneous, ProtocolFailure, NumNormalisedErrors
Errors GetErrorCode (ErrorGroup group=NumErrorGroups) const
int GetErrorNumber (ErrorGroup group=NumErrorGroups) const
virtual PString GetErrorText (ErrorGroup group=NumErrorGroups) const
static PString GetErrorText (Errors lastError, int osError=0)

Miscellaneous functions

enum  ShutdownValue { ShutdownRead = 0, ShutdownWrite = 1, ShutdownReadAndWrite = 2 }
void AbortCommandString ()
virtual BOOL Close ()
BOOL SendCommandString (const PString &command)
BOOL SetBufferSize (PINDEX newSize)
virtual BOOL Shutdown (ShutdownValue option)

Scattered read/write functions

typedef std::vector< SliceVectorOfSlice
virtual BOOL Read (const VectorOfSlice &slices)
virtual BOOL Write (const VectorOfSlice &slices)

Run Time Type functions

virtual const char * GetClass (unsigned=0) const
virtual BOOL InternalIsDescendant (const char *clsName) const
BOOL IsClass (const char *cls) const
static const char * Class ()

I/O functions

virtual void PrintOn (ostream &strm) const
virtual void ReadFrom (istream &strm)
ostream & operator<< (ostream &strm, const PObject &obj)
istream & operator>> (istream &strm, PObject &obj)

Public Types

enum  PXBlockType { PXReadBlock, PXWriteBlock, PXAcceptBlock, PXConnectBlock }

Public Member Functions

Miscellaneous functions
virtual PObjectClone () const
Overrides from class PObject
virtual Comparison Compare (const PObject &obj) const
virtual PINDEX HashFunction () const
Information functions
virtual PChannelGetBaseReadChannel () const
virtual PChannelGetBaseWriteChannel () const
int GetHandle () const
virtual PString GetName () const
virtual BOOL IsOpen () const
Reading functions
virtual PINDEX GetLastReadCount () const
PTimeInterval GetReadTimeout () const
virtual void OnReadComplete (void *buf, PINDEX len)
virtual BOOL Read (void *buf, PINDEX len)
virtual BOOL ReadAsync (void *buf, PINDEX len)
BOOL ReadBlock (void *buf, PINDEX len)
virtual int ReadChar ()
PString ReadString (PINDEX len)
void SetReadTimeout (const PTimeInterval &time)
Writing functions
virtual PINDEX GetLastWriteCount () const
PTimeInterval GetWriteTimeout () const
virtual void OnWriteComplete (const void *buf, PINDEX len)
void SetWriteTimeout (const PTimeInterval &time)
virtual BOOL Write (const void *buf, PINDEX len)
virtual BOOL WriteAsync (const void *buf, PINDEX len)
BOOL WriteChar (int c)
BOOL WriteString (const PString &str)
 PChannel ()
 Create the channel.
 ~PChannel ()
 Close down the channel.

Static Public Member Functions

static BOOL ConvertOSError (int libcReturnValue, Errors &lastError, int &osError)

Protected Member Functions

virtual BOOL ConvertOSError (int libcReturnValue, ErrorGroup group=LastGeneralError)
PChanneloperator= (const PChannel &)
 PChannel (const PChannel &)
int PXClose ()
BOOL PXSetIOBlock (PXBlockType type, const PTimeInterval &timeout)
int ReadCharWithTimeout (PTimeInterval &timeout)
BOOL ReceiveCommandString (int nextChar, const PString &reply, PINDEX &pos, PINDEX start)
BOOL SetErrorValues (Errors errorCode, int osError, ErrorGroup group=LastGeneralError)

Protected Attributes

PString channelName
Errors lastErrorCode [NumErrorGroups+1]
 The platform independant error code.
int lastErrorNumber [NumErrorGroups+1]
 The operating system error number (eg as returned by errno).
PINDEX lastReadCount
 Number of byte last read by the Read() function.
PINDEX lastWriteCount
 Number of byte last written by the Write() function.
int os_handle
 The operating system file handle return by standard open() function.
PXBlockType px_lastBlockType
PMutex px_selectMutex
PMutex px_threadMutex
PMutex px_writeMutex
PTimeInterval readTimeout
 Timeout for read operations.
PTimeInterval writeTimeout
 Timeout for write operations.

Private Member Functions

void Construct ()
 PCLASSINFO (PChannel, PObject)

Private Attributes

BOOL abortCommandString


struct  Slice

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

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