This class defines a thread of execution in the system. More...

#include <thread.h>

Inheritance diagram for PThread:

Collaboration diagram for PThread:

Classes
class	LocalStorageBase
	Thread local storage base class, see PThreadLocalStorage for template. More...

struct	Times
	Times for execution of the thread. More...

Public Member Functions
bool	IsAutoDelete () const

int	PXBlockOnChildTerminate (int pid, const PTimeInterval &timeout)

int	PXBlockOnIO (int handle, int type, const PTimeInterval &timeout)

void	PXAbortBlock () const

Overrides from <code>PObject</code>
void	PrintOn (ostream &strm) const
	Standard stream print function. More...

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

void	SetTraceContextIdentifier (unsigned id)

void	GetTraceContextIdentifier (PObject &obj)

void	GetTraceContextIdentifier (PObject *obj)

void	SetTraceContextIdentifier (const PObject &obj)

void	SetTraceContextIdentifier (const PObject *obj)

virtual	~PObject ()

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 PINDEX	HashFunction () const
	This function yields a hash value required by the `PDictionary` class. More...

virtual const char *	GetClass (unsigned ancestor=0) const
	Get the current dynamic type of the object instance. More...

PBoolean	IsClass (const char *cls) const

virtual PBoolean	InternalIsDescendant (const char *clsName) const
	Determine if the dynamic type of the current instance is a descendent of the specified class. More...

__inline const PObject *	PTraceObjectInstance () const

virtual Comparison	Compare (const PObject &obj) const
	Compare the two objects and return their relative rank. 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	ReadFrom (istream &strm)
	Input the contents of the object from the stream. More...

Protected Types
enum	Type { e_IsAutoDelete, e_IsManualDelete, e_IsProcess, e_IsExternal }

typedef std::list< const LocalStorageBase * >	LocalStorageList

Protected Attributes
enum PThread::Type	m_type

PINDEX	m_originalStackSize

PString	m_threadName

PMutex	m_threadNameMutex

PThreadIdentifier	m_threadId

LocalStorageList	m_localStorage

Protected Attributes inherited from PObject
unsigned	m_traceContextIdentifier

Construction
enum	Priority { LowestPriority, LowPriority, NormalPriority, HighPriority, HighestPriority, NumPriorities }
	Codes for thread priorities. More...

enum	AutoDeleteFlag { AutoDeleteThread, NoAutoDeleteThread }
	Codes for thread autodelete flag. More...

	PThread (PINDEX stack, AutoDeleteFlag deletion=AutoDeleteThread, Priority priorityLevel=NormalPriority, const PString &threadName=PString::Empty())
	Create a new thread instance. More...

	~PThread ()
	Destroy the thread, this simply calls the `Terminate()` function with all its restrictions and penalties. More...

Control functions
virtual void	Restart ()
	Restart a terminated thread using the same stack priority etc that was current when the thread terminated. More...

virtual void	Terminate ()
	Terminate the thread. More...

virtual PBoolean	IsTerminated () const
	Determine if the thread has been terminated or ran to completion. More...

void	WaitForTermination () const
	Block and wait for the thread to terminate. More...

PBoolean	WaitForTermination (const PTimeInterval &maxWait) const
	Block and wait for the thread to terminate. More...

virtual void	Suspend (PBoolean susp=true)
	Suspend or resume the thread. More...

virtual void	Resume ()
	Resume thread execution, this is identical to `Suspend(false)`. More...

virtual PBoolean	IsSuspended () const
	Determine if the thread is currently suspended. More...

virtual void	SetPriority (Priority priorityLevel)
	Set the priority of the thread relative to other threads in the current process. More...

virtual Priority	GetPriority () const
	Get the current priority of the thread in the current process. More...

virtual void	SetAutoDelete (AutoDeleteFlag deletion=AutoDeleteThread)
	Set the flag indicating thread object is to be automatically deleted when the thread ends. More...

void	SetNoAutoDelete ()
	Reet the flag indicating thread object is to be automatically deleted when the thread ends. More...

virtual PString	GetThreadName () const
	Get the name of the thread. More...

virtual void	SetThreadName (const PString &name)
	Change the name of the thread. More...

static void	Sleep (const PTimeInterval &delay)
	Suspend the current thread for the specified amount of time. More...

Miscellaneous
virtual PThreadIdentifier	GetThreadId () const
	Get operating system specific thread identifier for this thread. More...

bool	GetTimes (Times &times)
	Get the thread execution times. More...

virtual void	Main ()=0
	User override function for the main execution routine of the thread. More...

static PThreadIdentifier	GetCurrentThreadId ()

static PThread *	Current ()
	Get the currently running thread object instance. More...

static void	Yield ()
	Yield to another thread without blocking. More...

static PThread *	Create (const PNotifier &notifier, INT parameter=0, AutoDeleteFlag deletion=AutoDeleteThread, Priority priorityLevel=NormalPriority, const PString &threadName=PString::Empty(), PINDEX stackSize=0)
	Create a simple thread executing the specified notifier. More...

static PThread *	Create (const PNotifier &notifier, const PString &threadName)

Additional Inherited Members
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 PObject
static const char *	Class ()
	Get the name of the class as a C string. More...

static __inline const PObject *	PTraceObjectInstance (const char *)

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

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

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

Friends inherited from PObject

Detailed Description

This class defines a thread of execution in the system.

A thread is an independent flow of processor instructions. This differs from a process which also embodies a program address space and resource allocation. So threads can share memory and resources as they run in the context of a given process. A process always contains at least one thread. This is reflected in this library by the PProcess class being descended from the PThread class.

The implementation of a thread is platform dependent, but it is assumed that the platform has some support for native threads. Previous versions of PTLib/PWLib have some support for co-operative threads, but this has been removed.

Member Typedef Documentation

typedef std::list<const LocalStorageBase *> PThread::LocalStorageList

protected

Member Enumeration Documentation

enum PThread::AutoDeleteFlag

Codes for thread autodelete flag.

Enumerator
AutoDeleteThread	Automatically delete thread object on termination.
NoAutoDeleteThread	Don't delete thread as it may not be on heap.

enum PThread::Priority

Codes for thread priorities.

Enumerator
LowestPriority	Will only run if all other threads are blocked.
LowPriority	Runs approximately half as often as normal.
NormalPriority	Normal priority for a thread.
HighPriority	Runs approximately twice as often as normal.
HighestPriority	Is only thread that will run, unless blocked.
NumPriorities

enum PThread::Type

protected

Enumerator
e_IsAutoDelete
e_IsManualDelete
e_IsProcess
e_IsExternal

Constructor & Destructor Documentation

PThread::PThread	(	PINDEX	stack,
		AutoDeleteFlag	deletion = `AutoDeleteThread`,
		Priority	priorityLevel = `NormalPriority`,
		const PString &	threadName = `PString::Empty()`
	)

Create a new thread instance.

Unless the startSuspended parameter is true, the threads Main() function is called to execute the code for the thread.

Note that the exact timing of the execution of code in threads can never be predicted. Thus you you can get a race condition on intialising a descendent class. To avoid this problem a thread is always started suspended. You must call the Resume() function after your descendent class construction is complete.

If synchronisation is required between threads then the use of semaphores is essential.

If the deletion is set to AutoDeleteThread then the PThread is assumed to be allocated with the new operator and may be freed using the delete operator as soon as the thread is terminated or executes to completion (usually the latter).

The stack size argument is highly platform specific and should alamost always be zero for the default.

Parameters

stack	Stack size on some platforms, 0 == default
deletion	Automatically delete PThread instance on termination of thread.
priorityLevel	Initial priority of thread.
threadName	The name of the thread (for Debug/Trace)

PThread::~PThread ( )

Destroy the thread, this simply calls the Terminate() function with all its restrictions and penalties.

See that function for more information.

Note that the correct way for a thread to terminate is to return from the Main() function.

Member Function Documentation

static PThread* PThread::Create	(	const PNotifier &	notifier,
		INT	parameter = `0`,
		AutoDeleteFlag	deletion = `AutoDeleteThread`,
		Priority	priorityLevel = `NormalPriority`,
		const PString &	threadName = `PString::Empty()`,
		PINDEX	stackSize = `0`
	)

static

Create a simple thread executing the specified notifier.

This creates a simple PThread class that automatically executes the function defined by the PNotifier in the context of a new thread.

Parameters

notifier	Function to execute in thread.
parameter	Parameter value to pass to notifier.
deletion	Automatically delete PThread instance on termination of thread.
priorityLevel	Initial priority of thread.
threadName	The name of the thread (for Debug/Trace)
stackSize	Stack size on some platforms, 0 == default

static PThread* PThread::Create	(	const PNotifier &	notifier,
		const PString &	threadName
	)

inlinestatic

Parameters

notifier	Function to execute in thread.
threadName	The name of the thread (for Debug/Trace)

References Create(), NoAutoDeleteThread, and NormalPriority.

Referenced by Create().

static PThread* PThread::Current ( )

static

Get the currently running thread object instance.

It is possible, even likely, that the smae code may be executed in the context of differenct threads. Under some circumstances it may be necessary to know what the current codes thread is and this static function provides that information.

Returns: pointer to current thread.

static PThreadIdentifier PThread::GetCurrentThreadId ( )

static

virtual Priority PThread::GetPriority ( ) const

virtual

Get the current priority of the thread in the current process.

Returns: current thread priority.

virtual PThreadIdentifier PThread::GetThreadId ( ) const

inlinevirtual

Get operating system specific thread identifier for this thread.

Note that the return value from these functions is only valid if called by the owning thread. Calling this function for another thread that may be terminating is a very bad idea.

References m_threadId.

virtual PString PThread::GetThreadName ( ) const

virtual

Get the name of the thread.

Thread names are a optional debugging aid.

Returns: current thread name.

bool PThread::GetTimes ( Times & times )

Get the thread execution times.

Parameters

times Times for thread execution.

bool PThread::IsAutoDelete ( ) const

inline

References e_IsAutoDelete, e_IsExternal, and m_type.

virtual PBoolean PThread::IsSuspended ( ) const

virtual

Determine if the thread is currently suspended.

This checks the suspension count and if greater than zero returns true for a suspended thread.

Returns: true if thread is suspended.

virtual PBoolean PThread::IsTerminated ( ) const

virtual

Determine if the thread has been terminated or ran to completion.

Returns: true if the thread has been terminated.

virtual void PThread::Main ( )

pure virtual

User override function for the main execution routine of the thread.

A descendent class must provide the code that will be executed in the thread within this function.

Note that the correct way for a thread to terminate is to return from this function.

Implemented in PThreadObj2Arg< ObjType, Arg1Type, Arg2Type >, PThreadObj1Arg< ObjType, Arg1Type >, PLibraryProcess, PThreadObj< ObjType >, PThreadObj< PSNMPServer >, PThread3Arg< Arg1Type, Arg2Type, Arg3Type >, PThread2Arg< Arg1Type, Arg2Type >, PThread1Arg< Arg1Type >, PThreadFunctor< Functor >, PThreadMain, XMPP::BaseStreamHandler, PServiceProcess, and PHTTPServiceThread.

void PThread::PrintOn ( ostream & strm ) const

virtual

Standard stream print function.

The PObject class has a << operator defined that calls this function polymorphically.

Parameters

strm	Stream to output text representation

Reimplemented from PObject.

void PThread::PXAbortBlock ( ) const

int PThread::PXBlockOnChildTerminate	(	int	pid,
		const PTimeInterval &	timeout
	)

int PThread::PXBlockOnIO	(	int	handle,
		int	type,
		const PTimeInterval &	timeout
	)

virtual void PThread::Restart ( )

virtual

Restart a terminated thread using the same stack priority etc that was current when the thread terminated.

If the thread is still running then this function is ignored.

virtual void PThread::Resume ( )

virtual

Resume thread execution, this is identical to Suspend(false).

The Resume() method may be called from within the constructor of a PThread descendant. However, the Resume() should be in the constructor of the most descendant class. So, if you have a class B (which is descended of PThread), and a class C (which is descended of B), placing the call to Resume() in the constructor of B is unwise.

If you do place a call to Resume() in the constructor, it should be at the end of the constructor, after all the other initialisation in the constructor.

The reason the call to Resume() should be at the end of the construction process is simple - you want the thread to start when all the variables in the class have been correctly initialised.

Referenced by PThread1Arg< Arg1Type >::PThread1Arg(), PThread2Arg< Arg1Type, Arg2Type >::PThread2Arg(), PThread3Arg< Arg1Type, Arg2Type, Arg3Type >::PThread3Arg(), PThreadFunctor< Functor >::PThreadFunctor(), PThreadMain::PThreadMain(), PThreadObj< PSNMPServer >::PThreadObj(), PThreadObj1Arg< ObjType, Arg1Type >::PThreadObj1Arg(), and PThreadObj2Arg< ObjType, Arg1Type, Arg2Type >::PThreadObj2Arg().

virtual void PThread::SetAutoDelete ( AutoDeleteFlag deletion = AutoDeleteThread )

virtual

Set the flag indicating thread object is to be automatically deleted when the thread ends.

Parameters

deletion New auto delete setting.

Referenced by SetNoAutoDelete().

void PThread::SetNoAutoDelete ( )

inline

Reet the flag indicating thread object is to be automatically deleted when the thread ends.

References NoAutoDeleteThread, and SetAutoDelete().

virtual void PThread::SetPriority ( Priority priorityLevel )

virtual

Set the priority of the thread relative to other threads in the current process.

Parameters

priorityLevel New priority for thread.

virtual void PThread::SetThreadName ( const PString & name )

virtual

Change the name of the thread.

Thread names are a optional debugging aid.

Returns: current thread name.

Parameters

name	New name for the thread.

static void PThread::Sleep ( const PTimeInterval & delay )

static

Suspend the current thread for the specified amount of time.

Parameters

delay Time interval to sleep for.

virtual void PThread::Suspend ( PBoolean susp = true )

virtual

Suspend or resume the thread.

If susp is true this increments an internal count of suspensions that must be matched by an equal number of calls to Resume() or Suspend(false) before the thread actually executes again.

If susp is false then this decrements the internal count of suspensions. If the count is <= 0 then the thread will run. Note that the thread will not be suspended until an equal number of Suspend(true) calls are made.

Parameters

susp	Flag to suspend or resume a thread.

virtual void PThread::Terminate ( )

virtual

Terminate the thread.

It is highly recommended that this is not used except in abnormal abort situations as not all clean up of resources allocated to the thread will be executed. This is especially true in C++ as the destructors of objects that are automatic variables are not called causing at the very least the possiblity of memory leaks.

Note that the correct way for a thread to terminate is to return from the Main() function or self terminate by calling Terminate() within the context of the thread which can then assure that all resources are cleaned up.

Reimplemented in PProcess, and PServiceProcess.

void PThread::WaitForTermination ( ) const

Block and wait for the thread to terminate.

PBoolean PThread::WaitForTermination ( const PTimeInterval & maxWait ) const

Block and wait for the thread to terminate.

Returns: false if the thread has not terminated and the timeout has expired, true otherwise.

Parameters

maxWait Maximum time to wait for termination.

static void PThread::Yield ( )

static

Yield to another thread without blocking.

This duplicates the implicit thread yield that may occur on some I/O operations or system calls.

This may not be implemented on all platforms.

Member Data Documentation

LocalStorageList PThread::m_localStorage

protected

PINDEX PThread::m_originalStackSize

protected

PThreadIdentifier PThread::m_threadId

protected

Referenced by GetThreadId().

PString PThread::m_threadName

protected

PMutex PThread::m_threadNameMutex

protected

enum PThread::Type PThread::m_type

protected

Referenced by IsAutoDelete().

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

thread.h

Classes

Public Member Functions

Protected Types

Protected Attributes

Construction

Control functions

Miscellaneous

Additional Inherited Members

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation