PIGrabberBase< T > Class Template Reference

Base polling grabber thread with a pending queue, recording virtual methods, and a last-item snapshot. More...

#include <pigrabberbase.h>

Inheritance diagram for PIGrabberBase< T >:

Public Member Functions
	PIGrabberBase ()
	Constructs a closed non-recording grabber.
virtual	~PIGrabberBase ()
	Stops the grabber thread and releases recording/open state.
virtual bool	isOpened () const
	Returns whether the grabber is currently opened.
virtual bool	isRecording () const
	Returns whether captured items are currently being recorded.
virtual void	startRecord (const PIString &filename)
	Starts recording subsequent captured items if the grabber is opened and recording is not active yet.
virtual void	stopRecord ()
	Stops recording if it is active.
T	last () const
	Returns a copy of the last successfully captured item. This snapshot is kept separately from the pending queue and is not consumed by dequeue().
bool	isEmpty ()
	Returns whether the pending queue is empty.
int	queSize ()
	Returns the current number of pending captured items.
T	dequeue ()
	Dequeues and returns the oldest pending captured item. If the queue is empty, returns a default-constructed value.
void	stopGrabber (bool wait_forever=true)
	Stops the grabber thread. With wait_forever equal to false the method waits briefly and may terminate the thread forcibly.
bool	open ()
	Opens the grabber immediately. The thread loop also tries to open it automatically when running in a closed state.
void	close ()
	Closes the grabber and resets the last-item snapshot.
const PIDiagnostics &	diag () const
	Returns diagnostics collected for captured and recorded items.
void	clear ()
	Clears only the pending queue. The value returned by last() is not changed.
void	restart ()
	Clears the pending queue and closes the grabber.
Public Member Functions inherited from PIThread
	PIThread (void *data, ThreadFunc func, bool startNow=false, PISystemTime loop_delay={})
	Constructs a thread with user data, callback and optional immediate start.
	PIThread (std::function< void()> func, bool startNow=false, PISystemTime loop_delay={})
	Constructs a thread with a callback without custom data.
	PIThread (bool startNow=false, PISystemTime loop_delay={})
	Constructs a subclass-oriented thread with an optional loop delay.
virtual	~PIThread ()
	Destroys the thread object. If it is still running, destruction forces termination.
bool	start ()
	Starts the thread with the stored callback and loop delay.
bool	start (PISystemTime loop_delay)
	Stores a new loop delay and starts the thread.
bool	start (ThreadFunc func)
	Stores a callback and starts the thread.
bool	start (ThreadFunc func, PISystemTime loop_delay)
	Stores a callback and loop delay, then starts the thread.
bool	start (std::function< void()> func)
	Stores a lambda callback and starts the thread.
bool	start (std::function< void()> func, PISystemTime loop_delay)
	Stores a lambda callback and loop delay, then starts the thread.
bool	startOnce ()
	Starts a one-shot thread without the repeating loop. More...
bool	startOnce (ThreadFunc func)
	Stores a callback and starts one-shot execution. More...
bool	startOnce (std::function< void()> func)
	Stores a lambda callback and starts one-shot execution.
bool	stopAndWait (int timeout_ms) DEPRECATEDM("use stopAndWait(PISystemTime)")
	Deprecated overload of stopAndWait() that accepts milliseconds.
bool	stopAndWait (PISystemTime timeout={})
	Requests stop and waits for thread completion. Returns false if the timeout expires.
void	setData (void *d)
	Sets the data pointer passed to ThreadFunc callbacks.
void	setSlot (ThreadFunc func)
	Sets the callback executed after each run() pass.
void	setSlot (std::function< void()> func)
	Sets a lambda callback executed after each run() pass.
void	setPriority (PIThread::Priority prior)
	Sets the priority hint. If the thread is already running, applies it immediately.
void *	data () const
	Returns the data pointer passed to ThreadFunc callbacks.
PIThread::Priority	priority () const
	Returns the configured priority hint.
bool	isRunning () const
	Returns whether the thread is currently running.
bool	isStopping () const
	Returns whether stop has been requested and the thread is still finishing.
bool	waitForStart (PISystemTime timeout={})
	Waits until the thread starts. Returns false if the timeout expires first.
bool	waitForStart (int timeout_msecs) DEPRECATEDM("use waitForStart(PISystemTime)")
	Deprecated overload of waitForStart() that accepts milliseconds. More...
bool	waitForFinish (PISystemTime timeout={})
	Waits for thread completion. Returns false if the timeout expires first.
bool	waitForFinish (int timeout_msecs) DEPRECATEDM("use waitForFinish(PISystemTime)")
	Deprecated overload of waitForFinish() that accepts milliseconds. More...
void	needLockRun (bool need)
	Enables locking of the internal mutex around begin(), run(), callbacks and end().
PIMutex &	mutex () const
	Returns the internal mutex used by lock(), unlock() and needLockRun().
llong	tid () const
	Returns the system thread identifier, or -1 when the thread is not running.
void	stop ()
	Requests graceful thread shutdown. More...
void	terminate ()
	Forces thread termination. Use only as a last resort. More...
void	lock () const
	Locks the internal mutex.
void	unlock () const
	Unlocks the internal mutex.
void	started ()
	Raised after the thread has started.
void	stopped ()
	Raised when thread shutdown begins.
Public Member Functions inherited from PIObject
	PIObject (const PIString &name=PIString())
	Constructs an object and initializes its name property.
virtual	~PIObject ()
	Destroys the object, raises deleted() and disconnects it from the event graph.
PIString	name () const
	Returns the name property of this object.
virtual const char *	className () const
	Returns the registered class name of this object.
virtual uint	classNameID () const
	Returns the hash of className().
virtual const char *	parentClassName () const
	Returns the registered parent class name, or an empty string for the root.
bool	debug () const
	Returns whether piCoutObj output is enabled for this object.
void	setName (const PIString &name)
	Sets the name property of this object.
void	setDebug (bool debug)
	Enables or disables piCoutObj output for this object.
PIVariant	property (const char *name) const
	Returns the property with name "name".
void	setProperty (const char *name, const PIVariant &value)
	Sets the property "name" to "value" and creates it if needed. More...
bool	isPropertyExists (const char *name) const
	Returns whether the property "name" exists.
void	setThreadSafe (bool yes)
	Enables or disables the internal object mutex during handler execution. More...
bool	isThreadSafe () const
	Returns whether the internal object mutex is enabled for handler execution.
bool	execute (const PIString &method, const PIVector< PIVariantSimple > &vl)
	Executes a registered method or handler method by name with the supplied arguments. More...
bool	execute (const PIString &method)
	Overload of execute() for a method without arguments.
bool	execute (const PIString &method, const PIVariantSimple &v0)
	Overload of execute() for one argument.
bool	execute (const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1)
	Overload of execute() for two arguments.
bool	execute (const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2)
	Overload of execute() for three arguments.
bool	execute (const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2, const PIVariantSimple &v3)
	Overload of execute() for four arguments.
bool	executeQueued (PIObject *performer, const PIString &method, const PIVector< PIVariantSimple > &vl)
	Queues execution of a registered method on the performer object. More...
bool	executeQueued (PIObject *performer, const PIString &method)
	Overload of executeQueued() for a method without arguments.
bool	executeQueued (PIObject *performer, const PIString &method, const PIVariantSimple &v0)
	Overload of executeQueued() for one argument.
bool	executeQueued (PIObject *performer, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1)
	Overload of executeQueued() for two arguments.
bool	executeQueued (PIObject *performer, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2)
	Overload of executeQueued() for three arguments.
bool	executeQueued (PIObject *performer, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2, const PIVariantSimple &v3)
	Overload of executeQueued() for four arguments.
void	dump (const PIString &line_prefix=PIString()) const
	Dumps object diagnostics to the project output stream.
PIStringList	scopeList () const
	Returns the registered inheritance scope of this object, including its own class.
PIStringList	methodsEH () const
	Returns full signatures of all registered event and handler methods for this class scope.
bool	isMethodEHContains (const PIString &name) const
	Returns whether a registered event or handler method with this name exists.
PIString	methodEHArguments (const PIString &name) const
	Returns the comma-separated argument type list of a registered method.
PIString	methodEHFullFormat (const PIString &name) const
	Returns the full registered signature of a method.
PIString	methodEHFromAddr (const void *addr) const
	Returns the registered method name for the specified entry-point address.
void	piDisconnect (const PIString &sig, PIObject *dest, void *ev_h)
	Disconnects this source object from a specific destination handler for event "sig".
void	piDisconnect (const PIString &sig, PIObject *dest)
	Disconnects this source object from all connections of event "sig" to destination object "dest".
void	piDisconnect (const PIString &sig)
	Disconnects this source object from all connections of event "sig".
bool	isPIObject () const
	Returns whether this pointer still refers to a live PIObject instance.
template<typename T >
bool	isTypeOf () const
	Returns whether this object belongs to class "T" or one of its registered descendants.
template<typename T >
T *	cast () const
	Returns this object cast to "T" when isTypeOf<T>() succeeds, otherwise nullptr.
void	callQueuedEvents ()
	Executes all queued deliveries posted to this performer object.
bool	maybeCallQueuedEvents ()
	Executes queued deliveries only when this object was used as a performer. More...
void	deleteLater ()
	Schedules the object for deferred deletion. More...
void	deleted (PIObject *o)
	Raised immediately before object destruction. More...

Protected Member Functions
virtual void	init ()
	Virtual method executed once when the thread starts, before polling begins.
virtual bool	openInternal ()=0
	Opens the underlying grabber resource.
virtual void	closeInternal ()=0
	Closes the underlying grabber resource.
virtual int	get (T &val)=0
	Polls the next item into val. Return 0 when a new item was captured, a positive value when no item is ready yet, and a negative value on failure that should close the grabber.
virtual void	record (const T &val)
	Records a captured item when recording mode is active.
virtual void	startRecordInternal (const PIString &filename)
	Virtual method called before the recording flag becomes active.
virtual void	stopRecordInternal ()
	Virtual method called after the recording flag is cleared.
virtual void	begin ()
	Virtual method executed once after the system thread starts and before started().
virtual void	run ()
	Virtual method executed on each loop iteration until stop is requested.
virtual void	end ()
	Virtual method executed once during thread shutdown after stopped().
Protected Member Functions inherited from PIObject
PIObject *	emitter () const
	Returns the source object that raised the current event. More...
virtual void	propertyChanged (const char *name)
	Virtual method called after property "name" has been changed by setProperty().

Events
void	dataReady ()
	Raised after a new item has been captured, queued, and copied into last().
void	opened ()
	Raised when open() switches the grabber into the opened state.
void	closed ()
	Raised when close() closes a previously opened grabber.

Additional Inherited Members
Public Types inherited from PIThread
enum	Priority {   piLowerst , piLow , piNormal , piHigh ,   piHighest }
	Thread priority hint. More...
Static Public Member Functions inherited from PIThread
static void	runOnce (PIObject *object, const char *handler, const PIString &name=PIString())
	Creates a temporary thread and invokes handler handler of object object on it. More...
static void	runOnce (std::function< void()> func, const PIString &name=PIString())
	Creates a temporary thread and runs lambda expression func on it. More...
Static Public Member Functions inherited from PIObject
static bool	execute (PIObject *o, const PIString &method, const PIVector< PIVariantSimple > &vl)
	Static convenience wrapper for execute().
static bool	execute (PIObject *o, const PIString &method)
	Static overload of execute() without arguments.
static bool	execute (PIObject *o, const PIString &method, const PIVariantSimple &v0)
	Static overload of execute() for one argument.
static bool	execute (PIObject *o, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1)
	Static overload of execute() for two arguments.
static bool	execute (PIObject *o, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2)
	Static overload of execute() for three arguments.
static bool	execute (PIObject *o, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2, const PIVariantSimple &v3)
	Static overload of execute() for four arguments.
static bool	executeQueued (PIObject *o, PIObject *performer, const PIString &method, const PIVector< PIVariantSimple > &vl)
	Static convenience wrapper for executeQueued().
static bool	executeQueued (PIObject *o, PIObject *performer, const PIString &method)
	Static overload of executeQueued() without arguments.
static bool	executeQueued (PIObject *o, PIObject *performer, const PIString &method, const PIVariantSimple &v0)
	Static overload of executeQueued() for one argument.
static bool	executeQueued (PIObject *o, PIObject *performer, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1)
	Static overload of executeQueued() for two arguments.
static bool	executeQueued (PIObject *o, PIObject *performer, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2)
	Static overload of executeQueued() for three arguments.
static bool	executeQueued (PIObject *o, PIObject *performer, const PIString &method, const PIVariantSimple &v0, const PIVariantSimple &v1, const PIVariantSimple &v2, const PIVariantSimple &v3)
	Static overload of executeQueued() for four arguments.
static PIObject::Connection	piConnect (PIObject *src, const PIString &sig, PIObject *dest_o, void *dest, void *ev_h, void *e_h, int args, const char *loc)
	Low-level direct connection helper behind the legacy CONNECT* macros.
static PIObject::Connection	piConnectU (PIObject *src, const PIString &sig, PIObject *dest_o, void *dest, const PIString &hname, const char *loc, PIObject *performer=0)
	Low-level name-based connection helper behind CONNECTU() and CONNECTU_QUEUED().
static PIObject::Connection	piConnectLS (PIObject *src, const PIString &sig, std::function< void()> *f, const char *loc)
	Low-level helper that connects an event to a lambda or functor wrapper.
static void	piDisconnect (PIObject *src, const PIString &sig, PIObject *dest, void *ev_h)
	Disconnects source object "src" from a specific destination handler for event "sig".
static void	piDisconnect (PIObject *src, const PIString &sig, PIObject *dest)
	Disconnects source object "src" from all connections of event "sig" to destination object "dest".
static void	piDisconnect (PIObject *src, const PIString &sig)
	Disconnects source object "src" from all connections of event "sig".
static void	raiseEvent (PIObject *sender, const uint eventID)
	Internal event delivery helper for registered events without arguments.
template<typename T0 >
static void	raiseEvent (PIObject *sender, const uint eventID, const T0 &v0=T0())
	Internal event delivery helper for registered events with one argument.
template<typename T0 , typename T1 >
static void	raiseEvent (PIObject *sender, const uint eventID, const T0 &v0=T0(), const T1 &v1=T1())
	Internal event delivery helper for registered events with two arguments.
template<typename T0 , typename T1 , typename T2 >
static void	raiseEvent (PIObject *sender, const uint eventID, const T0 &v0=T0(), const T1 &v1=T1(), const T2 &v2=T2())
	Internal event delivery helper for registered events with three arguments.
template<typename T0 , typename T1 , typename T2 , typename T3 >
static void	raiseEvent (PIObject *sender, const uint eventID, const T0 &v0=T0(), const T1 &v1=T1(), const T2 &v2=T2(), const T3 &v3=T3())
	Internal event delivery helper for registered events with four arguments.
static PIObject *	findByName (const PIString &name)
	Returns the first live object with name "name", or nullptr.
static bool	isPIObject (const PIObject *o)
	Returns whether "o" points to a live PIObject instance.
static bool	isPIObject (const void *o)
	Overload of isPIObject() for an untyped pointer.
template<typename T >
static bool	isTypeOf (const PIObject *o)
	Returns whether "o" belongs to class "T" or one of its registered descendants.
template<typename T >
static bool	isTypeOf (const void *o)
	Overload of isTypeOf() for an untyped pointer.
static PIString	simplifyType (const char *a, bool readable=true)
	Simplifies a C++ type spelling for registered-method metadata.
Related Functions inherited from PIObject
#define	piCoutObj
	Macro used for conditional (piDebug && PIObject::debug()) output to PICout(StdOut) for subclasses of PIObject.
#define	piCerrObj
	Macro used for conditional (piDebug && PIObject::debug()) output to PICout(StdErr) for subclasses of PIObject.
#define	PIOBJECT(name)
	Put this macro inside a direct PIObject subclass definition to enable registered events, event handlers and class metadata.
#define	PIOBJECT_SUBCLASS(name, parent)
	Put this macro inside a PIObject subclass definition to inherit registered methods and class scope from "parent".
#define	EVENT_HANDLER0(ret, name)   ret name()
	Declare a registered event handler method with signature ret name().
#define	EVENT_HANDLER1(ret, name, type0, var0)   ret name(type0 var0)
	Declare a registered event handler method with one argument.
#define	EVENT_HANDLER2(ret, name, type0, var0, type1, var1)   ret name(type0 var0, type1 var1)
	Declare a registered event handler method with two arguments.
#define	EVENT_HANDLER3(ret, name, type0, var0, type1, var1, type2, var2)   ret name(type0 var0, type1 var1, type2 var2)
	Declare a registered event handler method with three arguments.
#define	EVENT_HANDLER4(ret, name, type0, var0, type1, var1, type2, var2, type3, var3)    ret name(type0 var0, type1 var1, type2 var2, type3 var3)
	Declare a registered event handler method with four arguments.
#define	EVENT_HANDLER   EVENT_HANDLER0
	Synonym of EVENT_HANDLER0.
#define	EVENT_VHANDLER0(ret, name)   virtual ret name()
	Declare a virtual registered event handler method with signature virtual ret name().
#define	EVENT_VHANDLER1(ret, name, type0, var0)   virtual ret name(type0 var0)
	Declare a virtual registered event handler method with one argument.
#define	EVENT_VHANDLER2(ret, name, type0, var0, type1, var1)   virtual ret name(type0 var0, type1 var1)
	Declare a virtual registered event handler method with two arguments.
#define	EVENT_VHANDLER3(ret, name, type0, var0, type1, var1, type2, var2)   virtual ret name(type0 var0, type1 var1, type2 var2)
	Declare a virtual registered event handler method with three arguments.
#define	EVENT_VHANDLER4(ret, name, type0, var0, type1, var1, type2, var2, type3, var3)    virtual ret name(type0 var0, type1 var1, type2 var2, type3 var3)
	Declare a virtual registered event handler method with four arguments.
#define	EVENT_VHANDLER   EVENT_VHANDLER0
	Synonym of EVENT_VHANDLER0.
#define	EVENT0(name)   void name();
	Declare an event method with no arguments.
#define	EVENT1(name, type0, var0)   void name(type0 var0);
	Declare an event method with one argument.
#define	EVENT2(name, type0, var0, type1, var1)   void name(type0 var0, type1 var1);
	Declare an event method with two arguments.
#define	EVENT3(name, type0, var0, type1, var1, type2, var2)   void name(type0 var0, type1 var1, type2 var2);
	Declare an event method with three arguments.
#define	EVENT4(name, type0, var0, type1, var1, type2, var2, type3, var3)   void name(type0 var0, type1 var1, type2 var2, type3 var3);
	Declare an event method with four arguments.
#define	EVENT   EVENT0
	Synonym of EVENT0.
#define	RAISE_EVENT0(src, event)
	Compatibility helper that raises event "event" on source object "src".
#define	RAISE_EVENT1(src, event, v0)
	Compatibility helper that raises event "event" with one argument.
#define	RAISE_EVENT2(src, event, v0, v1)
	Compatibility helper that raises event "event" with two arguments.
#define	RAISE_EVENT3(src, event, v0, v1, v2)
	Compatibility helper that raises event "event" with three arguments.
#define	RAISE_EVENT4(src, event, v0, v1, v2, v3)
	Compatibility helper that raises event "event" with four arguments.
#define	CONNECTU(src, event, dest, handler)
	Connect event "event" from object "src" to event handler or event "handler" of object "dest". More...
#define	CONNECTU_QUEUED(src, event, dest, handler, performer)
	Connect event "event" from object "src" to event handler or event "handler" of object "dest". More...
#define	CONNECTL(src, event, functor)
	Connect event "event" from object "src" to lambda-expression "functor". More...
#define	CONNECT0(ret, src, event, dest, handler)
	Legacy compatibility helper that connects an event to a registered handler with compile-time signature spelling. More...
#define	CONNECT1(ret, type0, src, event, dest, handler)
	Legacy compatibility helper for a one-argument registered event or handler. More...
#define	CONNECT2(ret, type0, type1, src, event, dest, handler)
	Legacy compatibility helper for a two-argument registered event or handler. More...
#define	CONNECT3(ret, type0, type1, type2, src, event, dest, handler)
	Legacy compatibility helper for a three-argument registered event or handler. More...
#define	CONNECT4(ret, type0, type1, type2, type3, src, event, dest, handler)
	Legacy compatibility helper for a four-argument registered event or handler. More...
#define	CONNECT   CONNECT0
	Synonym of CONNECT0. More...
#define	WEAK_CONNECT0(ret, src, event, dest, handler)
	Legacy compatibility helper that skips source method verification. More...
#define	WEAK_CONNECT1(ret, type0, src, event, dest, handler)
	Legacy compatibility helper that skips source method verification for one argument. More...
#define	WEAK_CONNECT2(ret, type0, type1, src, event, dest, handler)
	Legacy compatibility helper that skips source method verification for two arguments. More...
#define	WEAK_CONNECT3(ret, type0, type1, type2, src, event, dest, handler)
	Legacy compatibility helper that skips source method verification for three arguments. More...
#define	WEAK_CONNECT4(ret, type0, type1, type2, type3, src, event, dest, handler)
	Legacy compatibility helper that skips source method verification for four arguments. More...
#define	WEAK_CONNECT   WEAK_CONNECT0
	Synonym of WEAK_CONNECT0. More...
#define	DISCONNECT0(ret, src, event, dest, handler)
	Disconnect a registered event from a registered event handler.
#define	DISCONNECT1(ret, type0, src, event, dest, handler)
	Disconnect a one-argument registered event from a registered event handler.
#define	DISCONNECT2(ret, type0, type1, src, event, dest, handler)
	Disconnect a two-argument registered event from a registered event handler.
#define	DISCONNECT3(ret, type0, type1, type2, src, event, dest, handler)
	Disconnect a three-argument registered event from a registered event handler.
#define	DISCONNECT4(ret, type0, type1, type2, type3, src, event, dest, handler)
	Disconnect a four-argument registered event from a registered event handler.
#define	DISCONNECT   DISCONNECT0
	Synonym of DISCONNECT0.
#define	HANDLER(handler)
	Low-level helper that expands to the registered handler entry point.

Detailed Description

template<typename T = PIByteArray>
class PIGrabberBase< T >

Base polling grabber thread with a pending queue, recording virtual methods, and a last-item snapshot.

Captured items are appended to the internal queue and also copied into last(). The snapshot is independent from the queue.