Timer

class Timer

Very simple timer class that allows to create one instance of the timer at a time that can handles once-only tasks in the future or reoccuring (== periodic) tasks

Public Classes
enum timer_par: enum for class specific constants

Public Methods
long add_action( ActionType pAction, long argc = 0, char **argv = NULL ): adds a new function to the list of functions to be executed by the timer
void dump(): prints info to cout about the timer
void execute_actions(): member function that executes the actions
double get_time_interval(): returns the total time interval of the timer (from start to fire)
long how_many_times(): returns how many times the timer has been called
double how_much_time_left(): returns the number of seconds until the timer fires
BOOL is_active(): returns true if the timer is active (started)
BOOL is_periodic(): returns true if the timer is periodic
BOOL is_valid(): returns true if the timer is ok
long remove_action( ActionType pAction ): removes a formerly added action
void set_periodic(BOOL mPeriodic): allows to toggle back and forth between periodic and once only timer
void start(): starts the timer
void stop(): stops the timer
static void TheAction(int signum): TheAction to be executed
Timer( long iTsec = TSEC_UPDATE_DEF, long iTusec_update = TUSEC_UPDATE_DEF, BOOL periodic = false): Constructor - note the default values
~Timer(): dtor

Public
enum timer_par: enum for class specific constants

Private Fields
ActionType actions[MAX_ACTIONS]: pointer to functions (== actions) to be executed
long argc[MAX_ACTIONS]: number of arguments for calling action
char** argv[MAX_ACTIONS]: arguments as char* for actions
BOOL bActive: true if the timer is active
BOOL bPeriodic: true if the timer is periodic
BOOL bValid: flag - true if the timer is ok
long iSec_action: Number of seconds until it fires (from start)
long iUsec_action: Number of microseconds until it fires (from start)
static Timer* Myself: there is only one instance of the system clock !
long nActions: number of actions
long nTimes_fired: How many times the timer has fired (==1 for non-periodic timers)

Documentation

Very simple timer class that allows to create one instance of the timer at a time that can handles once-only tasks in the future or reoccuring (== periodic) tasks.
If a second instance is created the old one is invalidated. If the timer is declared periodic, then it will reoccur until it is turned off. Every time the timer is fired a series of functions are executed. The list of functions can be modified at any given time, i.e. more can be added or existing ones removed.
Protection is in place that the (periodic) timer cannot be called while it is executing its actions.
Comments:

Use of sleep etc ...
This class uses the POSIX ITIMER_REAL.
Therefore make sure you don't use the timer for something else while you have the timer active, e.g. sleep function uses itimer!!!
invoking member functions
The this pointer is not defined in invoking member functions. Therefore if a public member function is to be invoked, you must pass it as an argument argv[i] into a static member function which in turn unpacks the pointer and invokes the member function
memory allocation model
If arguments are to be passed into the function, then add_action assumes ownership of the char **argv. Therefore the caller must use new to create them and NOT call delete.
MODIFICATIONS :

enum timer_par

enum for class specific constants

Timer( long iTsec = TSEC_UPDATE_DEF, long iTusec_update = TUSEC_UPDATE_DEF, BOOL periodic = false)

Constructor - note the default values

~Timer()

dtor

static void TheAction(int signum)

TheAction to be executed. This is a static function, which in turns call all the functions that have been declared to be performed at the periodic interval. The reason that this is a static function is that it is called from a signal.
The ActionType is a typedef to typedef void (*ActionType)(int, char **)

void execute_actions()

member function that executes the actions

long add_action( ActionType pAction, long argc = 0, char **argv = NULL )

adds a new function to the list of functions to be executed by the timer. The Function pAction is invoked with the arguments argc and char** argv

long remove_action( ActionType pAction )

removes a formerly added action

void dump()

prints info to cout about the timer

long how_many_times()

returns how many times the timer has been called

double get_time_interval()

returns the total time interval of the timer (from start to fire)

double how_much_time_left()

returns the number of seconds until the timer fires

BOOL is_periodic()

returns true if the timer is periodic

void set_periodic(BOOL mPeriodic)

allows to toggle back and forth between periodic and once only timer

BOOL is_active()

returns true if the timer is active (started)

BOOL is_valid()

returns true if the timer is ok. Note: we have only one ITIMER_REAL. Therefore we disable the existing time (and set bValid to false) when we create a new timer

static Timer* Myself