class Poco::Util::Timer

Overview

A Timer allows to schedule tasks (TimerTask objects) for future execution in a background thread. More…

#include <Timer.h>

class Timer: protected Poco::Runnable
{
public:
    // construction

    Timer();
    Timer(Poco::Thread::Priority priority);

    // methods

    void
    cancel(bool wait = false);

    void
    schedule(
        TimerTask::Ptr pTask,
        Poco::Timestamp time
        );

    void
    schedule(
        TimerTask::Ptr pTask,
        Poco::Clock clock
        );

    void
    schedule(
        TimerTask::Ptr pTask,
        long delay,
        long interval
        );

    void
    schedule(
        TimerTask::Ptr pTask,
        Poco::Timestamp time,
        long interval
        );

    void
    schedule(
        TimerTask::Ptr pTask,
        Poco::Clock clock,
        long interval
        );

    void
    scheduleAtFixedRate(
        TimerTask::Ptr pTask,
        long delay,
        long interval
        );

    void
    scheduleAtFixedRate(
        TimerTask::Ptr pTask,
        Poco::Timestamp time,
        long interval
        );

    void
    scheduleAtFixedRate(
        TimerTask::Ptr pTask,
        Poco::Clock clock,
        long interval
        );

protected:
    // methods

    virtual
    void
    run();

    static
    void
    validateTask(const TimerTask::Ptr& pTask);
};

Inherited Members

public:
    // methods

    virtual
    void
    run() = 0;

Detailed Documentation

A Timer allows to schedule tasks (TimerTask objects) for future execution in a background thread.

Tasks may be scheduled for one-time execution, or for repeated execution at regular intervals.

The Timer object creates a thread that executes all scheduled tasks sequentially. Therefore, tasks should complete their work as quickly as possible, otherwise subsequent tasks may be delayed.

Timer is save for multithreaded use - multiple threads can schedule new tasks simultaneously.

Acknowledgement: The interface of this class has been inspired by the java.util.Timer class from Java 1.3.

Construction

Timer()

Creates the Timer.

Timer(Poco::Thread::Priority priority)

Creates the Timer, using a timer thread with the given priority.

Methods

void
cancel(bool wait = false)

Cancels all pending tasks.

If a task is currently running, it is allowed to finish.

Task cancellation is done asynchronously. If wait is false, cancel() returns immediately and the task queue will be purged as soon as the currently running task finishes. If wait is true, waits until the queue has been purged.

void
schedule(
    TimerTask::Ptr pTask,
    Poco::Timestamp time
    )

Schedules a task for execution at the specified time.

If the time lies in the past, the task is executed immediately.

Note: the relative time the task will be executed won’t change if the system’s time changes. If the given time is 10 seconds in the future at the point schedule() is called, the task will be executed 10 seconds later, even if the system time changes in between.

void
schedule(
    TimerTask::Ptr pTask,
    Poco::Clock clock
    )

Schedules a task for execution at the specified time.

If the time lies in the past, the task is executed immediately.

void
schedule(
    TimerTask::Ptr pTask,
    long delay,
    long interval
    )

Schedules a task for periodic execution.

The task is first executed after the given delay. Subsequently, the task is executed periodically with the given interval in milliseconds between invocations.

void
schedule(
    TimerTask::Ptr pTask,
    Poco::Timestamp time,
    long interval
    )

Schedules a task for periodic execution.

The task is first executed at the given time. Subsequently, the task is executed periodically with the given interval in milliseconds between invocations.

Note: the relative time the task will be executed won’t change if the system’s time changes. If the given time is 10 seconds in the future at the point schedule() is called, the task will be executed 10 seconds later, even if the system time changes in between.

void
schedule(
    TimerTask::Ptr pTask,
    Poco::Clock clock,
    long interval
    )

Schedules a task for periodic execution.

The task is first executed at the given time. Subsequently, the task is executed periodically with the given interval in milliseconds between invocations.

void
scheduleAtFixedRate(
    TimerTask::Ptr pTask,
    long delay,
    long interval
    )

Schedules a task for periodic execution at a fixed rate.

The task is first executed after the given delay. Subsequently, the task is executed periodically every number of milliseconds specified by interval.

If task execution takes longer than the given interval, further executions are delayed.

void
scheduleAtFixedRate(
    TimerTask::Ptr pTask,
    Poco::Timestamp time,
    long interval
    )

Schedules a task for periodic execution at a fixed rate.

The task is first executed at the given time. Subsequently, the task is executed periodically every number of milliseconds specified by interval.

If task execution takes longer than the given interval, further executions are delayed.

Note: the relative time the task will be executed won’t change if the system’s time changes. If the given time is 10 seconds in the future at the point scheduleAtFixedRate() is called, the task will be executed 10 seconds later, even if the system time changes in between.

void
scheduleAtFixedRate(
    TimerTask::Ptr pTask,
    Poco::Clock clock,
    long interval
    )

Schedules a task for periodic execution at a fixed rate.

The task is first executed at the given time. Subsequently, the task is executed periodically every number of milliseconds specified by interval.

If task execution takes longer than the given interval, further executions are delayed.

virtual
void
run()

Do whatever the thread needs to do.

Must be overridden by subclasses.