80 lines
2.2 KiB
C++
80 lines
2.2 KiB
C++
/*! \file
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* \brief \ref Bellringer that manages and activates time-triggered activities.
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*/
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#pragma once
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#include "../object/queue.h"
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#include "../thread/thread.h"
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#include "../types.h"
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struct Vault;
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/*! \brief Manages and activates time-triggered activities.
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* \ingroup ipc
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*
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* The Bellringer is regularly activated and checks whether any of the bells
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* should ring. The bells are stored in a Queue<Bell> that is managed by the
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* Bellringer. A clever implementation avoids iterating through the whole list
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* for every iteration by keeping the bells sorted and storing delta times. This
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* approach leads to a complexity of O(1) for the method called by the timer
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* interrupt in case no bells need to be rung.
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*/
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class Bellringer {
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// Prevent copies and assignments
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Bellringer(const Bellringer&) = delete;
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Bellringer& operator=(const Bellringer&) = delete;
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/**
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* @brief Contains a Thread and its remaining waiting time in timer ticks
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*
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*/
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struct Bell {
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// link pointer to the next bell in the bellringer's bell list
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Bell* queue_link = nullptr;
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Thread* thread;
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size_t counter;
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};
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/*! \brief List of bells currently managed.
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*
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* This list contains non-expired bells enqueued by job().
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* These bells will be checked on every call to check().
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*
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* All elements that should be inserted into a Queue instance
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* are required to be derived from Queue<Bell>::Node.
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*/
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Queue<Bell> bells;
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public:
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// constructor
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Bellringer() {}
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/*! \brief Checks whether there are bells to be rung.
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*
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* Every call to check elapses a tick. Once such a tick reduces a bell's
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* remaining time to zero, the bell will be rung (i.e., its thread is
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* ready).
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*
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* \param vault The vault containing the bellringer instance
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*
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*/
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void check(Vault& vault);
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/*! \brief Puts the calling thread to sleep for `ms` milliseconds by
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* enqueuing a \ref Bell.
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*
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* \param vault The vault containing the bellringer instance
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* \param ms Number of milliseconds that should be waited before
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* ringing the bell
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*
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*/
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void sleep(Vault& vault, unsigned int ms);
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/*! \brief Checks whether there are enqueued bells.
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* \return true if there are enqueued bells, false otherwise
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*
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*/
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bool bellPending() const;
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};
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