eventq.hh

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/*
 * Copyright (c) 2000-2005 The Regents of The University of Michigan
 * Copyright (c) 2013 Advanced Micro Devices, Inc.
 * Copyright (c) 2013 Mark D. Hill and David A. Wood
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/* @file
 * EventQueue interfaces
 */
 
#ifndef __SIM_EVENTQ_HH__
#define __SIM_EVENTQ_HH__
 
#include <algorithm>
#include <cassert>
#include <climits>
#include <functional>
#include <iosfwd>
#include <list>
#include <memory>
#include <string>
 
#include "base/debug.hh"
#include "base/flags.hh"
#include "base/named.hh"
#include "base/trace.hh"
#include "base/type_traits.hh"
#include "base/types.hh"
#include "base/uncontended_mutex.hh"
#include "debug/Event.hh"
#include "sim/cur_tick.hh"
#include "sim/serialize.hh"
 
namespace gem5
{
 
class EventQueue;       // forward declaration
class BaseGlobalEvent;
 
extern Tick simQuantum;
 
extern uint32_t numMainEventQueues;
 
extern std::vector<EventQueue *> mainEventQueue;
 
 
extern __thread EventQueue *_curEventQueue;
 
extern bool inParallelMode;
 
EventQueue *getEventQueue(uint32_t index);
 
inline EventQueue *curEventQueue() { return _curEventQueue; }
inline void curEventQueue(EventQueue *q);
 
class EventBase
{
  protected:
    typedef unsigned short FlagsType;
    typedef ::gem5::Flags<FlagsType> Flags;
 
    static const FlagsType PublicRead    = 0x003f; // public readable flags
    static const FlagsType PublicWrite   = 0x001d; // public writable flags
    static const FlagsType Squashed      = 0x0001; // has been squashed
    static const FlagsType Scheduled     = 0x0002; // has been scheduled
    static const FlagsType Managed       = 0x0004; // Use life cycle manager
    static const FlagsType AutoDelete    = Managed; // delete after dispatch
    static const FlagsType Reserved0     = 0x0008;
    static const FlagsType IsExitEvent   = 0x0010; // special exit event
    static const FlagsType IsMainQueue   = 0x0020; // on main event queue
    static const FlagsType Initialized   = 0x7a40; // somewhat random bits
    static const FlagsType InitMask      = 0xffc0; // mask for init bits
 
  public:
    typedef int8_t Priority;
 
 
    static const Priority Minimum_Pri =          SCHAR_MIN;
 
    static const Priority Debug_Enable_Pri =          -101;
 
    static const Priority Debug_Break_Pri =           -100;
 
    static const Priority CPU_Switch_Pri =             -31;
 
    static const Priority Delayed_Writeback_Pri =       -1;
 
    static const Priority Default_Pri =                  0;
 
    static const Priority DVFS_Update_Pri =             31;
 
    static const Priority Serialize_Pri =               32;
 
    static const Priority CPU_Tick_Pri =                50;
 
    static const Priority CPU_Exit_Pri =                64;
 
    static const Priority Stat_Event_Pri =              90;
 
    static const Priority Progress_Event_Pri =          95;
 
    static const Priority Sim_Exit_Pri =               100;
 
    static const Priority Maximum_Pri =          SCHAR_MAX;
};
 
/*
 * An item on an event queue.  The action caused by a given
 * event is specified by deriving a subclass and overriding the
 * process() member function.
 *
 * Caution, the order of members is chosen to maximize data packing.
 */
class Event : public EventBase, public Serializable
{
    friend class EventQueue;
 
  private:
    // The event queue is now a linked list of linked lists.  The
    // 'nextBin' pointer is to find the bin, where a bin is defined as
    // when+priority.  All events in the same bin will be stored in a
    // second linked list (a stack) maintained by the 'nextInBin'
    // pointer.  The list will be accessed in LIFO order.  The end
    // result is that the insert/removal in 'nextBin' is
    // linear/constant, and the lookup/removal in 'nextInBin' is
    // constant/constant.  Hopefully this is a significant improvement
    // over the current fully linear insertion.
    Event *nextBin;
    Event *nextInBin;
 
    static Event *insertBefore(Event *event, Event *curr);
    static Event *removeItem(Event *event, Event *last);
 
    Tick _when;         
    Priority _priority; 
    Flags flags;
 
#ifndef NDEBUG
    static Counter instanceCounter;
 
    Counter instance;
 
    EventQueue *queue;
#endif
 
#ifdef EVENTQ_DEBUG
    Tick whenCreated;   
    Tick whenScheduled; 
#endif
 
    void
    setWhen(Tick when, EventQueue *q)
    {
        _when = when;
#ifndef NDEBUG
        queue = q;
#endif
#ifdef EVENTQ_DEBUG
        whenScheduled = curTick();
#endif
    }
 
    bool
    initialized() const
    {
        return (flags & InitMask) == Initialized;
    }
 
  protected:
    Flags
    getFlags() const
    {
        return flags & PublicRead;
    }
 
    bool
    isFlagSet(Flags _flags) const
    {
        assert(_flags.noneSet(~PublicRead));
        return flags.isSet(_flags);
    }
 
    void
    setFlags(Flags _flags)
    {
        assert(_flags.noneSet(~PublicWrite));
        flags.set(_flags);
    }
 
    void
    clearFlags(Flags _flags)
    {
        assert(_flags.noneSet(~PublicWrite));
        flags.clear(_flags);
    }
 
    void
    clearFlags()
    {
        flags.clear(PublicWrite);
    }
 
    virtual void trace(const char *action);     
 
    const std::string instanceString() const;
 
  protected: /* Memory management */
    void acquire();
 
    void release();
 
    virtual void acquireImpl();
 
    virtual void releaseImpl();
 
  public:
 
    /*
     * Event constructor
     * @param queue that the event gets scheduled on
     *
     * @ingroup api_eventq
     */
    Event(Priority p = Default_Pri, Flags f = 0)
        : nextBin(nullptr), nextInBin(nullptr), _when(0), _priority(p),
          flags(Initialized | f)
    {
        assert(f.noneSet(~PublicWrite));
#ifndef NDEBUG
        instance = ++instanceCounter;
        queue = NULL;
#endif
#ifdef EVENTQ_DEBUG
        whenCreated = curTick();
        whenScheduled = 0;
#endif
    }
 
    virtual ~Event();
    virtual const std::string name() const;
 
    virtual const char *description() const;
 
    void dump() const; //end of api group
 
  public:
    /*
     * This member function is invoked when the event is processed
     * (occurs).  There is no default implementation; each subclass
     * must provide its own implementation.  The event is not
     * automatically deleted after it is processed (to allow for
     * statically allocated event objects).
     *
     * If the AutoDestroy flag is set, the object is deleted once it
     * is processed.
     *
     * @ingroup api_eventq
     */
    virtual void process() = 0;
 
    bool scheduled() const { return flags.isSet(Scheduled); }
 
    void squash() { flags.set(Squashed); }
 
    bool squashed() const { return flags.isSet(Squashed); }
 
    bool isExitEvent() const { return flags.isSet(IsExitEvent); }
 
    bool isManaged() const { return flags.isSet(Managed); }
 
    bool isAutoDelete() const { return isManaged(); }
 
    Tick when() const { return _when; }
 
    Priority priority() const { return _priority; }
 
    virtual BaseGlobalEvent *globalEvent() { return NULL; }
 
    void serialize(CheckpointOut &cp) const override;
    void unserialize(CheckpointIn &cp) override;
};
 
inline bool
operator<(const Event &l, const Event &r)
{
    return l.when() < r.when() ||
        (l.when() == r.when() && l.priority() < r.priority());
}
 
inline bool
operator>(const Event &l, const Event &r)
{
    return l.when() > r.when() ||
        (l.when() == r.when() && l.priority() > r.priority());
}
 
inline bool
operator<=(const Event &l, const Event &r)
{
    return l.when() < r.when() ||
        (l.when() == r.when() && l.priority() <= r.priority());
}
 
inline bool
operator>=(const Event &l, const Event &r)
{
    return l.when() > r.when() ||
        (l.when() == r.when() && l.priority() >= r.priority());
}
 
inline bool
operator==(const Event &l, const Event &r)
{
    return l.when() == r.when() && l.priority() == r.priority();
}
 
inline bool
operator!=(const Event &l, const Event &r)
{
    return l.when() != r.when() || l.priority() != r.priority();
}
 
class EventQueue
{
  private:
    friend void curEventQueue(EventQueue *);
 
    std::string objName;
    Event *head;
    Tick _curTick;
 
    UncontendedMutex async_queue_mutex;
 
    std::list<Event*> async_queue;
 
    UncontendedMutex service_mutex;
 
    void insert(Event *event);
    void remove(Event *event);
 
    void asyncInsert(Event *event);
 
    EventQueue(const EventQueue &);
 
  public:
    class ScopedMigration
    {
      public:
        ScopedMigration(EventQueue *_new_eq, bool _doMigrate = true)
            :new_eq(*_new_eq), old_eq(*curEventQueue()),
             doMigrate((&new_eq != &old_eq)&&_doMigrate)
        {
            if (doMigrate){
                old_eq.unlock();
                new_eq.lock();
                curEventQueue(&new_eq);
            }
        }
 
        ~ScopedMigration()
        {
            if (doMigrate){
                new_eq.unlock();
                old_eq.lock();
                curEventQueue(&old_eq);
            }
        }
 
      private:
        EventQueue &new_eq;
        EventQueue &old_eq;
        bool doMigrate;
    };
 
 
    class ScopedRelease
    {
      public:
        ScopedRelease(EventQueue *_eq)
            :  eq(*_eq)
        {
            eq.unlock();
        }
 
        ~ScopedRelease()
        {
            eq.lock();
        }
 
      private:
        EventQueue &eq;
    };
 
    EventQueue(const std::string &n);
 
    virtual const std::string name() const { return objName; }
    void name(const std::string &st) { objName = st; } //end of api_eventq group
 
    void
    schedule(Event *event, Tick when, bool global=false)
    {
        assert(when >= getCurTick());
        assert(!event->scheduled());
        assert(event->initialized());
 
        event->setWhen(when, this);
 
        // The check below is to make sure of two things
        // a. A thread schedules local events on other queues through the
        //    asyncq.
        // b. A thread schedules global events on the asyncq, whether or not
        //    this event belongs to this eventq. This is required to maintain
        //    a total order amongst the global events. See global_event.{cc,hh}
        //    for more explanation.
        if (inParallelMode && (this != curEventQueue() || global)) {
            asyncInsert(event);
        } else {
            insert(event);
        }
        event->flags.set(Event::Scheduled);
        event->acquire();
 
        if (debug::Event)
            event->trace("scheduled");
    }
 
    void
    deschedule(Event *event)
    {
        assert(event->scheduled());
        assert(event->initialized());
        assert(!inParallelMode || this == curEventQueue());
 
        remove(event);
 
        event->flags.clear(Event::Squashed);
        event->flags.clear(Event::Scheduled);
 
        if (debug::Event)
            event->trace("descheduled");
 
        event->release();
    }
 
    void
    reschedule(Event *event, Tick when, bool always=false)
    {
        assert(when >= getCurTick());
        assert(always || event->scheduled());
        assert(event->initialized());
        assert(!inParallelMode || this == curEventQueue());
 
        if (event->scheduled()) {
            remove(event);
        } else {
            event->acquire();
        }
 
        event->setWhen(when, this);
        insert(event);
        event->flags.clear(Event::Squashed);
        event->flags.set(Event::Scheduled);
 
        if (debug::Event)
            event->trace("rescheduled");
    }
 
    Tick nextTick() const { return head->when(); }
    void setCurTick(Tick newVal) { _curTick = newVal; }
 
    Tick getCurTick() const { return _curTick; }
    Event *getHead() const { return head; }
 
    Event *serviceOne();
 
    void
    serviceEvents(Tick when)
    {
        while (!empty()) {
            if (nextTick() > when)
                break;
 
            //assert(head->when() >= when && "event scheduled in the past");
            serviceOne();
        }
 
        setCurTick(when);
    }
 
    bool empty() const { return head == NULL; }
 
    void dump() const;
 
    bool debugVerify() const;
 
    void handleAsyncInsertions();
 
    virtual void wakeup(Tick when = (Tick)-1) { }
 
    Event* replaceHead(Event* s);
 
    void lock() { service_mutex.lock(); }
    void unlock() { service_mutex.unlock(); }
    void checkpointReschedule(Event *event);
 
    virtual ~EventQueue()
    {
        while (!empty())
            deschedule(getHead());
    }
};
 
inline void
curEventQueue(EventQueue *q)
{
    _curEventQueue = q;
    Gem5Internal::_curTickPtr = (q == nullptr) ? nullptr : &q->_curTick;
}
 
void dumpMainQueue();
 
class EventManager
{
  protected:
    EventQueue *eventq;
 
  public:
    EventManager(EventManager &em) : eventq(em.eventq) {}
    EventManager(EventManager *em) : eventq(em->eventq) {}
    EventManager(EventQueue *eq) : eventq(eq) {} //end of api_eventq group
 
    EventQueue *
    eventQueue() const
    {
        return eventq;
    }
 
    void
    schedule(Event &event, Tick when)
    {
        eventq->schedule(&event, when);
    }
 
    void
    deschedule(Event &event)
    {
        eventq->deschedule(&event);
    }
 
    void
    reschedule(Event &event, Tick when, bool always = false)
    {
        eventq->reschedule(&event, when, always);
    }
 
    void
    schedule(Event *event, Tick when)
    {
        eventq->schedule(event, when);
    }
 
    void
    deschedule(Event *event)
    {
        eventq->deschedule(event);
    }
 
    void
    reschedule(Event *event, Tick when, bool always = false)
    {
        eventq->reschedule(event, when, always);
    }
 
    void wakeupEventQueue(Tick when = (Tick)-1)
    {
        eventq->wakeup(when);
    }
 
    void setCurTick(Tick newVal) { eventq->setCurTick(newVal); }
};
 
template <auto F>
class MemberEventWrapper final: public Event, public Named
{
    using CLASS = MemberFunctionClass_t<F>;
    static_assert(std::is_same_v<void, MemberFunctionReturn_t<F>>);
    static_assert(std::is_same_v<MemberFunctionArgsTuple_t<F>, std::tuple<>>);
 
public:
    [[deprecated("Use reference version of this constructor instead")]]
    MemberEventWrapper(CLASS *object,
                       bool del = false,
                       Priority p = Default_Pri):
        MemberEventWrapper{*object, del, p}
    {}
 
    MemberEventWrapper(CLASS &object,
                       bool del = false,
                       Priority p = Default_Pri):
        Event(p),
        Named(object.name() + ".wrapped_event"),
        mObject(&object)
    {
        if (del) setFlags(AutoDelete);
        gem5_assert(mObject);
    }
 
    void process() override {
        (mObject->*F)();
    }
 
    const char *description() const override { return "EventWrapped"; }
private:
    CLASS *mObject;
};
 
template <class T, void (T::* F)()>
using EventWrapper [[deprecated("Use MemberEventWrapper instead")]]
    = MemberEventWrapper<F>;
 
class EventFunctionWrapper : public Event
{
  private:
      std::function<void(void)> callback;
      std::string _name;
 
  public:
    EventFunctionWrapper(const std::function<void(void)> &callback,
                         const std::string &name,
                         bool del = false,
                         Priority p = Default_Pri)
        : Event(p), callback(callback), _name(name)
    {
        if (del)
            setFlags(AutoDelete);
    }
 
    void process() { callback(); }
 
    const std::string
    name() const
    {
        return _name + ".wrapped_function_event";
    }
 
    const char *description() const { return "EventFunctionWrapped"; }
};
 
#define SERIALIZE_EVENT(event) event.serializeSection(cp, #event);
 
#define UNSERIALIZE_EVENT(event)                        \
    do {                                                \
        event.unserializeSection(cp, #event);           \
        eventQueue()->checkpointReschedule(&event);     \
    } while (0)
 
} // namespace gem5
 
#endif // __SIM_EVENTQ_HH__