eventq.hh revision 217 
1/*
2 * Copyright (c) 2003 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/* @file
30 * EventQueue interfaces
31 */
32
33#ifndef __EVENTQ_HH__
34#define __EVENTQ_HH__
35
36#include <assert.h>
37
38#include <algorithm>
39#include <map>
40#include <string>
41#include <vector>
42
43#include "sim/host.hh"	// for Tick
44
45#include "base/fast_alloc.hh"
46#include "sim/serialize.hh"
47#include "base/trace.hh"
48
49class EventQueue;	// forward declaration
50
51/*
52 * An item on an event queue.  The action caused by a given
53 * event is specified by deriving a subclass and overriding the
54 * process() member function.
55 */
56class Event : public Serializeable, public FastAlloc
57{
58    friend class EventQueue;
59
60  private:
61    /// queue to which this event belongs (though it may or may not be
62    /// scheduled on this queue yet)
63    EventQueue *queue;
64
65    Event *next;
66
67    Tick _when;	//!< timestamp when event should be processed
68    int _priority;	//!< event priority
69    char _flags;
70
71  protected:
72    enum Flags {
73        None = 0x0,
74        Squashed = 0x1,
75        Scheduled = 0x2,
76        AutoDelete = 0x4
77    };
78
79    bool getFlags(Flags f) const { return (_flags & f) == f; }
80    void setFlags(Flags f) { _flags |= f; }
81    void clearFlags(Flags f) { _flags &= ~f; }
82
83  protected:
84    EventQueue *theQueue() const { return queue; }
85
86#if TRACING_ON
87    Tick when_created;	//!< Keep track of creation time For debugging
88    Tick when_scheduled;	//!< Keep track of creation time For debugging
89
90    virtual void trace(const char *action);	//!< trace event activity
91#else
92    void trace(const char *) {}
93#endif
94
95    unsigned annotated_value;
96
97  public:
98
99    static const std::string defaultName;
100
101    /*
102     * Event constructor
103     * @param queue that the event gets scheduled on
104     */
105    Event(EventQueue *q, int p = 0)
106        : Serializeable(defaultName), queue(q), next(NULL),
107          _priority(p), _flags(None),
108#if TRACING_ON
109          when_created(curTick), when_scheduled(0),
110#endif
111          annotated_value(0)
112    {
113    }
114
115    ~Event() {}
116
117    /// Determine if the current event is scheduled
118    bool scheduled() const { return getFlags(Scheduled); }
119
120    /// Schedule the event with the current priority or default priority
121    void schedule(Tick t);
122
123    /// Schedule the event with a specific priority
124    void schedule(Tick t, int priority);
125
126    /// Reschedule the event with the current priority
127    void reschedule(Tick t);
128
129    /// Reschedule the event with a specific priority
130    void reschedule(Tick t, int priority);
131
132    /// Remove the event from the current schedule
133    void deschedule();
134
135    /// Return a C string describing the event.  This string should
136    /// *not* be dynamically allocated; just a const char array
137    /// describing the event class.
138    virtual const char *description();
139
140    /// Dump the current event data
141    void dump();
142
143    /*
144     * This member function is invoked when the event is processed
145     * (occurs).  There is no default implementation; each subclass
146     * must provide its own implementation.  The event is not
147     * automatically deleted after it is processed (to allow for
148     * statically allocated event objects).
149     *
150     * If the AutoDestroy flag is set, the object is deleted once it
151     * is processed.
152     */
153    virtual void process() = 0;
154
155    void annotate(unsigned value) { annotated_value = value; };
156    unsigned annotation() { return annotated_value; }
157
158    /// Squash the current event
159    void squash() { setFlags(Squashed); }
160
161    /// Check whether the event is squashed
162    bool squashed() { return getFlags(Squashed); }
163
164    /// Get the time that the event is scheduled
165    Tick when() const { return _when; }
166
167    /// Get the event priority
168    int priority() const { return _priority; }
169
170    struct priority_compare :
171    public std::binary_function<Event *, Event *, bool>
172    {
173        bool operator()(const Event *l, const Event *r) const {
174            return l->when() >= r->when() || l->priority() >= r->priority();
175        }
176    };
177};
178
179template <class T, void (T::* F)()>
180void
181DelayFunction(Tick when, T *object)
182{
183    class DelayEvent : public Event
184    {
185      private:
186        T *object;
187
188      public:
189        DelayEvent(Tick when, T *o)
190            : Event(&mainEventQueue), object(o)
191            { setFlags(AutoDestroy); schedule(when); }
192        void process() { (object->*F)(); }
193        const char *description() { return "delay"; }
194    };
195
196    new DelayEvent(when, object);
197}
198
199/*
200 * Queue of events sorted in time order
201 */
202class EventQueue : public Serializeable
203{
204  private:
205    Event *head;
206
207    void insert(Event *event);
208    void remove(Event *event);
209
210  public:
211
212    // constructor
213    EventQueue(const std::string &n)
214        : Serializeable(n), head(NULL)
215    {}
216
217    // schedule the given event on this queue
218    void schedule(Event *ev);
219    void deschedule(Event *ev);
220    void reschedule(Event *ev);
221
222    Tick nextTick() { return head->when(); }
223    void serviceOne();
224
225    // process all events up to the given timestamp.  we inline a
226    // quick test to see if there are any events to process; if so,
227    // call the internal out-of-line version to process them all.
228    void serviceEvents(Tick when) {
229        while (!empty()) {
230            if (nextTick() > when)
231                break;
232
233            assert(head->when() >= when && "event scheduled in the past");
234            serviceOne();
235        }
236    }
237
238    // default: process all events up to 'now' (curTick)
239    void serviceEvents() { serviceEvents(curTick); }
240
241    // return true if no events are queued
242    bool empty() { return head == NULL; }
243
244    void dump();
245
246    Tick nextEventTime() { return empty() ? curTick : head->when(); }
247
248    virtual void nameChildren();
249    virtual void serialize(std::ostream &os);
250};
251
252
253//////////////////////
254//
255// inline functions
256//
257// can't put these inside declaration due to circular dependence
258// between Event and EventQueue classes.
259//
260//////////////////////
261
262// schedule at specified time (place on event queue specified via
263// constructor)
264inline void
265Event::schedule(Tick t)
266{
267    assert(!scheduled());
268    setFlags(Scheduled);
269#if TRACING_ON
270    when_scheduled = curTick;
271#endif
272    _when = t;
273    queue->schedule(this);
274}
275
276inline void
277Event::schedule(Tick t, int p)
278{
279    _priority = p;
280    schedule(t);
281}
282
283inline void
284Event::deschedule()
285{
286    assert(scheduled());
287
288    clearFlags(Squashed);
289    clearFlags(Scheduled);
290    queue->deschedule(this);
291}
292
293inline void
294Event::reschedule(Tick t)
295{
296    assert(scheduled());
297    clearFlags(Squashed);
298
299#if TRACING_ON
300    when_scheduled = curTick;
301#endif
302    _when = t;
303    queue->reschedule(this);
304}
305
306inline void
307Event::reschedule(Tick t, int p)
308{
309    _priority = p;
310    reschedule(t);
311}
312
313inline void
314EventQueue::schedule(Event *event)
315{
316    insert(event);
317    if (DTRACE(Event))
318        event->trace("scheduled");
319}
320
321inline void
322EventQueue::deschedule(Event *event)
323{
324    remove(event);
325    if (DTRACE(Event))
326        event->trace("descheduled");
327}
328
329inline void
330EventQueue::reschedule(Event *event)
331{
332    remove(event);
333    insert(event);
334    if (DTRACE(Event))
335        event->trace("rescheduled");
336}
337
338
339//////////////////////
340//
341// Main Event Queue
342//
343// Events on this queue are processed at the *beginning* of each
344// cycle, before the pipeline simulation is performed.
345//
346// defined in eventq.cc
347//
348//////////////////////
349extern EventQueue mainEventQueue;
350
351#endif // __EVENTQ_HH__
352