#include "common/Finisher.h"
#include "common/Formatter.h"
+#define rdout(x) lgeneric_subdout(cct,reserver,x)
+
/**
* Manages a configurable number of asyncronous reservations.
*
unsigned min_priority;
Mutex lock;
- map<unsigned, list<pair<T, Context*> > > queues;
- map<T, pair<unsigned, typename list<pair<T, Context*> >::iterator > > queue_pointers;
- set<T> in_progress;
+ struct Reservation {
+ T item;
+ unsigned prio = 0;
+ Context *grant = 0;
+ Context *preempt = 0;
+ Reservation() {}
+ Reservation(T i, unsigned pr, Context *g, Context *p = 0)
+ : item(i), prio(pr), grant(g), preempt(p) {}
+ void dump(Formatter *f) const {
+ f->dump_stream("item") << item;
+ f->dump_unsigned("prio", prio);
+ f->dump_bool("can_preempt", !!preempt);
+ }
+ friend ostream& operator<<(ostream& out, const Reservation& r) {
+ return out << r.item << "(prio " << r.prio << " grant " << r.grant
+ << " preempt " << r.preempt << ")";
+ }
+ };
+
+ map<unsigned, list<Reservation>> queues;
+ map<T, pair<unsigned, typename list<Reservation>::iterator>> queue_pointers;
+ map<T,Reservation> in_progress;
+ set<pair<unsigned,T>> preempt_by_prio; ///< in_progress that can be preempted
+
+ void preempt_one() {
+ assert(!preempt_by_prio.empty());
+ auto q = in_progress.find(preempt_by_prio.begin()->second);
+ assert(q != in_progress.end());
+ Reservation victim = q->second;
+ rdout(10) << __func__ << " preempt " << victim << dendl;
+ f->queue(victim.preempt);
+ victim.preempt = nullptr;
+ in_progress.erase(q);
+ preempt_by_prio.erase(preempt_by_prio.begin());
+ }
void do_queues() {
- typename map<unsigned, list<pair<T, Context*> > >::reverse_iterator it;
- for (it = queues.rbegin();
- it != queues.rend() &&
- in_progress.size() < max_allowed &&
- it->first >= min_priority;
- ++it) {
- while (in_progress.size() < max_allowed &&
- !it->second.empty()) {
- pair<T, Context*> p = it->second.front();
- queue_pointers.erase(p.first);
- it->second.pop_front();
- f->queue(p.second);
- in_progress.insert(p.first);
+ rdout(20) << __func__ << ":\n";
+ JSONFormatter jf(true);
+ jf.open_object_section("queue");
+ _dump(&jf);
+ jf.close_section();
+ jf.flush(*_dout);
+ *_dout << dendl;
+
+ // in case min_priority was adjusted up or max_allowed was adjusted down
+ while (!preempt_by_prio.empty() &&
+ (in_progress.size() > max_allowed ||
+ preempt_by_prio.begin()->first < min_priority)) {
+ preempt_one();
+ }
+
+ while (!queues.empty()) {
+ // choose highest priority queue
+ auto it = queues.end();
+ --it;
+ assert(!it->second.empty());
+ if (it->first < min_priority) {
+ break;
+ }
+ if (in_progress.size() >= max_allowed &&
+ !preempt_by_prio.empty() &&
+ it->first > preempt_by_prio.begin()->first) {
+ preempt_one();
+ }
+ if (in_progress.size() >= max_allowed) {
+ break; // no room
+ }
+ // grant
+ Reservation p = it->second.front();
+ rdout(10) << __func__ << " grant " << p << dendl;
+ queue_pointers.erase(p.item);
+ it->second.pop_front();
+ if (it->second.empty()) {
+ queues.erase(it);
+ }
+ f->queue(p.grant);
+ p.grant = nullptr;
+ in_progress[p.item] = p;
+ if (p.preempt) {
+ preempt_by_prio.insert(make_pair(p.prio, p.item));
}
}
}
void dump(Formatter *f) {
Mutex::Locker l(lock);
+ _dump(f);
+ }
+ void _dump(Formatter *f) {
f->dump_unsigned("max_allowed", max_allowed);
f->dump_unsigned("min_priority", min_priority);
f->open_array_section("queues");
- for (typename map<unsigned, list<pair<T, Context*> > > ::const_iterator p =
- queues.begin(); p != queues.end(); ++p) {
+ for (auto& p : queues) {
f->open_object_section("queue");
- f->dump_unsigned("priority", p->first);
+ f->dump_unsigned("priority", p.first);
f->open_array_section("items");
- for (typename list<pair<T, Context*> >::const_iterator q =
- p->second.begin(); q != p->second.end(); ++q) {
- f->dump_stream("item") << q->first;
+ for (auto& q : p.second) {
+ f->dump_object("item", q);
}
f->close_section();
f->close_section();
}
f->close_section();
f->open_array_section("in_progress");
- for (typename set<T>::const_iterator p = in_progress.begin();
- p != in_progress.end();
- ++p) {
- f->dump_stream("item") << *p;
+ for (auto& p : in_progress) {
+ f->dump_object("item", p.second);
}
f->close_section();
}
void request_reservation(
T item, ///< [in] reservation key
Context *on_reserved, ///< [in] callback to be called on reservation
- unsigned prio
+ unsigned prio, ///< [in] priority
+ Context *on_preempt = 0 ///< [in] callback to be called if we are preempted (optional)
) {
Mutex::Locker l(lock);
+ Reservation r(item, prio, on_reserved, on_preempt);
+ rdout(10) << __func__ << " queue " << r << dendl;
assert(!queue_pointers.count(item) &&
!in_progress.count(item));
- queues[prio].push_back(make_pair(item, on_reserved));
- queue_pointers.insert(make_pair(item, make_pair(prio,--(queues[prio]).end())));
+ queues[prio].push_back(r);
+ queue_pointers.insert(make_pair(item,
+ make_pair(prio,--(queues[prio]).end())));
do_queues();
}
T item ///< [in] key for reservation to cancel
) {
Mutex::Locker l(lock);
- if (queue_pointers.count(item)) {
- unsigned prio = queue_pointers[item].first;
- delete queue_pointers[item].second->second;
- queues[prio].erase(queue_pointers[item].second);
- queue_pointers.erase(item);
+ auto i = queue_pointers.find(item);
+ if (i != queue_pointers.end()) {
+ unsigned prio = i->second.first;
+ const Reservation& r = *i->second.second;
+ rdout(10) << __func__ << " cancel " << r << " (was queued)" << dendl;
+ delete r.grant;
+ delete r.preempt;
+ queues[prio].erase(i->second.second);
+ if (queues[prio].empty()) {
+ queues.erase(prio);
+ }
+ queue_pointers.erase(i);
} else {
- in_progress.erase(item);
+ auto p = in_progress.find(item);
+ if (p != in_progress.end()) {
+ rdout(10) << __func__ << " cancel " << p->second
+ << " (was in progress)" << dendl;
+ if (p->second.preempt) {
+ preempt_by_prio.erase(make_pair(p->second.prio, p->second.item));
+ delete p->second.preempt;
+ }
+ in_progress.erase(p);
+ } else {
+ rdout(10) << __func__ << " cancel " << item << " (not found)" << dendl;
+ }
}
do_queues();
}
static const unsigned MAX_PRIORITY = (unsigned)-1;
};
+#undef rdout
#endif
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