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#pragma once
#include <cstdint>
#include <iterator> // IWYU pragma: keep
#include <map>
#include <set>
#include "sim/sim.h"
#include "util/assert.h"
namespace sim {
template<typename Element> struct Queue {
Scheduler &scheduler;
Schedulable *reader = nullptr;
std::set<Schedulable *> writers;
unsigned int min_latency;
std::multimap<std::uint64_t, Element> waiting;
Queue(Scheduler &scheduler, unsigned int min_latency)
: scheduler(scheduler)
, min_latency(min_latency)
{ }
void add_reader(Schedulable *x)
{
ASSERT(&x->scheduler == &scheduler, "Reader associated with incorrect Scheduler");
ASSERT(!reader, "Already have a reader");
reader = x;
if (min_latency == 0) {
for (const auto &w : writers)
scheduler.constrain(w, reader);
}
}
void add_writer(Schedulable *x)
{
ASSERT(&x->scheduler == &scheduler, "Writer associated with incorrect Scheduler");
writers.emplace(x);
if (min_latency == 0 && reader)
scheduler.constrain(x, reader);
}
void write(Element &&x)
{
write(std::move(x), min_latency);
}
void write(Element &&x, unsigned int latency)
{
ASSERT(latency >= min_latency, "Latency too low");
ASSERT(!scheduler.current_schedulable || writers.count(scheduler.current_schedulable), "Write lacks permission");
waiting.emplace(scheduler.now + min_latency, std::move(x));
}
unsigned int available()
{
ASSERT(!scheduler.current_schedulable || reader == scheduler.current_schedulable, "Read lacks permission");
unsigned int c = 0;
for (auto x = waiting.begin(); x != waiting.end() && x->first <= scheduler.now; ++x)
++c;
return c;
}
Element &peek(unsigned int i=0)
{
ASSERT(i < available(), "Peek past available elements");
auto x = waiting.begin();
std::advance(x, i);
return x->second;
}
Element read(unsigned int i=0)
{
ASSERT(i < available(), "Read past available elements");
auto x = waiting.begin();
std::advance(x, i);
Element e{std::move(x->second)};
waiting.erase(x);
return e;
}
};
}
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