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#pragma once
#include <library/cpp/actors/core/actor.h>
#include <library/cpp/actors/core/hfunc.h>
#include <library/cpp/actors/interconnect/events_local.h>
#include <deque>
namespace NActors {
class TBrokerLeaseHolder {
public:
TBrokerLeaseHolder(TActorId waiterId, TActorId brokerId)
: WaiterId(waiterId)
, BrokerId(brokerId) {
if (TActivationContext::Send(new IEventHandle(BrokerId, WaiterId, new TEvHandshakeBrokerTake()))) {
LeaseRequested = true;
}
}
~TBrokerLeaseHolder() {
if (LeaseRequested) {
TActivationContext::Send(new IEventHandle(BrokerId, WaiterId, new TEvHandshakeBrokerFree()));
}
}
bool IsLeaseRequested() {
return LeaseRequested;
}
void ForgetLease() {
// only call when TDtorException was caught
LeaseRequested = false;
}
private:
TActorId WaiterId;
TActorId BrokerId;
bool LeaseRequested = false;
};
class THandshakeBroker : public TActor<THandshakeBroker> {
private:
enum class ESelectionStrategy {
FIFO = 0,
LIFO,
Random,
};
private:
void PermitNext() {
if (Capacity == 0 && !Waiters.empty()) {
TActorId waiter;
switch (SelectionStrategy) {
case ESelectionStrategy::FIFO:
waiter = Waiters.front();
Waiters.pop_front();
SelectionStrategy = ESelectionStrategy::LIFO;
break;
case ESelectionStrategy::LIFO:
waiter = Waiters.back();
Waiters.pop_back();
SelectionStrategy = ESelectionStrategy::Random;
break;
case ESelectionStrategy::Random: {
const auto it = WaiterLookup.begin();
waiter = it->first;
Waiters.erase(it->second);
SelectionStrategy = ESelectionStrategy::FIFO;
break;
}
default:
Y_FAIL("Unimplimented selection strategy");
}
const size_t n = WaiterLookup.erase(waiter);
Y_ABORT_UNLESS(n == 1);
Send(waiter, new TEvHandshakeBrokerPermit());
PermittedLeases.insert(waiter);
} else {
Capacity += 1;
}
}
private:
using TWaiters = std::list<TActorId>;
TWaiters Waiters;
std::unordered_map<TActorId, TWaiters::iterator> WaiterLookup;
std::unordered_set<TActorId> PermittedLeases;
ESelectionStrategy SelectionStrategy = ESelectionStrategy::FIFO;
ui32 Capacity;
void Handle(TEvHandshakeBrokerTake::TPtr &ev) {
const TActorId sender = ev->Sender;
if (Capacity > 0) {
Capacity -= 1;
PermittedLeases.insert(sender);
Send(sender, new TEvHandshakeBrokerPermit());
} else {
const auto [it, inserted] = WaiterLookup.try_emplace(sender,
Waiters.insert(Waiters.end(), sender));
Y_ABORT_UNLESS(inserted);
}
}
void Handle(TEvHandshakeBrokerFree::TPtr& ev) {
const TActorId sender = ev->Sender;
if (!PermittedLeases.erase(sender)) {
// Lease was not permitted yet, remove sender from Waiters queue
const auto it = WaiterLookup.find(sender);
Y_ABORT_UNLESS(it != WaiterLookup.end());
Waiters.erase(it->second);
WaiterLookup.erase(it);
}
PermitNext();
}
public:
THandshakeBroker(ui32 inflightLimit)
: TActor(&TThis::StateFunc)
, Capacity(inflightLimit)
{
}
static constexpr char ActorName[] = "HANDSHAKE_BROKER_ACTOR";
STFUNC(StateFunc) {
switch (ev->GetTypeRewrite()) {
hFunc(TEvHandshakeBrokerTake, Handle);
hFunc(TEvHandshakeBrokerFree, Handle);
default:
Y_FAIL("unexpected event 0x%08" PRIx32, ev->GetTypeRewrite());
}
}
void Bootstrap() {
Become(&TThis::StateFunc);
}
};
inline IActor* CreateHandshakeBroker(ui32 maxCapacity) {
return new THandshakeBroker(maxCapacity);
}
inline TActorId MakeHandshakeBrokerOutId() {
char x[12] = {'I', 'C', 'H', 's', 'h', 'k', 'B', 'r', 'k', 'O', 'u', 't'};
return TActorId(0, TStringBuf(std::begin(x), std::end(x)));
}
}
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