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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "tickingthread.h"
#include "threadpool.h"
#include "runnable.h"
#include "thread.h"
#include <vespa/vespalib/stllike/asciistream.h>
#include <cassert>
namespace storage::framework {
ThreadWaitInfo ThreadWaitInfo::MORE_WORK_ENQUEUED(false);
ThreadWaitInfo ThreadWaitInfo::NO_MORE_CRITICAL_WORK_KNOWN(true);
void
ThreadWaitInfo::merge(const ThreadWaitInfo& other) {
if (!other._waitWanted) {
_waitWanted = false;
}
}
/**
* \brief Implementation actually doing lock handling, waiting, and allowing a
* global synchronization point where no thread is currently running.
*/
class TickingThreadRunner final : public Runnable {
std::mutex & _monitor;
std::condition_variable & _cond;
TickingThread & _tickingThread;
uint32_t _threadIndex;
bool _wantToFreeze;
bool _frozen;
char _state;
public:
using SP = std::shared_ptr<TickingThreadRunner>;
TickingThreadRunner(std::mutex& m,
std::condition_variable & cond,
TickingThread& ticker,
uint32_t threadIndex) noexcept
: _monitor(m), _cond(cond), _tickingThread(ticker),
_threadIndex(threadIndex), _wantToFreeze(false), _frozen(false), _state('n') {}
/**
* Call to freeze this thread. Returns then the thread has done executing
* tick and has frozen.
*/
void freeze() {
std::unique_lock guard(_monitor);
_wantToFreeze = true;
while (!_frozen) {
_cond.wait(guard);
}
}
/**
* Call to thaw up a frozen thread so it can continue.
*/
void thaw() {
{
std::lock_guard guard(_monitor);
_wantToFreeze = false;
}
_cond.notify_all();
}
[[nodiscard]] char getState() const { return _state; }
private:
void run(ThreadHandle& handle) override {
ThreadWaitInfo info = ThreadWaitInfo::MORE_WORK_ENQUEUED;
CycleType cycle = PROCESS_CYCLE;
int ticksExecutedAfterWait = 0;
while (!handle.interrupted()) {
{
std::unique_lock guard(_monitor);
if (info.waitWanted()) {
_state = 'w';
cycle = WAIT_CYCLE;
if (ticksExecutedAfterWait >= handle.getTicksBeforeWait()) {
_cond.wait_for(guard, handle.getWaitTime());
ticksExecutedAfterWait = 0;
}
}
if (_wantToFreeze) {
_state = 'f';
doFreeze(guard, _cond);
ticksExecutedAfterWait = 0;
}
_state = 'c';
info.merge(_tickingThread.doCriticalTick(_threadIndex));
_state = 'n';
}
handle.registerTick(cycle);
ticksExecutedAfterWait++;
cycle = PROCESS_CYCLE;
info = _tickingThread.doNonCriticalTick(_threadIndex);
}
_state = 's';
}
void doFreeze(std::unique_lock<std::mutex> & guard, std::condition_variable & cond) {
_frozen = true;
cond.notify_all();
while (_wantToFreeze) {
_cond.wait(guard);
}
_frozen = false;
}
};
class TickingThreadPoolImpl final : public TickingThreadPool {
const vespalib::string _name;
const vespalib::duration _waitTime;
const vespalib::duration _maxProcessTime;
const uint32_t _ticksBeforeWait;
std::mutex _lock;
std::condition_variable _cond;
std::vector<TickingThreadRunner::SP> _tickers;
std::vector<std::shared_ptr<Thread>> _threads;
struct FreezeGuard final : public TickingLockGuard::Impl {
TickingThreadPoolImpl& _pool;
explicit FreezeGuard(TickingThreadPoolImpl& pool) : _pool(pool) { _pool.freeze(); }
~FreezeGuard() override { _pool.thaw(); }
void broadcast() override {}
};
struct CriticalGuard final : public TickingLockGuard::Impl {
std::unique_lock<std::mutex> _guard;
std::condition_variable &_cond;
explicit CriticalGuard(std::mutex & lock, std::condition_variable & cond) : _guard(lock), _cond(cond) {}
void broadcast() override { _cond.notify_all(); }
};
public:
TickingThreadPoolImpl(vespalib::stringref name, vespalib::duration waitTime,
int ticksBeforeWait, vespalib::duration maxProcessTime)
: _name(name),
_waitTime(waitTime),
_maxProcessTime(maxProcessTime),
_ticksBeforeWait(ticksBeforeWait)
{ }
~TickingThreadPoolImpl() override {
stop();
}
void addThread(TickingThread& ticker) override {
ThreadIndex index = _tickers.size();
ticker.newThreadCreated(index);
_tickers.emplace_back(std::make_shared<TickingThreadRunner>(_lock, _cond, ticker, index));
}
void start(ThreadPool& pool) override {
assert(!_tickers.empty());
for (uint32_t i=0; i<_tickers.size(); ++i) {
vespalib::asciistream ost;
ost << _name.c_str() << " thread " << i;
_threads.push_back(std::shared_ptr<Thread>(pool.startThread(
*_tickers[i],
ost.str(),
_waitTime,
_maxProcessTime,
_ticksBeforeWait, std::nullopt)));
}
}
TickingLockGuard freezeAllTicks() override {
return TickingLockGuard(std::make_unique<FreezeGuard>(*this));
}
TickingLockGuard freezeCriticalTicks() override {
return TickingLockGuard(std::make_unique<CriticalGuard>(_lock, _cond));
}
void stop() override {
for (auto& t : _threads) {
t->interrupt();
}
{
_cond.notify_all();
}
for (auto& t : _threads) {
t->join();
}
}
vespalib::string getStatus() override {
vespalib::string result(_tickers.size(), ' ');
for (uint32_t i=0, n=_tickers.size(); i<n; ++i) {
result[i] = _tickers[i]->getState();
}
return result;
}
private:
void freeze() {
for (auto& t : _tickers) {
t->freeze();
}
}
void thaw() {
for (auto& t : _tickers) {
t->thaw();
}
}
};
TickingThreadPool::UP
TickingThreadPool::createDefault(
vespalib::stringref name,
vespalib::duration waitTime,
int ticksBeforeWait,
vespalib::duration maxProcessTime)
{
return std::make_unique<TickingThreadPoolImpl>(name, waitTime, ticksBeforeWait, maxProcessTime);
}
TickingThreadPool::UP
TickingThreadPool::createDefault(vespalib::stringref name, vespalib::duration waitTime)
{
return createDefault(name, waitTime, 1, 5s);
}
} // storage::framework
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