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Merged
geseq merged 1 commit into from
May 26, 2025
Merged

add return mode #51

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7 changes: 4 additions & 3 deletions bench/simple_bench.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -181,11 +181,12 @@ struct alignas(hardware_destructive_interference_size) AlignedData {
operator int() const { return value; }
};

template <typename T, size_t min_size, class PutWaitStrategy = YieldWaitStrategy, class GetWaitStrategy = YieldWaitStrategy>
template <typename T, size_t min_size, class PutWaitStrategy = YieldWaitStrategy, class GetWaitStrategy = YieldWaitStrategy,
ReturnMode put_mode = ReturnMode::Blocking, ReturnMode get_mode = ReturnMode::Blocking>
class RigtorpSPSC {
public:
using put_t = typename std::conditional<!std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value, void, bool>::type;
using get_t = typename std::conditional<!std::is_same<GetWaitStrategy, ReturnImmediateStrategy>::value, T, std::optional<T>>::type;
using put_t = typename std::conditional<put_mode == fastchan::ReturnMode::Blocking, void, bool>::type;
using get_t = typename std::conditional<get_mode == fastchan::ReturnMode::Blocking, T, std::optional<T>>::type;

RigtorpSPSC() = default;

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46 changes: 30 additions & 16 deletions include/mpsc.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,17 +4,19 @@
#include <mutex>
#include <optional>
#include <thread>
#include <variant>

#include "common.hpp"
#include "wait_strategy.hpp"

namespace fastchan {

template <typename T, size_t min_size, class PutWaitStrategy = YieldWaitStrategy, class GetWaitStrategy = YieldWaitStrategy>
template <typename T, size_t min_size, class PutWaitStrategy = YieldWaitStrategy, class GetWaitStrategy = YieldWaitStrategy,
ReturnMode put_mode = ReturnMode::Blocking, ReturnMode get_mode = ReturnMode::Blocking>
class MPSC {
public:
using put_t = typename std::conditional<!std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value, void, bool>::type;
using get_t = typename std::conditional<!std::is_same<GetWaitStrategy, ReturnImmediateStrategy>::value, T, std::optional<T>>::type;
using put_t = typename std::conditional<put_mode == ReturnMode::Blocking, void, bool>::type;
using get_t = typename std::conditional<get_mode == ReturnMode::Blocking, T, std::optional<T>>::type;

MPSC() = default;

Expand All @@ -24,7 +26,7 @@ class MPSC {
while (p.write_index_cache_ > (p.reader_index_cache_ + common_.index_mask_)) {
p.write_index_cache_ = next_free_index_.load(std::memory_order_acquire);
p.reader_index_cache_ = consumer_.reader_index_.load(std::memory_order_relaxed);
if constexpr (std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value) {
if constexpr (put_mode == ReturnMode::NonBlocking) {
return false;
} else {
common_.put_wait_.wait(
Expand All @@ -36,26 +38,33 @@ class MPSC {

contents_[p.write_index_cache_ & common_.index_mask_] = value;

// commit in the correct order to avoid problems
while (last_committed_index_.load(std::memory_order_relaxed) != p.write_index_cache_) {
// we don't return at this point even in case of ReturnImmediatelyStrategy as we've already taken the token
common_.put_wait_.wait([this] { return last_committed_index_.load(std::memory_order_relaxed) == p.write_index_cache_; });
if constexpr (put_mode == ReturnMode::Blocking) {
auto expected_index = p.write_index_cache_;
common_.put_wait_.wait([this, expected_index] { return last_committed_index_.load(std::memory_order_relaxed) == expected_index; });
}
}

last_committed_index_.store(++p.write_index_cache_, std::memory_order_release);

common_.get_wait_.notify();
common_.put_wait_.notify();
if constexpr (put_mode == ReturnMode::Blocking || get_mode == ReturnMode::Blocking) {
if constexpr (get_mode == ReturnMode::Blocking) {
common_.get_wait_.notify();
}
if constexpr (put_mode == ReturnMode::Blocking) {
common_.put_wait_.notify();
}
}

if constexpr (std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value) {
if constexpr (put_mode == ReturnMode::NonBlocking) {
return true;
}
}

get_t get() noexcept {
while (consumer_.reader_index_2_ >= consumer_.last_committed_index_cache_) {
consumer_.last_committed_index_cache_ = last_committed_index_.load(std::memory_order_relaxed);
if constexpr (std::is_same<GetWaitStrategy, ReturnImmediateStrategy>::value) {
if constexpr (get_mode == ReturnMode::NonBlocking) {
return std::nullopt;
} else {
common_.get_wait_.wait([this] { return consumer_.reader_index_2_ < last_committed_index_.load(std::memory_order_relaxed); });
Expand All @@ -65,7 +74,11 @@ class MPSC {
auto contents = contents_[consumer_.reader_index_2_ & common_.index_mask_];
consumer_.reader_index_.store(++consumer_.reader_index_2_, std::memory_order_release);

common_.put_wait_.notify();
if constexpr (put_mode == ReturnMode::Blocking || get_mode == ReturnMode::Blocking) {
if constexpr (put_mode == ReturnMode::Blocking) {
common_.put_wait_.notify();
}
}

return contents;
}
Expand All @@ -77,8 +90,6 @@ class MPSC {
bool isEmpty() const noexcept { return consumer_.reader_index_.load(std::memory_order_acquire) >= last_committed_index_.load(std::memory_order_acquire); }

bool isFull() const noexcept {
// this isFull is about whether there's all writer slots to the buffer are taken rather than whether those
// changes have actually been committed
return next_free_index_.load(std::memory_order_acquire) > (consumer_.reader_index_.load(std::memory_order_acquire) + common_.index_mask_);
}

Expand All @@ -89,8 +100,11 @@ class MPSC {
alignas(hardware_destructive_interference_size) std::atomic<std::size_t> last_committed_index_{0};

struct alignas(hardware_destructive_interference_size) Common {
GetWaitStrategy get_wait_{};
PutWaitStrategy put_wait_{};
static_assert(put_mode == ReturnMode::NonBlocking || std::is_base_of_v<WaitStrategyInterface<PutWaitStrategy>, PutWaitStrategy>);
static_assert(get_mode == ReturnMode::NonBlocking || std::is_base_of_v<WaitStrategyInterface<GetWaitStrategy>, GetWaitStrategy>);

typename std::conditional<get_mode == ReturnMode::Blocking, GetWaitStrategy, std::monostate>::type get_wait_{};
typename std::conditional<put_mode == ReturnMode::Blocking, PutWaitStrategy, std::monostate>::type put_wait_{};
const std::size_t index_mask_ = roundUpNextPowerOfTwo(min_size) - 1;
};

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37 changes: 24 additions & 13 deletions include/spsc.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,55 +6,63 @@
#include <optional>
#include <thread>
#include <type_traits>
#include <variant>

#include "common.hpp"
#include "wait_strategy.hpp"

namespace fastchan {

template <typename T, size_t min_size, class PutWaitStrategy = YieldWaitStrategy, class GetWaitStrategy = YieldWaitStrategy>
template <typename T, size_t min_size, class PutWaitStrategy = YieldWaitStrategy, class GetWaitStrategy = YieldWaitStrategy,
ReturnMode put_mode = ReturnMode::Blocking, ReturnMode get_mode = ReturnMode::Blocking>
class SPSC {
public:
using put_t = typename std::conditional<!std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value, void, bool>::type;
using get_t = typename std::conditional<!std::is_same<GetWaitStrategy, ReturnImmediateStrategy>::value, T, std::optional<T>>::type;
using put_t = typename std::conditional<put_mode == ReturnMode::Blocking, void, bool>::type;
using get_t = typename std::conditional<get_mode == ReturnMode::Blocking, T, std::optional<T>>::type;

SPSC() = default;

put_t put(const T &value) noexcept {
while (producer_.next_free_index_2_ > (producer_.reader_index_cache_ + common_.index_mask_)) {
producer_.reader_index_cache_ = consumer_.reader_index_.load(std::memory_order_acquire);
if constexpr (std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value) {
if constexpr (put_mode == ReturnMode::NonBlocking) {
return false;
} else {
common_.put_wait_.wait(
[this] { return producer_.next_free_index_2_ <= (consumer_.reader_index_.load(std::memory_order_acquire) + common_.index_mask_); });
}
}

contents_[producer_.next_free_index_2_ & common_.index_mask_] = value;
producer_.next_free_index_.store(++producer_.next_free_index_2_, std::memory_order_release);

common_.get_wait_.notify();
if constexpr (put_mode == ReturnMode::Blocking || get_mode == ReturnMode::Blocking) {
if constexpr (get_mode == ReturnMode::Blocking) {
common_.get_wait_.notify();
}
}

if constexpr (std::is_same<PutWaitStrategy, ReturnImmediateStrategy>::value) {
if constexpr (put_mode == ReturnMode::NonBlocking) {
return true;
}
}

get_t get() noexcept {
while (consumer_.reader_index_2_ >= consumer_.next_free_index_cache_) {
consumer_.next_free_index_cache_ = producer_.next_free_index_.load(std::memory_order_acquire);
if constexpr (std::is_same<GetWaitStrategy, ReturnImmediateStrategy>::value) {
if constexpr (get_mode == ReturnMode::NonBlocking) {
return std::nullopt;
} else {
common_.get_wait_.wait([this] { return consumer_.reader_index_2_ < producer_.next_free_index_.load(std::memory_order_acquire); });
}
}

auto contents = contents_[consumer_.reader_index_2_ & common_.index_mask_];
consumer_.reader_index_.store(++consumer_.reader_index_2_, std::memory_order_release);

common_.put_wait_.notify();
if constexpr (put_mode == ReturnMode::Blocking || get_mode == ReturnMode::Blocking) {
if constexpr (put_mode == ReturnMode::Blocking) {
common_.put_wait_.notify();
}
}

return contents;
}
Expand All @@ -75,8 +83,11 @@ class SPSC {
std::array<T, roundUpNextPowerOfTwo(min_size)> contents_;

struct alignas(hardware_destructive_interference_size) Common {
GetWaitStrategy get_wait_{};
PutWaitStrategy put_wait_{};
static_assert(put_mode == ReturnMode::NonBlocking || std::is_base_of_v<WaitStrategyInterface<PutWaitStrategy>, PutWaitStrategy>);
static_assert(get_mode == ReturnMode::NonBlocking || std::is_base_of_v<WaitStrategyInterface<GetWaitStrategy>, GetWaitStrategy>);

typename std::conditional<put_mode == ReturnMode::Blocking, PutWaitStrategy, std::monostate>::type put_wait_{};
typename std::conditional<get_mode == ReturnMode::Blocking, GetWaitStrategy, std::monostate>::type get_wait_{};
const std::size_t index_mask_ = roundUpNextPowerOfTwo(min_size) - 1;
};

Expand All @@ -96,5 +107,5 @@ class SPSC {
Producer producer_;
Consumer consumer_;
};
} // namespace fastchan

} // namespace fastchan
18 changes: 7 additions & 11 deletions include/wait_strategy.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2,14 +2,19 @@
#include <condition_variable>
#include <ratio>
#include <thread>

#include "common.hpp"

#ifndef FASTCHANWAIT_HPP
#define FASTCHANWAIT_HPP

namespace fastchan {

// Return mode enum to distinguish between blocking and non-blocking behavior
enum class ReturnMode {
Blocking,
NonBlocking
};

// WaitStrategyInterface is the interface for actual implementation of a wait strategy handler
template <typename Implementation>
class WaitStrategyInterface {
Expand All @@ -19,13 +24,6 @@ class WaitStrategyInterface {
inline void notify() {}
};

class ReturnImmediateStrategy : public WaitStrategyInterface<ReturnImmediateStrategy> {
public:
template <class Predicate>
inline void wait(Predicate p) {}
inline void notify() {}
};

class NoOpWaitStrategy : public WaitStrategyInterface<NoOpWaitStrategy> {
public:
template <class Predicate>
Expand All @@ -51,16 +49,14 @@ class YieldWaitStrategy : public WaitStrategyInterface<YieldWaitStrategy> {
inline void notify() {}
};

class CVWaitStrategy : public WaitStrategyInterface<PauseWaitStrategy> {
class CVWaitStrategy : public WaitStrategyInterface<CVWaitStrategy> {
public:
template <class Predicate>
inline void wait(Predicate p) {
std::unique_lock<std::mutex> lock(mutex_);
cv_.wait_for(lock, std::chrono::nanoseconds(100), p);
}

inline void notify() { cv_.notify_all(); }

private:
std::condition_variable cv_;
std::mutex mutex_;
Expand Down
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