ecency-mobile/ios/Pods/boost-for-react-native/boost/fiber/buffered_channel.hpp

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// Copyright Oliver Kowalke 2016.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// based on Dmitry Vyukov's MPMC queue
// (http://www.1024cores.net/home/lock-free-algorithms/queues/bounded-mpmc-queue)
#ifndef BOOST_FIBERS_BUFFERED_CHANNEL_H
#define BOOST_FIBERS_BUFFERED_CHANNEL_H
#include <atomic>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <type_traits>
#include <boost/config.hpp>
#include <boost/fiber/channel_op_status.hpp>
#include <boost/fiber/context.hpp>
#include <boost/fiber/detail/config.hpp>
#include <boost/fiber/detail/convert.hpp>
#include <boost/fiber/detail/spinlock.hpp>
#include <boost/fiber/exceptions.hpp>
#ifdef BOOST_HAS_ABI_HEADERS
# include BOOST_ABI_PREFIX
#endif
namespace boost {
namespace fibers {
template< typename T >
class buffered_channel {
public:
typedef T value_type;
private:
typedef typename std::aligned_storage< sizeof( T), alignof( T) >::type storage_type;
typedef context::wait_queue_t wait_queue_type;
struct alignas(cache_alignment) slot {
std::atomic< std::size_t > cycle{ 0 };
storage_type storage{};
slot() = default;
};
// procuder cacheline
alignas(cache_alignment) std::atomic< std::size_t > producer_idx_{ 0 };
// consumer cacheline
alignas(cache_alignment) std::atomic< std::size_t > consumer_idx_{ 0 };
// shared write cacheline
alignas(cache_alignment) std::atomic_bool closed_{ false };
mutable detail::spinlock splk_{};
wait_queue_type waiting_producers_{};
wait_queue_type waiting_consumers_{};
// shared read cacheline
alignas(cache_alignment) slot * slots_{ nullptr };
std::size_t capacity_;
char pad_[cacheline_length];
bool is_full_() {
std::size_t idx{ producer_idx_.load( std::memory_order_relaxed) };
return 0 > static_cast< std::intptr_t >( slots_[idx & (capacity_ - 1)].cycle.load( std::memory_order_acquire) ) - static_cast< std::intptr_t >( idx);
}
bool is_empty_() {
std::size_t idx{ consumer_idx_.load( std::memory_order_relaxed) };
return 0 > static_cast< std::intptr_t >( slots_[idx & (capacity_ - 1)].cycle.load( std::memory_order_acquire) ) - static_cast< std::intptr_t >( idx + 1);
}
template< typename ValueType >
channel_op_status try_push_( ValueType && value) {
slot * s{ nullptr };
std::size_t idx{ producer_idx_.load( std::memory_order_relaxed) };
for (;;) {
s = & slots_[idx & (capacity_ - 1)];
std::size_t cycle{ s->cycle.load( std::memory_order_acquire) };
std::intptr_t diff{ static_cast< std::intptr_t >( cycle) - static_cast< std::intptr_t >( idx) };
if ( 0 == diff) {
if ( producer_idx_.compare_exchange_weak( idx, idx + 1, std::memory_order_relaxed) ) {
break;
}
} else if ( 0 > diff) {
return channel_op_status::full;
} else {
idx = producer_idx_.load( std::memory_order_relaxed);
}
}
::new ( static_cast< void * >( std::addressof( s->storage) ) ) value_type( std::forward< ValueType >( value) );
s->cycle.store( idx + 1, std::memory_order_release);
return channel_op_status::success;
}
channel_op_status try_value_pop_( slot *& s, std::size_t & idx) {
idx = consumer_idx_.load( std::memory_order_relaxed);
for (;;) {
s = & slots_[idx & (capacity_ - 1)];
std::size_t cycle = s->cycle.load( std::memory_order_acquire);
std::intptr_t diff{ static_cast< std::intptr_t >( cycle) - static_cast< std::intptr_t >( idx + 1) };
if ( 0 == diff) {
if ( consumer_idx_.compare_exchange_weak( idx, idx + 1, std::memory_order_relaxed) ) {
break;
}
} else if ( 0 > diff) {
return channel_op_status::empty;
} else {
idx = consumer_idx_.load( std::memory_order_relaxed);
}
}
// incrementing the slot cycle must be deferred till the value has been consumed
// slot cycle tells procuders that the cell can be re-used (store new value)
return channel_op_status::success;
}
channel_op_status try_pop_( value_type & value) {
slot * s{ nullptr };
std::size_t idx{ 0 };
channel_op_status status{ try_value_pop_( s, idx) };
if ( channel_op_status::success == status) {
value = std::move( * reinterpret_cast< value_type * >( std::addressof( s->storage) ) );
s->cycle.store( idx + capacity_, std::memory_order_release);
}
return status;
}
public:
explicit buffered_channel( std::size_t capacity) :
capacity_{ capacity } {
if ( 0 == capacity_ || 0 != ( capacity_ & (capacity_ - 1) ) ) {
throw fiber_error( std::make_error_code( std::errc::invalid_argument),
"boost fiber: buffer capacity is invalid");
}
slots_ = new slot[capacity_]();
for ( std::size_t i = 0; i < capacity_; ++i) {
slots_[i].cycle.store( i, std::memory_order_relaxed);
}
}
~buffered_channel() {
close();
for (;;) {
slot * s{ nullptr };
std::size_t idx{ 0 };
if ( channel_op_status::success == try_value_pop_( s, idx) ) {
reinterpret_cast< value_type * >( std::addressof( s->storage) )->~value_type();
s->cycle.store( idx + capacity_, std::memory_order_release);
} else {
break;
}
}
delete [] slots_;
}
buffered_channel( buffered_channel const&) = delete;
buffered_channel & operator=( buffered_channel const&) = delete;
bool is_closed() const noexcept {
return closed_.load( std::memory_order_acquire);
}
void close() noexcept {
context * ctx{ context::active() };
detail::spinlock_lock lk{ splk_ };
closed_.store( true, std::memory_order_release);
// notify all waiting producers
while ( ! waiting_producers_.empty() ) {
context * producer_ctx{ & waiting_producers_.front() };
waiting_producers_.pop_front();
ctx->set_ready( producer_ctx);
}
// notify all waiting consumers
while ( ! waiting_consumers_.empty() ) {
context * consumer_ctx{ & waiting_consumers_.front() };
waiting_consumers_.pop_front();
ctx->set_ready( consumer_ctx);
}
}
channel_op_status try_push( value_type const& value) {
if ( is_closed() ) {
return channel_op_status::closed;
}
return try_push_( value);
}
channel_op_status try_push( value_type && value) {
if ( is_closed() ) {
return channel_op_status::closed;
}
return try_push_( std::move( value) );
}
channel_op_status push( value_type const& value) {
context * ctx{ context::active() };
for (;;) {
if ( is_closed() ) {
return channel_op_status::closed;
}
channel_op_status status{ try_push_( value) };
if ( channel_op_status::success == status) {
detail::spinlock_lock lk{ splk_ };
// notify one waiting consumer
if ( ! waiting_consumers_.empty() ) {
context * consumer_ctx{ & waiting_consumers_.front() };
waiting_consumers_.pop_front();
lk.unlock();
ctx->set_ready( consumer_ctx);
}
return status;
} else if ( channel_op_status::full == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
return channel_op_status::closed;
}
if ( ! is_full_() ) {
continue;
}
ctx->wait_link( waiting_producers_);
// suspend this producer
ctx->suspend( lk);
} else {
BOOST_ASSERT( channel_op_status::closed == status);
return status;
}
}
}
channel_op_status push( value_type && value) {
context * ctx{ context::active() };
for (;;) {
if ( is_closed() ) {
return channel_op_status::closed;
}
channel_op_status status{ try_push_( std::move( value) ) };
if ( channel_op_status::success == status) {
detail::spinlock_lock lk{ splk_ };
// notify one waiting consumer
if ( ! waiting_consumers_.empty() ) {
context * consumer_ctx{ & waiting_consumers_.front() };
waiting_consumers_.pop_front();
lk.unlock();
ctx->set_ready( consumer_ctx);
}
return status;
} else if ( channel_op_status::full == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
return channel_op_status::closed;
}
if ( ! is_full_() ) {
continue;
}
ctx->wait_link( waiting_producers_);
// suspend this producer
ctx->suspend( lk);
} else {
BOOST_ASSERT( channel_op_status::closed == status);
return status;
}
}
}
template< typename Rep, typename Period >
channel_op_status push_wait_for( value_type const& value,
std::chrono::duration< Rep, Period > const& timeout_duration) {
return push_wait_until( value,
std::chrono::steady_clock::now() + timeout_duration);
}
template< typename Rep, typename Period >
channel_op_status push_wait_for( value_type && value,
std::chrono::duration< Rep, Period > const& timeout_duration) {
return push_wait_until( std::forward< value_type >( value),
std::chrono::steady_clock::now() + timeout_duration);
}
template< typename Clock, typename Duration >
channel_op_status push_wait_until( value_type const& value,
std::chrono::time_point< Clock, Duration > const& timeout_time_) {
std::chrono::steady_clock::time_point timeout_time( detail::convert( timeout_time_) );
context * ctx{ context::active() };
for (;;) {
if ( is_closed() ) {
return channel_op_status::closed;
}
channel_op_status status{ try_push_( value) };
if ( channel_op_status::success == status) {
detail::spinlock_lock lk{ splk_ };
// notify one waiting consumer
if ( ! waiting_consumers_.empty() ) {
context * consumer_ctx{ & waiting_consumers_.front() };
waiting_consumers_.pop_front();
lk.unlock();
ctx->set_ready( consumer_ctx);
}
return status;
} else if ( channel_op_status::full == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
return channel_op_status::closed;
}
if ( ! is_full_() ) {
continue;
}
ctx->wait_link( waiting_producers_);
// suspend this producer
if ( ! ctx->wait_until( timeout_time, lk) ) {
// relock local lk
lk.lock();
// remove from waiting-queue
ctx->wait_unlink();
return channel_op_status::timeout;
}
} else {
BOOST_ASSERT( channel_op_status::closed == status);
return status;
}
}
}
template< typename Clock, typename Duration >
channel_op_status push_wait_until( value_type && value,
std::chrono::time_point< Clock, Duration > const& timeout_time_) {
std::chrono::steady_clock::time_point timeout_time( detail::convert( timeout_time_) );
context * ctx{ context::active() };
for (;;) {
if ( is_closed() ) {
return channel_op_status::closed;
}
channel_op_status status{ try_push_( std::move( value) ) };
if ( channel_op_status::success == status) {
detail::spinlock_lock lk{ splk_ };
// notify one waiting consumer
if ( ! waiting_consumers_.empty() ) {
context * consumer_ctx{ & waiting_consumers_.front() };
waiting_consumers_.pop_front();
lk.unlock();
ctx->set_ready( consumer_ctx);
}
return status;
} else if ( channel_op_status::full == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
return channel_op_status::closed;
}
if ( ! is_full_() ) {
continue;
}
ctx->wait_link( waiting_producers_);
// suspend this producer
if ( ! ctx->wait_until( timeout_time, lk) ) {
// relock local lk
lk.lock();
// remove from waiting-queue
ctx->wait_unlink();
return channel_op_status::timeout;
}
} else {
BOOST_ASSERT( channel_op_status::closed == status);
return status;
}
}
}
channel_op_status try_pop( value_type & value) {
channel_op_status status{ try_pop_( value) };
if ( channel_op_status::success != status) {
if ( is_closed() ) {
status = channel_op_status::closed;
}
}
return status;
}
channel_op_status pop( value_type & value) {
context * ctx{ context::active() };
for (;;) {
channel_op_status status{ try_pop_( value) };
if ( channel_op_status::success == status) {
detail::spinlock_lock lk{ splk_ };
// notify one waiting producer
if ( ! waiting_producers_.empty() ) {
context * producer_ctx{ & waiting_producers_.front() };
waiting_producers_.pop_front();
lk.unlock();
ctx->set_ready( producer_ctx);
}
return status;
} else if ( channel_op_status::empty == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
return channel_op_status::closed;
}
if ( ! is_empty_() ) {
continue;
}
ctx->wait_link( waiting_consumers_);
// suspend this consumer
ctx->suspend( lk);
} else {
BOOST_ASSERT( channel_op_status::closed == status);
return status;
}
}
}
value_type value_pop() {
context * ctx{ context::active() };
for (;;) {
slot * s{ nullptr };
std::size_t idx{ 0 };
channel_op_status status{ try_value_pop_( s, idx) };
if ( channel_op_status::success == status) {
value_type value{ std::move( * reinterpret_cast< value_type * >( std::addressof( s->storage) ) ) };
s->cycle.store( idx + capacity_, std::memory_order_release);
detail::spinlock_lock lk{ splk_ };
// notify one waiting producer
if ( ! waiting_producers_.empty() ) {
context * producer_ctx{ & waiting_producers_.front() };
waiting_producers_.pop_front();
lk.unlock();
ctx->set_ready( producer_ctx);
}
return std::move( value);
} else if ( channel_op_status::empty == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
throw fiber_error{
std::make_error_code( std::errc::operation_not_permitted),
"boost fiber: channel is closed" };
}
if ( ! is_empty_() ) {
continue;
}
ctx->wait_link( waiting_consumers_);
// suspend this consumer
ctx->suspend( lk);
} else {
BOOST_ASSERT( channel_op_status::closed == status);
throw fiber_error{
std::make_error_code( std::errc::operation_not_permitted),
"boost fiber: channel is closed" };
}
}
}
template< typename Rep, typename Period >
channel_op_status pop_wait_for( value_type & value,
std::chrono::duration< Rep, Period > const& timeout_duration) {
return pop_wait_until( value,
std::chrono::steady_clock::now() + timeout_duration);
}
template< typename Clock, typename Duration >
channel_op_status pop_wait_until( value_type & value,
std::chrono::time_point< Clock, Duration > const& timeout_time_) {
std::chrono::steady_clock::time_point timeout_time( detail::convert( timeout_time_) );
context * ctx{ context::active() };
for (;;) {
channel_op_status status{ try_pop_( value) };
if ( channel_op_status::success == status) {
detail::spinlock_lock lk{ splk_ };
// notify one waiting producer
if ( ! waiting_producers_.empty() ) {
context * producer_ctx{ & waiting_producers_.front() };
waiting_producers_.pop_front();
lk.unlock();
context::active()->set_ready( producer_ctx);
}
return status;
} else if ( channel_op_status::empty == status) {
BOOST_ASSERT( ! ctx->wait_is_linked() );
detail::spinlock_lock lk{ splk_ };
if ( is_closed() ) {
return channel_op_status::closed;
}
if ( ! is_empty_() ) {
continue;
}
ctx->wait_link( waiting_consumers_);
// suspend this consumer
if ( ! ctx->wait_until( timeout_time, lk) ) {
// relock local lk
lk.lock();
// remove from waiting-queue
ctx->wait_unlink();
return channel_op_status::timeout;
}
} else {
BOOST_ASSERT( channel_op_status::closed == status);
return status;
}
}
}
class iterator : public std::iterator< std::input_iterator_tag, typename std::remove_reference< value_type >::type > {
private:
typedef typename std::aligned_storage< sizeof( value_type), alignof( value_type) >::type storage_type;
buffered_channel * chan_{ nullptr };
storage_type storage_;
void increment_() {
BOOST_ASSERT( nullptr != chan_);
try {
::new ( static_cast< void * >( std::addressof( storage_) ) ) value_type{ chan_->value_pop() };
} catch ( fiber_error const&) {
chan_ = nullptr;
}
}
public:
typedef typename iterator::pointer pointer_t;
typedef typename iterator::reference reference_t;
iterator() noexcept = default;
explicit iterator( buffered_channel< T > * chan) noexcept :
chan_{ chan } {
increment_();
}
iterator( iterator const& other) noexcept :
chan_{ other.chan_ } {
}
iterator & operator=( iterator const& other) noexcept {
if ( this == & other) return * this;
chan_ = other.chan_;
return * this;
}
bool operator==( iterator const& other) const noexcept {
return other.chan_ == chan_;
}
bool operator!=( iterator const& other) const noexcept {
return other.chan_ != chan_;
}
iterator & operator++() {
increment_();
return * this;
}
iterator operator++( int) = delete;
reference_t operator*() noexcept {
return * reinterpret_cast< value_type * >( std::addressof( storage_) );
}
pointer_t operator->() noexcept {
return reinterpret_cast< value_type * >( std::addressof( storage_) );
}
};
friend class iterator;
};
template< typename T >
typename buffered_channel< T >::iterator
begin( buffered_channel< T > & chan) {
return typename buffered_channel< T >::iterator( & chan);
}
template< typename T >
typename buffered_channel< T >::iterator
end( buffered_channel< T > &) {
return typename buffered_channel< T >::iterator();
}
}}
#ifdef BOOST_HAS_ABI_HEADERS
# include BOOST_ABI_SUFFIX
#endif
#endif // BOOST_FIBERS_BUFFERED_CHANNEL_H