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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)
//
#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/waker.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:
using value_type = typename std::remove_reference<T>::type;
private:
using slot_type = value_type;
mutable detail::spinlock splk_{};
wait_queue waiting_producers_{};
wait_queue waiting_consumers_{};
slot_type * slots_;
std::size_t pidx_{ 0 };
std::size_t cidx_{ 0 };
std::size_t capacity_;
bool closed_{ false };
bool is_full_() const noexcept {
return cidx_ == ((pidx_ + 1) % capacity_);
}
bool is_empty_() const noexcept {
return cidx_ == pidx_;
}
bool is_closed_() const noexcept {
return closed_;
}
public:
explicit buffered_channel( std::size_t capacity) :
capacity_{ capacity } {
if ( BOOST_UNLIKELY( 2 > 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_type[capacity_];
}
~buffered_channel() {
close();
delete [] slots_;
}
buffered_channel( buffered_channel const&) = delete;
buffered_channel & operator=( buffered_channel const&) = delete;
bool is_closed() const noexcept {
detail::spinlock_lock lk{splk_, std::defer_lock};
for(;;) {
if(lk.try_lock())
break;
context::active()->yield();
}
return is_closed_();
}
void close() noexcept {
detail::spinlock_lock lk{splk_, std::defer_lock};
for(;;) {
if(lk.try_lock())
break;
context::active()->yield();
}
if ( ! closed_) {
closed_ = true;
waiting_producers_.notify_all();
waiting_consumers_.notify_all();
}
}
channel_op_status try_push( value_type const& value) {
detail::spinlock_lock lk{splk_, std::defer_lock};
for(;;) {
if(lk.try_lock())
break;
context::active()->yield();
}
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( is_full_() ) {
return channel_op_status::full;
}
slots_[pidx_] = value;
pidx_ = (pidx_ + 1) % capacity_;
waiting_consumers_.notify_one();
return channel_op_status::success;
}
channel_op_status try_push( value_type && value) {
detail::spinlock_lock lk{splk_, std::defer_lock};
for(;;) {
if(lk.try_lock())
break;
context::active()->yield();
}
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( is_full_() ) {
return channel_op_status::full;
}
slots_[pidx_] = std::move( value);
pidx_ = (pidx_ + 1) % capacity_;
waiting_consumers_.notify_one();
return channel_op_status::success;
}
channel_op_status push( value_type const& value) {
context * active_ctx = context::active();
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( is_full_() ) {
waiting_producers_.suspend_and_wait( lk, active_ctx);
} else {
slots_[pidx_] = value;
pidx_ = (pidx_ + 1) % capacity_;
waiting_consumers_.notify_one();
return channel_op_status::success;
}
}
}
channel_op_status push( value_type && value) {
context * active_ctx = context::active();
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( is_full_() ) {
waiting_producers_.suspend_and_wait( lk, active_ctx);
} else {
slots_[pidx_] = std::move( value);
pidx_ = (pidx_ + 1) % capacity_;
waiting_consumers_.notify_one();
return channel_op_status::success;
}
}
}
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_) {
context * active_ctx = context::active();
std::chrono::steady_clock::time_point timeout_time = detail::convert( timeout_time_);
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( is_full_() ) {
if ( ! waiting_producers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
return channel_op_status::timeout;
}
} else {
slots_[pidx_] = value;
pidx_ = (pidx_ + 1) % capacity_;
waiting_consumers_.notify_one();
return channel_op_status::success;
}
}
}
template< typename Clock, typename Duration >
channel_op_status push_wait_until( value_type && value,
std::chrono::time_point< Clock, Duration > const& timeout_time_) {
context * active_ctx = context::active();
std::chrono::steady_clock::time_point timeout_time = detail::convert( timeout_time_);
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( is_full_() ) {
if ( ! waiting_producers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
return channel_op_status::timeout;
}
} else {
slots_[pidx_] = std::move( value);
pidx_ = (pidx_ + 1) % capacity_;
// notify one waiting consumer
waiting_consumers_.notify_one();
return channel_op_status::success;
}
}
}
channel_op_status try_pop( value_type & value) {
detail::spinlock_lock lk{splk_, std::defer_lock};
for(;;) {
if(lk.try_lock())
break;
context::active()->yield();
}
if ( is_empty_() ) {
return is_closed_()
? channel_op_status::closed
: channel_op_status::empty;
}
value = std::move( slots_[cidx_]);
cidx_ = (cidx_ + 1) % capacity_;
waiting_producers_.notify_one();
return channel_op_status::success;
}
channel_op_status pop( value_type & value) {
context * active_ctx = context::active();
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( is_empty_() ) {
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
waiting_consumers_.suspend_and_wait( lk, active_ctx);
} else {
value = std::move( slots_[cidx_]);
cidx_ = (cidx_ + 1) % capacity_;
waiting_producers_.notify_one();
return channel_op_status::success;
}
}
}
value_type value_pop() {
context * active_ctx = context::active();
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( is_empty_() ) {
if ( BOOST_UNLIKELY( is_closed_() ) ) {
throw fiber_error{
std::make_error_code( std::errc::operation_not_permitted),
"boost fiber: channel is closed" };
}
waiting_consumers_.suspend_and_wait( lk, active_ctx);
} else {
value_type value = std::move( slots_[cidx_]);
cidx_ = (cidx_ + 1) % capacity_;
waiting_producers_.notify_one();
return value;
}
}
}
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_) {
context * active_ctx = context::active();
std::chrono::steady_clock::time_point timeout_time = detail::convert( timeout_time_);
for (;;) {
detail::spinlock_lock lk{splk_, std::try_to_lock};
if (!lk) {
active_ctx->yield();
continue;
}
if ( is_empty_() ) {
if ( BOOST_UNLIKELY( is_closed_() ) ) {
return channel_op_status::closed;
}
if ( ! waiting_consumers_.suspend_and_wait_until( lk, active_ctx, timeout_time)) {
return channel_op_status::timeout;
}
} else {
value = std::move( slots_[cidx_]);
cidx_ = (cidx_ + 1) % capacity_;
waiting_producers_.notify_one();
return channel_op_status::success;
}
}
}
class iterator {
private:
typedef typename std::aligned_storage< sizeof( value_type), alignof( value_type) >::type storage_type;
buffered_channel * chan_{ nullptr };
storage_type storage_;
void increment_( bool initial = false) {
BOOST_ASSERT( nullptr != chan_);
try {
if ( ! initial) {
reinterpret_cast< value_type * >( std::addressof( storage_) )->~value_type();
}
::new ( static_cast< void * >( std::addressof( storage_) ) ) value_type{ chan_->value_pop() };
} catch ( fiber_error const&) {
chan_ = nullptr;
}
}
public:
using iterator_category = std::input_iterator_tag;
using difference_type = std::ptrdiff_t;
using pointer = value_type *;
using reference = value_type &;
using pointer_t = pointer;
using reference_t = reference;
iterator() = default;
explicit iterator( buffered_channel< T > * chan) noexcept :
chan_{ chan } {
increment_( true);
}
iterator( iterator const& other) noexcept :
chan_{ other.chan_ } {
}
iterator & operator=( iterator const& other) noexcept {
if ( BOOST_LIKELY( this != & other) ) {
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++() {
reinterpret_cast< value_type * >( std::addressof( storage_) )->~value_type();
increment_();
return * this;
}
const 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
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