concurrent::MpscQueue< T > Class Template Reference

#include <userver/concurrent/mpsc_queue.hpp>

Detailed Description

template<typename T>
class concurrent::MpscQueue< T >

Multiple producer, single consumer queue

Example usage:

  static constexpr std::chrono::milliseconds kTimeout{10};
 
  auto queue = concurrent::MpscQueue<int>::Create();
  auto producer = queue->GetProducer();
  auto consumer = queue->GetConsumer();
 
  auto producer_task = utils::Async("producer", [&] {
    // ...
    if (!producer.Push(1, engine::Deadline::FromDuration(kTimeout))) {
      // The reader is dead
    }
  });
 
  auto consumer_task = utils::Async("consumer", [&] {
    for (;;) {
      // ...
      int item{};
      if (consumer.Pop(item, engine::Deadline::FromDuration(kTimeout))) {
        // processing the queue element
        ASSERT_EQ(item, 1);
      } else {
        // the queue is empty and there are no more live producers
        return;
      }
    }
  });
  producer_task.Get();
  consumer_task.Get();

See also

Synchronization Primitives

Definition at line 75 of file mpsc_queue.hpp.

Inheritance diagram for concurrent::MpscQueue< T >:

Collaboration diagram for concurrent::MpscQueue< T >:

Public Types
using	ValueType = T
using	Producer
using	Consumer
using	MultiProducer

Public Member Functions
Producer	GetProducer ()
MultiProducer	GetMultiProducer ()
Consumer	GetConsumer ()
void	SetSoftMaxSize (size_t size)
	Sets the limit on the queue size, pushes over this limit will block.
size_t	GetSoftMaxSize () const
	Gets the limit on the queue size.
size_t	GetSizeApproximate () const
	Gets the approximate size of queue.

Static Public Member Functions
static std::shared_ptr< MpscQueue >	Create (std::size_t max_size=kUnbounded)
	Create a new queue.

Static Public Attributes
static constexpr std::size_t	kUnbounded

Member Typedef Documentation

Consumer

template<typename T >

using concurrent::MpscQueue< T >::Consumer

Initial value:

 
      concurrent::Consumer<MpscQueue, ConsumerToken, EmplaceEnabler>

Definition at line 97 of file mpsc_queue.hpp.

MultiProducer

template<typename T >

using concurrent::MpscQueue< T >::MultiProducer

Initial value:

 
      concurrent::Producer<MpscQueue, impl::NoToken, EmplaceEnabler>

Definition at line 99 of file mpsc_queue.hpp.

Producer

template<typename T >

using concurrent::MpscQueue< T >::Producer

Initial value:

 
      concurrent::Producer<MpscQueue, ProducerToken, EmplaceEnabler>

Definition at line 95 of file mpsc_queue.hpp.

ValueType

template<typename T >

using concurrent::MpscQueue< T >::ValueType = T

Definition at line 93 of file mpsc_queue.hpp.

Member Function Documentation

Create()

template<typename T >

static std::shared_ptr< MpscQueue > concurrent::MpscQueue< T >::Create ( std::size_t max_size = kUnbounded )

inlinestatic

Create a new queue.

Definition at line 116 of file mpsc_queue.hpp.

GetConsumer()

template<typename T >

MpscQueue< T >::Consumer concurrent::MpscQueue< T >::GetConsumer

(

)

Get a Consumer which makes it possible to read items from the queue. Can be called only once. You may not use the Consumer simultaneously from multiple coroutines/threads.

Note

Consumer may outlive the queue and producers.

Definition at line 205 of file mpsc_queue.hpp.

GetMultiProducer()

template<typename T >

MpscQueue< T >::MultiProducer concurrent::MpscQueue< T >::GetMultiProducer

(

)

Get a MultiProducer which makes it possible to push items into the queue. Can be called multiple times. The resulting MultiProducer is thread-safe, so it can be used simultaneously from multiple coroutines/threads.

Note

MultiProducer may outlive the queue and the Consumer.

Definition at line 198 of file mpsc_queue.hpp.

GetProducer()

template<typename T >

MpscQueue< T >::Producer concurrent::MpscQueue< T >::GetProducer

(

)

Get a Producer which makes it possible to push items into the queue. Can be called multiple times. The resulting Producer is not thread-safe, so you have to use multiple Producers of the same queue to simultaneously write from multiple coroutines/threads.

Note

Producer may outlive the queue and the Consumer.

Definition at line 190 of file mpsc_queue.hpp.

GetSizeApproximate()

template<typename T >

size_t concurrent::MpscQueue< T >::GetSizeApproximate

(

)

const

Gets the approximate size of queue.

Definition at line 223 of file mpsc_queue.hpp.

GetSoftMaxSize()

template<typename T >

size_t concurrent::MpscQueue< T >::GetSoftMaxSize

(

)

const

Gets the limit on the queue size.

Definition at line 218 of file mpsc_queue.hpp.

SetSoftMaxSize()

template<typename T >

void concurrent::MpscQueue< T >::SetSoftMaxSize

(

size_t

size

)

Sets the limit on the queue size, pushes over this limit will block.

Note

This is a soft limit and may be slightly overrun under load.

Definition at line 213 of file mpsc_queue.hpp.

Friends And Related Symbol Documentation

Consumer< MpscQueue, ConsumerToken, EmplaceEnabler >

template<typename T >

friend class Consumer< MpscQueue, ConsumerToken, EmplaceEnabler >

friend

Definition at line 76 of file mpsc_queue.hpp.

Producer< MpscQueue, ProducerToken, EmplaceEnabler >

template<typename T >

friend class Producer< MpscQueue, ProducerToken, EmplaceEnabler >

friend

Definition at line 76 of file mpsc_queue.hpp.

Member Data Documentation

kUnbounded

template<typename T >

constexpr std::size_t concurrent::MpscQueue< T >::kUnbounded

staticconstexpr

Initial value:

=
      std::numeric_limits<std::size_t>::max()

Definition at line 90 of file mpsc_queue.hpp.

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The documentation for this class was generated from the following file:

• userver/concurrent/mpsc_queue.hpp