neograph::util::RequestQueue Class Reference

Lock-free task queue with a fixed worker thread pool and backpressure. More...

#include <request_queue.h>

Classes
struct	Stats
	Runtime statistics for monitoring queue health. More...

Public Member Functions
void	close ()
	Stop accepting work, cancel queued tasks, and wait for workers.
bool	is_closed () const noexcept
	True once close() has started rejecting new work.
	RequestQueue (size_t num_workers=128, size_t max_queue_size=10000)
	Construct a request queue with a worker thread pool.
Stats	stats () const
	Get current queue statistics.
template<typename F >
std::pair< bool, std::future< void > >	submit (F &&task)
	Submit a task to the queue.
	~RequestQueue ()
	Destructor: applies the same cancel-on-close policy as close().

Detailed Description

Lock-free task queue with a fixed worker thread pool and backpressure.

Tasks are submitted via submit() and executed asynchronously by worker threads. When the queue is full, new tasks are rejected (backpressure).

RequestQueue queue(4, 1000);  // 4 workers, max 1000 pending tasks
auto [accepted, future] = queue.submit([]{ do_work(); });
if (accepted) future.wait();

Definition at line 96 of file request_queue.h.

Constructor & Destructor Documentation

RequestQueue()

neograph::util::RequestQueue::RequestQueue ( size_t  num_workers = 128, size_t  max_queue_size = 10000  )

inline

Construct a request queue with a worker thread pool.

Parameters

num_workers	Number of worker threads to spawn (default: 128).
max_queue_size	Maximum number of pending tasks before backpressure (default: 10000).

Exceptions

std::invalid_argument

if num_workers is zero.

Definition at line 322 of file request_queue.h.

Member Function Documentation

close()

void neograph::util::RequestQueue::close ( )

inline

Stop accepting work, cancel queued tasks, and wait for workers.

The first caller transitions the queue to closed. Work a worker claimed before that transition may finish; all unclaimed work completes its future with std::runtime_error("RequestQueue is closed"). Concurrent and repeated external callers wait for that same shutdown to complete. A task may call close() to initiate shutdown, but cannot wait for itself.

Definition at line 381 of file request_queue.h.

Referenced by ~RequestQueue().

stats()

Stats neograph::util::RequestQueue::stats ( ) const

inline

Get current queue statistics.

Returns

Stats snapshot with pending, active, completed, and rejected counts.

Definition at line 395 of file request_queue.h.

submit()

template<typename F >

std::pair< bool, std::future< void > > neograph::util::RequestQueue::submit ( F &&  task )

inline

Submit a task to the queue.

Admission atomically reserves one pending slot before enqueueing, so concurrent submitters cannot exceed max_queue_size. A full queue returns {false, invalid_future}. If the underlying queue rejects an already reserved task, the reservation is rolled back and the returned future is valid but completes with an exception.

Template Parameters

F	Callable type (must be invocable with no arguments).

Parameters

task	The task to execute.

Returns

A pair of {accepted, future}: accepted is true if the task was enqueued; future can be waited on for completion. Capacity rejection returns an invalid future; enqueue failure returns a valid future that propagates the failure. Closure rejection returns an invalid future.

Definition at line 368 of file request_queue.h.

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

• include/neograph/util/request_queue.h