eve.rt.pool

Thread Pool for Parallel Task Execution

This module provides a thread pool implementation for executing tasks across multiple worker threads. It integrates with the EVE runtime layer to enable efficient parallel and concurrent execution patterns.

The thread pool manages a fixed number of worker threads that pull tasks from a shared work queue. This amortizes thread creation overhead and provides backpressure when the system is overloaded.

Copyright

License

Boost Software License, Version 1.0

alias Task

enum PoolState SubmitResult

class ThreadPool

fn defaultWorkerCount

Types 4

enumPoolState : ubyte

State of the thread pool.

CREATEDPool has been created but not yet started.

RUNNINGPool is running and accepting tasks.

STOPPINGPool is shutting down; no new tasks accepted.

STOPPEDPool has fully stopped; all workers have exited.

enumSubmitResult : ubyte

Result of attempting to submit a task to the pool.

SUCCESSTask was successfully queued.

REJECTEDPool is not accepting new tasks (stopping or stopped).

QUEUE_FULLTask queue is full (for bounded pools).

aliasTask = void delegate() @safe

A task to be executed by the thread pool.

Tasks are simple delegates that take no arguments and return nothing. Any results should be communicated through captured variables, futures, or channels.

classThreadPool

A pool of worker threads for executing tasks in parallel.

The ThreadPool manages a collection of worker threads that execute submitted tasks. Tasks are queued and executed in approximate FIFO order, though no strict ordering is guaranteed due to concurrent execution.

Example:

auto pool = ThreadPool.create(4);  // 4 worker threads
pool.start();

pool.submit(() @safe {
  // Task code here
});

pool.shutdown();
pool.awaitTermination();

Fields

Thread[] workers

Task[] taskQueue

size_t queueHead

size_t queueTail

size_t queueCount

size_t queueCapacity

Mutex mutex

Condition workAvailable

Condition queueNotFull

PoolState state_

size_t activeWorkers_

ulong tasksCompleted_

ulong tasksSubmitted_

size_t numWorkers_

bool waitForTasks_

Methods

ThreadPool create(size_t numWorkers = 0, size_t queueCapacity = 1024) @trustedCreate a new thread pool with the specified number of workers.

void start() @trustedStart the thread pool, spawning worker threads.

SubmitResult submit(Task task) @trustedSubmit a task for execution by the thread pool.

SubmitResult trySubmit(Task task) @trustedTry to submit a task without blocking.

void shutdown(bool waitForTasks = true) @trustedInitiate graceful shutdown of the thread pool.

void awaitTermination() @trustedWait for all worker threads to terminate.

PoolState state() @property const @trusted nothrow @nogcGet the current state of the pool.

size_t numWorkers() @property const pure @safe nothrow @nogcGet the number of worker threads in the pool.

size_t activeWorkers() @property const @trusted nothrow @nogcGet the number of currently active (executing) workers.

size_t pendingTasks() @property @trustedGet the number of tasks waiting in the queue.

ulong completedTasks() @property const @trusted nothrow @nogcGet the total number of tasks that have been completed.

ulong submittedTasks() @property const @trusted nothrow @nogcGet the total number of tasks that have been submitted.

void workerLoop() @trusted

Constructors

this()

this(size_t numWorkers, size_t queueCapacity)

Functions 1

fnsize_t defaultWorkerCount() @trustedGet the default number of worker threads based on CPU count.