53 lines
1.1 KiB
C++
53 lines
1.1 KiB
C++
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#pragma once
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#include "sync.hh"
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#include "util.hh"
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#include <queue>
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#include <functional>
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#include <thread>
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namespace nix {
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/* A simple thread pool that executes a queue of work items
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(lambdas). */
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class ThreadPool
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{
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public:
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ThreadPool(size_t nrThreads = 0);
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// FIXME: use std::packaged_task?
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typedef std::function<void()> work_t;
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/* Enqueue a function to be executed by the thread pool. */
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void enqueue(const work_t & t);
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/* Execute work items until the queue is empty. Note that work
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items are allowed to add new items to the queue; this is
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handled correctly. Queue processing stops prematurely if any
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work item throws an exception. This exception is propagated to
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the calling thread. If multiple work items throw an exception
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concurrently, only one item is propagated; the others are
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printed on stderr and otherwise ignored. */
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void process();
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private:
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size_t nrThreads;
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struct State
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{
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std::queue<work_t> left;
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size_t pending = 0;
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std::exception_ptr exception;
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};
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Sync<State> state;
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std::condition_variable wakeup;
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};
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}
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