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#pragma once
#include <Common/ThreadPool.h>
#include <Common/scope_guard_safe.h>
#include <Common/CurrentThread.h>
#include <Common/setThreadName.h>
#include <future>
namespace DB
{
/// High-order function to run callbacks (functions with 'void()' signature) somewhere asynchronously.
template <typename Result, typename Callback = std::function<Result()>>
using ThreadPoolCallbackRunner = std::function<std::future<Result>(Callback &&, Priority)>;
/// Creates CallbackRunner that runs every callback with 'pool->scheduleOrThrowOnError()'.
template <typename Result, typename Callback = std::function<Result()>>
ThreadPoolCallbackRunner<Result, Callback> threadPoolCallbackRunner(ThreadPool & pool, const std::string & thread_name)
{
return [my_pool = &pool, thread_group = CurrentThread::getGroup(), thread_name](Callback && callback, Priority priority) mutable -> std::future<Result>
{
auto task = std::make_shared<std::packaged_task<Result()>>([thread_group, thread_name, my_callback = std::move(callback)]() mutable -> Result
{
if (thread_group)
CurrentThread::attachToGroup(thread_group);
SCOPE_EXIT_SAFE({
{
/// Release all captutred resources before detaching thread group
/// Releasing has to use proper memory tracker which has been set here before callback
[[maybe_unused]] auto tmp = std::move(my_callback);
}
if (thread_group)
CurrentThread::detachFromGroupIfNotDetached();
});
setThreadName(thread_name.data());
return my_callback();
});
auto future = task->get_future();
/// ThreadPool is using "bigger is higher priority" instead of "smaller is more priority".
/// Note: calling method scheduleOrThrowOnError in intentional, because we don't want to throw exceptions
/// in critical places where this callback runner is used (e.g. loading or deletion of parts)
my_pool->scheduleOrThrowOnError([my_task = std::move(task)]{ (*my_task)(); }, priority);
return future;
};
}
template <typename Result, typename T>
std::future<Result> scheduleFromThreadPool(T && task, ThreadPool & pool, const std::string & thread_name, Priority priority = {})
{
auto schedule = threadPoolCallbackRunner<Result, T>(pool, thread_name);
return schedule(std::move(task), priority);
}
}
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