fortuna: add task runner "do_task"; link pthread

CMakeLists.txt

@@ -183,8 +183,9 @@ add_subdirectory(lib/fmt EXCLUDE_FROM_ALL)
     endif(NOT CMAKE_EXE_LINKER_FLAGS MATCHES "-fuse-ld=lld")
   endif()
 
-add_executable(fortuna main.cpp generator.cpp generator.h fortuna.cpp fortuna.h accumulator.cpp accumulator.h pool.cpp pool.h event_adder.h event_adder_impl.h event_scheduler.h entropy_src.h urandom_entropy_src.h)
+add_executable(fortuna main.cpp generator.cpp generator.h fortuna.cpp fortuna.h accumulator.cpp accumulator.h pool.cpp pool.h event_adder.h event_adder_impl.h event_scheduler.h entropy_src.h urandom_entropy_src.h do_task.cpp do_task.h)
 # ref: https://cmake.org/pipermail/cmake/2016-May/063400.html
 target_link_libraries(fortuna
     PRIVATE cryptopp
-    PRIVATE fmt::fmt-header-only)
+    PRIVATE fmt::fmt-header-only
+    PRIVATE pthread)

do_task.cpp

@@ -0,0 +1,37 @@
+#ifndef FORTUNA_DO_TASK_CPP
+#define FORTUNA_DO_TASK_CPP
+
+#include "do_task.h"
+
+#include <utility>
+
+namespace fortuna {
+
+auto DoTask::die_pls() -> void {
+	do_sleep.unlock();
+	threadie.join();
+}
+
+auto DoTask::thread_pls(const std::chrono::seconds& interval,
+		std::function<void()> callback) -> void {
+	if (threadie.joinable()) {
+		die_pls();
+	}
+
+	do_sleep.lock();
+	threadie = std::thread([this, interval, callback = std::move(callback)] {
+		while (!do_sleep.try_lock_for(interval)) {
+			callback();
+		}
+	});
+}
+
+DoTask::~DoTask() noexcept {
+	if (threadie.joinable()) {
+		die_pls();
+	}
+}
+
+} //namespace fortuna
+
+#endif//FORTUNA_DO_TASK_CPP

do_task.h

@@ -0,0 +1,26 @@
+#ifndef FORTUNA_DO_TASK_H
+#define FORTUNA_DO_TASK_H
+
+#include <chrono>
+#include <functional>
+#include <mutex>
+#include <thread>
+
+namespace fortuna {
+
+class DoTask {
+private:
+	std::timed_mutex do_sleep;
+	std::thread threadie;
+public:
+	~DoTask() noexcept;
+
+	auto thread_pls(const std::chrono::seconds& interval,
+			std::function<void()> callback) -> void;
+	auto die_pls() -> void;
+
+}; // class DoTask
+
+} // namespace fortuna
+
+#endif//FORTUNA_DO_TASK_H