simplify disk thread a little bit (#1504)

simplify disk thread a little bit

include/libtorrent/disk_io_thread.hpp

@@ -351,14 +351,6 @@ namespace libtorrent
 		{ return m_disk_cache.is_disk_buffer(buffer); }
 #endif
 
-		enum class thread_type_t : std::uint8_t
-		{
-			generic,
-			hasher
-		};
-
-		void thread_fun(thread_type_t type, io_service::work w);
-
 		virtual file_pool& files() override { return m_file_pool; }
 
 		int prep_read_job_impl(disk_io_job* j, bool check_fence = true);
@@ -395,20 +387,24 @@ namespace libtorrent
 
 		struct job_queue : pool_thread_interface
 		{
-			job_queue(disk_io_thread& owner, thread_type_t type)
-				: m_owner(owner), m_type(type)
-			{}
+			explicit job_queue(disk_io_thread& owner) : m_owner(owner) {}
 
 			virtual void notify_all() override
 			{
 				m_job_cond.notify_all();
 			}
 
-			virtual void thread_fun(io_service::work work) override
-			{ m_owner.thread_fun(m_type, work); }
+			void thread_fun(disk_io_thread_pool& pool, io_service::work work) override
+			{
+				m_owner.thread_fun(*this, pool);
+
+				// w's dtor releases the io_service to allow the run() call to return
+				// we do this once we stop posting new callbacks to it.
+				// after the dtor has been called, the disk_io_thread object may be destructed
+				TORRENT_UNUSED(work);
+			}
 
 			disk_io_thread& m_owner;
-			thread_type_t const m_type;
 
 			// used to wake up the disk IO thread when there are new
 			// jobs on the job queue (m_queued_jobs)
@@ -418,6 +414,8 @@ namespace libtorrent
 			jobqueue_t m_queued_jobs;
 		};
 
+		void thread_fun(job_queue& queue, disk_io_thread_pool& pool);
+
 		// returns true if the thread should exit
 		static bool wait_for_job(job_queue& jobq, disk_io_thread_pool& threads
 			, std::unique_lock<std::mutex>& l);

include/libtorrent/disk_io_thread_pool.hpp

@@ -45,12 +45,14 @@ POSSIBILITY OF SUCH DAMAGE.
 
 namespace libtorrent
 {
+	struct disk_io_thread_pool;
+
 	struct pool_thread_interface
 	{
 		virtual ~pool_thread_interface() {}
 
 		virtual void notify_all() = 0;
-		virtual void thread_fun(io_service::work /* work */) = 0;
+		virtual void thread_fun(disk_io_thread_pool&, io_service::work) = 0;
 	};
 
 	// this class implements the policy for creating and destroying I/O threads

simulation/test_thread_pool.cpp

@@ -42,7 +42,7 @@ struct test_threads : lt::pool_thread_interface
 	test_threads() {}
 
 	void notify_all() override { m_cond.notify_all(); }
-	void thread_fun(lt::io_service::work w) override
+	void thread_fun(lt::disk_io_thread_pool&, lt::io_service::work) override
 	{
 		std::unique_lock<std::mutex> l(m_mutex);
 		for (;;)

src/disk_io_thread.cpp

@@ -191,9 +191,9 @@ namespace libtorrent
 	disk_io_thread::disk_io_thread(io_service& ios
 		, counters& cnt
 		, int const block_size)
-		: m_generic_io_jobs(*this, thread_type_t::generic)
+		: m_generic_io_jobs(*this)
 		, m_generic_threads(m_generic_io_jobs, ios)
-		, m_hash_io_jobs(*this, thread_type_t::hasher)
+		, m_hash_io_jobs(*this)
 		, m_hash_threads(m_hash_io_jobs, ios)
 		, m_disk_cache(block_size, ios, std::bind(&disk_io_thread::trigger_cache_trim, this))
 		, m_stats_counters(cnt)
@@ -3045,10 +3045,10 @@ namespace libtorrent
 		return false;
 	}
 
-	void disk_io_thread::thread_fun(thread_type_t type
-		, io_service::work w)
+	void disk_io_thread::thread_fun(job_queue& queue
+		, disk_io_thread_pool& pool)
 	{
-		std::thread::id thread_id = std::this_thread::get_id();
+		std::thread::id const thread_id = std::this_thread::get_id();
 #if DEBUG_DISK_THREAD
 		std::stringstream thread_id_str;
 		thread_id_str << thread_id;
@@ -3065,24 +3065,14 @@ namespace libtorrent
 		for (;;)
 		{
 			disk_io_job* j = nullptr;
-			if (type == thread_type_t::generic)
-			{
-				bool const should_exit = wait_for_job(m_generic_io_jobs, m_generic_threads, l);
+			bool const should_exit = wait_for_job(queue, pool, l);
 			if (should_exit) break;
-				j = m_generic_io_jobs.m_queued_jobs.pop_front();
-			}
-			else if (type == thread_type_t::hasher)
-			{
-				bool const should_exit = wait_for_job(m_hash_io_jobs, m_hash_threads, l);
-				if (should_exit) break;
-				j = m_hash_io_jobs.m_queued_jobs.pop_front();
-			}
-
+			j = queue.m_queued_jobs.pop_front();
 			l.unlock();
 
 			TORRENT_ASSERT((j->flags & disk_io_job::in_progress) || !j->storage);
 
-			if (thread_id == m_generic_threads.first_thread_id() && type == thread_type_t::generic)
+			if (&pool == &m_generic_threads && thread_id == pool.first_thread_id())
 			{
 				// there's no need for all threads to be doing this
 				maybe_flush_write_blocks();
@@ -3147,11 +3137,6 @@ namespace libtorrent
 		TORRENT_ASSERT(m_magic == 0x1337);
 
 		COMPLETE_ASYNC("disk_io_thread::work");
-
-		// w's dtor releases the io_service to allow the run() call to return
-		// we do this once we stop posting new callbacks to it.
-		// after the dtor has been called, the disk_io_thread object may be destructed
-		TORRENT_UNUSED(w);
 	}
 
 	void disk_io_thread::abort_jobs()

src/disk_io_thread_pool.cpp

@@ -173,7 +173,8 @@ namespace libtorrent
 			// event refers to a disk buffer it will try to free it, but the
 			// buffer pool won't exist anymore, and crash. This prevents that.
 			m_threads.emplace_back(&pool_thread_interface::thread_fun
-				, &m_thread_iface, io_service::work(m_idle_timer.get_io_service()));
+				, &m_thread_iface, std::ref(*this)
+				, io_service::work(m_idle_timer.get_io_service()));
 		}
 	}