diff options
Diffstat (limited to 'libbuild2/scheduler.hxx')
| -rw-r--r-- | libbuild2/scheduler.hxx | 108 |
1 files changed, 81 insertions, 27 deletions
diff --git a/libbuild2/scheduler.hxx b/libbuild2/scheduler.hxx index dcde79b..3cc206e 100644 --- a/libbuild2/scheduler.hxx +++ b/libbuild2/scheduler.hxx @@ -5,11 +5,10 @@ #define LIBBUILD2_SCHEDULER_HXX #include <list> -#include <mutex> #include <tuple> #include <atomic> -#include <type_traits> // aligned_storage, etc -#include <condition_variable> +#include <cstddef> // max_align_t +#include <type_traits> // decay, etc #include <libbuild2/types.hxx> #include <libbuild2/utility.hxx> @@ -193,13 +192,15 @@ namespace build2 // // The external flag indicates whether the wait is for an event external // to the scheduler, that is, triggered by something other than one of the - // threads managed by the scheduler. + // threads managed by the scheduler. This is used to suspend deadlock + // detection (which is progress-based and which cannot be measured for + // external events). // void deactivate (bool external); void - activate (bool external, bool = false); + activate (bool external); // Sleep for the specified duration, deactivating the thread before going // to sleep and re-activating it after waking up (which means this @@ -218,7 +219,7 @@ namespace build2 // Allocate additional active thread count to the current active thread, // for example, to be "passed" to an external program: // - // scheduler::alloc_guard ag (ctx.sched, ctx.sched.max_active () / 2); + // scheduler::alloc_guard ag (*ctx.sched, ctx.sched->max_active () / 2); // args.push_back ("-flto=" + to_string (1 + ag.n)); // run (args); // ag.deallocate (); @@ -243,14 +244,38 @@ namespace build2 void deallocate (size_t); + // Similar to allocate() but reserve all the available threads blocking + // until this becomes possible. Call unlock() on the specified lock before + // deactivating and lock() after activating (can be used to unlock the + // phase). Typical usage: + // + // scheduler::alloc_guard ag (*ctx.sched, + // phase_unlock (ctx, true /* delay */)); + // + // Or, without unlocking the phase: + // + // scheduler::alloc_guard ag (*ctx.sched, phase_unlock (nullptr)); + // + template <typename L> + size_t + serialize (L& lock); + struct alloc_guard { size_t n; alloc_guard (): n (0), s_ (nullptr) {} alloc_guard (scheduler& s, size_t m): n (s.allocate (m)), s_ (&s) {} - alloc_guard (alloc_guard&& x): n (x.n), s_ (x.s_) {x.s_ = nullptr;} - alloc_guard& operator= (alloc_guard&& x) + + template <typename L, + typename std::enable_if<!std::is_integral<L>::value, int>::type = 0> + alloc_guard (scheduler& s, L&& l): n (s.serialize (l)), s_ (&s) {} + + alloc_guard (alloc_guard&& x) noexcept + : n (x.n), s_ (x.s_) {x.s_ = nullptr;} + + alloc_guard& + operator= (alloc_guard&& x) noexcept { if (&x != this) { @@ -301,14 +326,25 @@ namespace build2 // If the maximum threads or task queue depth arguments are unspecified, // then appropriate defaults are used. // + // Passing non-zero orig_max_active (normally the real max active) allows + // starting up a pre-tuned scheduler. In particular, starting a pre-tuned + // to serial scheduler is relatively cheap since starting the deadlock + // detection thread is delayed until the scheduler is re-tuned. + // explicit scheduler (size_t max_active, size_t init_active = 1, size_t max_threads = 0, size_t queue_depth = 0, - optional<size_t> max_stack = nullopt) + optional<size_t> max_stack = nullopt, + size_t orig_max_active = 0) { - startup (max_active, init_active, max_threads, queue_depth, max_stack); + startup (max_active, + init_active, + max_threads, + queue_depth, + max_stack, + orig_max_active); } // Start the scheduler. @@ -318,7 +354,8 @@ namespace build2 size_t init_active = 1, size_t max_threads = 0, size_t queue_depth = 0, - optional<size_t> max_stack = nullopt); + optional<size_t> max_stack = nullopt, + size_t orig_max_active = 0); // Return true if the scheduler was started up. // @@ -343,12 +380,19 @@ namespace build2 size_t tune (size_t max_active); + bool + tuned () const {return max_active_ != orig_max_active_;} + struct tune_guard { tune_guard (): s_ (nullptr), o_ (0) {} tune_guard (scheduler& s, size_t ma): s_ (&s), o_ (s_->tune (ma)) {} - tune_guard (tune_guard&& x): s_ (x.s_), o_ (x.o_) {x.s_ = nullptr;} - tune_guard& operator= (tune_guard&& x) + + tune_guard (tune_guard&& x) noexcept + : s_ (x.s_), o_ (x.o_) {x.s_ = nullptr;} + + tune_guard& + operator= (tune_guard&& x) noexcept { if (&x != this) { @@ -416,8 +460,8 @@ namespace build2 { explicit monitor_guard (scheduler* s = nullptr): s_ (s) {} - monitor_guard (monitor_guard&& x): s_ (x.s_) {x.s_ = nullptr;} - monitor_guard& operator= (monitor_guard&& x) + monitor_guard (monitor_guard&& x) noexcept: s_ (x.s_) {x.s_ = nullptr;} + monitor_guard& operator= (monitor_guard&& x) noexcept { if (&x != this) { @@ -480,7 +524,7 @@ namespace build2 static size_t hardware_concurrency () { - return std::thread::hardware_concurrency (); + return build2::thread::hardware_concurrency (); } // Return a prime number that can be used as a lock shard size that's @@ -497,7 +541,7 @@ namespace build2 // to become idle. Return the lock over the scheduler mutex. Normally you // don't need to call this function directly. // - using lock = std::unique_lock<std::mutex>; + using lock = build2::mlock; lock wait_idle (); @@ -533,8 +577,8 @@ namespace build2 atomic_count* task_count; size_t start_count; - func_type func; args_type args; + func_type func; template <size_t... i> void @@ -559,7 +603,7 @@ namespace build2 size_t monitor_init_; // Initial count. function<size_t (size_t)> monitor_func_; - std::mutex mutex_; + build2::mutex mutex_; bool shutdown_ = true; // Shutdown flag. optional<size_t> max_stack_; @@ -599,8 +643,8 @@ namespace build2 // size_t orig_max_active_ = 0; - std::condition_variable idle_condv_; // Idle helpers queue. - std::condition_variable ready_condv_; // Ready masters queue. + build2::condition_variable idle_condv_; // Idle helpers queue. + build2::condition_variable ready_condv_; // Ready masters queue. // Statistics counters. // @@ -619,8 +663,8 @@ namespace build2 // Deadlock detection. // - std::thread dead_thread_; - std::condition_variable dead_condv_; + build2::thread dead_thread_; + build2::condition_variable dead_condv_; static void* deadlock_monitor (void*); @@ -641,8 +685,8 @@ namespace build2 // struct wait_slot { - std::mutex mutex; - std::condition_variable condv; + build2::mutex mutex; + build2::condition_variable condv; size_t waiters = 0; const atomic_count* task_count; bool shutdown = true; @@ -663,7 +707,11 @@ namespace build2 // struct task_data { - std::aligned_storage<sizeof (void*) * 8>::type data; + static const size_t data_size = (sizeof (void*) == 4 + ? sizeof (void*) * 16 + : sizeof (void*) * 8); + + alignas (std::max_align_t) unsigned char data[data_size]; void (*thunk) (scheduler&, lock&, void*); }; @@ -714,7 +762,7 @@ namespace build2 struct task_queue: task_queue_data { - std::mutex mutex; + build2::mutex mutex; bool shutdown = false; size_t stat_full = 0; // Number of times push() returned NULL. @@ -913,6 +961,12 @@ namespace build2 private: optional<size_t> wait_impl (size_t, const atomic_count&, work_queue); + + void + deactivate_impl (bool, lock&&); + + lock + activate_impl (bool, bool); }; } |