diff options
Diffstat (limited to 'libbuild2/scheduler.hxx')
| -rw-r--r-- | libbuild2/scheduler.hxx | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/libbuild2/scheduler.hxx b/libbuild2/scheduler.hxx index 3cc206e..2d4d189 100644 --- a/libbuild2/scheduler.hxx +++ b/libbuild2/scheduler.hxx @@ -452,9 +452,11 @@ namespace build2 // should be set before any tasks are queued and cleared after all of // them have completed. // - // The counter must go in one direction, either increasing or decreasing, - // and should contain the initial value during the call. Zero threshold - // value is reserved. + // The counter can go in either direction and should contain the initial + // value during the call. The callback function is called when the current + // value differs form the previous/initial by at least the specified + // threshold. The callback returns the new threshold. Zero threshold value + // is reserved. The callback calls are serialized and synchronized. // struct monitor_guard { @@ -488,7 +490,9 @@ namespace build2 }; monitor_guard - monitor (atomic_count&, size_t threshold, function<size_t (size_t)>); + monitor (atomic_count&, + size_t threshold, + function<size_t (size_t previous, size_t current)>); // If initially active thread(s) (besides the one that calls startup()) // exist before the call to startup(), then they must call join() before @@ -598,10 +602,10 @@ namespace build2 // Monitor. // - atomic_count* monitor_count_ = nullptr; // NULL if not used. - atomic_count monitor_tshold_; // 0 means locked. - size_t monitor_init_; // Initial count. - function<size_t (size_t)> monitor_func_; + atomic_count* monitor_count_ = nullptr; // NULL if not used. + atomic_count monitor_tshold_; // 0 means locked. + size_t monitor_prev_; // Previous values. + function<size_t (size_t, size_t)> monitor_func_; build2::mutex mutex_; bool shutdown_ = true; // Shutdown flag. @@ -914,19 +918,19 @@ namespace build2 if (monitor_tshold_.compare_exchange_strong ( t, 0, - memory_order_release, + memory_order_acq_rel, // Synchronize on success. memory_order_relaxed)) { - // Now we are the only ones messing with this. + // Now we are the only ones messing with this and everything + // is synchronized. // + size_t p (monitor_prev_); size_t v (monitor_count_->load (memory_order_relaxed)); - if (v != monitor_init_) + if ((p > v ? p - v : p < v ? v - p : 0) >= t) { - // See which direction we are going. - // - if (v > monitor_init_ ? (v >= t) : (v <= t)) - t = monitor_func_ (v); + t = monitor_func_ (p, v); + monitor_prev_= v; } monitor_tshold_.store (t, memory_order_release); |