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Merge branch 'master' into C++BestEffortUpdater

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This commit is contained in:
Thomas Harte 2017-10-05 18:12:33 -04:00
commit ec202ed8be
2 changed files with 10 additions and 2 deletions
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10
Concurrency/BestEffortUpdater.cpp
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@ -13,15 +13,20 @@
using namespace Concurrency;
void BestEffortUpdater::update() {
// Perform an update only if one is not currently ongoing.
if(!update_is_ongoing_.test_and_set()) {
async_task_queue_.enqueue([this]() {
// Get time now using the highest-resolution clock provided by the implementation, and determine
// the duration since the last time this section was entered.
std::chrono::time_point<std::chrono::high_resolution_clock> now = std::chrono::high_resolution_clock::now();
auto elapsed = now - previous_time_point_;
previous_time_point_ = now;
if(has_previous_time_point_) {
int64_t timestamp = std::chrono::duration_cast<std::chrono::nanoseconds>(elapsed).count();
double cycles = ((timestamp * clock_rate_) / 1e9) + error_;
// If the duration is valid, convert it to integer cycles, maintaining a rolling error and call the delegate
// if there is one.
int64_t duration = std::chrono::duration_cast<std::chrono::nanoseconds>(elapsed).count();
double cycles = ((static_cast<double>(duration) * clock_rate_) / 1e9) + error_;
error_ = fmod(cycles, 1.0);
if(delegate_) {
@ -32,6 +37,7 @@ void BestEffortUpdater::update() {
has_previous_time_point_ = true;
}
// Allow furthers updates to occur.
update_is_ongoing_.clear();
});
} else {

2
Concurrency/BestEffortUpdater.hpp
View File

@ -20,6 +20,8 @@ namespace Concurrency {
Accepts timing cues from multiple threads and ensures that a delegate receives calls to total
a certain number of cycles per second, that those calls are strictly serialised, and that no
backlog of calls accrues.
No guarantees about the thread that the delegate will be called on are made.
*/
class BestEffortUpdater {
public: