bool startObservingFile(const std::string& filePath,
folly::EventBase& evb,
uint32_t pollPeriodMs,
uint32_t sleepBeforeUpdateMs,
std::function<void(std::string)> onUpdate,
std::function<void()> fallbackOnError) {
std::shared_ptr<FileDataProvider> provider;
try {
provider = std::make_shared<FileDataProvider>(filePath);
onUpdate(provider->load());
} catch (const std::exception& e) {
VLOG(0) << "Can not start watching " << filePath <<
" for modifications: " << e.what();
checkAndExecuteFallbackOnError(std::move(fallbackOnError));
return false;
}
VLOG(0) << "Watching " << filePath << " for modifications.";
FileObserverData data(std::move(provider),
std::move(onUpdate),
std::move(fallbackOnError),
pollPeriodMs,
sleepBeforeUpdateMs);
return evb.runInEventBaseThread([&evb, data = std::move(data)]() {
scheduleObserveFile(evb, std::move(data));
});
}
bool FileObserver::startObserving(const std::string& filePath,
PeriodicTaskScheduler& taskScheduler,
uint32_t pollPeriodMs,
uint32_t sleepBeforeUpdateMs,
std::function<void(std::string)> onUpdate,
std::function<void()> fallbackOnError)
{
std::shared_ptr<FileDataProvider> provider;
try {
provider = std::make_shared<FileDataProvider>(filePath);
onUpdate(provider->load());
} catch (const std::exception& e) {
VLOG(0) << "Can not start watching " << filePath <<
" for modifications: " << e.what();
checkAndExecuteFallbackOnError(fallbackOnError);
return false;
}
VLOG(0) << "Watching " << filePath << " for modifications.";
taskScheduler.scheduleTask(
/* tmo_ms = */ pollPeriodMs,
[onUpdate, fallbackOnError, sleepBeforeUpdateMs, provider]
(PeriodicTaskScheduler& scheduler)
{
try {
if (!provider->hasUpdate()) {
return;
}
scheduler.sleepThread(sleepBeforeUpdateMs);
onUpdate(provider->load());
} catch (...) {
checkAndExecuteFallbackOnError(fallbackOnError);
throw;
}
}
);
return true;
}
