salmanoff/smocore/serializedAsynchronousContinuation.cpp

#include <config.h>
#include <serializedAsynchronousContinuation.h>
#include <qutex.h>

namespace smo {

#ifdef CONFIG_ENABLE_DEBUG_LOCKS

template <class OriginalCbFnT>
template <class InvocationTargetT>
bool
SerializedAsynchronousContinuation<OriginalCbFnT>
::LockerAndInvoker<InvocationTargetT>
::traceContinuationHistoryForDeadlockOn(Qutex& firstFailedQutex)
{
	/**	EXPLANATION:
	 * In this function we will trace through the chain of continuations that
	 * led up to this Lockvoker's continuation. For each continuation which is
	 * a SerializedAsynchronousContinuation, we check through its LockSet to see
	 * if it contains the lock that failed acquisition. If it does, we have a
	 * deadlock.
	 */

	/* We can't start with the continuation directly referenced by this starting
	 * Lockvoker as it would contain the all locks we're currently trying to
	 * acquire...and rightly so because it's the continuation for this current
	 * lockvoker.
	 */
	for (std::shared_ptr<AsynchronousContinuationChainLink> currContin =
			this->serializedContinuation.getCallersContinuation();
		 currContin != nullptr;
		 currContin = currContin->getCallersContinuation())
	{
		auto serializedCont = std::dynamic_pointer_cast<
			SerializedAsynchronousContinuation<OriginalCbFnT>>(currContin);

		if (serializedCont == nullptr) { continue; }

		// Check if the firstFailedQutex is in this continuation's LockSet
		try {
			const auto& lockUsageDesc = serializedCont->requiredLocks
				.getLockUsageDesc(firstFailedQutex);
		} catch (const std::runtime_error& e) {
			std::cerr << __func__ << ": " << e.what() << std::endl;
			continue;
		}

		std::cout << __func__ << ":Deadlock detected: Found "
			<< "firstFailedQutex @" << &firstFailedQutex
			<< " (" << firstFailedQutex.name << ") in LockSet of "
			<< "SerializedAsynchronousContinuation @"
			<< serializedCont.get() << std::endl;

		return true;
	}

	return false;
}

template <class OriginalCbFnT>
template <class InvocationTargetT>
bool
SerializedAsynchronousContinuation<OriginalCbFnT>
::LockerAndInvoker<InvocationTargetT>
::traceContinuationHistoryForGridlockOn(Qutex &firstFailedQutex)
{
	// Empty implementation - to be filled in later
	return false;
}

template <class OriginalCbFnT>
template <class InvocationTargetT>
void
SerializedAsynchronousContinuation<OriginalCbFnT>
::LockerAndInvoker<InvocationTargetT>
::handleDeadlock(Qutex& firstFailedQutex)
{
	std::cerr << __func__ << ": Deadlock: "
		<< "Lockvoker has been waiting for "
		<< std::chrono::duration_cast<std::chrono::milliseconds>(
			std::chrono::steady_clock::now() - this->creationTimestamp)
			.count()
		<< "ms, failed on qutex @" << &firstFailedQutex
		<< " (" << firstFailedQutex.name << ")" << std::endl;
}
#endif

// Explicit template instantiations for the types we need
// Add more as needed for your specific use cases

} // namespace smo