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Fix changing shared memory in multi-process setup (#3462)

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This change fixes two bugs:

1. A dead-lock that occurs between osrm-datastore and libosrm when an
   old dataset is free during a data update. This happened because the
   mutexes where acquired in a different order.

2. A region is deleted eventhough it is still in use. This happens when
   libosrm gets overtaken by osrm-datastore, so the new dataset is in
   the same region the old one was.
This commit is contained in:
Patrick Niklaus 2016-12-16 22:50:17 +01:00 committed by Daniel Patterson
parent 37051e1583
commit c4b3cdfd80
1 changed files with 11 additions and 7 deletions
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18
include/engine/datafacade/shared_memory_datafacade.hpp
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@ -38,29 +38,33 @@ class SharedMemoryDataFacade : public ContiguousInternalMemoryDataFacadeBase
// used anymore. We crash hard here if something goes wrong (noexcept).
virtual ~SharedMemoryDataFacade() noexcept
{
// Now check if this is still the newest dataset
boost::interprocess::sharable_lock<boost::interprocess::named_upgradable_mutex>
current_regions_lock(shared_barriers->current_regions_mutex,
boost::interprocess::defer_lock);
boost::interprocess::scoped_lock<boost::interprocess::named_sharable_mutex> exclusive_lock(
data_region == storage::DATA_1 ? shared_barriers->regions_1_mutex
: shared_barriers->regions_2_mutex,
boost::interprocess::defer_lock);
// if this returns false this is still in use
if (exclusive_lock.try_lock())
if (current_regions_lock.try_lock() && exclusive_lock.try_lock())
{
if (storage::SharedMemory::RegionExists(data_region))
{
BOOST_ASSERT(storage::SharedMemory::RegionExists(layout_region));
// Now check if this is still the newest dataset
const boost::interprocess::sharable_lock<boost::interprocess::named_upgradable_mutex>
lock(shared_barriers->current_regions_mutex);
auto shared_regions = storage::makeSharedMemory(storage::CURRENT_REGIONS);
const auto current_timestamp =
static_cast<const storage::SharedDataTimestamp *>(shared_regions->Ptr());
if (current_timestamp->timestamp == shared_timestamp)
// check if the memory region referenced by this facade needs cleanup
if (current_timestamp->data == data_region)
{
util::Log(logDEBUG) << "Retaining data with shared timestamp " << shared_timestamp;
BOOST_ASSERT(current_timestamp->layout == layout_region);
util::Log(logDEBUG) << "Retaining data with shared timestamp "
<< shared_timestamp;
}
else
{