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Attempt to fix race condition in recursive RWLock

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This commit is contained in:
Alexey Milovidov 2019-05-05 05:01:23 +03:00
parent c462b0fabb
commit 50a9d733b4
2 changed files with 5 additions and 12 deletions
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14
dbms/src/Common/RWLock.cpp
View File

@ -122,6 +122,9 @@ RWLockImpl::LockHolder RWLockImpl::getLock(RWLockImpl::Type type, const String &
LockHolder res(new LockHolderImpl(shared_from_this(), it_group, it_client));
/// Wait a notification until we will be the only in the group.
it_group->cv.wait(lock, [&] () { return it_group == queue.begin(); });
/// Insert myself (weak_ptr to the holder) to threads set to implement recursive lock
thread_to_holder.emplace(this_thread_id, res);
res->thread_id = this_thread_id;
@ -130,17 +133,6 @@ RWLockImpl::LockHolder RWLockImpl::getLock(RWLockImpl::Type type, const String &
query_id_to_holder.emplace(query_id, res);
res->query_id = query_id;
/// We are first, we should not wait anything
/// If we are not the first client in the group, a notification could be already sent
if (it_group == queue.begin())
{
finalize_metrics();
return res;
}
/// Wait a notification
it_group->cv.wait(lock, [&] () { return it_group == queue.begin(); });
finalize_metrics();
return res;
}

3
dbms/src/Common/RWLock.h
View File

@ -1,6 +1,7 @@
#pragma once
#include <Core/Types.h>
#include <boost/core/noncopyable.hpp>
#include <list>
#include <vector>
#include <mutex>