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Fixed race condition in checking init_initialized on prim view

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Flag init_initialized_ must be checked before changing the
state to s_initializing in on_primary_view() in order to avoid
race between main thread and applier thread. Otherwise it is
possible that main thread gains control after setting state
to initializing and changes the flag init_initialized_ to true
before the check is done in on_primary_view().
This commit is contained in:
Teemu Ollakka
2019-01-23 19:07:08 +02:00
parent 136767ae04
commit 632f8c3b14
1 changed files with 10 additions and 1 deletions
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11
src/server_state.cpp
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@ -705,8 +705,17 @@ void wsrep::server_state::on_primary_view(
if (state_ == s_connected)
{
state(lock, s_joiner);
// We need to assign init_initialized_ here to local
// variable. If the value here was false, we need to skip
// the initializing -> initialized -> joined state cycle
// below. However, if we don't assign the value to
// local, it is possible that the main thread gets control
// between changing the state to initializing and checking
// initialized flag, which may cause the initialzing -> initialized
// state change to be executed even if it should not be.
const bool was_initialized(init_initialized_);
state(lock, s_initializing);
if (init_initialized_)
if (was_initialized)
{
// If server side has already been initialized,
// skip directly to s_joined.