[Consensus] Add locking on the chain index vector. #950
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Problem
tsan identified a data race on CChain, particularly concurrent access to the underlying vector's
operator[]
,size
, andresize
member functions.Solution
Create a new lock
cs_vchain
and markvchain
as guarded by it, and ensure that the lock is taken prior to any use.For the
operator==
member function, grab both the locks in a prescribed order to avoid a deadlock.Tested
Configured with --with-sanitizers=tsan, built with clang, run on regtest with 2 SHA mining threads enabled.