Simplify mutex locking, fix deadlocks #480

pull gavinandresen wants to merge 3 commits into bitcoin:master from gavinandresen:deadlocks changing 11 files +689 −746

gavinandresen commented at 4:46 PM on August 31, 2011: contributor

I collapsed several wallet mutexes into two: one for the keystore, and one for the wallet. That fixes many potential deadlocks due to wallet code acquiring the various locks in different orders.

And I fixed several other potential deadlocks by requiring that code that needs both the cs_main and cs_wallet mutexes acquire them in that order.

One somewhat scary semantic change: Transaction times reported by in the rpc interface and in the GUI are now always the time the transaction was received by this node (and not the average-time-of-the-last-n-blocks-that-the-transaction-ended-up-in).

Having transaction times change as they were confirmed was a mistake, in my humble opinion, but the main reason I changed this behavior was so that CWallet::GetTxTime() doesn't require the cs_main lock.

I'd like to further compartmentalize locking, but that's a task for another day...
Highlight mis-matching locks b0243da77c

Fix rpc-hanging deadlocks

Collapsed multiple wallet mutexes to a single cs_wallet, to avoid deadlocks with wallet methods that acquired locks in different order.
Also change master RPC call handler to acquire cs_main and cs_wallet locks before executing RPC calls; requiring each RPC call to acquire the right set of locks in the right order was too error-prone.

6cc4a62c0e

Fixed potential deadlocks in GUI code.

Also changed semantics of CWalletTx::GetTxTime(); now always returns the time the transaction was received by this node, not the average block time.
And added information about -DDEBUG_LOCKORDER to coding.txt.

471426fb3b

gavinandresen referenced this in commit cb6c4b883d on Aug 31, 2011
gavinandresen merged this on Aug 31, 2011
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