RPC interface hangs on getaccountaddress with empty wallet #185

If "getaccountaddress" is the first RPC method to be called on an empty wallet, it will hang and crash the RPC interface. To reproduce:

1. remove wallet.dat
2. start "./bitcoind"
3. check if running with "./bitcoind help"
4. run "./bitcoind getaccountaddress foo"
5. observe that the call never returns

Note: This will not happen, if you call "getinfo" or "getnewaddress" (and possibly others) before the call to getaccountaddress.

Some debugging shows the hang to happen on line 348 in rpc.cpp when GetKeyFromKeyPool() is called.

This is on Debian Squeeze, with libdb4.7 and build with USE_UPNP undefined

ArtForz was able to track this down further: The problem is that GetAccountAddress() in rpc.cpp starts an atomic db operation with walletdb.TxnBegin(); If may then happen, that GetKeyFromKeyPool() is called and when the key pool is not topped up, new keys will be generated and written to the database. This write operation then blocks, presumably waiting for the atomic operation to be completed.

I'm not sure what a good solution would be. I tried a workaround here: https://github.com/javgh/bitcoin/commit/1049dc625f7b1d695092de72ad0c5bb7d329edfa That contains a method to top up the key pool separately and does though before starting the atomic db operation.

Seems to be fixed. I can't reproduce it anymore.