Add more comprehensive unit tests for CCoinsViewCache. Right now it is hard to
refactor caching code or fix bugs in the caching logic because you have to try
to mentally enumerate all the different states the cache might be in to make
sure a change doesn't cause unintended consequences. The new tests explicitly
enumerate relevant cache states, documenting and verifying the behavior in each
state, so it will be safer and easier to make changes to the caching code in
the future.
There are only a few uses of `insecure_random` outside the tests.
This PR replaces uses of insecure_random (and its accompanying global
state) in the core code with an FastRandomContext that is automatically
seeded on creation.
This is meant to be used for inner loops. The FastRandomContext
can be in the outer scope, or the class itself, then rand32() is used
inside the loop. Useful e.g. for pushing addresses in CNode or the fee
rounding, or randomization for coin selection.
As a context is created per purpose, thus it gets rid of
cross-thread unprotected shared usage of a single set of globals, this
should also get rid of the potential race conditions.
- I'd say TxMempool::check is not called enough to warrant using a special
fast random context, this is switched to GetRand() (open for
discussion...)
- The use of `insecure_rand` in ConnectThroughProxy has been replaced by
an atomic integer counter. The only goal here is to have a different
credentials pair for each connection to go on a different Tor circuit,
it does not need to be random nor unpredictable.
- To avoid having a FastRandomContext on every CNode, the context is
passed into PushAddress as appropriate.
There remains an insecure_random for test usage in `test_random.h`.
Add a method Cursor() to CCoinsView that returns a cursor which can be
used to iterate over the whole UTXO set.
- rpc: Change gettxoutsetinfo to use new Cursor method
- txdb: Remove GetStats method - Now that GetStats is implemented in
terms of Cursor, remove it.
Previously it would break if you flushed a parent cache while there was a child cache referring to it. This change will allow the flushing of parent caches.
Make sure that chainparams and logging is properly initialized. Doing
this for every test may be overkill, but this initialization is so
simple that that does not matter.
This should fix the travis issues.
