680bc2cbb Use range-based for loops (C++11) when looping over map elements (practicalswift)
Pull request description:
Before this commit:
```c++
for (std::map<T1, T2>::iterator x = y.begin(); x != y.end(); ++x) {
T1 z = (*x).first;
…
}
```
After this commit:
```c++
for (auto& x : y) {
T1 z = x.first;
…
}
```
Tree-SHA512: 954b136b7f5e6df09f39248a6b530fd9baa9ab59d7c2c7eb369fd4afbb591b7a52c92ee25f87f1745f47b41d6828b7abfd395b43daf84a55b4e6a3d45015e3a0
6e8c48dc5 Add const to methods that do not modify the object for which it is called (practicalswift)
Pull request description:
Tree-SHA512: a6888111ba16fb796e320e60806e1a77d36f545989b5405dc7319992291800109eab0b8e8c286b784778f41f1ff5289e7cb6b4afd7aec77f385fbcafc02cffc1
This removes the possibility for GetCoin/HaveCoin/HaveCoinInCache to return
true while the respective coin is spent. By doing it across all calls, some
extra checks can be eliminated.
coins_tests is modified to call HaveCoin sometimes before and sometimes
after AccessCoin. A further change is needed because the semantics for
GetCoin slightly changed, causing a pruned entry in the parent cache to not
be pulled into the child in FetchCoin.
5a9b508 [trivial] Add end of namespace comments (practicalswift)
Tree-SHA512: 92b0fcae4d1d3f4da9e97569ae84ef2d6e09625a5815cd0e5f0eb6dd2ecba9852fa85c184c5ae9de5117050330ce995e9867b451fa8cd5512169025990541a2b
3ff1fa8 Use override keyword on CCoinsView overrides (Russell Yanofsky)
24e44c3 Don't return stale data from CCoinsViewCache::Cursor() (Russell Yanofsky)
Tree-SHA512: 08699dae0925ffb9c018f02612ac6b7eaf73ec331e2f4f934f1fe25a2ce120735fa38596926e924897c203f7470e99f0a99cf70d2ce31ff428b105e16583a861
This patch makes several related changes:
* Changes the CCoinsView virtual methods (GetCoins, HaveCoins, ...)
to be COutPoint/Coin-based rather than txid/CCoins-based.
* Changes the chainstate db to a new incompatible format that is also
COutPoint/Coin based.
* Implements reconstruction code for hash_serialized_2.
* Adapts the coins_tests unit tests (thanks to Russell Yanofsky).
A side effect of the new CCoinsView model is that we can no longer
use the (unreliable) test for transaction outputs in the UTXO set
to determine whether we already have a particular transaction.
The earlier CTxInUndo class now holds the same information as the Coin
class. Instead of duplicating functionality, replace CTxInUndo with a
serialization adapter for Coin.
This makes the following changes:
* In undo data and the chainstate database, the transaction nVersion
field is removed from the data structures, always written as 0, and
ignored when reading.
* The definition of hash_serialized in gettxoutsetinfo is changed to no
longer incude the nVersion field. It is renamed to hash_serialized_2
to avoid confusion. The new definition also includes transaction
height and coinbase information, as this information was missing
before.
This depends on having a CHashVerifier-based undo data checksum
verifier.
Apart from changing the definition of serialized_hash, downgrading
after using this patch is supported, as no release ever used the value
of nVersion field in UTXO entries.
The error() function unconditionally reports an error. It should only
be used for actually exception situations, and not for the type of
inconsistencies that ApplyTxInUndo/DisconnectBlock can graciously deal
with.
This also makes a subtle semantics change: in ApplyTxInUndo, when a
record with metadata is encountered (indicating it is the last spend
from a tx), don't wipe the CCoins record if it wasn't empty at that
point. This makes sure that UTXO operations never affect any other
UTXOs (including those from the same tx).
ad1ae7a Check and enable -Wshadow by default. (Pavel Janík)
9de90bb Do not shadow variables (gcc set) (Pavel Janík)
Tree-SHA512: 9517feb423dc8ddd63896016b25324673bfbe0bffa97f22996f59d7a3fcbdc2ebf2e43ac02bc067546f54e293e9b2f2514be145f867321e9031f895c063d9fb8
We were marking coins FRESH before being sure they were not overwriting dirty undo data. This condition was never reached in existing code because undo data was always flushed before UpdateCoins was called with new transactions, but could have been exposed in an otherwise safe refactor.
Clarify in the comments the assumptions made in ModifyNewCoins.
Add ability to undo transactions to UpdateCoins unit test.
Thanks to Russ Yanofsky for suggestion on how to make logic clearer and fixing up the ccoins_modify_new test cases.
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.
