Also:
1. Have CChainState::LoadMempool and ::ThreadImport take in paths and
pass it through untouched to LoadMempool.
2. Make LoadMempool exit early if the load_path is empty.
3. Adjust the call to ::ThreadImport in ::AppInitMain to correctly pass
in an empty path if mempool persistence is disabled.
Not only does this increase coverage, it is also more correct in that
when ::LoadMempool is called with a mempool and chainstate, it calls
AcceptToMemoryPool with just the chainstate.
AcceptToMemoryPool will then act on the chainstate's mempool via
CChainState::GetMempool, which may be different from the mempool
originally passed to ::LoadMempool. (In this fuzz test's case, it
definitely is different)
Also, move DummyChainstate to its own file since it's now used by the
validation_load_mempool fuzz test to replace CChainState's m_mempool.
Also introduce node::{ShouldPersistMempool,MempoolPath} helper functions
in node/mempool_persist_args.{h,cpp} which are used by non-kernel
DumpMempool callers to determine whether or not to automatically dump
the mempool and where to dump it to.
Reviewers: Note that CTxMemPool now requires a non-defaulted
CTxMemPool::Options for its constructor. Meaning that there's no need to
worry about a stray CTxMemPool constructor somewhere defaulting to
something incorrect. All instances of CTxMemPool construction are
addressed here in this commit.
We set options for CTxMemPool and construct it in many different ways. A
good example can be seen in how we determine CTxMemPool's check_ratio in
AppInitMain(...).
1. We first set the default based on chainparams's
DefaultConsistencyChecks()
2. Then, we apply the ArgsManager option on top of that default
3. Finally, we clamp the result of that between 0 and 1 Million
With this patch, most CTxMemPool construction are along the lines of:
MemPoolOptions mempool_opts{...default overrides...};
ApplyArgsManOptions(argsman, mempool_opts);
...hard overrides...
CTxMemPool pool{mempool_opts};
This "compositional" style of building options means that we can omit
unnecessary/irrelevant steps wherever we want but also maintain full
customizability.
For example:
- For users of libbitcoinkernel, where we eventually want to remove
ArgsManager, they simply won't call (or even know about)
ApplyArgsManOptions.
- See src/init.cpp to see how the check_ratio CTxMemPool option works
after this change.
A MemPoolOptionsForTest helper was also added and used by tests/fuzz
tests where a local CTxMemPool needed to be created.
The change in src/test/fuzz/tx_pool.cpp seemingly changes behaviour by
applying ArgsManager options on top of the CTxMemPool::Options defaults.
However, in future commits where we introduce flags like -maxmempool,
the call to ApplyArgsManOptions is actually what preserves the existing
behaviour. Previously, although it wasn't obvious, our CTxMemPool would
consult gArgs for flags like -maxmempool when it needed it, so it
already relied on ArgsManager information. This patchset just laid bare
the obfuscatory perils of globals.
[META] As this patchset progresses, we will move more and more
CTxMemPool-relevant options into MemPoolOptions and add their
ArgsMan-related logic to ApplyArgsManOptions.
