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author | Russell Yanofsky <russ@yanofsky.org> | 2021-02-16 22:36:26 -0500 |
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committer | Russell Yanofsky <russ@yanofsky.org> | 2021-11-15 09:11:44 -0500 |
commit | d8ee8f3cd32bbfefec931724f5798cbb088ceb6f (patch) | |
tree | 09bea6475822b6b37ca0050d03a4394946af35a3 /src/util/overloaded.h | |
parent | 2efc8c0999a4b99cfe3076f7312806e83e778261 (diff) | |
download | bitcoin-d8ee8f3cd32bbfefec931724f5798cbb088ceb6f.tar.xz |
refactor: Make CWalletTx sync state type-safe
Current CWalletTx state representation makes it possible to set
inconsistent states that won't be handled correctly by wallet sync code
or serialized & deserialized back into the same form.
For example, it is possible to call setConflicted without setting a
conflicting block hash, or setConfirmed with no transaction index. And
it's possible update individual m_confirm and fInMempool data fields
without setting an overall consistent state that can be serialized and
handled correctly.
Fix this without changing behavior by using std::variant, instead of an
enum and collection of fields, to represent sync state, so state
tracking code is safer and more legible.
This is a first step to fixing state tracking bugs
https://github.com/bitcoin-core/bitcoin-devwiki/wiki/Wallet-Transaction-Conflict-Tracking,
by adding an extra margin of safety that can prevent new bugs from being
introduced as existing bugs are fixed.
Diffstat (limited to 'src/util/overloaded.h')
-rw-r--r-- | src/util/overloaded.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/src/util/overloaded.h b/src/util/overloaded.h new file mode 100644 index 0000000000..6be7453f81 --- /dev/null +++ b/src/util/overloaded.h @@ -0,0 +1,22 @@ +// Copyright (c) 2021 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#ifndef BITCOIN_UTIL_OVERLOADED_H +#define BITCOIN_UTIL_OVERLOADED_H + +namespace util { +//! Overloaded helper for std::visit. This helper and std::visit in general are +//! useful to write code that switches on a variant type. Unlike if/else-if and +//! switch/case statements, std::visit will trigger compile errors if there are +//! unhandled cases. +//! +//! Implementation comes from and example usage can be found at +//! https://en.cppreference.com/w/cpp/utility/variant/visit#Example +template<class... Ts> struct Overloaded : Ts... { using Ts::operator()...; }; + +//! Explicit deduction guide (not needed as of C++20) +template<class... Ts> Overloaded(Ts...) -> Overloaded<Ts...>; +} // namespace util + +#endif // BITCOIN_UTIL_OVERLOADED_H |