57865eb512
and mark the inherited CBlockIndex#GetBlockHash public interface member
as deleted, to disallow calling it in the derived CDiskBlockIndex class.
Here is a failing test on master demonstrating the inconsistent behavior of the
current design: calling the same inherited public interface functions on the
same CDiskBlockIndex object should yield identical behavior.
```diff
diff --git a/src/test/validation_chainstatemanager_tests.cpp b/src/test/validation_chainstatemanager_tests.cpp
index 6dc522b421..dac3840f32 100644
--- a/src/test/validation_chainstatemanager_tests.cpp
+++ b/src/test/validation_chainstatemanager_tests.cpp
@@ -240,6 +240,15 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_activate_snapshot, TestChain100Setup)
const CBlockIndex* tip = chainman.ActiveTip();
BOOST_CHECK_EQUAL(tip->nChainTx, au_data.nChainTx);
+ // CDiskBlockIndex "is a" CBlockIndex, as it publicly inherits from it.
+ // Test that calling the same inherited interface functions on the same
+ // object yields identical behavior.
+ CDiskBlockIndex index{tip};
+ CBlockIndex *pB = &index;
+ CDiskBlockIndex *pD = &index;
+ BOOST_CHECK_EQUAL(pB->GetBlockHash(), pD->GetBlockHash());
+ BOOST_CHECK_EQUAL(pB->ToString(), pD->ToString());
+
```
The GetBlockHash() test assertion only passes on master because the different
methods invoked by the current design happen to return the same result. If one
of the two is changed, it fails like the ToString() assertion does.
Redefining inherited non-virtual functions is well-documented as incorrect
design to avoid inconsistent behavior (see Scott Meyers, "Effective C++", Item
36). Class usage is confusing when the behavior depends on the pointer
definition instead of the object definition (static binding happening where
dynamic binding was expected). This can lead to unsuspected or hard-to-track
bugs.
Outside of critical hot spots, correctness usually comes before optimisation,
but the current design dates back to main.cpp and it may possibly have been
chosen to avoid the overhead of dynamic dispatch. This solution does the same:
the class sizes are unchanged and no vptr or vtbl is added.
There are better designs for doing this that use composition instead of
inheritance or that separate the public interface from the private
implementations. One example of the latter would be a non-virtual public
interface that calls private virtual implementation methods, i.e. the Template
pattern via the Non-Virtual Interface (NVI) idiom.
|
||
|---|---|---|
| .github | ||
| .tx | ||
| build_msvc | ||
| build-aux/m4 | ||
| ci | ||
| contrib | ||
| depends | ||
| doc | ||
| share | ||
| src | ||
| test | ||
| .cirrus.yml | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| .python-version | ||
| .style.yapf | ||
| autogen.sh | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| INSTALL.md | ||
| libbitcoinconsensus.pc.in | ||
| Makefile.am | ||
| README.md | ||
| REVIEWERS | ||
| SECURITY.md | ||
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/licenses/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled in configure) with: make check. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: test/functional/test_runner.py
The CI (Continuous Integration) systems make sure that every pull request is built for Windows, Linux, and macOS, and that unit/sanity tests are run automatically.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.