1abbdac677
When a wallet uses avoid_reuse and has a large number of outputs in a single destination, it groups these outputs in OutputGroups that are no larger than OUTPUT_GROUP_MAX_ENTRIES. The goal is to spend as many outputs as possible from the destination while not breaking consensus due to a huge number of inputs and also not surprise the use with high fees. If there are n outputs in a destination and n > OUTPUT_GROUP_MAX_ENTRIES then this results in one or many groups of size OUTPUT_GROUP_MAX_ENTRIES and possibly one group of size < OUTPUT_GROUP_MAX_ENTRIES. Prior to this commit the coin selection in the case where n > OUTPUT_GROUP_MAX_ENTRIES was skewed towards the one group of size < OUTPUT_GROUP_MAX_ENTRIES if it exists and the amount to be spent by the transaction is smaller than the aggregate of those of the group size < OUTPUT_GROUP_MAX_ENTRIES. The reason is that the coin selection decides between the different groups based on fees and mostly the smaller group will cause smaller fees. The behavior that users of the avoid_reuse flag seek is that the full groups of size OUTPUT_GROUP_MAX_ENTRIES get used first. This commit implements this by pretending that the small group has a large number of ancestors (one smallet than the maximum allowed for this wallet). This dumps the small group to the bottom of the list of priorities in the coin selection algorithm.
Bitcoin Core integration/staging tree
What is Bitcoin?
Bitcoin is an experimental digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network. Bitcoin Core is the name of open source software which enables the use of this currency.
For more information, as well as an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/, or read the original whitepaper.
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 and tested, but is not guaranteed to be
completely stable. Tags are created
regularly to indicate new official, stable release versions of Bitcoin Core.
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, that are run automatically on the build server.
These tests can be run (if the test dependencies are installed) with: test/functional/test_runner.py
The Travis CI system makes 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.
Translators should also subscribe to the mailing list.