c90c23d388
25bed560betest: add forward-compat functional test for txindex (sedited)703304ed8cdoc: add release notes for txindex disk usage and downgrading (Andrew Toth)8e5320a2d2tests: cover txindex hash prefix collisions and legacy fallback (Andrew Toth)b75efa19batxindex: skip bloom filters and legacy lookups for new databases (Andrew Toth)004d7c098ctxindex: hash key prefixes and pack block positions (Andrew Toth)5a255970fdrefactor: move txindex db constants and legacy key to txindex_key.h (Andrew Toth)327660134ctxindex: pass the full block to DB::WriteTxs (Andrew Toth)42771e7998txindex: use a new block locator for downgrade safety (Andrew Toth)4b08baed72txindex: return optional tx and block hash from FindTx (Andrew Toth) Pull request description: The current txindex uses the full 32-byte txid as keys, which takes up about 66 GB of disk space today on mainnet. Using a 5-byte key prefix instead drops the disk usage to 26 GB - cutting the size to less than half. Using the full 32-bytes is unnecessary since a 5-byte salted siphash will produce collisions in about 1 in 1.1 trillion. Some collisions will occur, but the penalty is just an extra disk read, deserialization and hash. The tx position can be appended to the key instead of used as a value, and a LevelDB iterator can seek to the prefix and then scan for the correct tx. This is an almost identical approach to `txospenderindex`. Also instead of storing the file position of the block, we can store only the sequence of the connected block and offset of the transaction in the block. This can be packed into a 6-byte key suffix using 3-byte representations of the sequence and offset in the block. The block file can be recovered by the CBlockIndex that is already in memory. The sequence is mapped to the block hash in the db, so we can lookup the block hash to find the CBlockIndex during reads. If a tx is not found with this method, we fallback to looking up the legacy entry. With this method a user with an existing db can opt to erase the `indexes/txindex` folder and reindex, or keep the current index and new entries will be appended with the smaller footprint. The time to index was faster on my machine with this method, 1h19m vs current 1h50m. Lookups are roughly the same, around 0.2ms per lookup with `getrawtransaction`. When testing on mainnet, I got 894,549 2-way collisions, 395 3-way collision, and 1 4-way collision that worst case could cause an extra 3 false positives when reading. ACKs for top commit: l0rinc: diff reACK25bed560besedited: ACK25bed560beajtowns: ACK25bed560beTree-SHA512: a25c79ca7e722e2f372b65f5fc11c8b194ad49f2240b4881c7e606306aabbd3604aede3f1c33606b467486affac3a3f503638f513c896935cebbc02709cb60d8
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/license/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 during the generation of the build system) with: ctest. 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: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.
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.