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e6e622e5a0e22c2ac1b50b96af818e412d67ac54 Implement O(1) OP_IF/NOTIF/ELSE/ENDIF logic (Pieter Wuille) d0e8f4d5d8ddaccb37f98b7989fb944081e41ab8 [refactor] interpreter: define interface for vfExec (Anthony Towns) 89fb241c54fc85befacfa3703d8e21bf3b8a76eb Benchmark script verification with 100 nested IFs (Pieter Wuille) Pull request description: While investigating what mechanisms are possible to maximize the per-opcode verification cost of scripts, I noticed that the logic for determining whether a particular opcode is to be executed is O(n) in the nesting depth. This issue was also pointed out by Sergio Demian Lerner in https://bitslog.wordpress.com/2017/04/17/new-quadratic-delays-in-bitcoin-scripts/, and this PR implements a variant of the O(1) algorithm suggested there. This is not a problem currently, because even with a nesting depth of 100 (the maximum possible right now due to the 201 ops limit), the slowdown caused by this on my machine is around 70 ns per opcode (or 0.25 s per block) at worst, far lower than what is possible with other opcodes. This PR mostly serves as a proof of concept that it's possible to avoid it, which may be relevant in discussions around increasing the opcode limits in future script versions. Without it, the execution time of scripts can grow quadratically with the nesting depth, which very quickly becomes unreasonable. This improves upon #14245 by completely removing the `vfExec` vector. ACKs for top commit: jnewbery: Code review ACK e6e622e5a0e22c2ac1b50b96af818e412d67ac54 MarcoFalke: ACK e6e622e5a0e22c2ac1b50b96af818e412d67ac54 🐴 fjahr: ACK e6e622e5a0e22c2ac1b50b96af818e412d67ac54 ajtowns: ACK e6e622e5a0e22c2ac1b50b96af818e412d67ac54 laanwj: concept and code review ACK e6e622e5a0e22c2ac1b50b96af818e412d67ac54 jonatack: ACK e6e622e5a0e22c2ac1b50b96af818e412d67ac54 code review, build, benches, fuzzing Tree-SHA512: 1dcfac3411ff04773de461959298a177f951cb5f706caa2734073bcec62224d7cd103767cfeef85cd129813e70c14c74fa8f1e38e4da70ec38a0f615aab1f7f7
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.