3f8776a1391c3978ed66144df15fd9bcb9edd35d Re-add dead code detection (flack)
Pull request description:
This re-adds unreachable code detection for Python based on `vulture`.
Effectively, this reverts f4beb4996d27f2cdaf4f0a63e7dc044bf17decce. The difference to the previous version is that this runs with the `--min-confidence 100` setting. From https://pypi.org/project/vulture/:
> Use `--min-confidence 100` to only report code that is guaranteed to be unused within the analyzed files.
So this should avoid the previous issues where static analysis had wrong positives due to the dynamic nature of Python code by only reporting things that are unambiguous (such as code after a `return` statement). As such, there is not suppressions list.
My motivation was mainly #21081 which would have been caught by this (as can be seen by the CI run failing). This is still marked as draft because #21081 is needed to get the linter to pass. Also, there is a second problem that this found (see https://github.com/bitcoin/bitcoin/pull/19509/files#r571454691). From what I can tell, this is a spurious type comment that could just be removed (or if that line has no side effects it could also be deleted altogether?). I could add a commit here to fix it, but I wanted to see if there is interest in having this linter again in the first place
ACKs for top commit:
practicalswift:
ACK 3f8776a1391c3978ed66144df15fd9bcb9edd35d
Tree-SHA512: 52314ad4f627d969de1eb15375ca677ed86a2e816fe773756a1ce22421214ba407b5a09a4bf701a3aab1a10c7b336f548e4cef3327edf154acba55e987db21f6
f4beb4996d27f2cdaf4f0a63e7dc044bf17decce test: Remove python dead code linter (Wladimir J. van der Laan)
Pull request description:
Primarily I'd like to remove this because it is very imprecise, due to Python's dynamic nature, giving it a large list of false positives that need to be listed as exceptions. See for example #16906.
It's also a frequent source of complaints. I'm doubtful of the usefulness of checking for dead code in a linter in the first place.
Having some dead code in the test framework for a while is not a
disaster.
ACKs for top commit:
sdaftuar:
utACK f4beb4996d27f2cdaf4f0a63e7dc044bf17decce
practicalswift:
ACK f4beb4996d27f2cdaf4f0a63e7dc044bf17decce -- diff looks correct
jamesob:
ACK f4beb4996d
Tree-SHA512: 329b1555210311d5d15799fd2cb794b3208b0ac4d8a2ffaf4dece1bcc3e0e8b1fe952d5e7a394f94a98919cab579fb579eae7db2a796cc9a1a42ef495dd17507
72a18a73af26ea551d39397787a2d178c8bbde7b tests: Add information on how to add Vulture suppressions (practicalswift)
Pull request description:
Add information on how to add `vulture` suppressions.
As requested by MarcoFalke in https://github.com/bitcoin/bitcoin/issues/16906#issuecomment-533264107 -- your wish is my command! :)
ACKs for top commit:
fanquake:
ACK 72a18a73af26ea551d39397787a2d178c8bbde7b - similar sort of message as in [lint-spelling.sh](https://github.com/bitcoin/bitcoin/blob/master/test/lint/lint-spelling.sh).
Tree-SHA512: b347f8cea33d4b0ba987a972979b0ac3423938084fea923a2c457a8081bc839a94ad818689d147477104b9197dc35be413f76a96026cd1507b4411d7513e3464
13782b8ba8 docs: add perf section to developer docs (James O'Beirne)
58180b5fd4 tests: add utility to easily profile node performance with perf (James O'Beirne)
Pull request description:
Adds a context manager to easily (and selectively) profile node performance during functional test execution using `perf`.
While writing some tests, I encountered some odd bitcoind slowness. I wrote up a utility (`TestNode.profile_with_perf`) that generates performance diagnostics for a node by running `perf` during the execution of a particular region of test code.
`perf` usage is detailed in the excellent (and sadly unmerged) https://github.com/bitcoin/bitcoin/pull/12649; all due props to @eklitzke.
### Example
```python
with node.profile_with_perf("large-msgs"):
for i in range(200):
node.p2p.send_message(some_large_msg)
node.p2p.sync_with_ping()
```
This generates a perf data file in the test node's datadir (`/tmp/testtxmpod0y/node0/node-0-TestName-large-msgs.perf.data`).
Running `perf report` generates nice output about where the node spent most of its time while running that part of the test:
```bash
$ perf report -i /tmp/testtxmpod0y/node0/node-0-TestName-large-msgs.perf.data --stdio \
| c++filt \
| less
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 135 of event 'cycles:pp'
# Event count (approx.): 1458205679493582
#
# Children Self Command Shared Object Symbol
# ........ ........ ............... ................... ........................................................................................................................................................................................................................................................................
#
70.14% 0.00% bitcoin-net bitcoind [.] CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)
|
---CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)
70.14% 0.00% bitcoin-net bitcoind [.] CNetMessage::readData(char const*, unsigned int)
|
---CNetMessage::readData(char const*, unsigned int)
CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)
35.52% 0.00% bitcoin-net bitcoind [.] std::vector<char, zero_after_free_allocator<char> >::_M_fill_insert(__gnu_cxx::__normal_iterator<char*, std::vector<char, zero_after_free_allocator<char> > >, unsigned long, char const&)
|
---std::vector<char, zero_after_free_allocator<char> >::_M_fill_insert(__gnu_cxx::__normal_iterator<char*, std::vector<char, zero_after_free_allocator<char> > >, unsigned long, char const&)
CNetMessage::readData(char const*, unsigned int)
CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)
...
```
Tree-SHA512: 9ac4ceaa88818d5eca00994e8e3c8ad42ae019550d6583972a0a4f7b0c4f61032e3d0c476b4ae58756bc5eb8f8015a19a7fc26c095bd588f31d49a37ed0c6b3e
c82190cdb6 tests: Add Python dead code linter (vulture) (practicalswift)
590a57fdec tests: Remove unused testing code (practicalswift)
Pull request description:
Add Python dead code linter (`vulture`) to Travis.
Rationale for allowing dead code only after explicit opt-in (via `--ignore-names`):
* Less is more :-)
* Unused code is by definition "untested"
* Unused code can be an indication of bugs/logical errors. By making the contributor aware of newly introduced unused code it gives him/her an opportunity to investigate if the unused code they introduce is malignant or benign :-)
* Unused code is hard to spot for humans and is thus often missed during manual review
* [YAGNI](https://en.wikipedia.org/wiki/You_aren%27t_gonna_need_it)
Based on #14312 to make linter job pass.
Tree-SHA512: 4c581df7c34986e226e4ade479e0d3c549daf38f4a4dc4564b25564d63e773a1830ba55d1289c771b1fa325483e8855b82b56e61859fe8e4b7dfa54034b093b6
