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refactor: performance-for-range-copy in psbt.h #30253

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Merged
fanquake merged 1 commit into from
Jun 10, 2024
Merged

refactor: performance-for-range-copy in psbt.h #30253

fanquake merged 1 commit into from
Jun 10, 2024

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@maflcko maflcko commented Jun 9, 2024

A copy of the partial signatures is not required before serializing them.

For reference, this was found by switching the codebase to std::span (not sure why it wasn't found with Span though):

./psbt.h:240:23: error: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy,-warnings-as-errors]
  240 |             for (auto sig_pair : partial_sigs) {
      |                       ^
      |                  const  &

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DrahtBot commented Jun 9, 2024 •
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maflcko commented Jun 9, 2024

Reference CI run: https://github.com/bitcoin/bitcoin/runs/25847037350

tdb3
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Approach ACK.
Less copying makes sense. Briefly searched for other instances in psbt.h where potentially unnecessary copying is done.

Would it also make sense to adjust these references to const (or is there a specific reason why const should not be used here)? Adjusted to const auto& entry and ran unit and functional tests (no issues observed).

bitcoin/src/psbt.h

Lines 355 to 359 in fab01b5

// Write unknown things
for (auto& entry : unknown) {
s << entry.first;
s << entry.second;
}

bitcoin/src/psbt.h

Lines 780 to 784 in fab01b5

// Write unknown things
for (auto& entry : unknown) {
s << entry.first;
s << entry.second;
}

bitcoin/src/psbt.h

Lines 1013 to 1017 in fab01b5

// Write the unknown things
for (auto& entry : unknown) {
s << entry.first;
s << entry.second;
}

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maflcko commented Jun 9, 2024

Less copying makes sense. Briefly searched for other instances in psbt.h where potentially unnecessary copying is done.

The examples you provided are already const references. In C++, when calling a member method that is marked const, member access will be const. Moreover, auto& is a reference that hides the type, including the const-ness, so const auto& and auto& should be identical in this context (const references that do not copy), and no further change should be needed.

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theStack approved these changes Jun 9, 2024
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utACK fab01b5

@DrahtBot DrahtBot requested a review from tdb3 June 9, 2024 17:51
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tdb3 commented Jun 9, 2024

no further change should be needed.

Thanks.
ACK fab01b5

@fanquake fanquake merged commit ea88a75 into bitcoin:master Jun 10, 2024
@maflcko maflcko deleted the 2406-performance-for-range-copy branch June 10, 2024 08:35
luke-jr pushed a commit to bitcoinknots/bitcoin that referenced this pull request Jun 13, 2024
@luke-jr
refactor: performance-for-range-copy in psbt.h
9691293 
Github-Pull: bitcoin#30253
Rebased-From: fab01b5
PastaPastaPasta pushed a commit to PastaPastaPasta/dash that referenced this pull request Feb 20, 2025
@fanquake @PastaPastaPasta
Merge bitcoin#30253: refactor: performance-for-range-copy in psbt.h
a74b1e2 
fab01b5 refactor: performance-for-range-copy in psbt.h (MarcoFalke)

Pull request description:

  A copy of the partial signatures is not required before serializing them.

  For reference, this was found by switching the codebase to `std::span` (not sure why it wasn't found with `Span` though):

  ```
  ./psbt.h:240:23: error: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy,-warnings-as-errors]
    240 |             for (auto sig_pair : partial_sigs) {
        |                       ^
        |                  const  &

ACKs for top commit:
  tdb3:
    ACK fab01b5
  theStack:
    utACK fab01b5

Tree-SHA512: b55513d8191118499716684190ee568d171b50ae9171d246ca6e047f0cfd3ec14c9453d721e88af55e47bb41fa66cbafdbfb47bc5f9b8d82789e0a9b634b371b
PastaPastaPasta added a commit to dashpay/dash that referenced this pull request Feb 21, 2025
@PastaPastaPasta
Merge #6582: backport: trivial 2025 02 12
456add2 
c34e7ab Merge bitcoin#30534: guix: move bison from global scope, to Linux (merge-script)
da11d29 Merge bitcoin#30282: Revert "contrib: macdeploy: monkey-patch gen-sdk to be deterministic" (merge-script)
20bcee8 Merge bitcoin#30281: Update leveldb subtree to latest upstream (merge-script)
a74b1e2 Merge bitcoin#30253: refactor: performance-for-range-copy in psbt.h (merge-script)
2ea479f Merge bitcoin#29650: depends: drop 1 Qt determinism patch (fanquake)
6506f52 Merge bitcoin#28833: wallet: refactor: remove unused `SignatureData` instances in spkm's `FillPSBT` methods (Ava Chow)
6235590 Merge bitcoin#29213: doc, test: test and explain service flag handling (Ava Chow)
34bbe69 Merge bitcoin#28965: guix: remove input labels (fanquake)
490b390 Merge bitcoin#28859: guix: update signapple (drop macho & altgraph) (fanquake)
a12ad80 Merge bitcoin#28325: test: wallet_backup.py, fix intermittent failure in "restore using dumped wallet" (fanquake)
15f8b74 Merge bitcoin#27779: guix: remove cURL from build env (fanquake)
1289d32 Merge bitcoin#27801: wallet: Add tracing for sqlite statements (fanquake)
ba3aff7 Merge bitcoin-core/gui#729: test: Add missed header (Hennadii Stepanov)
536a265 Merge bitcoin#27209: ci: Remove unused EXPECTED_TESTS_DURATION_IN_SECONDS env var (glozow)
f2caccd Merge bitcoin#27174: ci: bump lint task to bookworm for git v2.38 (fanquake)
0be2932 Merge bitcoin#27009: validation: Skip VerifyDB checks of level >=3 if dbcache is too small (fanquake)

Pull request description:

  ## Issue being fixed or feature implemented
  Batch of trivial back ports

  ## What was done?

  ## How Has This Been Tested?
  Built locally; haven't reviewed commits yet.

  ## Breaking Changes

  ## Checklist:
    _Go over all the following points, and put an `x` in all the boxes that apply._
  - [ ] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  UdjinM6:
    utACK c34e7ab
  kwvg:
    utACK c34e7ab

Tree-SHA512: e20270e48273ad5fd5926e75b025fe69a70e698a82f0a11a1fa646c44a7affbd7a5f33eebcd7faa606e7adc2a888df141c660339d7240e6ed64f8525558215de
@bitcoin bitcoin locked and limited conversation to collaborators Jun 10, 2025
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@tdb3 tdb3 Awaiting requested review from tdb3

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