chore: improve signal performance by reducing duplicate deps #14945
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🦋 Changeset detectedLatest commit: bca2f22 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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Rich-Harris
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Jan 8, 2025
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this is ingenious!
I think we should either use write_version and read_version in place of w_version and r_version or, if we're trying to be compact, vw and vr (and rely on Intellisense to explain what they are). Having something in between means we don't really get the benefits of compactness or understandability
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This PR introduces read versioning, which is different from write versioning (the existing version naming has been updating to be
wvrespectfully). When we read a signal in a given reactive context we can provide it a read version. This provides us a benefit in that if we have duplicate reads of the same signal, we avoid populating the same signal many X times in the same reaction's dependencies. This is actually significant in many stress-cases where you might reada[x]in a loop, where aais a signal. Ifxis10000, we end up with 10k ofaas a dependency, when only a single is satisfactory.This optimisation adds an extra field to source and derived signals, which is probably worth while given the real-world implications of having a huge reactive dependency array and reactive graph because of additional re-visits.
In terms of of our reactive benchmark the benefits are clear:
Before:
After:
