experiment(tag_filterlist): try trie-based tag membership set approach

[tobz]

Summary

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

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References

[tobz]

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• experiment(tag_filterlist): try trie-based tag membership set approach #1304 👈 (View in Graphite)
• experiment(context): amortized/deferred mutable view over tag set filtering (#1293 cherry pick) #1295
• chore(ci): add smp experiments for tag filtering #1296
• enhancement(agent-data-plane): add metric tag filterlist #1293
• main

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[Copilot]

Pull request overview

This PR introduces a trie-based approach for tag membership checking in the metric tag filterlist component. Instead of using HashSet-based lookups, it uses the trie-hard library to build a trie data structure for O(log n) prefix-based lookups. The change includes refactoring the core filtering logic, adding comprehensive benchmarks, and introducing a new TagNameSet struct that wraps the trie with unsafe code to maintain static lifetimes.

Changes:

• Introduces TagNameSet struct using trie-hard for tag name membership checking with artificial 'static lifetime management
• Converts compile_filters to use a two-pass approach: first merge with HashSets, then convert to tries
• Adds comprehensive benchmarks comparing three approaches (std HashSet, foldhash HashSet, and trie) across different tag set sizes and lookup patterns
• Updates dependencies to include trie-hard 0.2 and criterion for benchmarking

Reviewed changes

Copilot reviewed 2 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
LICENSE-3rdparty.csv	Adds Apache-2.0 licensed trie-hard library from Cloudflare
Cargo.toml	Adds trie-hard 0.2 dependency to workspace
Cargo.lock	Adds trie-hard 0.2.0 and related phf dependencies
bin/agent-data-plane/Cargo.toml	Adds trie-hard and criterion dependencies to agent-data-plane
bin/agent-data-plane/src/components/tag_filterlist/mod.rs	Implements TagNameSet with trie-based lookups, refactors compile_filters, and updates filter_metric_tags function
bin/agent-data-plane/benches/tag_filterlist.rs	New benchmark file comparing performance of different tag lookup implementations

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 7 changed files in this pull request and generated 4 comments.

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[Copilot]

This PR adds a dependency on trie-hard from a custom git branch (tobz/optimize). Using a git branch dependency instead of a published release version can create reproducibility and maintenance issues. Consider either publishing this as a proper release, using a specific commit hash, or waiting for the changes to be merged upstream and released officially.

Suggested change

	trie-hard = { git = "https://github.com/tobz/trie-hard.git", branch = "tobz/optimize", default-features = false }
	trie-hard = { git = "https://github.com/tobz/trie-hard.git", rev = "<current-commit-sha>", default-features = false }

[Copilot]

The tokio version has been downgraded from 1.50 to 1.49. This appears to be intentional, but the PR description is empty and doesn't explain why. Verify that this downgrade is intentional and doesn't cause any compatibility issues with other dependencies.

[Copilot]

The libc version has been downgraded from 0.2.183 to 0.2.169. The PR description is empty and doesn't explain why this downgrade was made. Verify that this is intentional and understand the reason for this version change.

[Copilot]

The .cargo/config.toml has been significantly modified: the rustflags format changed from an array to a string, and target-specific rustflags with SSE features were added. The PR description is empty and doesn't explain these infrastructure changes. Verify that these changes are intentional and compatible with the build system.