fix(ci): improve cache hit rate with shared-key and job-level sccache env#2324
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fix(ci): improve cache hit rate with shared-key and job-level sccache env#2324
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rust-cache and sccache serve distinct layers: rust-cache covers registry downloads (~/.cargo/registry, ~/.cargo/git) while sccache covers compiled artifacts. With cache-targets=false they don't overlap. Primary fix: add shared-key so all jobs in the same workflow share one rust-cache entry instead of each creating an independent key. Without shared-key, every job misses the cache and re-downloads the full registry. - lint-clippy, build-tests: shared-key="ci" (same toolchain + feature set) - coverage: shared-key="coverage" (instrument-coverage artifacts are distinct) - bundle-check matrix: shared-key="bundle-check" (all 5 shards share one entry) - release build-binaries: shared-key="release-<target>" per target Secondary fix: move RUSTC_WRAPPER and SCCACHE_GHA_ENABLED from step-level env to job-level env so all cargo invocations in the job route through sccache, not just the explicit cargo step. release.yml: add sccache for native builds only; cross builds run inside a container where host sccache is not available.
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Summary
shared-keyto allSwatinem/rust-cachesteps so jobs in the same workflow share one registry cache entry instead of creating independent keys per job. Without this, every job misses and re-downloads the full~/.cargo/registry.RUSTC_WRAPPER: sccache/SCCACHE_GHA_ENABLED: "true"from step-levelenvto job-levelenvso all cargo invocations in the job route through sccache, not just the explicit cargo step.release.ymlfor native builds; skip forcrossbuilds (run in a container where host sccache is unavailable).Cache layers (non-overlapping)
rust-cache(cache-targets=false)~/.cargo/registry,~/.cargo/gitshared-key + Cargo.lock hashsccache.rlibKey assignments
shared-keylint-clippy,build-testscicoveragecoverage(instrument-coverage artifacts differ from normal builds)bundle-check(5-shard matrix)bundle-checkreleasebuild-binariesrelease-<target>Expected outcome
After 2 consecutive warm runs on main: registry cache hit rate ~95%, sccache hit rate ~70-85% for incremental PRs (few files changed). Overall cache hit rate should rise from ~18% to 80%+.