ci: improve stability and caching

Make a number of improvements to ci similar to what were done here:
MystenLabs/sui#1164

.cargo/config

@@ -0,0 +1,10 @@
+[alias]
+# Collection of project wide clippy lints. This is done via an alias because
+# clippy doesn't currently allow for specifiying project-wide lints in a
+# configuration file. This is a similar workaround to the ones presented here:
+# <https://github.com/EmbarkStudios/rust-ecosystem/issues/59>
+xclippy = [
+    "clippy", "--all-targets", "--",
+    "-Wclippy::all",
+    "-Wclippy::disallowed_methods",
+]

.github/workflows/codecov.yml

@@ -15,20 +15,27 @@ jobs:
     strategy:
       fail-fast: true
     steps:
-      - name: install toolchain according to rust-toolchain
-        uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly
+          toolchain: beta
           profile: default
           override: true
           components: llvm-tools-preview
-      - name: Checkout sources
-        uses: actions/checkout@v2
-      - uses: Swatinem/rust-cache@v1
+      # Enable caching of the 'librocksdb-sys' crate by additionally caching the
+      # 'librocksdb-sys' src directory which is managed by cargo
+      - uses: bmwill/rust-cache@v1 # Fork of 'Swatinem/rust-cache' which allows caching additional paths
+        with:
+          path: ~/.cargo/registry/src/**/librocksdb-sys-*
       - name: Install grcov, and cache the binary
         uses: baptiste0928/cargo-install@v1
         with:
           crate: grcov
+          locked: true
+      # Normally generating code coverage requires use of a nightly compiler
+      # In order to have a more stable and less noisy experience, lets instead
+      # opt to use the stable toolchain specified via the 'rust-toolchain' file
+      # and instead enable nightly features via 'RUSTC_BOOTSTRAP'
       - name: Build
         uses: actions-rs/cargo@v1
         with:
@@ -41,9 +48,8 @@ jobs:
           RUSTFLAGS: '-Cinstrument-coverage'
           RUSTDOCFLAGS: '-Cinstrument-coverage'
           LLVM_PROFILE_FILE: 'codecov-instrumentation-%p-%m.profraw'
-        run: |
-          cargo test 
+        run: cargo test
       - name: Run grcov
         run: grcov . --binary-path target/debug/ -s . -t lcov --branch --ignore-not-existing --ignore '../**' --ignore '/*' -o coverage.lcov
       - name: Upload to codecov.io
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v1

.github/workflows/nightly.yml

@@ -0,0 +1,48 @@
+name: nightly
+
+on:
+  schedule:
+    - cron: '0 0 * * *'  # every day at midnight
+
+env:
+  CARGO_TERM_COLOR: always
+  # Disable incremental compilation.
+  #
+  # Incremental compilation is useful as part of an edit-build-test-edit cycle,
+  # as it lets the compiler avoid recompiling code that hasn't changed. However,
+  # on CI, we're not making small edits; we're almost always building the entire
+  # project from scratch. Thus, incremental compilation on CI actually
+  # introduces *additional* overhead to support making future builds
+  # faster...but no future builds will ever occur in any given CI environment.
+  #
+  # See https://matklad.github.io/2021/09/04/fast-rust-builds.html#ci-workflow
+  # for details.
+  CARGO_INCREMENTAL: 0
+  # Allow more retries for network requests in cargo (downloading crates) and
+  # rustup (installing toolchains). This should help to reduce flaky CI failures
+  # from transient network timeouts or other issues.
+  CARGO_NET_RETRY: 10
+  RUSTUP_MAX_RETRIES: 10
+  # Don't emit giant backtraces in the CI logs.
+  RUST_BACKTRACE: short
+
+jobs:
+  beta:
+    name: Run test on the beta channel
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install beta toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: beta
+          components: clippy
+          override: true
+      # See '.cargo/config' for list of enabled/disappled clippy lints
+      - name: cargo clippy
+        run: cargo xclippy -D warnings
+      - name: cargo test
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --all-features

.github/workflows/rust.yml

@@ -30,68 +30,59 @@ env:
   RUST_BACKTRACE: short
 
 jobs:
+  license-check:
+    name: license-check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - run: scripts/license_check.sh
+
   test:
-    name: Test Rust ${{matrix.toolchain}} on ${{matrix.os}}
-    runs-on: ${{matrix.os}}-latest
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
-      matrix:
-        toolchain: [stable, nightly]
-        os: [ubuntu]
     steps:
       - uses: actions/checkout@v2
-      - name: Install rust
-        uses: actions-rs/toolchain@v1
+      - uses: actions-rs/toolchain@v1
+      # Enable caching of the 'librocksdb-sys' crate by additionally caching the
+      # 'librocksdb-sys' src directory which is managed by cargo
+      - uses: bmwill/rust-cache@v1 # Fork of 'Swatinem/rust-cache' which allows caching additional paths
         with:
-          toolchain: ${{matrix.toolchain}}
-          profile: minimal
-          override: true
-      - uses: Swatinem/rust-cache@v1
-      - name: Test
+          path: ~/.cargo/registry/src/**/librocksdb-sys-*
+      - name: cargo test
         uses: actions-rs/cargo@v1
         with:
           command: test
           args: --all-features
 
   clippy:
-    name: Clippy
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install minimal nightly with clippy
-        uses: actions-rs/toolchain@v1
+      - uses: actions-rs/toolchain@v1
         with:
-          profile: minimal
-          toolchain: nightly
           components: clippy
-          override: true
-      - uses: Swatinem/rust-cache@v1
-      - name: Clippy
-        uses: actions-rs/cargo@v1
+      # Enable caching of the 'librocksdb-sys' crate by additionally caching the
+      # 'librocksdb-sys' src directory which is managed by cargo
+      - uses: bmwill/rust-cache@v1 # Fork of 'Swatinem/rust-cache' which allows caching additional paths
         with:
-          command: clippy
-          args: --all --tests -- -D clippy::all -D warnings -D clippy::disallowed_method
+          path: ~/.cargo/registry/src/**/librocksdb-sys-*
+      # See '.cargo/config' for list of enabled/disappled clippy lints
+      - name: cargo clippy
+        run: cargo xclippy -D warnings
 
   rustfmt:
-    name: rustfmt
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install minimal nightly with rustfmt
-        uses: actions-rs/toolchain@v1
+      - uses: actions-rs/toolchain@v1
         with:
-          profile: minimal
-          toolchain: nightly
           components: rustfmt
-          override: true
-      - uses: Swatinem/rust-cache@v1
       - name: rustfmt
         uses: actions-rs/cargo@v1
         with:
           command: fmt
-          args: --all -- --check
-      - name: check license headers
-        run: scripts/license_check.sh
+          args: --all --check
 
   cargo-deny:
     name: cargo-deny (advisories, licenses, bans, ...)
@@ -100,21 +91,24 @@ jobs:
     - uses: actions/checkout@v2
     - uses: EmbarkStudios/cargo-deny-action@v1
 
-  udeps:
-    name: cargo-udeps
+  cargo-udeps:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install minimal nightly
-        uses: actions-rs/toolchain@v1
+      - uses: actions-rs/toolchain@v1
+      # Enable caching of the 'librocksdb-sys' crate by additionally caching the
+      # 'librocksdb-sys' src directory which is managed by cargo
+      - uses: bmwill/rust-cache@v1 # Fork of 'Swatinem/rust-cache' which allows caching additional paths
         with:
-          profile: minimal
-          toolchain: nightly
-          override: true
-      - uses: Swatinem/rust-cache@v1
+          path: ~/.cargo/registry/src/**/librocksdb-sys-*
       - name: Install cargo-udeps, and cache the binary
         uses: baptiste0928/cargo-install@v1
         with:
           crate: cargo-udeps
+          locked: true
+      # Normally running cargo-udeps requires use of a nightly compiler
+      # In order to have a more stable and less noisy experience, lets instead
+      # opt to use the stable toolchain specified via the 'rust-toolchain' file
+      # and instead enable nightly features via 'RUSTC_BOOTSTRAP'
       - name: run cargo-udeps
-        run: cargo +nightly udeps
+        run: RUSTC_BOOTSTRAP=1 cargo udeps