Speed up CI jobs with parallelism and caching (#33)

* Speed up CI jobs with parallelism and caching

The zenoh-c build can take nearly four minutes to complete. This change
allows zenoh-c and up-cpp to build in parallel and caches zenoh-c's
build results (using zenoh-c's HEAD hash as the cache key).

When the upstream zenoh-c repo has change (and therefore no valid cache
exists), this change saves around 40 seconds of build time by not making
up-cpp wait for zenoh-c.

When the cache is valid, the zenoh-c build is skipped resulting in a
further three minute reduction in total CI run time.

* Additional CI speed-ups

Adding a cache for up-cpp build artifacts cuts another 30 seconds out of
the best-case build times (i.e. when cache is valid).

The same technique of checking the HEAD hash for the upstream repo and
providing that as the cache key is used here. Whenever HEAD is changed
in up-cpp (typically a new PR is merged), the cache is invalidated and
up-cpp is rebuilt.

Also cuts ~10 seconds out by reusing the caches we already have in the
up-client-zenoh-cpp build step. Caches load faster than uploading and
downloading additional artifacts.

* Capture up-client-zenoh-cpp's tests as artifacts

This will allow the tests to be reused in future jobs (checking
coverage, running valgrind, producing test reports, etc.)

.github/workflows/ci.yml

@@ -9,44 +9,142 @@ on:
   workflow_dispatch:
 
 jobs:
-  build:
-    name: Build
+  build-zenoh-c:
+    name: Build Zenoh-C
     runs-on: ubuntu-latest
+    env:
+      Zenoh_C_Repo: https://github.com/eclipse-zenoh/zenoh-c.git
+      Zenoh_C_Cache_PFX: libzenohc
+    outputs:
+      Zenoh_C_Cache: ${{ env.Zenoh_C_Cache_PFX }}-${{ steps.zenoh-c-head.outputs.Zenoh_C_HEAD }}
 
     steps:
-      - uses: actions/checkout@v4
+      - name: Check remote head hash
+        id: zenoh-c-head
+        shell: bash
+        run: '{ echo -n "Zenoh_C_HEAD="; git ls-remote "$Zenoh_C_Repo" HEAD | cut -f1; } | tee -a "$GITHUB_OUTPUT"'
+
+      - name: Cache compiled zenoh-c library
+        id: cache-libzenohc
+        uses: actions/cache@v4
+        with:
+          key: ${{ env.Zenoh_C_Cache_PFX }}-${{ steps.zenoh-c-head.outputs.Zenoh_C_HEAD }}
+          path: |
+            ~/local
+
+      - name: Install Rust toolchain
+        if: ${{ steps.cache-libzenohc.outputs.cache-hit != 'true' }}
+        run: rustup component add rustfmt clippy
+
+      # NOTE: Checks out the head revision we found using ls-remote above
+      #       to avoid race conditions resulting in mismatch between cache
+      #       and contents of repo.
+      - name: Clone Zenoh-C
+        if: ${{ steps.cache-libzenohc.outputs.cache-hit != 'true' }}
+        env:
+          Zenoh_C_HEAD: ${{ steps.zenoh-c-head.outputs.Zenoh_C_HEAD }}
+        shell: bash
+        run: |
+          pwd
+          git clone "$Zenoh_C_Repo"
+          cd zenoh-c && git checkout "$Zenoh_C_HEAD"
+
+      - name: Build and install Zenoh-C
+        if: ${{ steps.cache-libzenohc.outputs.cache-hit != 'true' }}
+        shell: bash
+        run: |
+          mkdir -p zenoh-c/build && cd zenoh-c/build
+          cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=~/local
+          cmake --build . --target install --config Release -- -j
+
+  build-up-cpp:
+    name: Build up-cpp
+    runs-on: ubuntu-latest
+    env:
+      UP_CPP_Repo: https://github.com/eclipse-uprotocol/up-cpp.git
+      UP_CPP_Cache_PFX: up-cpp-conan2
+    outputs:
+      UP_CPP_Cache: ${{ env.UP_CPP_Cache_PFX }}-${{ steps.up-cpp-head.outputs.UP_CPP_HEAD }}
+
+    steps:
+      - name: Check remote head hash
+        id: up-cpp-head
+        shell: bash
+        run: '{ echo -n "UP_CPP_HEAD="; git ls-remote "$UP_CPP_Repo" HEAD | cut -f1; } | tee -a "$GITHUB_OUTPUT"'
+
+      - name: Cache conan artifacts
+        id: cache-conan2
+        uses: actions/cache@v4
+        with:
+          key: ${{ env.UP_CPP_Cache_PFX }}-${{ steps.up-cpp-head.outputs.UP_CPP_HEAD }}
+          path: |
+            ~/.conan2
 
       - name: Install Conan
+        if: ${{ steps.cache-conan2.outputs.cache-hit != 'true' }}
         id: conan
         uses: turtlebrowser/get-conan@main
 
-      - name: Conan version
-        run: echo "${{ steps.conan.outputs.version }}"
-
-
       - name: Create default Conan profile
+        if: ${{ steps.cache-conan2.outputs.cache-hit != 'true' }}
         run: conan profile detect
 
-      - name: Install Rust toolchain
-        run: rustup component add rustfmt clippy
+      # NOTE: Checks out the head revision we found using ls-remote above
+      #       to avoid race conditions resulting in mismatch between cache
+      #       and contents of repo.
+      - name: Clone up-cpp repo
+        if: ${{ steps.cache-conan2.outputs.cache-hit != 'true' }}
+        shell: bash
+        env:
+          UP_CPP_HEAD: ${{ steps.up-cpp-head.outputs.UP_CPP_HEAD }}
+        run: |
+          git clone "$UP_CPP_Repo"
+          cd up-cpp && git checkout "$UP_CPP_HEAD"
+          git submodule update --init --recursive
 
       - name: Create up-cpp Conan package
+        if: ${{ steps.cache-conan2.outputs.cache-hit != 'true' }}
         shell: bash
         run: |
-          git clone https://github.com/eclipse-uprotocol/up-cpp.git
           cd up-cpp
-          git submodule update --init --recursive
           conan create . --build=missing
 
-      - name: Build and install Zenoh-C
-        shell: bash
-        run: |
-          git clone https://github.com/eclipse-zenoh/zenoh-c.git
-          cd zenoh-c && mkdir -p build && cd build 
-          cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=~/local
-          cmake --build . --target install --config Release -- -j
+      - name: Clean up conan build files
+        if: ${{ steps.cache-conan2.outputs.cache-hit != 'true' }}
+        run: conan cache clean '*'
 
-      - name: Build && install up-client-zenoh-cpp
+  build-up-client-zenoh-cpp:
+    name: Build up-client-zenoh-cpp
+    needs: [ build-zenoh-c, build-up-cpp ]
+    runs-on: ubuntu-latest
+    env:
+      Zenoh_C_Cache: ${{ needs.build-zenoh-c.outputs.Zenoh_C_Cache }}
+      UP_CPP_Cache: ${{ needs.build-up-cpp.outputs.UP_CPP_Cache }}
+
+    steps:
+      # Note: will never update here since it will always match from previous job
+      - name: Get cached zenoh-c library
+        uses: actions/cache@v4
+        with:
+          key: ${{ env.Zenoh_C_Cache }}
+          path: |
+            ~/local
+
+      # Note: will never update here since it will always match from previous job
+      - name: Get cached up-cpp conan artifacts
+        uses: actions/cache@v4
+        with:
+          key: ${{ env.UP_CPP_Cache }}
+          path: |
+            ~/.conan2
+
+      - name: Install Conan
+        id: conan
+        uses: turtlebrowser/get-conan@main
+
+      - uses: actions/checkout@v4
+
+      - name: Build and install up-client-zenoh-cpp
         shell: bash
         run: |
           export CMAKE_PREFIX_PATH="$HOME/local"
@@ -57,8 +155,14 @@ jobs:
           cmake ../ -DCMAKE_TOOLCHAIN_FILE=conan_toolchain.cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=~/local
           cmake --build . --target install --config Release -- -j
 
+      - name: Upload test binaries
+        uses: actions/upload-artifact@v4
+        with:
+          name: tests_up-client-zenoh-cpp
+          path: |
+            build/bin
+          retention-days: 1
 
-  
   # NOTE: In GitHub repository settings, the "Require status checks to pass
   # before merging" branch protection rule ensures that commits are only merged
   # from branches where specific status checks have passed. These checks are
@@ -67,7 +171,7 @@ jobs:
   ci:
     name: CI status checks
     runs-on: ubuntu-latest
-    needs: build
+    needs: [ build-zenoh-c, build-up-cpp, build-up-client-zenoh-cpp ]
     if: always()
     steps:
       - name: Check whether all jobs pass