Update CI script

Copied from lib-p2p master; fixes error with windows dependencies.

.github/workflows/ci.yml

@@ -43,12 +43,43 @@ jobs:
         with:
           path: nim-dagger
           submodules: true
+
+      - name: Derive environment variables
+        shell: bash
+        run: |
+          if [[ '${{ matrix.target.cpu }}' == 'amd64' ]]; then
+            ARCH=64
+            PLATFORM=x64
+          else
+            ARCH=32
+            PLATFORM=x86
+          fi
+          echo "ARCH=$ARCH" >> $GITHUB_ENV
+          echo "PLATFORM=$PLATFORM" >> $GITHUB_ENV
+          ncpu=
+          ext=
+          case '${{ runner.os }}' in
+          'Linux')
+            ncpu=$(nproc)
+            ;;
+          'macOS')
+            ncpu=$(sysctl -n hw.ncpu)
+            ;;
+          'Windows')
+            ncpu=$NUMBER_OF_PROCESSORS
+            ext=.exe
+            ;;
+          esac
+          [[ -z "$ncpu" || $ncpu -le 0 ]] && ncpu=1
+          echo "ncpu=$ncpu" >> $GITHUB_ENV
+          echo "ext=$ext" >> $GITHUB_ENV
+
       - name: Install build dependencies (Linux i386)
         if: runner.os == 'Linux' && matrix.target.cpu == 'i386'
         run: |
           sudo dpkg --add-architecture i386
-          sudo apt-fast update -qq
+          sudo apt-get update -qq
-          sudo DEBIAN_FRONTEND='noninteractive' apt-fast install \
+          sudo DEBIAN_FRONTEND='noninteractive' apt-get install \
             --no-install-recommends -yq gcc-multilib g++-multilib \
             libssl-dev:i386
           mkdir -p external/bin
@@ -63,22 +94,50 @@ jobs:
           chmod 755 external/bin/gcc external/bin/g++
           echo '${{ github.workspace }}/external/bin' >> $GITHUB_PATH
 
-      - name: Install build dependencies (Windows)
+      - name: Restore MinGW-W64 (Windows) from cache
         if: runner.os == 'Windows'
+        id: windows-mingw-cache
+        uses: actions/cache@v2
+        with:
+          path: external/mingw-${{ matrix.target.cpu }}
+          key: 'mingw-${{ matrix.target.cpu }}'
+
+      - name: Restore Nim DLLs dependencies (Windows) from cache
+        if: runner.os == 'Windows'
+        id: windows-dlls-cache
+        uses: actions/cache@v2
+        with:
+          path: external/dlls-${{ matrix.target.cpu }}
+          key: 'dlls-${{ matrix.target.cpu }}'
+
+      - name: Install MinGW64 dependency (Windows)
+        if: >
+          steps.windows-mingw-cache.outputs.cache-hit != 'true' &&
+          runner.os == 'Windows'
         shell: bash
         run: |
-          mkdir external
+          mkdir -p external
-          if [[ '${{ matrix.target.cpu }}' == 'amd64' ]]; then
+          curl -L "https://nim-lang.org/download/mingw$ARCH.7z" -o "external/mingw-${{ matrix.target.cpu }}.7z"
-            arch=64
+          7z x -y "external/mingw-${{ matrix.target.cpu }}.7z" -oexternal/
-          else
+          mv external/mingw$ARCH external/mingw-${{ matrix.target.cpu }}
-            arch=32
+
-          fi
+      - name: Install DLLs dependencies (Windows)
-          curl -L "https://nim-lang.org/download/mingw$arch-6.3.0.7z" -o "external/mingw$arch.7z"
+        if: >
+          steps.windows-dlls-cache.outputs.cache-hit != 'true' &&
+          runner.os == 'Windows'
+        shell: bash
+        run: |
+          mkdir -p external
           curl -L "https://nim-lang.org/download/windeps.zip" -o external/windeps.zip
-          7z x "external/mingw$arch.7z" -oexternal/
+          7z x -y external/windeps.zip -oexternal/dlls-${{ matrix.target.cpu }}
-          7z x external/windeps.zip -oexternal/dlls
+
-          echo '${{ github.workspace }}'"/external/mingw$arch/bin" >> $GITHUB_PATH
+      - name: Path to cached dependencies (Windows)
-          echo '${{ github.workspace }}'"/external/dlls" >> $GITHUB_PATH
+        if: >
+          runner.os == 'Windows'
+        shell: bash
+        run: |
+          echo "${{ github.workspace }}/external/mingw-${{ matrix.target.cpu }}/bin" >> $GITHUB_PATH
+          echo "${{ github.workspace }}/external/dlls-${{ matrix.target.cpu }}" >> $GITHUB_PATH
 
       - name: Setup environment
         shell: bash
@@ -133,20 +192,6 @@ jobs:
         if: steps.nim-cache.outputs.cache-hit != 'true'
         shell: bash
         run: |
-          ncpu=
-          ext=
-          case '${{ runner.os }}' in
-          'Linux')
-            ncpu=$(nproc)
-            ;;
-          'macOS')
-            ncpu=$(sysctl -n hw.ncpu)
-            ;;
-          'Windows')
-            ncpu=$NUMBER_OF_PROCESSORS
-            ext=.exe
-            ;;
-          esac
           [[ -z "$ncpu" || $ncpu -le 0 ]] && ncpu=1
           if [[ ! -e csources/bin/nim$ext ]]; then
             make -C csources -j $ncpu CC=gcc ucpu='${{ matrix.target.cpu }}'