github/workflows: add benchmark workflow

Author: zchee

.github/workflows/benchmark.yml

@@ -0,0 +1,75 @@
+name: Benchmark
+
+on:
+  push:
+    branches: "*"
+    tags:
+      - "v*"
+  pull_request:
+    branches: "*"
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  benchmark:
+    strategy:
+      matrix:
+        os:
+          # https://github.com/actions/virtual-environments/blob/ubuntu20/20201210.0/images/linux/Ubuntu2004-README.md
+          - ubuntu-20.04
+        go-version:
+          - 1.15.x
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - name: Set flag environment variable
+      run: |
+        echo "OS=$(echo ${{ runner.os }} | tr '[:upper:]' '[:lower:]')" >> $GITHUB_ENV
+        echo "GO_VERSION=$(echo ${{ matrix.go-version }} | cut -d. -f-2)" >> $GITHUB_ENV
+
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Cache Go module and build cache
+      uses: actions/cache@v2
+      with:
+        key: ${{ env.OS }}-go-${{ hashFiles('**/go.sum') }}
+        path: |
+          ~/go/pkg/mod              # Module download cache
+          ~/.cache/go-build         # Build cache (Linux)
+        restore-keys: |
+          ${{ env.OS }}-go-
+
+    - name: Cache nvim binary for linux and darwin
+      uses: actions/cache@v2
+      id: cache-nvim
+      with:
+        key: ${{ env.OS }}-nvim-${{ hashFiles('~/nvim/bin/nvim') }}
+        path: |
+          ~/nvim
+        restore-keys: |
+          ${{ env.OS }}-nvim-
+
+    - name: Install nvim binary
+      uses: rhysd/action-setup-vim@v1
+      if: steps.cache-nvim.outputs.cache-hit != 'true'
+      with:
+        neovim: true
+        version: nightly
+
+    - name: Run Benchmark
+      run: |
+        go test -v -count=3 -run=none -bench=. -benchmem -timeout=15m ./... | tee bench-${{ env.OS }}-${{ env.GO_VERSION }}.txt
+
+    - name: 'Upload benchmark Artifact'
+      uses: actions/upload-artifact@v2
+      with:
+        name: bench-${{ env.OS }}-${{ env.GO_VERSION }}.txt
+        path: bench-${{ env.OS }}-${{ env.GO_VERSION }}.txt