CI: added ccache test

.github/workflows/test_ccache.yml

@@ -0,0 +1,33 @@
+name: test ccache
+
+on: [push, pull_request, workflow_dispatch]
+# paths:
+# - "*"
+# - "!README.md" <-- don't rebuild on doc change
+concurrency:
+  group: ci-${{github.workflow}}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-20.04
+    container: ardupilot/ardupilot-dev-${{ matrix.toolchain }}:latest
+    strategy:
+      fail-fast: false  # don't cancel if a job from the matrix fails
+      matrix:
+        toolchain: [
+            chibios,
+        ]
+        gcc: [10]
+    steps:
+      # git checkout the PR
+      - uses: actions/checkout@v2
+        with:
+          submodules: 'recursive'
+      - name: ccache test
+        shell: bash
+        run: |
+          PATH="/usr/lib/ccache:/opt/gcc-arm-none-eabi-${{matrix.gcc}}/bin:$PATH"
+          Tools/scripts/build_tests/test_ccache.py --boards MatekF405,MatekF405-bdshot --min-cache-pct=75
+          Tools/scripts/build_tests/test_ccache.py --boards CubeOrange,Durandal --min-cache-pct=75
+

Tools/scripts/build_tests/test_ccache.py

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+#!/usr/bin/env python3
+# test ccache efficiency building two similar boards
+# AP_FLAKE8_CLEAN
+
+import subprocess
+import re
+import argparse
+import sys
+import os
+
+parser = argparse.ArgumentParser(description='test ccache performance')
+parser.add_argument('--boards', default='MatekF405,MatekF405-bdshot', help='boards to test')
+parser.add_argument('--min-cache-pct', type=int, default=75, help='minimum acceptable ccache hit rate')
+
+args = parser.parse_args()
+
+
+def ccache_stats():
+    '''return hits/misses from ccache -s'''
+    hits = 0
+    miss = 0
+    stats = str(subprocess.Popen(["ccache", "-s"], stdout=subprocess.PIPE).communicate()[0], encoding='ascii')
+    for line in stats.split('\n'):
+        m = re.match(r"cache.hit\D*(\d+)$", line)
+        if m is not None:
+            hits += int(m.group(1))
+        m = re.match(r"cache.miss\D*(\d+)", line)
+        if m is not None:
+            miss += int(m.group(1))
+    return (hits, miss)
+
+
+def build_board(boardname):
+    subprocess.run(["./waf", "configure", "--board", boardname])
+    subprocess.run(["./waf", "clean", "copter"])
+
+
+boards = args.boards.split(",")
+if len(boards) != 2:
+    print(boards)
+    print("Must specify exactly 2 boards (comma separated)")
+    sys.exit(1)
+
+os.environ['CCACHE_DIR'] = os.path.join(os.getcwd(), 'build', 'ccache')
+subprocess.run(["ccache", "-C", "-z"])
+build_board(boards[0])
+subprocess.run(["ccache", "-z"])
+build_board(boards[1])
+subprocess.run(["ccache", "-s"])
+
+post = ccache_stats()
+hit_pct = 100 * post[0] / float(post[0]+post[1])
+print("ccache hit percentage: %.1f%%  %s" % (hit_pct, post))
+if hit_pct < args.min_cache_pct:
+    print("ccache hits too low, need %d%%" % args.min_cache_pct)
+    sys.exit(1)
+else:
+    print("ccache hits good")