Merge pull request #2142 from swt2c/ci_linux_ccache

Use ccache to speed up Linux CI

.azure/ci-linux-job.yml

@@ -15,7 +15,9 @@ jobs:
       Py310:
         python.version: '3.10'
 
-  variables: {'PYTHONUNBUFFERED': '1'}
+  variables:
+    PYTHONUNBUFFERED: '1'
+    CCACHE_DIR: $(Pipeline.Workspace)/ccache
 
   steps:
   - checkout: self
@@ -27,13 +29,22 @@ jobs:
 
   - script: |
       sudo apt-get update
-      sudo apt-get install -y build-essential
+      sudo apt-get install -y build-essential ccache
       sudo apt-get install -y libgtk-3-dev libjpeg-dev libtiff-dev \
               libsdl2-dev libgstreamer-plugins-base1.0-dev libnotify-dev \
               libsm-dev libwebkit2gtk-4.0-dev libxtst-dev libexpat1-dev \
               libgl1-mesa-dev libglu1-mesa-dev libcurl4-openssl-dev \
               libgstreamer-plugins-bad1.0-dev
-    displayName: 'Install deb package requirements'
+      echo "##vso[task.prependpath]/usr/lib/ccache"
+    displayName: 'Install deb package requirements & setup ccache'
+
+  - task: Cache@2
+    inputs:
+      key: 'ccache | "$(Agent.OS)" | "$(python.version)"'
+      path: $(CCACHE_DIR)
+      restoreKeys: |
+        ccache | "$(Agent.OS)" | "$(python.version)"
+    displayName: ccache
 
   - script: |
       python -m pip install -U pip setuptools wheel