[ci] Polishing build.py, wave 2 (#7800)

Issue: #7269 

### Brief Summary

- Setting a skbuild platform name to ensure the Android build can
coexist with the Linux build of the C-API shared library.
- Run ensurepip in bootstraping
- Probe mirror before use

.github/workflows/scripts/aot-demo.sh

@@ -58,11 +58,10 @@ function prepare-unity-build-env {
 
     export TAICHI_REPO_DIR=$(pwd)
 
-    setup-android-ndk-env
     git clone --reference-if-able /var/lib/git-cache -b "$TAICHI_UNITY2_BRANCH" "$TAICHI_UNITY2_URL"
     mkdir tu2-build
     pushd tu2-build
-    cmake ../taichi-unity2 -DTAICHI_C_API_INSTALL_DIR=$TAICHI_REPO_DIR/_skbuild/linux-x86_64-3.9/cmake-install/c_api $TAICHI_CMAKE_ARGS
+    cmake ../taichi-unity2 $TAICHI_CMAKE_ARGS
     cmake --build .
     popd
     cp tu2-build/bin/libtaichi_unity.so Taichi-UnityExample/Assets/Plugins/Android

.github/workflows/scripts/ti_build/android.py

@@ -49,6 +49,7 @@ def build_android(python: Command, pip: Command) -> None:
     cmake_args['TI_WITH_C_API'] = True
     cmake_args['TI_BUILD_TESTS'] = False
     cmake_args.writeback()
+    os.environ['TAICHI_FORCE_PLAT_NAME'] = 'android-arm64'  # affects setup.py
     pip.install('-r', 'requirements_dev.txt')
     python('setup.py', 'clean')
     python('setup.py', 'build_ext')

.github/workflows/scripts/ti_build/bootstrap.py

@@ -79,8 +79,10 @@ def ensure_dependencies(*deps: str):
             sys.executable, '-m', 'pip', 'install', '--no-user',
             f'--target={bootstrap_root}', '-U'
         ]
+        if run([sys.executable, '-m', 'ensurepip']):
+            raise Exception('Unable to run ensurepip!')
         if run(*pipcmd, 'pip', 'setuptools'):
-            raise Exception('Unable to upgrade pip!')
+            raise Exception('Unable to install pip!')
         if run(*pipcmd, *deps, env={'PYTHONPATH': str(bootstrap_root)}):
             raise Exception('Unable to install dependencies!')
 

.github/workflows/scripts/ti_build/dep.py

@@ -10,7 +10,7 @@
 import requests
 
 # -- own --
-from .misc import get_cache_home
+from .misc import get_cache_home, info
 from .tinysh import bash, sh, sudo, tar
 
 
@@ -55,6 +55,40 @@ def escape_url(url):
     return url.replace('/', '_').replace(':', '_')
 
 
+SHOULD_USE_MIRROR = {
+    'ci': False,
+    'aliyun': False,
+    '_probed': False,
+}
+
+
+def probe_mirrors():
+    if SHOULD_USE_MIRROR['_probed']:
+        return
+
+    try:
+        resp = requests.get('http://botmaster.tgr:9000/misc/canary.txt',
+                            timeout=0.5)
+        if resp.ok and resp.text.strip() == 'in-taichi-ci-environment':
+            info('Enabling Taichi CI cluster mirror')
+            SHOULD_USE_MIRROR['ci'] = True
+    except Exception:
+        pass
+
+    google_ok = True
+    try:
+        resp = requests.head('https://google.com', timeout=2)
+        google_ok = resp.ok
+    except Exception:
+        google_ok = False
+
+    if not google_ok:
+        info('Enabling Aliyun mirror')
+        SHOULD_USE_MIRROR['aliyun'] = True
+
+    SHOULD_USE_MIRROR['_probed'] = True
+
+
 def download_dep(url,
                  outdir,
                  *,
@@ -80,14 +114,21 @@ def download_dep(url,
     depcache.mkdir(parents=True, exist_ok=True)
     local_cached = depcache / escaped
 
-    urls = [
-        f'http://botmaster.tgr:9000/misc/depcache/{escaped}/{name}',
-        f'https://taichi-bots.oss-cn-beijing.aliyuncs.com/depcache/{escaped}/{name}',
-        url,
-    ]
+    probe_mirrors()
+
+    urls = [url]
+
+    if SHOULD_USE_MIRROR['aliyun']:
+        urls.append(
+            f'https://taichi-bots.oss-cn-beijing.aliyuncs.com/depcache/{escaped}/{name}'
+        )
+
+    if SHOULD_USE_MIRROR['ci']:
+        urls.append(
+            f'http://botmaster.tgr:9000/misc/depcache/{escaped}/{name}')
 
     size = -1
-    for u in urls:
+    for u in reversed(urls):
         try:
             resp = requests.head(u,
                                  headers={'Accept-Encoding': 'identity'},

setup.py

@@ -208,6 +208,12 @@ def sign_development_for_apple_m1():
 
 
 copy_assets()
+
+force_plat_name = os.getenv('TAICHI_FORCE_PLAT_NAME', '').strip()
+if force_plat_name:
+    from skbuild.constants import set_skbuild_plat_name
+    set_skbuild_plat_name(force_plat_name)
+
 setup(name=project_name,
       packages=packages,
       package_dir={"": package_dir},