Reuse Android compiler outputs and remove old build artifacts

tools/build_cache.py

@@ -0,0 +1,40 @@
+"""Keep compiler outputs while their source selection and toolchain stay compatible."""
+from __future__ import annotations
+import json, os, shutil
+from pathlib import Path
+from common import ROOT, COMMIT, CPUS, ProbeError, sha256, write_json
+
+def cached_project(cpu: str, resolution: dict, logs: Path) -> Path:
+    if cpu not in CPUS:raise ProbeError('Unsupported Android CPU')
+    cache=ROOT/'build/work'/cpu
+    for directory in (ROOT/'build',ROOT/'build/work',cache):
+        if directory.is_symlink():raise ProbeError('Build cache must not be a symlink: '+str(directory))
+    cache.mkdir(parents=True,exist_ok=True)
+    project=cache/'application'
+    if project.is_symlink():raise ProbeError('Cached project must not be a symlink')
+    inputs={
+        'schema':1,'cpu':cpu,'upstream_commit':COMMIT,
+        'manifest':sha256(ROOT/'app/CastleEngineManifest.xml'),
+        'source_contract':sha256(ROOT/'config/extra-paths.json'),
+        'paths':{key:[str(path) for path in resolution[key]]
+                 for key in ('compiler_source_paths','library_paths')},
+        'environment':{key:os.environ.get(key) for key in
+            ('KAM_TOOLCHAIN_IMAGE','CASTLE_ENGINE_PATH','FPCDIR','ANDROID_NDK_ROOT',
+             'ANDROID_HOME','ANDROID_SDK_ROOT','JAVA_HOME')},
+        # Removing or adding a unit can change compiler precedence even at the same paths.
+        'source_files':sorted({str(path) for directory in resolution['compiler_source_paths']
+            for path in directory.iterdir() if path.suffix.lower() in ('.pas','.pp','.inc') and path.is_file()}),
+    }
+    if not os.environ.get('KAM_TOOLCHAIN_IMAGE'):
+        inputs['tools']={}
+        for name in ('castle-engine','fpc'):
+            executable=shutil.which(name)
+            inputs['tools'][name]=None if executable is None else sha256(Path(executable).resolve())
+    marker=cache/'inputs.json'
+    try:previous=json.loads(marker.read_text())
+    except (FileNotFoundError,ValueError):previous=None
+    reused=project.is_dir() and previous==inputs
+    if project.exists() and not reused:shutil.rmtree(project)
+    write_json(marker,inputs)
+    write_json(logs/'compiler-cache.json',{'project':str(project),'reused':reused,'inputs':inputs})
+    return project