Add asset extraction invalidation by version keys

Introduces invalidateKey support to asset extraction utilities, allowing unpacked assets to be invalidated based on Python or app version. Updates Android plugin and Dart code to provide app and Python version info for more robust cache invalidation when extracting Python bundles and site-packages.

Author: FeodorFitsner

src/serious_python_android/android/src/main/java/com/flet/serious_python_android/AndroidPlugin.java

@@ -60,6 +60,22 @@ public void onAttachedToActivity(@NonNull ActivityPluginBinding activityPluginBi
   public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
     if (call.method.equals("getPlatformVersion")) {
       result.success("Android " + android.os.Build.VERSION.RELEASE);
+    } else if (call.method.equals("getAppVersion")) {
+      try {
+        String packageName = context.getPackageName();
+        android.content.pm.PackageManager pm = context.getPackageManager();
+        android.content.pm.PackageInfo info = pm.getPackageInfo(packageName, 0);
+        String versionName = info.versionName;
+        long versionCode;
+        if (android.os.Build.VERSION.SDK_INT >= 28) {
+          versionCode = info.getLongVersionCode();
+        } else {
+          versionCode = info.versionCode;
+        }
+        result.success(versionName + "+" + versionCode);
+      } catch (Exception e) {
+        result.error("Error", e.getMessage(), null);
+      }
     } else if (call.method.equals("getNativeLibraryDir")) {
       ContextWrapper contextWrapper = new ContextWrapper(context);
       String nativeLibraryDir = contextWrapper.getApplicationInfo().nativeLibraryDir;

src/serious_python_android/lib/serious_python_android.dart

@@ -4,6 +4,7 @@ import 'dart:io';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
+import 'package:ffi/ffi.dart';
 import 'package:path/path.dart' as p;
 import 'package:serious_python_platform_interface/serious_python_platform_interface.dart';
 
@@ -47,6 +48,28 @@ class SeriousPythonAndroid extends SeriousPythonPlatform {
       spDebug("Unable to load libpyjni.so library: $e");
     }
 
+    const pythonSharedLib = "libpython3.12.so";
+
+    String? getPythonFullVersion() {
+      try {
+        final cpython = getCPython(pythonSharedLib);
+        final versionPtr = cpython.Py_GetVersion();
+        return versionPtr.cast<Utf8>().toDartString();
+      } catch (e) {
+        spDebug("Unable to read Python version for invalidation: $e");
+        return null;
+      }
+    }
+
+    Future<String?> getAppVersion() async {
+      try {
+        return await methodChannel.invokeMethod<String>('getAppVersion');
+      } catch (e) {
+        spDebug("Unable to get app version for invalidation: $e");
+        return null;
+      }
+    }
+
     // unpack python bundle
     final nativeLibraryDir =
         await methodChannel.invokeMethod<String>('getNativeLibraryDir');
@@ -58,8 +81,11 @@ class SeriousPythonAndroid extends SeriousPythonPlatform {
     if (!await File(bundlePath).exists()) {
       throw Exception("Python bundle not found: $bundlePath");
     }
-    var pythonLibPath =
-        await extractFileZip(bundlePath, targetPath: "python_bundle");
+    final pythonVersion = getPythonFullVersion();
+    final pythonInvalidateKey =
+        pythonVersion != null ? "python:$pythonVersion" : "python:$pythonSharedLib";
+    var pythonLibPath = await extractFileZip(bundlePath,
+        targetPath: "python_bundle", invalidateKey: pythonInvalidateKey);
     spDebug("pythonLibPath: $pythonLibPath");
 
     var programDirPath = p.dirname(appPath);
@@ -72,8 +98,12 @@ class SeriousPythonAndroid extends SeriousPythonPlatform {
     ];
 
     if (await File(sitePackagesZipPath).exists()) {
+      final appVersion = await getAppVersion();
+      final sitePackagesInvalidateKey =
+          appVersion != null ? "app:$appVersion" : null;
       var sitePackagesPath = await extractFileZip(sitePackagesZipPath,
-          targetPath: "python_site_packages");
+          targetPath: "python_site_packages",
+          invalidateKey: sitePackagesInvalidateKey);
       spDebug("sitePackagesPath: $sitePackagesPath");
       moduleSearchPaths.add(sitePackagesPath);
     }
@@ -94,6 +124,6 @@ class SeriousPythonAndroid extends SeriousPythonPlatform {
     }
 
     return runPythonProgramFFI(
-        sync ?? false, "libpython3.12.so", appPath, script ?? "");
+        sync ?? false, pythonSharedLib, appPath, script ?? "");
   }
 }

src/serious_python_platform_interface/lib/src/utils.dart

@@ -8,12 +8,18 @@ import 'package:path/path.dart' as p;
 import 'package:path_provider/path_provider.dart';
 
 Future<String> extractAssetOrFile(String path,
-    {bool isAsset = true, String? targetPath, bool checkHash = false}) async {
+    {bool isAsset = true,
+    String? targetPath,
+    bool checkHash = false,
+    String? invalidateKey}) async {
   WidgetsFlutterBinding.ensureInitialized();
   final supportDir = await getApplicationSupportDirectory();
   final destDir =
       Directory(p.join(supportDir.path, "flet", targetPath ?? p.dirname(path)));
 
+  var invalidateFile = File(p.join(destDir.path, ".invalidate"));
+  String existingInvalidateKey = "";
+
   String assetHash = "";
   // read asset hash from asset
   try {
@@ -30,18 +36,36 @@ Future<String> extractAssetOrFile(String path,
       // always re-create in debug mode
       await destDir.delete(recursive: true);
     } else {
-      if (checkHash) {
-        if (await hashFile.exists()) {
-          destHash = (await hashFile.readAsString()).trim();
+      var shouldDelete = false;
+
+      if (invalidateKey != null) {
+        if (await invalidateFile.exists()) {
+          existingInvalidateKey =
+              (await invalidateFile.readAsString()).trim();
+        }
+        if (existingInvalidateKey != invalidateKey) {
+          shouldDelete = true;
+        }
+      }
+
+      if (!shouldDelete) {
+        if (checkHash) {
+          if (await hashFile.exists()) {
+            destHash = (await hashFile.readAsString()).trim();
+          }
+        }
+
+        if (assetHash != destHash ||
+            (checkHash && assetHash == "" && destHash == "")) {
+          shouldDelete = true;
+        } else {
+          debugPrint("Application archive already unpacked to ${destDir.path}");
+          return destDir.path;
         }
       }
 
-      if (assetHash != destHash ||
-          (checkHash && assetHash == "" && destHash == "")) {
+      if (shouldDelete) {
         await destDir.delete(recursive: true);
-      } else {
-        debugPrint("Application archive already unpacked to ${destDir.path}");
-        return destDir.path;
       }
     }
   }
@@ -77,19 +101,34 @@ Future<String> extractAssetOrFile(String path,
     await hashFile.writeAsString(assetHash);
   }
 
+  if (invalidateKey != null) {
+    debugPrint(
+        "Writing invalidate file: ${invalidateFile.path}, key: $invalidateKey");
+    await invalidateFile.writeAsString(invalidateKey);
+  }
+
   return destDir.path;
 }
 
 Future<String> extractAssetZip(String assetPath,
-    {String? targetPath, bool checkHash = false}) async {
+    {String? targetPath,
+    bool checkHash = false,
+    String? invalidateKey}) async {
   return extractAssetOrFile(assetPath,
-      targetPath: targetPath, checkHash: checkHash);
+      targetPath: targetPath,
+      checkHash: checkHash,
+      invalidateKey: invalidateKey);
 }
 
 Future<String> extractFileZip(String filePath,
-    {String? targetPath, bool checkHash = false}) async {
+    {String? targetPath,
+    bool checkHash = false,
+    String? invalidateKey}) async {
   return extractAssetOrFile(filePath,
-      isAsset: false, targetPath: targetPath, checkHash: checkHash);
+      isAsset: false,
+      targetPath: targetPath,
+      checkHash: checkHash,
+      invalidateKey: invalidateKey);
 }
 
 Future<String> extractAsset(String assetPath) async {