feat: add unified cache policy primitives

2026-03-20 15:21:52 +08:00
parent cbbed29a75
commit 035ca46bd0
4 changed files with 91 additions and 0 deletions
@@ -0,0 +1,49 @@
+class CacheDecision {
+  final bool canUseCached;
+  final bool shouldRefreshInBackground;
+  final bool mustBlockForNetwork;
+
+  const CacheDecision({
+    required this.canUseCached,
+    required this.shouldRefreshInBackground,
+    required this.mustBlockForNetwork,
+  });
+}
+
+class CachePolicy {
+  final Duration softTtl;
+  final Duration hardTtl;
+  final Duration minRefreshInterval;
+
+  const CachePolicy({
+    required this.softTtl,
+    required this.hardTtl,
+    this.minRefreshInterval = Duration.zero,
+  });
+
+  CacheDecision evaluate({required DateTime now, required DateTime fetchedAt}) {
+    final age = now.difference(fetchedAt);
+    if (age >= hardTtl) {
+      return const CacheDecision(
+        canUseCached: false,
+        shouldRefreshInBackground: false,
+        mustBlockForNetwork: true,
+      );
+    }
+
+    if (age >= softTtl) {
+      final shouldRefresh = age >= minRefreshInterval;
+      return CacheDecision(
+        canUseCached: true,
+        shouldRefreshInBackground: shouldRefresh,
+        mustBlockForNetwork: false,
+      );
+    }
+
+    return const CacheDecision(
+      canUseCached: true,
+      shouldRefreshInBackground: false,
+      mustBlockForNetwork: false,
+    );
+  }
+}