stage 1

internal/cache/writer.go

@@ -0,0 +1,57 @@
+package cache
+
+import (
+	"context"
+	"errors"
+	"io"
+	"time"
+
+	"github.com/any-hub/any-hub/internal/hubmodule"
+)
+
+// ErrStoreUnavailable 表示当前模块未注入缓存存储实例。
+var ErrStoreUnavailable = errors.New("cache store unavailable")
+
+// StrategyWriter 注入模块的缓存策略，提供 TTL 决策与写入封装。
+type StrategyWriter struct {
+	store    Store
+	strategy hubmodule.CacheStrategyProfile
+	now      func() time.Time
+}
+
+// NewStrategyWriter 构造策略感知的写入器，默认使用 time.Now 作为时钟。
+func NewStrategyWriter(store Store, strategy hubmodule.CacheStrategyProfile) StrategyWriter {
+	return StrategyWriter{
+		store:    store,
+		strategy: strategy,
+		now:      time.Now,
+	}
+}
+
+// Enabled 返回当前是否具备缓存写入能力。
+func (w StrategyWriter) Enabled() bool {
+	return w.store != nil
+}
+
+// Put 写入缓存正文，并保持与 Store 相同的语义。
+func (w StrategyWriter) Put(ctx context.Context, locator Locator, body io.Reader, opts PutOptions) (*Entry, error) {
+	if w.store == nil {
+		return nil, ErrStoreUnavailable
+	}
+	return w.store.Put(ctx, locator, body, opts)
+}
+
+// ShouldBypassValidation 根据策略 TTL 判断是否可以直接复用缓存，避免重复 HEAD。
+func (w StrategyWriter) ShouldBypassValidation(entry Entry) bool {
+	ttl := w.strategy.TTLHint
+	if ttl <= 0 {
+		return false
+	}
+	expireAt := entry.ModTime.Add(ttl)
+	return w.now().Before(expireAt)
+}
+
+// SupportsValidation 返回当前策略是否允许通过 HEAD/Etag 等方式再验证。
+func (w StrategyWriter) SupportsValidation() bool {
+	return w.strategy.ValidationMode != hubmodule.ValidationModeNever
+}