图片缓存不过期

internal/diskcache/cache.go

@@ -30,6 +30,11 @@ const (
 	defaultMaxSizeMB       = 100
 	defaultTTLMinutes      = 60
 	defaultCleanupInterval = 10
+
+	// DefaultExpiration applies the cache-wide default TTL.
+	DefaultExpiration time.Duration = 0
+	// NoExpiration stores the item without a TTL. Size limits and LRU eviction still apply.
+	NoExpiration time.Duration = -1
 )
 
 var (
@@ -103,13 +108,14 @@ func New(basePath string) *DiskCache {
 	return c
 }
 
-// Set stores a key-value pair in the cache with a specific TTL.
-// If ttl <= 0, the default cache TTL is used.
+// Set stores a key-value pair in the cache.
+// Use DefaultExpiration for the configured default TTL, NoExpiration for no
+// TTL, or a positive duration for a business-specific TTL.
 func (c *DiskCache) Set(key string, value []byte, ttl time.Duration) error {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	if ttl <= 0 {
+	if ttl == DefaultExpiration {
 		ttl = c.defaultTTL
 	}
 

internal/diskcache/cache_test.go

@@ -95,6 +95,69 @@ func TestDiskCacheTTL(t *testing.T) {
 	}
 }
 
+func TestDiskCacheExpirationPolicies(t *testing.T) {
+	testDir := "uploads/test_diskcache_expiration_policies"
+	defer func() { _ = os.RemoveAll(testDir) }()
+	_ = os.RemoveAll(testDir)
+
+	c := New(testDir)
+	defer func() { _ = c.Clear() }()
+	c.defaultTTL = 50 * time.Millisecond
+
+	if err := c.Set("default", []byte("default"), DefaultExpiration); err != nil {
+		t.Fatalf("Set(default, DefaultExpiration) returned error: %v", err)
+	}
+	if err := c.Set("custom", []byte("custom"), 100*time.Millisecond); err != nil {
+		t.Fatalf("Set(custom, 100ms) returned error: %v", err)
+	}
+	if err := c.Set("permanent", []byte("permanent"), NoExpiration); err != nil {
+		t.Fatalf("Set(permanent, NoExpiration) returned error: %v", err)
+	}
+
+	time.Sleep(75 * time.Millisecond)
+
+	if _, err := c.Get("default"); err != ErrCacheMiss {
+		t.Errorf("Get(default) error = %v, want ErrCacheMiss", err)
+	}
+	if _, err := c.Get("custom"); err != nil {
+		t.Errorf("Get(custom) returned error before custom TTL elapsed: %v", err)
+	}
+	if _, err := c.Get("permanent"); err != nil {
+		t.Errorf("Get(permanent) returned error: %v", err)
+	}
+
+	time.Sleep(50 * time.Millisecond)
+
+	if _, err := c.Get("custom"); err != ErrCacheMiss {
+		t.Errorf("Get(custom) error = %v, want ErrCacheMiss", err)
+	}
+	if _, err := c.Get("permanent"); err != nil {
+		t.Errorf("Get(permanent) returned error after other entries expired: %v", err)
+	}
+}
+
+func TestDiskCacheNoExpirationSurvivesReload(t *testing.T) {
+	testDir := "uploads/test_diskcache_no_expiration_reload"
+	defer func() { _ = os.RemoveAll(testDir) }()
+	_ = os.RemoveAll(testDir)
+
+	c := New(testDir)
+	if err := c.Set("permanent", []byte("value"), NoExpiration); err != nil {
+		t.Fatalf("Set(permanent, NoExpiration) returned error: %v", err)
+	}
+
+	reloaded := New(testDir)
+	defer func() { _ = reloaded.Clear() }()
+
+	got, err := reloaded.Get("permanent")
+	if err != nil {
+		t.Fatalf("reloaded Get(permanent) returned error: %v", err)
+	}
+	if !bytes.Equal(got, []byte("value")) {
+		t.Errorf("reloaded Get(permanent) = %q, want %q", got, "value")
+	}
+}
+
 func TestDiskCacheLRUEviction(t *testing.T) {
 	testDir := "uploads/test_diskcache_lru"
 	defer func() { _ = os.RemoveAll(testDir) }()
@@ -109,13 +172,13 @@ func TestDiskCacheLRUEviction(t *testing.T) {
 	c.lruEnabled = true
 
 	// Write item 1: 8 + 2 = 10 bytes
-	err := c.Set("k1", []byte("v1"), 0)
+	err := c.Set("k1", []byte("v1"), DefaultExpiration)
 	if err != nil {
 		t.Fatalf("failed to set k1: %v", err)
 	}
 
 	// Write item 2: 8 + 2 = 10 bytes
-	err = c.Set("k2", []byte("v2"), 0)
+	err = c.Set("k2", []byte("v2"), DefaultExpiration)
 	if err != nil {
 		t.Fatalf("failed to set k2: %v", err)
 	}
@@ -133,7 +196,7 @@ func TestDiskCacheLRUEviction(t *testing.T) {
 	// wait, let's access k1 again to make it the most recently used, so k2 becomes oldest!
 	_, _ = c.Get("k1") // k1 is now MRU, k2 is LRU
 
-	err = c.Set("k3", []byte("v3"), 0)
+	err = c.Set("k3", []byte("v3"), DefaultExpiration)
 	if err != nil {
 		t.Fatalf("failed to set k3: %v", err)
 	}