chore: add cacheCloser to cleanup all opened files (#18473)

coderd/files/cache.go

@@ -19,6 +19,10 @@ import (
 	"github.com/coder/coder/v2/coderd/util/lazy"
 )
 
+type FileAcquirer interface {
+	Acquire(ctx context.Context, fileID uuid.UUID) (*CloseFS, error)
+}
+
 // NewFromStore returns a file cache that will fetch files from the provided
 // database.
 func NewFromStore(store database.Store, registerer prometheus.Registerer, authz rbac.Authorizer) *Cache {

coderd/files/closer.go

@@ -0,0 +1,57 @@
+package files
+
+import (
+	"context"
+	"sync"
+
+	"github.com/google/uuid"
+	"golang.org/x/xerrors"
+)
+
+// CacheCloser is a cache wrapper used to close all acquired files.
+// This is a more simple interface to use if opening multiple files at once.
+type CacheCloser struct {
+	cache FileAcquirer
+
+	closers []func()
+	mu      sync.Mutex
+}
+
+func NewCacheCloser(cache FileAcquirer) *CacheCloser {
+	return &CacheCloser{
+		cache:   cache,
+		closers: make([]func(), 0),
+	}
+}
+
+func (c *CacheCloser) Close() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	for _, doClose := range c.closers {
+		doClose()
+	}
+
+	// Prevent further acquisitions
+	c.cache = nil
+	// Remove any references
+	c.closers = nil
+}
+
+func (c *CacheCloser) Acquire(ctx context.Context, fileID uuid.UUID) (*CloseFS, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.cache == nil {
+		return nil, xerrors.New("cache is closed, and cannot acquire new files")
+	}
+
+	f, err := c.cache.Acquire(ctx, fileID)
+	if err != nil {
+		return nil, err
+	}
+
+	c.closers = append(c.closers, f.close)
+
+	return f, nil
+}