chore: use database in current context for file cache (#18490)

Using the db.Store when in a TX causes a deadlock for dbmem.
In production, this can cause a deadlock if at the current conn pool
limit.

coderd/files/cache.go

@@ -20,38 +20,15 @@ import (
 )
 
 type FileAcquirer interface {
-	Acquire(ctx context.Context, fileID uuid.UUID) (*CloseFS, error)
+	Acquire(ctx context.Context, db database.Store, 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 {
-	fetch := func(ctx context.Context, fileID uuid.UUID) (CacheEntryValue, error) {
-		// Make sure the read does not fail due to authorization issues.
-		// Authz is checked on the Acquire call, so this is safe.
-		//nolint:gocritic
-		file, err := store.GetFileByID(dbauthz.AsFileReader(ctx), fileID)
-		if err != nil {
-			return CacheEntryValue{}, xerrors.Errorf("failed to read file from database: %w", err)
-		}
-
-		content := bytes.NewBuffer(file.Data)
-		return CacheEntryValue{
-			Object: file.RBACObject(),
-			FS:     archivefs.FromTarReader(content),
-			Size:   int64(len(file.Data)),
-		}, nil
-	}
-
-	return New(fetch, registerer, authz)
-}
-
-func New(fetch fetcher, registerer prometheus.Registerer, authz rbac.Authorizer) *Cache {
+// New returns a file cache that will fetch files from a database
+func New(registerer prometheus.Registerer, authz rbac.Authorizer) *Cache {
 	return (&Cache{
-		lock:    sync.Mutex{},
-		data:    make(map[uuid.UUID]*cacheEntry),
-		fetcher: fetch,
-		authz:   authz,
+		lock:  sync.Mutex{},
+		data:  make(map[uuid.UUID]*cacheEntry),
+		authz: authz,
 	}).registerMetrics(registerer)
 }
 
@@ -110,9 +87,8 @@ func (c *Cache) registerMetrics(registerer prometheus.Registerer) *Cache {
 // loaded into memory exactly once. We hold those files until there are no
 // longer any open connections, and then we remove the value from the map.
 type Cache struct {
-	lock sync.Mutex
-	data map[uuid.UUID]*cacheEntry
-	fetcher
+	lock  sync.Mutex
+	data  map[uuid.UUID]*cacheEntry
 	authz rbac.Authorizer
 
 	// metrics
@@ -142,8 +118,6 @@ type cacheEntry struct {
 	value    *lazy.ValueWithError[CacheEntryValue]
 }
 
-type fetcher func(context.Context, uuid.UUID) (CacheEntryValue, error)
-
 var _ fs.FS = (*CloseFS)(nil)
 
 // CloseFS is a wrapper around fs.FS that implements io.Closer. The Close()
@@ -163,12 +137,12 @@ func (f *CloseFS) Close() { f.close() }
 //
 // Safety: Every call to Acquire that does not return an error must have a
 // matching call to Release.
-func (c *Cache) Acquire(ctx context.Context, fileID uuid.UUID) (*CloseFS, error) {
+func (c *Cache) Acquire(ctx context.Context, db database.Store, fileID uuid.UUID) (*CloseFS, error) {
 	// It's important that this `Load` call occurs outside `prepare`, after the
 	// mutex has been released, or we would continue to hold the lock until the
 	// entire file has been fetched, which may be slow, and would prevent other
 	// files from being fetched in parallel.
-	it, err := c.prepare(ctx, fileID).Load()
+	it, err := c.prepare(ctx, db, fileID).Load()
 	if err != nil {
 		c.release(fileID)
 		return nil, err
@@ -195,14 +169,14 @@ func (c *Cache) Acquire(ctx context.Context, fileID uuid.UUID) (*CloseFS, error)
 	}, nil
 }
 
-func (c *Cache) prepare(ctx context.Context, fileID uuid.UUID) *lazy.ValueWithError[CacheEntryValue] {
+func (c *Cache) prepare(ctx context.Context, db database.Store, fileID uuid.UUID) *lazy.ValueWithError[CacheEntryValue] {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
 	entry, ok := c.data[fileID]
 	if !ok {
 		value := lazy.NewWithError(func() (CacheEntryValue, error) {
-			val, err := c.fetcher(ctx, fileID)
+			val, err := fetch(ctx, db, fileID)
 
 			// Always add to the cache size the bytes of the file loaded.
 			if err == nil {
@@ -269,3 +243,20 @@ func (c *Cache) Count() int {
 
 	return len(c.data)
 }
+
+func fetch(ctx context.Context, store database.Store, fileID uuid.UUID) (CacheEntryValue, error) {
+	// Make sure the read does not fail due to authorization issues.
+	// Authz is checked on the Acquire call, so this is safe.
+	//nolint:gocritic
+	file, err := store.GetFileByID(dbauthz.AsFileReader(ctx), fileID)
+	if err != nil {
+		return CacheEntryValue{}, xerrors.Errorf("failed to read file from database: %w", err)
+	}
+
+	content := bytes.NewBuffer(file.Data)
+	return CacheEntryValue{
+		Object: file.RBACObject(),
+		FS:     archivefs.FromTarReader(content),
+		Size:   int64(len(file.Data)),
+	}, nil
+}