Use generics in readContainerStore

... and use it in many more places. Signed-off-by: Miloslav Trmač <[email protected]>
containers · Apr 17, 2023 · 74899ec · 74899ec
1 parent 1cd37e8
commit 74899ec
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Showing 2 changed files with 73 additions and 106 deletions.
diff --git a/check.go b/check.go
@@ -570,10 +570,10 @@ func (s *store) Check(options *CheckOptions) (CheckReport, error) {
 	}
 
 	// Iterate over each container in turn.
-	if done, err := s.readContainerStore(func() (bool, error) {
+	if _, err := readContainerStore(s, func() (void, error) {
 		containers, err := s.containerStore.Containers()
 		if err != nil {
-			return true, err
+			return void{}, err
 		}
 		for i := range containers {
 			container := containers[i]
@@ -622,8 +622,8 @@ func (s *store) Check(options *CheckOptions) (CheckReport, error) {
 				referencedLayers[container.LayerID] = true
 			}
 		}
-		return false, nil
-	}); done {
+		return void{}, nil
+	}); err != nil {
 		return CheckReport{}, err
 	}
 

diff --git a/store.go b/store.go
@@ -1234,9 +1234,10 @@ func writeToImageStore[T any](s *store, fn func() (T, error)) (T, error) {
 // readContainerStore is a convenience helper for working with store.containerStore:
 // It locks the store for reading, checks for updates, and calls fn(), which can then access store.containerStore.
 // It returns the return value of fn, or its own error initializing the store.
-func (s *store) readContainerStore(fn func() (bool, error)) (bool, error) {
+func readContainerStore[T any](s *store, fn func() (T, error)) (T, error) {
 	if err := s.containerStore.startReading(); err != nil {
-		return true, err
+		var zeroRes T // A zero value of T
+		return zeroRes, err
 	}
 	defer s.containerStore.stopReading()
 	return fn()
@@ -1827,19 +1828,12 @@ func (s *store) Metadata(id string) (string, error) {
 		return res, err
 	}
 
-	var res string
-	if done, err := s.readContainerStore(func() (bool, error) {
+	return readContainerStore(s, func() (string, error) {
 		if s.containerStore.Exists(id) {
-			var err error
-			res, err = s.containerStore.Metadata(id)
-			return true, err
+			return s.containerStore.Metadata(id)
 		}
-		return false, nil
-	}); done {
-		return res, err
-	}
-
-	return "", ErrNotAnID
+		return "", ErrNotAnID
+	})
 }
 
 func (s *store) ListImageBigData(id string) ([]string, error) {
@@ -2135,12 +2129,9 @@ func (s *store) ContainerSize(id string) (int64, error) {
 }
 
 func (s *store) ListContainerBigData(id string) ([]string, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return nil, err
-	}
-	defer s.containerStore.stopReading()
-
-	return s.containerStore.BigDataNames(id)
+	return readContainerStore(s, func() ([]string, error) {
+		return s.containerStore.BigDataNames(id)
+	})
 }
 
 func (s *store) ContainerBigDataSize(id, key string) (int64, error) {
@@ -2156,11 +2147,9 @@ func (s *store) ContainerBigDataDigest(id, key string) (digest.Digest, error) {
 }
 
 func (s *store) ContainerBigData(id, key string) ([]byte, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return nil, err
-	}
-	defer s.containerStore.stopReading()
-	return s.containerStore.BigData(id, key)
+	return readContainerStore(s, func() ([]byte, error) {
+		return s.containerStore.BigData(id, key)
+	})
 }
 
 func (s *store) SetContainerBigData(id, key string, data []byte) error {
@@ -2189,11 +2178,10 @@ func (s *store) Exists(id string) bool {
 		return res // false if err != nil
 	}
 
-	if err := s.containerStore.startReading(); err != nil {
-		return false
-	}
-	defer s.containerStore.stopReading()
-	return s.containerStore.Exists(id)
+	res, _ := readContainerStore(s, func() (bool, error) {
+		return s.containerStore.Exists(id), nil
+	})
+	return res // false if err != nil
 }
 
 func dedupeStrings(names []string) []string {
@@ -2326,14 +2314,12 @@ func (s *store) Names(id string) ([]string, error) {
 		return res, err
 	}
 
-	if err := s.containerStore.startReading(); err != nil {
-		return nil, err
-	}
-	defer s.containerStore.stopReading()
-	if c, err := s.containerStore.Get(id); c != nil && err == nil {
-		return c.Names, nil
-	}
-	return nil, ErrLayerUnknown
+	return readContainerStore(s, func() ([]string, error) {
+		if c, err := s.containerStore.Get(id); c != nil && err == nil {
+			return c.Names, nil
+		}
+		return nil, ErrLayerUnknown
+	})
 }
 
 func (s *store) Lookup(name string) (string, error) {
@@ -2355,15 +2341,12 @@ func (s *store) Lookup(name string) (string, error) {
 		return res, err
 	}
 
-	if err := s.containerStore.startReading(); err != nil {
-		return "", err
-	}
-	defer s.containerStore.stopReading()
-	if c, err := s.containerStore.Get(name); c != nil && err == nil {
-		return c.ID, nil
-	}
-
-	return "", ErrLayerUnknown
+	return readContainerStore(s, func() (string, error) {
+		if c, err := s.containerStore.Get(name); c != nil && err == nil {
+			return c.ID, nil
+		}
+		return "", ErrLayerUnknown
+	})
 }
 
 func (s *store) DeleteLayer(id string) error {
@@ -2967,12 +2950,9 @@ func (s *store) Images() ([]Image, error) {
 }
 
 func (s *store) Containers() ([]Container, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return nil, err
-	}
-	defer s.containerStore.stopReading()
-
-	return s.containerStore.Containers()
+	return readContainerStore(s, func() ([]Container, error) {
+		return s.containerStore.Containers()
+	})
 }
 
 func (s *store) Layer(id string) (*Layer, error) {
@@ -3138,36 +3118,29 @@ func (s *store) ImagesByDigest(d digest.Digest) ([]*Image, error) {
 }
 
 func (s *store) Container(id string) (*Container, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return nil, err
-	}
-	defer s.containerStore.stopReading()
-
-	return s.containerStore.Get(id)
+	return readContainerStore(s, func() (*Container, error) {
+		return s.containerStore.Get(id)
+	})
 }
 
 func (s *store) ContainerLayerID(id string) (string, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return "", err
-	}
-	defer s.containerStore.stopReading()
-	container, err := s.containerStore.Get(id)
-	if err != nil {
-		return "", err
-	}
-	return container.LayerID, nil
+	return readContainerStore(s, func() (string, error) {
+		container, err := s.containerStore.Get(id)
+		if err != nil {
+			return "", err
+		}
+		return container.LayerID, nil
+	})
 }
 
 func (s *store) ContainerByLayer(id string) (*Container, error) {
 	layer, err := s.Layer(id)
 	if err != nil {
 		return nil, err
 	}
-	if err := s.containerStore.startReading(); err != nil {
-		return nil, err
-	}
-	defer s.containerStore.stopReading()
-	containerList, err := s.containerStore.Containers()
+	containerList, err := readContainerStore(s, func() ([]Container, error) {
+		return s.containerStore.Containers()
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -3181,41 +3154,35 @@ func (s *store) ContainerByLayer(id string) (*Container, error) {
 }
 
 func (s *store) ContainerDirectory(id string) (string, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return "", err
-	}
-	defer s.containerStore.stopReading()
-
-	id, err := s.containerStore.Lookup(id)
-	if err != nil {
-		return "", err
-	}
+	return readContainerStore(s, func() (string, error) {
+		id, err := s.containerStore.Lookup(id)
+		if err != nil {
+			return "", err
+		}
 
-	middleDir := s.graphDriverName + "-containers"
-	gcpath := filepath.Join(s.GraphRoot(), middleDir, id, "userdata")
-	if err := os.MkdirAll(gcpath, 0700); err != nil {
-		return "", err
-	}
-	return gcpath, nil
+		middleDir := s.graphDriverName + "-containers"
+		gcpath := filepath.Join(s.GraphRoot(), middleDir, id, "userdata")
+		if err := os.MkdirAll(gcpath, 0700); err != nil {
+			return "", err
+		}
+		return gcpath, nil
+	})
 }
 
 func (s *store) ContainerRunDirectory(id string) (string, error) {
-	if err := s.containerStore.startReading(); err != nil {
-		return "", err
-	}
-	defer s.containerStore.stopReading()
-
-	id, err := s.containerStore.Lookup(id)
-	if err != nil {
-		return "", err
-	}
+	return readContainerStore(s, func() (string, error) {
+		id, err := s.containerStore.Lookup(id)
+		if err != nil {
+			return "", err
+		}
 
-	middleDir := s.graphDriverName + "-containers"
-	rcpath := filepath.Join(s.RunRoot(), middleDir, id, "userdata")
-	if err := os.MkdirAll(rcpath, 0700); err != nil {
-		return "", err
-	}
-	return rcpath, nil
+		middleDir := s.graphDriverName + "-containers"
+		rcpath := filepath.Join(s.RunRoot(), middleDir, id, "userdata")
+		if err := os.MkdirAll(rcpath, 0700); err != nil {
+			return "", err
+		}
+		return rcpath, nil
+	})
 }
 
 func (s *store) SetContainerDirectoryFile(id, file string, data []byte) error {