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util.go
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util.go
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// Copyright 2020-2021 Buf Technologies, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package storage
import (
"context"
"errors"
"io"
"sort"
"go.uber.org/multierr"
)
// errIsNotEmpty is used to break out of the Walk function early in IsEmpty.
//
// If errors.Is(err, errIsNotEmpty), the Walk function found a file.
var errIsNotEmpty = errors.New("__is_not_empty__")
// ReadPath is analogous to os.ReadFile.
//
// Returns an error that fufills IsNotExist if the path does not exist.
func ReadPath(ctx context.Context, readBucket ReadBucket, path string) (_ []byte, retErr error) {
readObject, err := readBucket.Get(ctx, path)
if err != nil {
return nil, err
}
defer func() {
if err := readObject.Close(); err != nil && retErr == nil {
retErr = err
}
}()
return io.ReadAll(readObject)
}
// PutPath puts the data at the path.
func PutPath(ctx context.Context, writeBucket WriteBucket, path string, data []byte) (retErr error) {
writeObject, err := writeBucket.Put(ctx, path)
if err != nil {
return err
}
defer func() {
retErr = multierr.Append(retErr, writeObject.Close())
}()
_, err = writeObject.Write(data)
return err
}
// WalkReadObjects walks the bucket and calls get on each, closing the resulting ReadObjectCloser
// when done.
func WalkReadObjects(
ctx context.Context,
readBucket ReadBucket,
prefix string,
f func(ReadObject) error,
) error {
return readBucket.Walk(
ctx,
prefix,
func(objectInfo ObjectInfo) error {
readObjectCloser, err := readBucket.Get(ctx, objectInfo.Path())
if err != nil {
return err
}
return multierr.Append(f(readObjectCloser), readObjectCloser.Close())
},
)
}
// AllPaths walks the bucket and gets all the paths.
func AllPaths(ctx context.Context, readBucket ReadBucket, prefix string) ([]string, error) {
var allPaths []string
if err := readBucket.Walk(
ctx,
prefix,
func(objectInfo ObjectInfo) error {
allPaths = append(allPaths, objectInfo.Path())
return nil
},
); err != nil {
return nil, err
}
return allPaths, nil
}
// Exists returns true if the path exists, false otherwise.
//
// Returns error on system error.
func Exists(ctx context.Context, readBucket ReadBucket, path string) (bool, error) {
_, err := readBucket.Stat(ctx, path)
if err != nil {
if IsNotExist(err) {
return false, nil
}
return false, err
}
return true, nil
}
// IsEmpty returns true if the bucket is empty under the prefix.
//
// A prefix of "" or "." will check if the entire bucket is empty.
func IsEmpty(ctx context.Context, readBucket ReadBucket, prefix string) (bool, error) {
if err := readBucket.Walk(
ctx,
prefix,
func(ObjectInfo) error {
return errIsNotEmpty
},
); err != nil {
if errors.Is(err, errIsNotEmpty) {
return false, nil
}
return false, err
}
return true, nil
}
// allObjectInfos walks the bucket and gets all the ObjectInfos.
func allObjectInfos(ctx context.Context, readBucket ReadBucket, prefix string) ([]ObjectInfo, error) {
var allObjectInfos []ObjectInfo
if err := readBucket.Walk(
ctx,
prefix,
func(objectInfo ObjectInfo) error {
allObjectInfos = append(allObjectInfos, objectInfo)
return nil
},
); err != nil {
return nil, err
}
return allObjectInfos, nil
}
func pathToObjectInfo(objectInfos []ObjectInfo) map[string]ObjectInfo {
m := make(map[string]ObjectInfo, len(objectInfos))
for _, objectInfo := range objectInfos {
m[objectInfo.Path()] = objectInfo
}
return m
}
func sortObjectInfos(objectInfos []ObjectInfo) {
sort.Slice(
objectInfos,
func(i int, j int) bool {
return objectInfos[i].Path() < objectInfos[j].Path()
},
)
}
type compositeReadObjectCloser struct {
ObjectInfo
io.ReadCloser
}
type compositeReadWriteBucket struct {
ReadBucket
WriteBucket
}