prometheus/storage/local/index/interface.go

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// Copyright 2014 The Prometheus Authors
// 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 index
import "encoding"
// KeyValueStore persists key/value pairs. Implementations must be fundamentally
// goroutine-safe. However, it is the caller's responsibility that keys and
// values can be safely marshaled and unmarshaled (via the MarshalBinary and
// UnmarshalBinary methods of the keys and values). For example, if you call the
// Put method of a KeyValueStore implementation, but the key or the value are
// modified concurrently while being marshaled into its binary representation,
// you obviously have a problem. Methods of KeyValueStore return only after
// (un)marshaling is complete.
type KeyValueStore interface {
Put(key, value encoding.BinaryMarshaler) error
// Get unmarshals the result into value. It returns false if no entry
// could be found for key. If value is nil, Get behaves like Has.
Get(key encoding.BinaryMarshaler, value encoding.BinaryUnmarshaler) (bool, error)
Has(key encoding.BinaryMarshaler) (bool, error)
// Delete returns an error if key does not exist.
Delete(key encoding.BinaryMarshaler) error
NewBatch() Batch
Commit(b Batch) error
// ForEach iterates through the complete KeyValueStore and calls the
// supplied function for each mapping.
ForEach(func(kv KeyValueAccessor) error) error
Close() error
}
// KeyValueAccessor allows access to the key and value of an entry in a
// KeyValueStore.
type KeyValueAccessor interface {
Key(encoding.BinaryUnmarshaler) error
Value(encoding.BinaryUnmarshaler) error
}
// Batch allows KeyValueStore mutations to be pooled and committed together. An
// implementation does not have to be goroutine-safe. Never modify a Batch
// concurrently or commit the same batch multiple times concurrently. Marshaling
// of keys and values is guaranteed to be complete when the Put or Delete methods
// have returned.
type Batch interface {
Put(key, value encoding.BinaryMarshaler) error
Delete(key encoding.BinaryMarshaler) error
Reset()
}