prometheus/storage/raw/interface.go
Matt T. Proud a73f061d3c Persist solely Protocol Buffers.
An design question was open for me in the beginning was whether to
serialize other types to disk, but Protocol Buffers quickly won out,
which allows us to drop support for other types.  This is a good
start to cleaning up a lot of cruft in the storage stack and
can let us eventually decouple the various moving parts into
separate subsystems for easier reasoning.

This commit is not strictly required, but it is a start to making
the rest a lot more enjoyable to interact with.
2013-06-08 11:02:35 +02:00

62 lines
2.3 KiB
Go

// Copyright 2013 Prometheus Team
// 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 raw
import (
"code.google.com/p/goprotobuf/proto"
"github.com/prometheus/prometheus/storage"
)
// Persistence models a key-value store for bytes that supports various
// additional operations.
type Persistence interface {
// Close reaps all of the underlying system resources associated with this
// persistence.
Close()
// Has informs the user whether a given key exists in the database.
Has(key proto.Message) (bool, error)
// Get retrieves the key from the database if it exists or returns nil if
// it is absent.
Get(key, value proto.Message) (present bool, err error)
// Drop removes the key from the database.
Drop(key proto.Message) error
// Put sets the key to a given value.
Put(key, value proto.Message) error
// ForEach is responsible for iterating through all records in the database
// until one of the following conditions are met:
//
// 1.) A system anomaly in the database scan.
// 2.) The last record in the database is reached.
// 3.) A FilterResult of STOP is emitted by the Filter.
//
// Decoding errors for an entity cause that entity to be skipped.
ForEach(storage.RecordDecoder, storage.RecordFilter, storage.RecordOperator) (scannedEntireCorpus bool, err error)
// Commit applies the Batch operations to the database.
Commit(Batch) error
}
// Batch models a pool of mutations for the database that can be committed
// en masse. The interface implies no protocol around the atomicity of
// effectuation.
type Batch interface {
// Close reaps all of the underlying system resources associated with this
// batch mutation.
Close()
// Put follows the same protocol as Persistence.Put.
Put(key, value proto.Message)
// Drop follows the same protocol as Persistence.Drop.
Drop(key proto.Message)
}