90 lines
3.3 KiB
Go
90 lines
3.3 KiB
Go
// Copyright 2013 Prometheus Team
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package raw
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import (
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"code.google.com/p/goprotobuf/proto"
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"github.com/prometheus/prometheus/storage"
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)
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// Database provides a few very basic methods to manage a database and inquire
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// its state.
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type Database interface {
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// Close reaps all of the underlying system resources associated with
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// this database. For databases that don't need that kind of clean-up,
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// it is implemented as a no-op (so that clients don't need to reason
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// and always call Close 'just in case').
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Close() error
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// State reports the state of the database as a DatabaseState object.
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State() *DatabaseState
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// Size returns the total size of the database in bytes. The number may
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// be an approximation, depending on the underlying database type.
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Size() (uint64, error)
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}
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// ForEacher is implemented by databases that can be iterated through.
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type ForEacher interface {
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// ForEach is responsible for iterating through all records in the
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// database until one of the following conditions are met:
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//
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// 1.) A system anomaly in the database scan.
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// 2.) The last record in the database is reached.
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// 3.) A FilterResult of STOP is emitted by the Filter.
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//
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// Decoding errors for an entity cause that entity to be skipped.
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ForEach(storage.RecordDecoder, storage.RecordFilter, storage.RecordOperator) (scannedEntireCorpus bool, err error)
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}
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// Pruner is implemented by a database that can be pruned in some way.
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type Pruner interface {
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Prune()
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}
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// Persistence models a key-value store for bytes that supports various
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// additional operations.
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type Persistence interface {
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Database
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ForEacher
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// Has informs the user whether a given key exists in the database.
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Has(key proto.Message) (bool, error)
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// Get populates 'value' with the value of 'key', if present, in which
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// case 'present' is returned as true.
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Get(key, value proto.Message) (present bool, err error)
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// Drop removes the key from the database.
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Drop(key proto.Message) error
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// Put sets the key to a given value.
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Put(key, value proto.Message) error
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// PutRaw sets the key to a given raw bytes value.
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PutRaw(key proto.Message, value []byte) error
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// Commit applies the Batch operations to the database.
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Commit(Batch) error
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}
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// Batch models a pool of mutations for the database that can be committed
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// en masse. The interface implies no protocol around the atomicity of
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// effectuation.
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type Batch interface {
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// Close reaps all of the underlying system resources associated with
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// this batch mutation.
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Close()
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// Put follows the same protocol as Persistence.Put.
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Put(key, value proto.Message)
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// PutRaw follows the same protocol as Persistence.PutRaw.
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PutRaw(key proto.Message, value []byte)
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// Drop follows the same protocol as Persistence.Drop.
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Drop(key proto.Message)
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}
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