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// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package ethdb defines the interfaces for an Ethereum data store.
package ethdb

import "io"

// KeyValueReader wraps the Has and Get method of a backing data store.
type KeyValueReader interface {
    // Has retrieves if a key is present in the key-value data store.
    Has(key []byte) (bool, error)

    // Get retrieves the given key if it's present in the key-value data store.
    Get(key []byte) ([]byte, error)
}

// KeyValueWriter wraps the Put method of a backing data store.
type KeyValueWriter interface {
    // Put inserts the given value into the key-value data store.
    Put(key []byte, value []byte) error

    // Delete removes the key from the key-value data store.
    Delete(key []byte) error
}

// Stater wraps the Stat method of a backing data store.
type Stater interface {
    // Stat returns a particular internal stat of the database.
    Stat(property string) (string, error)
}

// Compacter wraps the Compact method of a backing data store.
type Compacter interface {
    // Compact flattens the underlying data store for the given key range. In essence,
    // deleted and overwritten versions are discarded, and the data is rearranged to
    // reduce the cost of operations needed to access them.
    //
    // A nil start is treated as a key before all keys in the data store; a nil limit
    // is treated as a key after all keys in the data store. If both is nil then it
    // will compact entire data store.
    Compact(start []byte, limit []byte) error
}

// KeyValueStore contains all the methods required to allow handling different
// key-value data stores backing the high level database.
type KeyValueStore interface {
    KeyValueReader
    KeyValueWriter
    Batcher
    Iteratee
    Stater
    Compacter
    io.Closer
}

// AncientReader contains the methods required to read from immutable ancient data.
type AncientReader interface {
    // HasAncient returns an indicator whether the specified data exists in the
    // ancient store.
    HasAncient(kind string, number uint64) (bool, error)

    // Ancient retrieves an ancient binary blob from the append-only immutable files.
    Ancient(kind string, number uint64) ([]byte, error)

    // Ancients returns the ancient store length
    Ancients() (uint64, error)
}

// AncientWriter contains the methods required to write to immutable ancient data.
type AncientWriter interface {
    // AppendAncient injects all binary blobs belong to block at the end of the
    // append-only immutable table files.
    AppendAncient(number uint64, hash, header, body, receipt, td []byte) error

    // TruncateAncients discards all but the first n ancient data from the ancient store.
    TruncateAncients(n uint64) error

    // Sync flushes all in-memory ancient store data to disk.
    Sync() error
}

// Reader contains the methods required to read data from both key-value as well as
// immutable ancient data.
type Reader interface {
    KeyValueReader
    AncientReader
}

// Writer contains the methods required to write data to both key-value as well as
// immutable ancient data.
type Writer interface {
    KeyValueWriter
    AncientWriter
}

// AncientStore contains all the methods required to allow handling different
// ancient data stores backing immutable chain data store.
type AncientStore interface {
    AncientReader
    AncientWriter
    io.Closer
}

// Database contains all the methods required by the high level database to not
// only access the key-value data store but also the chain freezer.
type Database interface {
    Reader
    Writer
    Batcher
    Iteratee
    Stater
    Compacter
    io.Closer
}