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57 lines
2.4 KiB
57 lines
2.4 KiB
6 years ago
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// Copyright 2019 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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/*
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Package localstore provides disk storage layer for Swarm Chunk persistence.
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It uses swarm/shed abstractions on top of github.com/syndtr/goleveldb LevelDB
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implementation.
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The main type is DB which manages the storage by providing methods to
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access and add Chunks and to manage their status.
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Modes are abstractions that do specific changes to Chunks. There are three
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mode types:
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- ModeGet, for Chunk access
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- ModePut, for adding Chunks to the database
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- ModeSet, for changing Chunk statuses
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Every mode type has a corresponding type (Getter, Putter and Setter)
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that provides adequate method to perform the opperation and that type
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should be injected into localstore consumers instead the whole DB.
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This provides more clear insight which operations consumer is performing
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on the database.
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Getters, Putters and Setters accept different get, put and set modes
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to perform different actions. For example, ModeGet has two different
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variables ModeGetRequest and ModeGetSync and two different Getters
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can be constructed with them that are used when the chunk is requested
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or when the chunk is synced as this two events are differently changing
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the database.
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Subscription methods are implemented for a specific purpose of
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continuous iterations over Chunks that should be provided to
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Push and Pull syncing.
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DB implements an internal garbage collector that removes only synced
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Chunks from the database based on their most recent access time.
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Internally, DB stores Chunk data and any required information, such as
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store and access timestamps in different shed indexes that can be
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iterated on by garbage collector or subscriptions.
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*/
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package localstore
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