forked from cerc-io/ipfs-ethdb
116 lines
3.8 KiB
Go
116 lines
3.8 KiB
Go
// VulcanizeDB
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// Copyright © 2020 Vulcanize
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero 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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// This program 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 Affero General Public License for more details.
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package pgipfsethdb
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import (
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/jmoiron/sqlx"
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)
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const (
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initPgStr = `SELECT eth_key, data FROM public.blocks
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INNER JOIN eth.key_preimages ON (ipfs_key = key)
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WHERE eth_key = $1`
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nextPgStr = `SELECT eth_key, data FROM public.blocks
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INNER JOIN eth.key_preimages ON (ipfs_key = key)
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WHERE eth_key > $1
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ORDER BY eth_key LIMIT 1`
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nextPgStrWithPrefix = `SELECT eth_key, data FROM public.blocks
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INNER JOIN eth.key_preimages ON (ipfs_key = key)
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WHERE eth_key > $1 AND prefix = $2
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ORDER BY eth_key LIMIT 1`
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)
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type nextModel struct {
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Key []byte `db:"eth_key"`
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Value []byte `db:"data"`
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}
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// Iterator is the type that satisfies the ethdb.Iterator interface for PG-IPFS Ethereum data using a direct Postgres connection
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type Iterator struct {
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db *sqlx.DB
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currentKey, prefix, currentValue []byte
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err error
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init bool
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}
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// NewIterator returns an ethdb.Iterator interface for PG-IPFS
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func NewIterator(start, prefix []byte, db *sqlx.DB) ethdb.Iterator {
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return &Iterator{
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db: db,
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prefix: prefix,
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currentKey: start,
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init: start != nil,
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}
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}
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// Next satisfies the ethdb.Iterator interface
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// Next moves the iterator to the next key/value pair
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// It returns whether the iterator is exhausted
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func (i *Iterator) Next() bool {
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next := new(nextModel)
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if i.init {
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i.init = false
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if err := i.db.Get(next, initPgStr, i.currentKey); err != nil {
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i.currentKey, i.currentValue, i.err = nil, nil, err
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return false
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}
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} else if i.prefix != nil {
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if err := i.db.Get(next, nextPgStrWithPrefix, i.currentKey, i.prefix); err != nil {
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i.currentKey, i.currentValue, i.err = nil, nil, err
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return false
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}
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} else {
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if err := i.db.Get(next, nextPgStr, i.currentKey); err != nil {
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i.currentKey, i.currentValue, i.err = nil, nil, err
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return false
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}
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}
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i.currentKey, i.currentValue, i.err = next.Key, next.Value, nil
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return true
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}
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// Error satisfies the ethdb.Iterator interface
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// Error returns any accumulated error
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// Exhausting all the key/value pairs is not considered to be an error
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func (i *Iterator) Error() error {
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return i.err
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}
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// Key satisfies the ethdb.Iterator interface
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// Key returns the key of the current key/value pair, or nil if done
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// The caller should not modify the contents of the returned slice
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// and its contents may change on the next call to Next
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func (i *Iterator) Key() []byte {
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return i.currentKey
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}
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// Value satisfies the ethdb.Iterator interface
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// Value returns the value of the current key/value pair, or nil if done
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// The caller should not modify the contents of the returned slice
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// and its contents may change on the next call to Next
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func (i *Iterator) Value() []byte {
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return i.currentValue
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}
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// Release satisfies the ethdb.Iterator interface
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// Release releases associated resources
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// Release should always succeed and can be called multiple times without causing error
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func (i *Iterator) Release() {
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i.db, i.currentKey, i.currentValue, i.err, i.prefix = nil, nil, nil, nil, nil
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}
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