forked from cerc-io/plugeth
b8040a430e
This removes auto-configuration of the snap.*.ethdisco.net DNS discovery tree. Since measurements have shown that > 75% of nodes in all.*.ethdisco.net support snap, we have decided to retire the dedicated index for snap and just use the eth tree instead. The dial iterators of eth and snap now use the same DNS tree in the default configuration, so both iterators should use the same DNS discovery client instance. This ensures that the record cache and rate limit are shared. Records will not be requested multiple times. While testing the change, I noticed that duplicate DNS requests do happen even when the client instance is shared. This is because the two iterators request the tree root, link tree root, and first levels of the tree in lockstep. To avoid this problem, the change also adds a singleflight.Group instance in the client. When one iterator attempts to resolve an entry which is already being resolved, the singleflight object waits for the existing resolve call to finish and returns the entry to both places.
64 lines
2.0 KiB
Go
64 lines
2.0 KiB
Go
// 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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package eth
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import (
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"github.com/ethereum/go-ethereum/core"
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"github.com/ethereum/go-ethereum/core/forkid"
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"github.com/ethereum/go-ethereum/p2p/enode"
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"github.com/ethereum/go-ethereum/rlp"
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)
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// ethEntry is the "eth" ENR entry which advertises eth protocol
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// on the discovery network.
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type ethEntry struct {
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ForkID forkid.ID // Fork identifier per EIP-2124
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// Ignore additional fields (for forward compatibility).
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Rest []rlp.RawValue `rlp:"tail"`
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}
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// ENRKey implements enr.Entry.
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func (e ethEntry) ENRKey() string {
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return "eth"
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}
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// startEthEntryUpdate starts the ENR updater loop.
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func (eth *Ethereum) startEthEntryUpdate(ln *enode.LocalNode) {
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var newHead = make(chan core.ChainHeadEvent, 10)
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sub := eth.blockchain.SubscribeChainHeadEvent(newHead)
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go func() {
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defer sub.Unsubscribe()
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for {
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select {
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case <-newHead:
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ln.Set(eth.currentEthEntry())
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case <-sub.Err():
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// Would be nice to sync with eth.Stop, but there is no
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// good way to do that.
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return
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}
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}
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}()
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}
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func (eth *Ethereum) currentEthEntry() *ethEntry {
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return ðEntry{ForkID: forkid.NewID(eth.blockchain.Config(), eth.blockchain.Genesis().Hash(),
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eth.blockchain.CurrentHeader().Number.Uint64())}
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}
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