124 lines
3.5 KiB
Go
124 lines
3.5 KiB
Go
// Copyright 2017 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 downloader
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import (
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"sync"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/log"
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)
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// syncState starts downloading state with the given root hash.
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func (d *Downloader) syncState(root common.Hash) *stateSync {
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// Create the state sync
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s := newStateSync(d, root)
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select {
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case d.stateSyncStart <- s:
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// If we tell the statesync to restart with a new root, we also need
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// to wait for it to actually also start -- when old requests have timed
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// out or been delivered
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<-s.started
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case <-d.quitCh:
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s.err = errCancelStateFetch
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close(s.done)
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}
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return s
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}
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// stateFetcher manages the active state sync and accepts requests
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// on its behalf.
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func (d *Downloader) stateFetcher() {
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for {
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select {
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case s := <-d.stateSyncStart:
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for next := s; next != nil; {
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next = d.runStateSync(next)
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}
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case <-d.quitCh:
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return
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}
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}
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}
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// runStateSync runs a state synchronisation until it completes or another root
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// hash is requested to be switched over to.
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func (d *Downloader) runStateSync(s *stateSync) *stateSync {
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log.Trace("State sync starting", "root", s.root)
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go s.run()
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defer s.Cancel()
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for {
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select {
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case next := <-d.stateSyncStart:
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return next
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case <-s.done:
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return nil
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}
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}
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}
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// stateSync schedules requests for downloading a particular state trie defined
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// by a given state root.
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type stateSync struct {
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d *Downloader // Downloader instance to access and manage current peerset
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root common.Hash // State root currently being synced
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started chan struct{} // Started is signalled once the sync loop starts
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cancel chan struct{} // Channel to signal a termination request
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cancelOnce sync.Once // Ensures cancel only ever gets called once
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done chan struct{} // Channel to signal termination completion
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err error // Any error hit during sync (set before completion)
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}
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// newStateSync creates a new state trie download scheduler. This method does not
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// yet start the sync. The user needs to call run to initiate.
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func newStateSync(d *Downloader, root common.Hash) *stateSync {
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return &stateSync{
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d: d,
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root: root,
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cancel: make(chan struct{}),
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done: make(chan struct{}),
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started: make(chan struct{}),
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}
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}
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// run starts the task assignment and response processing loop, blocking until
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// it finishes, and finally notifying any goroutines waiting for the loop to
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// finish.
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func (s *stateSync) run() {
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close(s.started)
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s.err = s.d.SnapSyncer.Sync(s.root, s.cancel)
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close(s.done)
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}
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// Wait blocks until the sync is done or canceled.
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func (s *stateSync) Wait() error {
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<-s.done
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return s.err
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}
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// Cancel cancels the sync and waits until it has shut down.
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func (s *stateSync) Cancel() error {
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s.cancelOnce.Do(func() {
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close(s.cancel)
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})
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return s.Wait()
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}
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