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eth/downloader: improve deliverNodeData (#3588)

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Commit d3b751e accidentally deleted a crucial 'return' statement,
leading to a crash in case of an issue with node data. This change
improves the fix in PR #3591 by removing the lock entirely.
This commit is contained in:
Felix Lange 2017-01-24 13:20:37 +01:00 committed by GitHub
parent 2718b42828
commit f1069a30b9
1 changed files with 52 additions and 72 deletions
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120
eth/downloader/queue.go
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@ -23,7 +23,6 @@ import (
"errors"
"fmt"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
@ -103,8 +102,7 @@ type queue struct {
stateDatabase ethdb.Database // [eth/63] Trie database to populate during state reassembly
stateScheduler *state.StateSync // [eth/63] State trie synchronisation scheduler and integrator
stateProcessors int32 // [eth/63] Number of currently running state processors
stateSchedLock sync.RWMutex // [eth/63] Lock serialising access to the state scheduler
stateWriters int // [eth/63] Number of running state DB writer goroutines
resultCache []*fetchResult // Downloaded but not yet delivered fetch results
resultOffset uint64 // Offset of the first cached fetch result in the block chain
@ -143,9 +141,6 @@ func (q *queue) Reset() {
q.lock.Lock()
defer q.lock.Unlock()
q.stateSchedLock.Lock()
defer q.stateSchedLock.Unlock()
q.closed = false
q.mode = FullSync
q.fastSyncPivot = 0
@ -209,13 +204,24 @@ func (q *queue) PendingReceipts() int {
// PendingNodeData retrieves the number of node data entries pending for retrieval.
func (q *queue) PendingNodeData() int {
q.stateSchedLock.RLock()
defer q.stateSchedLock.RUnlock()
q.lock.Lock()
defer q.lock.Unlock()
return q.pendingNodeDataLocked()
}
// pendingNodeDataLocked retrieves the number of node data entries pending for retrieval.
// The caller must hold q.lock.
func (q *queue) pendingNodeDataLocked() int {
var n int
if q.stateScheduler != nil {
return q.stateScheduler.Pending()
n = q.stateScheduler.Pending()
}
return 0
// Ensure that PendingNodeData doesn't return 0 until all state is written.
if q.stateWriters > 0 {
n++
}
return n
}
// InFlightHeaders retrieves whether there are header fetch requests currently
@ -251,7 +257,7 @@ func (q *queue) InFlightNodeData() bool {
q.lock.Lock()
defer q.lock.Unlock()
return len(q.statePendPool)+int(atomic.LoadInt32(&q.stateProcessors)) > 0
return len(q.statePendPool)+q.stateWriters > 0
}
// Idle returns if the queue is fully idle or has some data still inside. This
@ -264,12 +270,9 @@ func (q *queue) Idle() bool {
pending := len(q.blockPendPool) + len(q.receiptPendPool) + len(q.statePendPool)
cached := len(q.blockDonePool) + len(q.receiptDonePool)
q.stateSchedLock.RLock()
if q.stateScheduler != nil {
queued += q.stateScheduler.Pending()
}
q.stateSchedLock.RUnlock()
return (queued + pending + cached) == 0
}
@ -398,9 +401,7 @@ func (q *queue) Schedule(headers []*types.Header, from uint64) []*types.Header {
req.Hashes = make(map[common.Hash]int) // Make sure executing requests fail, but don't disappear
}
q.stateSchedLock.Lock()
q.stateScheduler = state.NewStateSync(header.Root, q.stateDatabase)
q.stateSchedLock.Unlock()
}
inserts = append(inserts, header)
q.headerHead = hash
@ -459,7 +460,7 @@ func (q *queue) countProcessableItems() int {
// resultCache has space for fsHeaderForceVerify items. Not
// doing this could leave us unable to download the required
// amount of headers.
if i > 0 || len(q.stateTaskPool) > 0 || q.PendingNodeData() > 0 {
if i > 0 || len(q.stateTaskPool) > 0 || q.pendingNodeDataLocked() > 0 {
return i
}
for j := 0; j < fsHeaderForceVerify; j++ {
@ -524,9 +525,6 @@ func (q *queue) ReserveHeaders(p *peer, count int) *fetchRequest {
func (q *queue) ReserveNodeData(p *peer, count int) *fetchRequest {
// Create a task generator to fetch status-fetch tasks if all schedules ones are done
generator := func(max int) {
q.stateSchedLock.Lock()
defer q.stateSchedLock.Unlock()
if q.stateScheduler != nil {
for _, hash := range q.stateScheduler.Missing(max) {
q.stateTaskPool[hash] = q.stateTaskIndex
@ -1068,7 +1066,7 @@ func (q *queue) DeliverNodeData(id string, data [][]byte, callback func(int, boo
}
}
// Iterate over the downloaded data and verify each of them
accepted, errs := 0, make([]error, 0)
errs := make([]error, 0)
process := []trie.SyncResult{}
for _, blob := range data {
// Skip any state trie entries that were not requested
@ -1079,70 +1077,52 @@ func (q *queue) DeliverNodeData(id string, data [][]byte, callback func(int, boo
}
// Inject the next state trie item into the processing queue
process = append(process, trie.SyncResult{Hash: hash, Data: blob})
accepted++
delete(request.Hashes, hash)
delete(q.stateTaskPool, hash)
}
// Start the asynchronous node state data injection
atomic.AddInt32(&q.stateProcessors, 1)
go func() {
defer atomic.AddInt32(&q.stateProcessors, -1)
q.deliverNodeData(process, callback)
}()
// Return all failed or missing fetches to the queue
for hash, index := range request.Hashes {
q.stateTaskQueue.Push(hash, float32(index))
}
if q.stateScheduler == nil {
return 0, errNoFetchesPending
}
// Run valid nodes through the trie download scheduler. It writes completed nodes to a
// batch, which is committed asynchronously. This may lead to over-fetches because the
// scheduler treats everything as written after Process has returned, but it's
// unlikely to be an issue in practice.
batch := q.stateDatabase.NewBatch()
progressed, nproc, procerr := q.stateScheduler.Process(process, batch)
q.stateWriters += 1
go func() {
if procerr == nil {
nproc = len(process)
procerr = batch.Write()
}
// Return processing errors through the callback so the sync gets canceled. The
// number of writers is decremented prior to the call so PendingNodeData will
// return zero when the callback runs.
q.lock.Lock()
q.stateWriters -= 1
q.lock.Unlock()
callback(nproc, progressed, procerr)
// Wake up WaitResults after the state has been written because it might be
// waiting for completion of the pivot block's state download.
q.active.Signal()
}()
// If none of the data items were good, it's a stale delivery
switch {
case len(errs) == 0:
return accepted, nil
return len(process), nil
case len(errs) == len(request.Hashes):
return accepted, errStaleDelivery
return len(process), errStaleDelivery
default:
return accepted, fmt.Errorf("multiple failures: %v", errs)
return len(process), fmt.Errorf("multiple failures: %v", errs)
}
}
// deliverNodeData is the asynchronous node data processor that injects a batch
// of sync results into the state scheduler.
func (q *queue) deliverNodeData(results []trie.SyncResult, callback func(int, bool, error)) {
// Wake up WaitResults after the state has been written because it
// might be waiting for the pivot block state to get completed.
defer q.active.Signal()
// Process results one by one to permit task fetches in between
progressed := false
for i, result := range results {
q.stateSchedLock.Lock()
if q.stateScheduler == nil {
// Syncing aborted since this async delivery started, bail out
q.stateSchedLock.Unlock()
callback(i, progressed, errNoFetchesPending)
return
}
batch := q.stateDatabase.NewBatch()
prog, _, err := q.stateScheduler.Process([]trie.SyncResult{result}, batch)
if err != nil {
q.stateSchedLock.Unlock()
callback(i, progressed, err)
return
}
if err = batch.Write(); err != nil {
q.stateSchedLock.Unlock()
callback(i, progressed, err)
return // TODO(karalabe): If a DB write fails (disk full), we ought to cancel the sync
}
// Item processing succeeded, release the lock (temporarily)
progressed = progressed || prog
q.stateSchedLock.Unlock()
}
callback(len(results), progressed, nil)
}
// Prepare configures the result cache to allow accepting and caching inbound
// fetch results.
func (q *queue) Prepare(offset uint64, mode SyncMode, pivot uint64, head *types.Header) {