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core/rawdb, core/state/snapshot: runtime snapshot generation

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This commit is contained in:
Péter Szilágyi
2019-11-26 09:48:29 +02:00
parent f300c0df01
commit 351a5903b0
21 changed files with 1551 additions and 486 deletions
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206
core/state/snapshot/difflayer.go
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@ -17,13 +17,52 @@
package snapshot
import (
"encoding/binary"
"fmt"
"math"
"sort"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
"github.com/steakknife/bloomfilter"
)
var (
// aggregatorMemoryLimit is the maximum size of the bottom-most diff layer
// that aggregates the writes from above until it's flushed into the disk
// layer.
//
// Note, bumping this up might drastically increase the size of the bloom
// filters that's stored in every diff layer. Don't do that without fully
// understanding all the implications.
aggregatorMemoryLimit = uint64(4 * 1024 * 1024)
// aggregatorItemLimit is an approximate number of items that will end up
// in the agregator layer before it's flushed out to disk. A plain account
// weighs around 14B (+hash), a storage slot 32B (+hash), so 50 is a very
// rough average of what we might see.
aggregatorItemLimit = aggregatorMemoryLimit / 55
// bloomTargetError is the target false positive rate when the aggregator
// layer is at its fullest. The actual value will probably move around up
// and down from this number, it's mostly a ballpark figure.
//
// Note, dropping this down might drastically increase the size of the bloom
// filters that's stored in every diff layer. Don't do that without fully
// understanding all the implications.
bloomTargetError = 0.02
// bloomSize is the ideal bloom filter size given the maximum number of items
// it's expected to hold and the target false positive error rate.
bloomSize = math.Ceil(float64(aggregatorItemLimit) * math.Log(bloomTargetError) / math.Log(1/math.Pow(2, math.Log(2))))
// bloomFuncs is the ideal number of bits a single entry should set in the
// bloom filter to keep its size to a minimum (given it's size and maximum
// entry count).
bloomFuncs = math.Round((bloomSize / float64(aggregatorItemLimit)) * math.Log(2))
)
// diffLayer represents a collection of modifications made to a state snapshot
@ -33,8 +72,9 @@ import (
// The goal of a diff layer is to act as a journal, tracking recent modifications
// made to the state, that have not yet graduated into a semi-immutable state.
type diffLayer struct {
parent snapshot // Parent snapshot modified by this one, never nil
memory uint64 // Approximate guess as to how much memory we use
origin *diskLayer // Base disk layer to directly use on bloom misses
parent snapshot // Parent snapshot modified by this one, never nil
memory uint64 // Approximate guess as to how much memory we use
root common.Hash // Root hash to which this snapshot diff belongs to
stale bool // Signals that the layer became stale (state progressed)
@ -44,9 +84,39 @@ type diffLayer struct {
storageList map[common.Hash][]common.Hash // List of storage slots for iterated retrievals, one per account. Any existing lists are sorted if non-nil
storageData map[common.Hash]map[common.Hash][]byte // Keyed storage slots for direct retrival. one per account (nil means deleted)
diffed *bloomfilter.Filter // Bloom filter tracking all the diffed items up to the disk layer
lock sync.RWMutex
}
// accountBloomHasher is a wrapper around a common.Hash to satisfy the interface
// API requirements of the bloom library used. It's used to convert an account
// hash into a 64 bit mini hash.
type accountBloomHasher common.Hash
func (h accountBloomHasher) Write(p []byte) (n int, err error) { panic("not implemented") }
func (h accountBloomHasher) Sum(b []byte) []byte { panic("not implemented") }
func (h accountBloomHasher) Reset() { panic("not implemented") }
func (h accountBloomHasher) BlockSize() int { panic("not implemented") }
func (h accountBloomHasher) Size() int { return 8 }
func (h accountBloomHasher) Sum64() uint64 {
return binary.BigEndian.Uint64(h[:8])
}
// storageBloomHasher is a wrapper around a [2]common.Hash to satisfy the interface
// API requirements of the bloom library used. It's used to convert an account
// hash into a 64 bit mini hash.
type storageBloomHasher [2]common.Hash
func (h storageBloomHasher) Write(p []byte) (n int, err error) { panic("not implemented") }
func (h storageBloomHasher) Sum(b []byte) []byte { panic("not implemented") }
func (h storageBloomHasher) Reset() { panic("not implemented") }
func (h storageBloomHasher) BlockSize() int { panic("not implemented") }
func (h storageBloomHasher) Size() int { return 8 }
func (h storageBloomHasher) Sum64() uint64 {
return binary.BigEndian.Uint64(h[0][:8]) ^ binary.BigEndian.Uint64(h[1][:8])
}
// newDiffLayer creates a new diff on top of an existing snapshot, whether that's a low
// level persistent database or a hierarchical diff already.
func newDiffLayer(parent snapshot, root common.Hash, accounts map[common.Hash][]byte, storage map[common.Hash]map[common.Hash][]byte) *diffLayer {
@ -57,9 +127,18 @@ func newDiffLayer(parent snapshot, root common.Hash, accounts map[common.Hash][]
accountData: accounts,
storageData: storage,
}
// Determine mem size
switch parent := parent.(type) {
case *diskLayer:
dl.rebloom(parent)
case *diffLayer:
dl.rebloom(parent.origin)
default:
panic("unknown parent type")
}
// Determine memory size and track the dirty writes
for _, data := range accounts {
dl.memory += uint64(len(data))
dl.memory += uint64(common.HashLength + len(data))
snapshotDirtyAccountWriteMeter.Mark(int64(len(data)))
}
// Fill the storage hashes and sort them for the iterator
dl.storageList = make(map[common.Hash][]common.Hash)
@ -80,16 +159,56 @@ func newDiffLayer(parent snapshot, root common.Hash, accounts map[common.Hash][]
if account, ok := accounts[accountHash]; account == nil || !ok {
log.Error(fmt.Sprintf("storage in %#x exists, but account nil (exists: %v)", accountHash, ok))
}
// Determine mem size
// Determine memory size and track the dirty writes
for _, data := range slots {
dl.memory += uint64(len(data))
dl.memory += uint64(common.HashLength + len(data))
snapshotDirtyStorageWriteMeter.Mark(int64(len(data)))
}
}
dl.memory += uint64(len(dl.storageList) * common.HashLength)
return dl
}
// rebloom discards the layer's current bloom and rebuilds it from scratch based
// on the parent's and the local diffs.
func (dl *diffLayer) rebloom(origin *diskLayer) {
dl.lock.Lock()
defer dl.lock.Unlock()
defer func(start time.Time) {
snapshotBloomIndexTimer.Update(time.Since(start))
}(time.Now())
// Inject the new origin that triggered the rebloom
dl.origin = origin
// Retrieve the parent bloom or create a fresh empty one
if parent, ok := dl.parent.(*diffLayer); ok {
parent.lock.RLock()
dl.diffed, _ = parent.diffed.Copy()
parent.lock.RUnlock()
} else {
dl.diffed, _ = bloomfilter.New(uint64(bloomSize), uint64(bloomFuncs))
}
// Iterate over all the accounts and storage slots and index them
for hash := range dl.accountData {
dl.diffed.Add(accountBloomHasher(hash))
}
for accountHash, slots := range dl.storageData {
for storageHash := range slots {
dl.diffed.Add(storageBloomHasher{accountHash, storageHash})
}
}
// Calculate the current false positive rate and update the error rate meter.
// This is a bit cheating because subsequent layers will overwrite it, but it
// should be fine, we're only interested in ballpark figures.
k := float64(dl.diffed.K())
n := float64(dl.diffed.N())
m := float64(dl.diffed.M())
snapshotBloomErrorGauge.Update(math.Pow(1.0-math.Exp((-k)*(n+0.5)/(m-1)), k))
}
// Root returns the root hash for which this snapshot was made.
func (dl *diffLayer) Root() common.Hash {
return dl.root
@ -124,6 +243,26 @@ func (dl *diffLayer) Account(hash common.Hash) (*Account, error) {
// AccountRLP directly retrieves the account RLP associated with a particular
// hash in the snapshot slim data format.
func (dl *diffLayer) AccountRLP(hash common.Hash) ([]byte, error) {
// Check the bloom filter first whether there's even a point in reaching into
// all the maps in all the layers below
dl.lock.RLock()
hit := dl.diffed.Contains(accountBloomHasher(hash))
dl.lock.RUnlock()
// If the bloom filter misses, don't even bother with traversing the memory
// diff layers, reach straight into the bottom persistent disk layer
if !hit {
snapshotBloomAccountMissMeter.Mark(1)
return dl.origin.AccountRLP(hash)
}
// The bloom filter hit, start poking in the internal maps
return dl.accountRLP(hash)
}
// accountRLP is an internal version of AccountRLP that skips the bloom filter
// checks and uses the internal maps to try and retrieve the data. It's meant
// to be used if a higher layer's bloom filter hit already.
func (dl *diffLayer) accountRLP(hash common.Hash) ([]byte, error) {
dl.lock.RLock()
defer dl.lock.RUnlock()
@ -135,9 +274,17 @@ func (dl *diffLayer) AccountRLP(hash common.Hash) ([]byte, error) {
// If the account is known locally, return it. Note, a nil account means it was
// deleted, and is a different notion than an unknown account!
if data, ok := dl.accountData[hash]; ok {
snapshotDirtyAccountHitMeter.Mark(1)
snapshotDirtyAccountReadMeter.Mark(int64(len(data)))
snapshotBloomAccountTrueHitMeter.Mark(1)
return data, nil
}
// Account unknown to this diff, resolve from parent
if diff, ok := dl.parent.(*diffLayer); ok {
return diff.accountRLP(hash)
}
// Failed to resolve through diff layers, mark a bloom error and use the disk
snapshotBloomAccountFalseHitMeter.Mark(1)
return dl.parent.AccountRLP(hash)
}
@ -145,6 +292,26 @@ func (dl *diffLayer) AccountRLP(hash common.Hash) ([]byte, error) {
// within a particular account. If the slot is unknown to this diff, it's parent
// is consulted.
func (dl *diffLayer) Storage(accountHash, storageHash common.Hash) ([]byte, error) {
// Check the bloom filter first whether there's even a point in reaching into
// all the maps in all the layers below
dl.lock.RLock()
hit := dl.diffed.Contains(storageBloomHasher{accountHash, storageHash})
dl.lock.RUnlock()
// If the bloom filter misses, don't even bother with traversing the memory
// diff layers, reach straight into the bottom persistent disk layer
if !hit {
snapshotBloomStorageMissMeter.Mark(1)
return dl.origin.Storage(accountHash, storageHash)
}
// The bloom filter hit, start poking in the internal maps
return dl.storage(accountHash, storageHash)
}
// storage is an internal version of Storage that skips the bloom filter checks
// and uses the internal maps to try and retrieve the data. It's meant to be
// used if a higher layer's bloom filter hit already.
func (dl *diffLayer) storage(accountHash, storageHash common.Hash) ([]byte, error) {
dl.lock.RLock()
defer dl.lock.RUnlock()
@ -157,13 +324,23 @@ func (dl *diffLayer) Storage(accountHash, storageHash common.Hash) ([]byte, erro
// account means it was deleted, and is a different notion than an unknown account!
if storage, ok := dl.storageData[accountHash]; ok {
if storage == nil {
snapshotDirtyStorageHitMeter.Mark(1)
snapshotBloomStorageTrueHitMeter.Mark(1)
return nil, nil
}
if data, ok := storage[storageHash]; ok {
snapshotDirtyStorageHitMeter.Mark(1)
snapshotDirtyStorageReadMeter.Mark(int64(len(data)))
snapshotBloomStorageTrueHitMeter.Mark(1)
return data, nil
}
}
// Account - or slot within - unknown to this diff, resolve from parent
// Storage slot unknown to this diff, resolve from parent
if diff, ok := dl.parent.(*diffLayer); ok {
return diff.storage(accountHash, storageHash)
}
// Failed to resolve through diff layers, mark a bloom error and use the disk
snapshotBloomStorageFalseHitMeter.Mark(1)
return dl.parent.Storage(accountHash, storageHash)
}
@ -224,22 +401,11 @@ func (dl *diffLayer) flatten() snapshot {
storageData: parent.storageData,
accountList: parent.accountList,
accountData: parent.accountData,
diffed: dl.diffed,
memory: parent.memory + dl.memory,
}
}
// Journal commits an entire diff hierarchy to disk into a single journal file.
// This is meant to be used during shutdown to persist the snapshot without
// flattening everything down (bad for reorgs).
func (dl *diffLayer) Journal() error {
writer, err := dl.journal()
if err != nil {
return err
}
writer.Close()
return nil
}
// AccountList returns a sorted list of all accounts in this difflayer.
func (dl *diffLayer) AccountList() []common.Hash {
dl.lock.Lock()