prysm-pulse/beacon-chain/cache/active_balance.go
Raul Jordan 84916672c6
Remove Eth2-Types Dependency in Prysm (#10578)
* replace eth2 types

* replace protos

* regen proto

* replace

* gaz

* deps

* amend

* regen proto

* mod

* gaz

* gaz

* ensure build

* ssz

* add dep

* no more eth2 types

* no more eth2

* remg

* all builds

* buidl

* tidy

* clean

* fmt

* val serv

* gaz

Co-authored-by: Preston Van Loon <preston@prysmaticlabs.com>
2022-04-29 10:32:11 -04:00

116 lines
3.4 KiB
Go

//go:build !fuzz
// +build !fuzz
package cache
import (
"encoding/binary"
"sync"
lru "github.com/hashicorp/golang-lru"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"github.com/prysmaticlabs/prysm/beacon-chain/state"
lruwrpr "github.com/prysmaticlabs/prysm/cache/lru"
"github.com/prysmaticlabs/prysm/config/params"
ethTypes "github.com/prysmaticlabs/prysm/consensus-types/primitives"
)
const (
// maxBalanceCacheSize defines the max number of active balances can cache.
maxBalanceCacheSize = int(4)
)
var (
// BalanceCacheMiss tracks the number of balance requests that aren't present in the cache.
balanceCacheMiss = promauto.NewCounter(prometheus.CounterOpts{
Name: "total_effective_balance_cache_miss",
Help: "The number of get requests that aren't present in the cache.",
})
// BalanceCacheHit tracks the number of balance requests that are in the cache.
balanceCacheHit = promauto.NewCounter(prometheus.CounterOpts{
Name: "total_effective_balance_cache_hit",
Help: "The number of get requests that are present in the cache.",
})
)
// BalanceCache is a struct with 1 LRU cache for looking up balance by epoch.
type BalanceCache struct {
cache *lru.Cache
lock sync.RWMutex
}
// NewEffectiveBalanceCache creates a new effective balance cache for storing/accessing total balance by epoch.
func NewEffectiveBalanceCache() *BalanceCache {
return &BalanceCache{
cache: lruwrpr.New(maxBalanceCacheSize),
}
}
// AddTotalEffectiveBalance adds a new total effective balance entry for current balance for state `st` into the cache.
func (c *BalanceCache) AddTotalEffectiveBalance(st state.ReadOnlyBeaconState, balance uint64) error {
key, err := balanceCacheKey(st)
if err != nil {
return err
}
c.lock.Lock()
defer c.lock.Unlock()
_ = c.cache.Add(key, balance)
return nil
}
// Get returns the current epoch's effective balance for state `st` in cache.
func (c *BalanceCache) Get(st state.ReadOnlyBeaconState) (uint64, error) {
key, err := balanceCacheKey(st)
if err != nil {
return 0, err
}
c.lock.RLock()
defer c.lock.RUnlock()
value, exists := c.cache.Get(key)
if !exists {
balanceCacheMiss.Inc()
return 0, ErrNotFound
}
balanceCacheHit.Inc()
return value.(uint64), nil
}
// Given input state `st`, balance key is constructed as:
// (block_root in `st` at epoch_start_slot - 1) + current_epoch + validator_count
func balanceCacheKey(st state.ReadOnlyBeaconState) (string, error) {
slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
currentEpoch := st.Slot().DivSlot(slotsPerEpoch)
epochStartSlot, err := slotsPerEpoch.SafeMul(uint64(currentEpoch))
if err != nil {
// impossible condition due to early division
return "", errors.Errorf("start slot calculation overflows: %v", err)
}
prevSlot := ethTypes.Slot(0)
if epochStartSlot > 1 {
prevSlot = epochStartSlot - 1
}
r, err := st.BlockRootAtIndex(uint64(prevSlot % params.BeaconConfig().SlotsPerHistoricalRoot))
if err != nil {
// impossible condition because index is always constrained within state
return "", err
}
// Mix in current epoch
b := make([]byte, 8)
binary.LittleEndian.PutUint64(b, uint64(currentEpoch))
key := append(r, b...)
// Mix in validator count
b = make([]byte, 8)
binary.LittleEndian.PutUint64(b, uint64(st.NumValidators()))
key = append(key, b...)
return string(key), nil
}