plugeth/miner/payload_building.go

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// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>
package miner
import (
"math/big"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/beacon"
"github.com/ethereum/go-ethereum/core/types"
)
// BuildPayloadArgs contains the provided parameters for building payload.
// Check engine-api specification for more details.
// https://github.com/ethereum/execution-apis/blob/main/src/engine/specification.md#payloadattributesv1
type BuildPayloadArgs struct {
Parent common.Hash // The parent block to build payload on top
Timestamp uint64 // The provided timestamp of generated payload
FeeRecipient common.Address // The provided recipient address for collecting transaction fee
Random common.Hash // The provided randomness value
}
// Payload wraps the built payload(block waiting for sealing). According to the
// engine-api specification, EL should build the initial version of the payload
// which has an empty transaction set and then keep update it in order to maximize
// the revenue. Therefore, the empty-block here is always available and full-block
// will be set/updated afterwards.
type Payload struct {
empty *types.Block
full *types.Block
fullFees *big.Int
stop chan struct{}
lock *sync.Mutex
cond *sync.Cond
}
// newPayload initializes the payload object.
func newPayload(empty *types.Block) *Payload {
lock := new(sync.Mutex)
return &Payload{
empty: empty,
stop: make(chan struct{}),
lock: lock,
cond: sync.NewCond(lock),
}
}
// update updates the full-block with latest built version.
func (payload *Payload) update(block *types.Block, fees *big.Int) {
payload.lock.Lock()
defer payload.lock.Unlock()
select {
case <-payload.stop:
return // reject stale update
default:
}
// Ensure the newly provided full block has a higher transaction fee.
// In post-merge stage, there is no uncle reward anymore and transaction
// fee(apart from the mev revenue) is the only indicator for comparison.
if payload.full == nil || fees.Cmp(payload.fullFees) > 0 {
payload.full = block
payload.fullFees = fees
}
payload.cond.Broadcast() // fire signal for notifying full block
}
// Resolve returns the latest built payload and also terminates the background
// thread for updating payload. It's safe to be called multiple times.
func (payload *Payload) Resolve() *beacon.ExecutableDataV1 {
payload.lock.Lock()
defer payload.lock.Unlock()
select {
case <-payload.stop:
default:
close(payload.stop)
}
if payload.full != nil {
return beacon.BlockToExecutableData(payload.full)
}
return beacon.BlockToExecutableData(payload.empty)
}
// ResolveEmpty is basically identical to Resolve, but it expects empty block only.
// It's only used in tests.
func (payload *Payload) ResolveEmpty() *beacon.ExecutableDataV1 {
payload.lock.Lock()
defer payload.lock.Unlock()
return beacon.BlockToExecutableData(payload.empty)
}
// ResolveFull is basically identical to Resolve, but it expects full block only.
// It's only used in tests.
func (payload *Payload) ResolveFull() *beacon.ExecutableDataV1 {
payload.lock.Lock()
defer payload.lock.Unlock()
if payload.full == nil {
select {
case <-payload.stop:
return nil
default:
}
payload.cond.Wait()
}
return beacon.BlockToExecutableData(payload.full)
}
// buildPayload builds the payload according to the provided parameters.
func (w *worker) buildPayload(args *BuildPayloadArgs) (*Payload, error) {
// Build the initial version with no transaction included. It should be fast
// enough to run. The empty payload can at least make sure there is something
// to deliver for not missing slot.
empty, _, err := w.getSealingBlock(args.Parent, args.Timestamp, args.FeeRecipient, args.Random, true)
if err != nil {
return nil, err
}
// Construct a payload object for return.
payload := newPayload(empty)
// Spin up a routine for updating the payload in background. This strategy
// can maximum the revenue for including transactions with highest fee.
go func() {
// Setup the timer for re-building the payload. The initial clock is kept
// for triggering process immediately.
timer := time.NewTimer(0)
defer timer.Stop()
// Setup the timer for terminating the process if SECONDS_PER_SLOT (12s in
// the Mainnet configuration) have passed since the point in time identified
// by the timestamp parameter.
endTimer := time.NewTimer(time.Second * 12)
for {
select {
case <-timer.C:
block, fees, err := w.getSealingBlock(args.Parent, args.Timestamp, args.FeeRecipient, args.Random, false)
if err == nil {
payload.update(block, fees)
}
timer.Reset(w.recommit)
case <-payload.stop:
return
case <-endTimer.C:
return
}
}
}()
return payload, nil
}