path: root/les/bloombits.go

// Copyright 2017 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 les

import (
    "time"

    "github.com/ethereum/go-ethereum/common/bitutil"
    "github.com/ethereum/go-ethereum/light"
)

const (
    // bloomServiceThreads is the number of goroutines used globally by an Ethereum
    // instance to service bloombits lookups for all running filters.
    bloomServiceThreads = 16

    // bloomFilterThreads is the number of goroutines used locally per filter to
    // multiplex requests onto the global servicing goroutines.
    bloomFilterThreads = 3

    // bloomRetrievalBatch is the maximum number of bloom bit retrievals to service
    // in a single batch.
    bloomRetrievalBatch = 16

    // bloomRetrievalWait is the maximum time to wait for enough bloom bit requests
    // to accumulate request an entire batch (avoiding hysteresis).
    bloomRetrievalWait = time.Microsecond * 100
)

// startBloomHandlers starts a batch of goroutines to accept bloom bit database
// retrievals from possibly a range of filters and serving the data to satisfy.
func (eth *LightEthereum) startBloomHandlers() {
    for i := 0; i < bloomServiceThreads; i++ {
        go func() {
            for {
                select {
                case <-eth.shutdownChan:
                    return

                case request := <-eth.bloomRequests:
                    task := <-request
                    task.Bitsets = make([][]byte, len(task.Sections))
                    compVectors, err := light.GetBloomBits(task.Context, eth.odr, task.Bit, task.Sections)
                    if err == nil {
                        for i := range task.Sections {
                            if blob, err := bitutil.DecompressBytes(compVectors[i], int(light.BloomTrieFrequency/8)); err == nil {
                                task.Bitsets[i] = blob
                            } else {
                                task.Error = err
                            }
                        }
                    } else {
                        task.Error = err
                    }
                    request <- task
                }
            }
        }()
    }
}

const (
    // bloomConfirms is the number of confirmation blocks before a bloom section is
    // considered probably final and its rotated bits are calculated.
    bloomConfirms = 256

    // bloomThrottling is the time to wait between processing two consecutive index
    // sections. It's useful during chain upgrades to prevent disk overload.
    bloomThrottling = 100 * time.Millisecond
)