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service.go
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service.go
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// Copyright 2021 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 server
import (
"net"
"strings"
"sync"
"time"
"github.com/electroneum/electroneum-sc/les/utils"
"github.com/electroneum/electroneum-sc/les/vflux"
"github.com/electroneum/electroneum-sc/log"
"github.com/electroneum/electroneum-sc/p2p/enode"
"github.com/electroneum/electroneum-sc/rlp"
)
type (
// Server serves vflux requests
Server struct {
limiter *utils.Limiter
lock sync.Mutex
services map[string]*serviceEntry
delayPerRequest time.Duration
}
// Service is a service registered at the Server and identified by a string id
Service interface {
Handle(id enode.ID, address string, name string, data []byte) []byte // never called concurrently
}
serviceEntry struct {
id, desc string
backend Service
}
)
// NewServer creates a new Server
func NewServer(delayPerRequest time.Duration) *Server {
return &Server{
limiter: utils.NewLimiter(1000),
delayPerRequest: delayPerRequest,
services: make(map[string]*serviceEntry),
}
}
// Register registers a Service
func (s *Server) Register(b Service, id, desc string) {
srv := &serviceEntry{backend: b, id: id, desc: desc}
if strings.Contains(srv.id, ":") {
// srv.id + ":" will be used as a service database prefix
log.Error("Service ID contains ':'", "id", srv.id)
return
}
s.lock.Lock()
s.services[srv.id] = srv
s.lock.Unlock()
}
// Serve serves a vflux request batch
// Note: requests are served by the Handle functions of the registered services. Serve
// may be called concurrently but the Handle functions are called sequentially and
// therefore thread safety is guaranteed.
func (s *Server) Serve(id enode.ID, address string, requests vflux.Requests) vflux.Replies {
reqLen := uint(len(requests))
if reqLen == 0 || reqLen > vflux.MaxRequestLength {
return nil
}
// Note: the value parameter will be supplied by the token sale module (total amount paid)
ch := <-s.limiter.Add(id, address, 0, reqLen)
if ch == nil {
return nil
}
// Note: the limiter ensures that the following section is not running concurrently,
// the lock only protects against contention caused by new service registration
s.lock.Lock()
results := make(vflux.Replies, len(requests))
for i, req := range requests {
if service := s.services[req.Service]; service != nil {
results[i] = service.backend.Handle(id, address, req.Name, req.Params)
}
}
s.lock.Unlock()
time.Sleep(s.delayPerRequest * time.Duration(reqLen))
close(ch)
return results
}
// ServeEncoded serves an encoded vflux request batch and returns the encoded replies
func (s *Server) ServeEncoded(id enode.ID, addr *net.UDPAddr, req []byte) []byte {
var requests vflux.Requests
if err := rlp.DecodeBytes(req, &requests); err != nil {
return nil
}
results := s.Serve(id, addr.String(), requests)
if results == nil {
return nil
}
res, _ := rlp.EncodeToBytes(&results)
return res
}
// Stop shuts down the server
func (s *Server) Stop() {
s.limiter.Stop()
}