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-rw-r--r--les/flowcontrol/control.go172
1 files changed, 172 insertions, 0 deletions
diff --git a/les/flowcontrol/control.go b/les/flowcontrol/control.go
new file mode 100644
index 000000000..0b8d7f58f
--- /dev/null
+++ b/les/flowcontrol/control.go
@@ -0,0 +1,172 @@
+// Copyright 2016 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 flowcontrol implements a client side flow control mechanism
+package flowcontrol
+
+import (
+ "sync"
+ "time"
+
+ "github.com/ethereum/go-ethereum/common/mclock"
+)
+
+const fcTimeConst = 1000000
+
+type ServerParams struct {
+ BufLimit, MinRecharge uint64
+}
+
+type ClientNode struct {
+ params *ServerParams
+ bufValue uint64
+ lastTime int64
+ lock sync.Mutex
+ cm *ClientManager
+ cmNode *cmNode
+}
+
+func NewClientNode(cm *ClientManager, params *ServerParams) *ClientNode {
+ node := &ClientNode{
+ cm: cm,
+ params: params,
+ bufValue: params.BufLimit,
+ lastTime: getTime(),
+ }
+ node.cmNode = cm.addNode(node)
+ return node
+}
+
+func (peer *ClientNode) Remove(cm *ClientManager) {
+ cm.removeNode(peer.cmNode)
+}
+
+func (peer *ClientNode) recalcBV(time int64) {
+ dt := uint64(time - peer.lastTime)
+ if time < peer.lastTime {
+ dt = 0
+ }
+ peer.bufValue += peer.params.MinRecharge * dt / fcTimeConst
+ if peer.bufValue > peer.params.BufLimit {
+ peer.bufValue = peer.params.BufLimit
+ }
+ peer.lastTime = time
+}
+
+func (peer *ClientNode) AcceptRequest() (uint64, bool) {
+ peer.lock.Lock()
+ defer peer.lock.Unlock()
+
+ time := getTime()
+ peer.recalcBV(time)
+ return peer.bufValue, peer.cm.accept(peer.cmNode, time)
+}
+
+func (peer *ClientNode) RequestProcessed(cost uint64) (bv, realCost uint64) {
+ peer.lock.Lock()
+ defer peer.lock.Unlock()
+
+ time := getTime()
+ peer.recalcBV(time)
+ peer.bufValue -= cost
+ peer.recalcBV(time)
+ rcValue, rcost := peer.cm.processed(peer.cmNode, time)
+ if rcValue < peer.params.BufLimit {
+ bv := peer.params.BufLimit - rcValue
+ if bv > peer.bufValue {
+ peer.bufValue = bv
+ }
+ }
+ return peer.bufValue, rcost
+}
+
+type ServerNode struct {
+ bufEstimate uint64
+ lastTime int64
+ params *ServerParams
+ sumCost uint64 // sum of req costs sent to this server
+ pending map[uint64]uint64 // value = sumCost after sending the given req
+ lock sync.Mutex
+}
+
+func NewServerNode(params *ServerParams) *ServerNode {
+ return &ServerNode{
+ bufEstimate: params.BufLimit,
+ lastTime: getTime(),
+ params: params,
+ pending: make(map[uint64]uint64),
+ }
+}
+
+func getTime() int64 {
+ return int64(mclock.Now())
+}
+
+func (peer *ServerNode) recalcBLE(time int64) {
+ dt := uint64(time - peer.lastTime)
+ if time < peer.lastTime {
+ dt = 0
+ }
+ peer.bufEstimate += peer.params.MinRecharge * dt / fcTimeConst
+ if peer.bufEstimate > peer.params.BufLimit {
+ peer.bufEstimate = peer.params.BufLimit
+ }
+ peer.lastTime = time
+}
+
+func (peer *ServerNode) canSend(maxCost uint64) uint64 {
+ if peer.bufEstimate >= maxCost {
+ return 0
+ }
+ return (maxCost - peer.bufEstimate) * fcTimeConst / peer.params.MinRecharge
+}
+
+func (peer *ServerNode) CanSend(maxCost uint64) uint64 {
+ peer.lock.Lock()
+ defer peer.lock.Unlock()
+
+ return peer.canSend(maxCost)
+}
+
+// blocks until request can be sent
+func (peer *ServerNode) SendRequest(reqID, maxCost uint64) {
+ peer.lock.Lock()
+ defer peer.lock.Unlock()
+
+ peer.recalcBLE(getTime())
+ for peer.bufEstimate < maxCost {
+ time.Sleep(time.Duration(peer.canSend(maxCost)))
+ peer.recalcBLE(getTime())
+ }
+ peer.bufEstimate -= maxCost
+ peer.sumCost += maxCost
+ if reqID >= 0 {
+ peer.pending[reqID] = peer.sumCost
+ }
+}
+
+func (peer *ServerNode) GotReply(reqID, bv uint64) {
+ peer.lock.Lock()
+ defer peer.lock.Unlock()
+
+ sc, ok := peer.pending[reqID]
+ if !ok {
+ return
+ }
+ delete(peer.pending, reqID)
+ peer.bufEstimate = bv - (peer.sumCost - sc)
+ peer.lastTime = getTime()
+}