plugeth/les/freeclient.go

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// 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 les
import (
"io"
"math"
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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"net"
"sync"
"time"
"github.com/ethereum/go-ethereum/common/mclock"
"github.com/ethereum/go-ethereum/common/prque"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/les/csvlogger"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
)
// freeClientPool implements a client database that limits the connection time
// of each client and manages accepting/rejecting incoming connections and even
// kicking out some connected clients. The pool calculates recent usage time
// for each known client (a value that increases linearly when the client is
// connected and decreases exponentially when not connected). Clients with lower
// recent usage are preferred, unknown nodes have the highest priority. Already
// connected nodes receive a small bias in their favor in order to avoid accepting
// and instantly kicking out clients.
//
// Note: the pool can use any string for client identification. Using signature
// keys for that purpose would not make sense when being known has a negative
// value for the client. Currently the LES protocol manager uses IP addresses
// (without port address) to identify clients.
type freeClientPool struct {
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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db ethdb.Database
lock sync.Mutex
clock mclock.Clock
closed bool
removePeer func(string)
connectedLimit, totalLimit int
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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freeClientCap uint64
logger *csvlogger.Logger
logTotalFreeConn *csvlogger.Channel
addressMap map[string]*freeClientPoolEntry
connPool, disconnPool *prque.Prque
startupTime mclock.AbsTime
logOffsetAtStartup int64
}
const (
recentUsageExpTC = time.Hour // time constant of the exponential weighting window for "recent" server usage
fixedPointMultiplier = 0x1000000 // constant to convert logarithms to fixed point format
connectedBias = time.Minute // this bias is applied in favor of already connected clients in order to avoid kicking them out very soon
)
// newFreeClientPool creates a new free client pool
func newFreeClientPool(db ethdb.Database, freeClientCap uint64, totalLimit int, clock mclock.Clock, removePeer func(string), metricsLogger, eventLogger *csvlogger.Logger) *freeClientPool {
pool := &freeClientPool{
db: db,
clock: clock,
addressMap: make(map[string]*freeClientPoolEntry),
connPool: prque.New(poolSetIndex),
disconnPool: prque.New(poolSetIndex),
freeClientCap: freeClientCap,
totalLimit: totalLimit,
logger: eventLogger,
logTotalFreeConn: metricsLogger.NewChannel("totalFreeConn", 0),
removePeer: removePeer,
}
pool.loadFromDb()
return pool
}
func (f *freeClientPool) stop() {
f.lock.Lock()
f.closed = true
f.saveToDb()
f.lock.Unlock()
}
// freeClientId returns a string identifier for the peer. Multiple peers with the
// same identifier can not be in the free client pool simultaneously.
func freeClientId(p *peer) string {
if addr, ok := p.RemoteAddr().(*net.TCPAddr); ok {
if addr.IP.IsLoopback() {
// using peer id instead of loopback ip address allows multiple free
// connections from local machine to own server
return p.id
} else {
return addr.IP.String()
}
}
return ""
}
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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// registerPeer implements clientPool
func (f *freeClientPool) registerPeer(p *peer) {
if freeId := freeClientId(p); freeId != "" {
if !f.connect(freeId, p.id) {
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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f.removePeer(p.id)
}
}
}
// connect should be called after a successful handshake. If the connection was
// rejected, there is no need to call disconnect.
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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func (f *freeClientPool) connect(address, id string) bool {
f.lock.Lock()
defer f.lock.Unlock()
if f.closed {
return false
}
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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f.logger.Event("freeClientPool: connecting from " + address + ", " + id)
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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if f.connectedLimit == 0 {
f.logger.Event("freeClientPool: rejected, " + id)
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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log.Debug("Client rejected", "address", address)
return false
}
e := f.addressMap[address]
now := f.clock.Now()
var recentUsage int64
if e == nil {
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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e = &freeClientPoolEntry{address: address, index: -1, id: id}
f.addressMap[address] = e
} else {
if e.connected {
f.logger.Event("freeClientPool: already connected, " + id)
log.Debug("Client already connected", "address", address)
return false
}
recentUsage = int64(math.Exp(float64(e.logUsage-f.logOffset(now)) / fixedPointMultiplier))
}
e.linUsage = recentUsage - int64(now)
// check whether (linUsage+connectedBias) is smaller than the highest entry in the connected pool
if f.connPool.Size() == f.connectedLimit {
i := f.connPool.PopItem().(*freeClientPoolEntry)
if e.linUsage+int64(connectedBias)-i.linUsage < 0 {
// kick it out and accept the new client
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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f.dropClient(i, now)
f.logger.Event("freeClientPool: kicked out, " + i.id)
} else {
// keep the old client and reject the new one
f.connPool.Push(i, i.linUsage)
f.logger.Event("freeClientPool: rejected, " + id)
log.Debug("Client rejected", "address", address)
return false
}
}
f.disconnPool.Remove(e.index)
e.connected = true
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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e.id = id
f.connPool.Push(e, e.linUsage)
f.logTotalFreeConn.Update(float64(uint64(f.connPool.Size()) * f.freeClientCap))
if f.connPool.Size()+f.disconnPool.Size() > f.totalLimit {
f.disconnPool.Pop()
}
f.logger.Event("freeClientPool: accepted, " + id)
log.Debug("Client accepted", "address", address)
return true
}
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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// unregisterPeer implements clientPool
func (f *freeClientPool) unregisterPeer(p *peer) {
if freeId := freeClientId(p); freeId != "" {
f.disconnect(freeId)
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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}
}
// disconnect should be called when a connection is terminated. If the disconnection
// was initiated by the pool itself using disconnectFn then calling disconnect is
// not necessary but permitted.
func (f *freeClientPool) disconnect(address string) {
f.lock.Lock()
defer f.lock.Unlock()
if f.closed {
return
}
// Short circuit if the peer hasn't been registered.
e := f.addressMap[address]
if e == nil {
return
}
now := f.clock.Now()
if !e.connected {
log.Debug("Client already disconnected", "address", address)
return
}
f.connPool.Remove(e.index)
f.logTotalFreeConn.Update(float64(uint64(f.connPool.Size()) * f.freeClientCap))
f.calcLogUsage(e, now)
e.connected = false
f.disconnPool.Push(e, -e.logUsage)
f.logger.Event("freeClientPool: disconnected, " + e.id)
log.Debug("Client disconnected", "address", address)
}
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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// setConnLimit sets the maximum number of free client slots and also drops
// some peers if necessary
func (f *freeClientPool) setLimits(count int, totalCap uint64) {
f.lock.Lock()
defer f.lock.Unlock()
f.connectedLimit = int(totalCap / f.freeClientCap)
if count < f.connectedLimit {
f.connectedLimit = count
}
now := mclock.Now()
for f.connPool.Size() > f.connectedLimit {
i := f.connPool.PopItem().(*freeClientPoolEntry)
f.dropClient(i, now)
f.logger.Event("freeClientPool: setLimits kicked out, " + i.id)
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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}
}
// dropClient disconnects a client and also moves it from the connected to the
// disconnected pool
func (f *freeClientPool) dropClient(i *freeClientPoolEntry, now mclock.AbsTime) {
f.connPool.Remove(i.index)
f.logTotalFreeConn.Update(float64(uint64(f.connPool.Size()) * f.freeClientCap))
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
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f.calcLogUsage(i, now)
i.connected = false
f.disconnPool.Push(i, -i.logUsage)
log.Debug("Client kicked out", "address", i.address)
f.removePeer(i.id)
}
// logOffset calculates the time-dependent offset for the logarithmic
// representation of recent usage
func (f *freeClientPool) logOffset(now mclock.AbsTime) int64 {
// Note: fixedPointMultiplier acts as a multiplier here; the reason for dividing the divisor
// is to avoid int64 overflow. We assume that int64(recentUsageExpTC) >> fixedPointMultiplier.
logDecay := int64((time.Duration(now - f.startupTime)) / (recentUsageExpTC / fixedPointMultiplier))
return f.logOffsetAtStartup + logDecay
}
// calcLogUsage converts recent usage from linear to logarithmic representation
// when disconnecting a peer or closing the client pool
func (f *freeClientPool) calcLogUsage(e *freeClientPoolEntry, now mclock.AbsTime) {
dt := e.linUsage + int64(now)
if dt < 1 {
dt = 1
}
e.logUsage = int64(math.Log(float64(dt))*fixedPointMultiplier) + f.logOffset(now)
}
// freeClientPoolStorage is the RLP representation of the pool's database storage
type freeClientPoolStorage struct {
LogOffset uint64
List []*freeClientPoolEntry
}
// loadFromDb restores pool status from the database storage
// (automatically called at initialization)
func (f *freeClientPool) loadFromDb() {
enc, err := f.db.Get([]byte("freeClientPool"))
if err != nil {
return
}
var storage freeClientPoolStorage
err = rlp.DecodeBytes(enc, &storage)
if err != nil {
log.Error("Failed to decode client list", "err", err)
return
}
f.logOffsetAtStartup = int64(storage.LogOffset)
f.startupTime = f.clock.Now()
for _, e := range storage.List {
log.Debug("Loaded free client record", "address", e.address, "logUsage", e.logUsage)
f.addressMap[e.address] = e
f.disconnPool.Push(e, -e.logUsage)
}
}
// saveToDb saves pool status to the database storage
// (automatically called during shutdown)
func (f *freeClientPool) saveToDb() {
now := f.clock.Now()
storage := freeClientPoolStorage{
LogOffset: uint64(f.logOffset(now)),
List: make([]*freeClientPoolEntry, len(f.addressMap)),
}
i := 0
for _, e := range f.addressMap {
if e.connected {
f.calcLogUsage(e, now)
}
storage.List[i] = e
i++
}
enc, err := rlp.EncodeToBytes(storage)
if err != nil {
log.Error("Failed to encode client list", "err", err)
} else {
f.db.Put([]byte("freeClientPool"), enc)
}
}
// freeClientPoolEntry represents a client address known by the pool.
// When connected, recent usage is calculated as linUsage + int64(clock.Now())
// When disconnected, it is calculated as exp(logUsage - logOffset) where logOffset
// also grows linearly with time while the server is running.
// Conversion between linear and logarithmic representation happens when connecting
// or disconnecting the node.
//
// Note: linUsage and logUsage are values used with constantly growing offsets so
// even though they are close to each other at any time they may wrap around int64
// limits over time. Comparison should be performed accordingly.
type freeClientPoolEntry struct {
les, les/flowcontrol: improved request serving and flow control (#18230) This change - implements concurrent LES request serving even for a single peer. - replaces the request cost estimation method with a cost table based on benchmarks which gives much more consistent results. Until now the allowed number of light peers was just a guess which probably contributed a lot to the fluctuating quality of available service. Everything related to request cost is implemented in a single object, the 'cost tracker'. It uses a fixed cost table with a global 'correction factor'. Benchmark code is included and can be run at any time to adapt costs to low-level implementation changes. - reimplements flowcontrol.ClientManager in a cleaner and more efficient way, with added capabilities: There is now control over bandwidth, which allows using the flow control parameters for client prioritization. Target utilization over 100 percent is now supported to model concurrent request processing. Total serving bandwidth is reduced during block processing to prevent database contention. - implements an RPC API for the LES servers allowing server operators to assign priority bandwidth to certain clients and change prioritized status even while the client is connected. The new API is meant for cases where server operators charge for LES using an off-protocol mechanism. - adds a unit test for the new client manager. - adds an end-to-end test using the network simulator that tests bandwidth control functions through the new API.
2019-02-26 11:32:48 +00:00
address, id string
connected bool
disconnectFn func()
linUsage, logUsage int64
index int
}
func (e *freeClientPoolEntry) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, []interface{}{e.address, uint64(e.logUsage)})
}
func (e *freeClientPoolEntry) DecodeRLP(s *rlp.Stream) error {
var entry struct {
Address string
LogUsage uint64
}
if err := s.Decode(&entry); err != nil {
return err
}
e.address = entry.Address
e.logUsage = int64(entry.LogUsage)
e.connected = false
e.index = -1
return nil
}
// poolSetIndex callback is used by both priority queues to set/update the index of
// the element in the queue. Index is needed to remove elements other than the top one.
func poolSetIndex(a interface{}, i int) {
a.(*freeClientPoolEntry).index = i
}