vendor/google.golang.org/grpc/transport/control.go - gddo - Git at Google

 /*
  *
  * Copyright 2014 gRPC authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  */

 package transport

 import (
 	"fmt"
 	"math"
 	"sync"
 	"time"

 	"golang.org/x/net/http2"
 )

 const (
 	// The default value of flow control window size in HTTP2 spec.
 	defaultWindowSize = 65535
 	// The initial window size for flow control.
 	initialWindowSize             = defaultWindowSize // for an RPC
 	infinity                      = time.Duration(math.MaxInt64)
 	defaultClientKeepaliveTime    = infinity
 	defaultClientKeepaliveTimeout = time.Duration(20 * time.Second)
 	defaultMaxStreamsClient       = 100
 	defaultMaxConnectionIdle      = infinity
 	defaultMaxConnectionAge       = infinity
 	defaultMaxConnectionAgeGrace  = infinity
 	defaultServerKeepaliveTime    = time.Duration(2 * time.Hour)
 	defaultServerKeepaliveTimeout = time.Duration(20 * time.Second)
 	defaultKeepalivePolicyMinTime = time.Duration(5 * time.Minute)
 	// max window limit set by HTTP2 Specs.
 	maxWindowSize = math.MaxInt32
 )

 // The following defines various control items which could flow through
 // the control buffer of transport. They represent different aspects of
 // control tasks, e.g., flow control, settings, streaming resetting, etc.
 type windowUpdate struct {
 	streamID  uint32
 	increment uint32
 	flush     bool
 }

 func (*windowUpdate) item() {}

 type settings struct {
 	ack bool
 	ss  []http2.Setting
 }

 func (*settings) item() {}

 type resetStream struct {
 	streamID uint32
 	code     http2.ErrCode
 }

 func (*resetStream) item() {}

 type goAway struct {
 	code      http2.ErrCode
 	debugData []byte
 	headsUp   bool
 	closeConn bool
 }

 func (*goAway) item() {}

 type flushIO struct {
 }

 func (*flushIO) item() {}

 type ping struct {
 	ack  bool
 	data [8]byte
 }

 func (*ping) item() {}

 // quotaPool is a pool which accumulates the quota and sends it to acquire()
 // when it is available.
 type quotaPool struct {
 	c chan int

 	mu    sync.Mutex
 	quota int
 }

 // newQuotaPool creates a quotaPool which has quota q available to consume.
 func newQuotaPool(q int) *quotaPool {
 	qb := &quotaPool{
 		c: make(chan int, 1),
 	}
 	if q > 0 {
 		qb.c <- q
 	} else {
 		qb.quota = q
 	}
 	return qb
 }

 // add cancels the pending quota sent on acquired, incremented by v and sends
 // it back on acquire.
 func (qb *quotaPool) add(v int) {
 	qb.mu.Lock()
 	defer qb.mu.Unlock()
 	select {
 	case n := <-qb.c:
 		qb.quota += n
 	default:
 	}
 	qb.quota += v
 	if qb.quota <= 0 {
 		return
 	}
 	// After the pool has been created, this is the only place that sends on
 	// the channel. Since mu is held at this point and any quota that was sent
 	// on the channel has been retrieved, we know that this code will always
 	// place any positive quota value on the channel.
 	select {
 	case qb.c <- qb.quota:
 		qb.quota = 0
 	default:
 	}
 }

 // acquire returns the channel on which available quota amounts are sent.
 func (qb *quotaPool) acquire() <-chan int {
 	return qb.c
 }

 // inFlow deals with inbound flow control
 type inFlow struct {
 	mu sync.Mutex
 	// The inbound flow control limit for pending data.
 	limit uint32
 	// pendingData is the overall data which have been received but not been
 	// consumed by applications.
 	pendingData uint32
 	// The amount of data the application has consumed but grpc has not sent
 	// window update for them. Used to reduce window update frequency.
 	pendingUpdate uint32
 	// delta is the extra window update given by receiver when an application
 	// is reading data bigger in size than the inFlow limit.
 	delta uint32
 }

 // newLimit updates the inflow window to a new value n.
 // It assumes that n is always greater than the old limit.
 func (f *inFlow) newLimit(n uint32) uint32 {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	d := n - f.limit
 	f.limit = n
 	return d
 }

 func (f *inFlow) maybeAdjust(n uint32) uint32 {
 	if n > uint32(math.MaxInt32) {
 		n = uint32(math.MaxInt32)
 	}
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	// estSenderQuota is the receiver's view of the maximum number of bytes the sender
 	// can send without a window update.
 	estSenderQuota := int32(f.limit - (f.pendingData + f.pendingUpdate))
 	// estUntransmittedData is the maximum number of bytes the sends might not have put
 	// on the wire yet. A value of 0 or less means that we have already received all or
 	// more bytes than the application is requesting to read.
 	estUntransmittedData := int32(n - f.pendingData) // Casting into int32 since it could be negative.
 	// This implies that unless we send a window update, the sender won't be able to send all the bytes
 	// for this message. Therefore we must send an update over the limit since there's an active read
 	// request from the application.
 	if estUntransmittedData > estSenderQuota {
 		// Sender's window shouldn't go more than 2^31 - 1 as speecified in the HTTP spec.
 		if f.limit+n > maxWindowSize {
 			f.delta = maxWindowSize - f.limit
 		} else {
 			// Send a window update for the whole message and not just the difference between
 			// estUntransmittedData and estSenderQuota. This will be helpful in case the message
 			// is padded; We will fallback on the current available window(at least a 1/4th of the limit).
 			f.delta = n
 		}
 		return f.delta
 	}
 	return 0
 }

 // onData is invoked when some data frame is received. It updates pendingData.
 func (f *inFlow) onData(n uint32) error {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	f.pendingData += n
 	if f.pendingData+f.pendingUpdate > f.limit+f.delta {
 		return fmt.Errorf("received %d-bytes data exceeding the limit %d bytes", f.pendingData+f.pendingUpdate, f.limit)
 	}
 	return nil
 }

 // onRead is invoked when the application reads the data. It returns the window size
 // to be sent to the peer.
 func (f *inFlow) onRead(n uint32) uint32 {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	if f.pendingData == 0 {
 		return 0
 	}
 	f.pendingData -= n
 	if n > f.delta {
 		n -= f.delta
 		f.delta = 0
 	} else {
 		f.delta -= n
 		n = 0
 	}
 	f.pendingUpdate += n
 	if f.pendingUpdate >= f.limit/4 {
 		wu := f.pendingUpdate
 		f.pendingUpdate = 0
 		return wu
 	}
 	return 0
 }

 func (f *inFlow) resetPendingUpdate() uint32 {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	n := f.pendingUpdate
 	f.pendingUpdate = 0
 	return n
 }
	/*
	*
	* Copyright 2014 gRPC authors.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	*/

	package transport

	import (
	"fmt"
	"math"
	"sync"
	"time"

	"golang.org/x/net/http2"
	)

	const (
	// The default value of flow control window size in HTTP2 spec.
	defaultWindowSize = 65535
	// The initial window size for flow control.
	initialWindowSize = defaultWindowSize // for an RPC
	infinity = time.Duration(math.MaxInt64)
	defaultClientKeepaliveTime = infinity
	defaultClientKeepaliveTimeout = time.Duration(20 * time.Second)
	defaultMaxStreamsClient = 100
	defaultMaxConnectionIdle = infinity
	defaultMaxConnectionAge = infinity
	defaultMaxConnectionAgeGrace = infinity
	defaultServerKeepaliveTime = time.Duration(2 * time.Hour)
	defaultServerKeepaliveTimeout = time.Duration(20 * time.Second)
	defaultKeepalivePolicyMinTime = time.Duration(5 * time.Minute)
	// max window limit set by HTTP2 Specs.
	maxWindowSize = math.MaxInt32
	)

	// The following defines various control items which could flow through
	// the control buffer of transport. They represent different aspects of
	// control tasks, e.g., flow control, settings, streaming resetting, etc.
	type windowUpdate struct {
	streamID uint32
	increment uint32
	flush bool
	}

	func (*windowUpdate) item() {}

	type settings struct {
	ack bool
	ss []http2.Setting
	}

	func (*settings) item() {}

	type resetStream struct {
	streamID uint32
	code http2.ErrCode
	}

	func (*resetStream) item() {}

	type goAway struct {
	code http2.ErrCode
	debugData []byte
	headsUp bool
	closeConn bool
	}

	func (*goAway) item() {}

	type flushIO struct {
	}

	func (*flushIO) item() {}

	type ping struct {
	ack bool
	data [8]byte
	}

	func (*ping) item() {}

	// quotaPool is a pool which accumulates the quota and sends it to acquire()
	// when it is available.
	type quotaPool struct {
	c chan int

	mu sync.Mutex
	quota int
	}

	// newQuotaPool creates a quotaPool which has quota q available to consume.
	func newQuotaPool(q int) *quotaPool {
	qb := &quotaPool{
	c: make(chan int, 1),
	}
	if q > 0 {
	qb.c <- q
	} else {
	qb.quota = q
	}
	return qb
	}

	// add cancels the pending quota sent on acquired, incremented by v and sends
	// it back on acquire.
	func (qb *quotaPool) add(v int) {
	qb.mu.Lock()
	defer qb.mu.Unlock()
	select {
	case n := <-qb.c:
	qb.quota += n
	default:
	}
	qb.quota += v
	if qb.quota <= 0 {
	return
	}
	// After the pool has been created, this is the only place that sends on
	// the channel. Since mu is held at this point and any quota that was sent
	// on the channel has been retrieved, we know that this code will always
	// place any positive quota value on the channel.
	select {
	case qb.c <- qb.quota:
	qb.quota = 0
	default:
	}
	}

	// acquire returns the channel on which available quota amounts are sent.
	func (qb *quotaPool) acquire() <-chan int {
	return qb.c
	}

	// inFlow deals with inbound flow control
	type inFlow struct {
	mu sync.Mutex
	// The inbound flow control limit for pending data.
	limit uint32
	// pendingData is the overall data which have been received but not been
	// consumed by applications.
	pendingData uint32
	// The amount of data the application has consumed but grpc has not sent
	// window update for them. Used to reduce window update frequency.
	pendingUpdate uint32
	// delta is the extra window update given by receiver when an application
	// is reading data bigger in size than the inFlow limit.
	delta uint32
	}

	// newLimit updates the inflow window to a new value n.
	// It assumes that n is always greater than the old limit.
	func (f *inFlow) newLimit(n uint32) uint32 {
	f.mu.Lock()
	defer f.mu.Unlock()
	d := n - f.limit
	f.limit = n
	return d
	}

	func (f *inFlow) maybeAdjust(n uint32) uint32 {
	if n > uint32(math.MaxInt32) {
	n = uint32(math.MaxInt32)
	}
	f.mu.Lock()
	defer f.mu.Unlock()
	// estSenderQuota is the receiver's view of the maximum number of bytes the sender
	// can send without a window update.
	estSenderQuota := int32(f.limit - (f.pendingData + f.pendingUpdate))
	// estUntransmittedData is the maximum number of bytes the sends might not have put
	// on the wire yet. A value of 0 or less means that we have already received all or
	// more bytes than the application is requesting to read.
	estUntransmittedData := int32(n - f.pendingData) // Casting into int32 since it could be negative.
	// This implies that unless we send a window update, the sender won't be able to send all the bytes
	// for this message. Therefore we must send an update over the limit since there's an active read
	// request from the application.
	if estUntransmittedData > estSenderQuota {
	// Sender's window shouldn't go more than 2^31 - 1 as speecified in the HTTP spec.
	if f.limit+n > maxWindowSize {
	f.delta = maxWindowSize - f.limit
	} else {
	// Send a window update for the whole message and not just the difference between
	// estUntransmittedData and estSenderQuota. This will be helpful in case the message
	// is padded; We will fallback on the current available window(at least a 1/4th of the limit).
	f.delta = n
	}
	return f.delta
	}
	return 0
	}

	// onData is invoked when some data frame is received. It updates pendingData.
	func (f *inFlow) onData(n uint32) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.pendingData += n
	if f.pendingData+f.pendingUpdate > f.limit+f.delta {
	return fmt.Errorf("received %d-bytes data exceeding the limit %d bytes", f.pendingData+f.pendingUpdate, f.limit)
	}
	return nil
	}

	// onRead is invoked when the application reads the data. It returns the window size
	// to be sent to the peer.
	func (f *inFlow) onRead(n uint32) uint32 {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.pendingData == 0 {
	return 0
	}
	f.pendingData -= n
	if n > f.delta {
	n -= f.delta
	f.delta = 0
	} else {
	f.delta -= n
	n = 0
	}
	f.pendingUpdate += n
	if f.pendingUpdate >= f.limit/4 {
	wu := f.pendingUpdate
	f.pendingUpdate = 0
	return wu
	}
	return 0
	}

	func (f *inFlow) resetPendingUpdate() uint32 {
	f.mu.Lock()
	defer f.mu.Unlock()
	n := f.pendingUpdate
	f.pendingUpdate = 0
	return n
	}