/*
 *
 * 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 (
	
	
	
	
)

// writeQuota is a soft limit on the amount of data a stream can
// schedule before some of it is written out.
type writeQuota struct {
	_ noCopy
	// get waits on read from when quota goes less than or equal to zero.
	// replenish writes on it when quota goes positive again.
	ch chan struct{}
	// done is triggered in error case.
	done <-chan struct{}
	// replenish is called by loopyWriter to give quota back to.
	// It is implemented as a field so that it can be updated
	// by tests.
	replenish func(n int)
	quota     int32
}

// init allows a writeQuota to be initialized in-place, which is useful for
// resetting a buffer or for avoiding a heap allocation when the buffer is
// embedded in another struct.
func ( *writeQuota) ( int32,  <-chan struct{}) {
	.quota = 
	.ch = make(chan struct{}, 1)
	.done = 
	.replenish = .realReplenish
}

func ( *writeQuota) ( int32) error {
	for {
		if atomic.LoadInt32(&.quota) > 0 {
			atomic.AddInt32(&.quota, -)
			return nil
		}
		select {
		case <-.ch:
			continue
		case <-.done:
			return errStreamDone
		}
	}
}

func ( *writeQuota) ( int) {
	 := int32()
	 := atomic.AddInt32(&.quota, )
	 :=  - 
	if  <= 0 &&  > 0 {
		select {
		case .ch <- struct{}{}:
		default:
		}
	}
}

type trInFlow struct {
	limit               uint32
	unacked             uint32
	effectiveWindowSize uint32
}

func ( *trInFlow) ( uint32) uint32 {
	 :=  - .limit
	.limit = 
	.updateEffectiveWindowSize()
	return 
}

func ( *trInFlow) ( uint32) uint32 {
	.unacked += 
	if .unacked < .limit/4 {
		.updateEffectiveWindowSize()
		return 0
	}
	return .reset()
}

func ( *trInFlow) () uint32 {
	 := .unacked
	.unacked = 0
	.updateEffectiveWindowSize()
	return 
}

func ( *trInFlow) () {
	atomic.StoreUint32(&.effectiveWindowSize, .limit-.unacked)
}

func ( *trInFlow) () uint32 {
	return atomic.LoadUint32(&.effectiveWindowSize)
}

// TODO(mmukhi): Simplify this code.
// 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 ( *inFlow) ( uint32) {
	.mu.Lock()
	.limit = 
	.mu.Unlock()
}

func ( *inFlow) ( uint32) uint32 {
	if  > uint32(math.MaxInt32) {
		 = uint32(math.MaxInt32)
	}
	.mu.Lock()
	defer .mu.Unlock()
	// estSenderQuota is the receiver's view of the maximum number of bytes the sender
	// can send without a window update.
	 := int32(.limit - (.pendingData + .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.
	 := int32( - .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  >  {
		// Sender's window shouldn't go more than 2^31 - 1 as specified in the HTTP spec.
		if .limit+ > maxWindowSize {
			.delta = maxWindowSize - .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).
			.delta = 
		}
		return .delta
	}
	return 0
}

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

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