diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/internal/transport/bdp_estimator.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/internal/transport/bdp_estimator.go | 140 |
1 files changed, 0 insertions, 140 deletions
diff --git a/vendor/google.golang.org/grpc/internal/transport/bdp_estimator.go b/vendor/google.golang.org/grpc/internal/transport/bdp_estimator.go deleted file mode 100644 index 63cd262..0000000 --- a/vendor/google.golang.org/grpc/internal/transport/bdp_estimator.go +++ /dev/null @@ -1,140 +0,0 @@ -/* - * - * Copyright 2017 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 ( - "sync" - "time" -) - -const ( - // bdpLimit is the maximum value the flow control windows - // will be increased to. - bdpLimit = (1 << 20) * 4 - // alpha is a constant factor used to keep a moving average - // of RTTs. - alpha = 0.9 - // If the current bdp sample is greater than or equal to - // our beta * our estimated bdp and the current bandwidth - // sample is the maximum bandwidth observed so far, we - // increase our bbp estimate by a factor of gamma. - beta = 0.66 - // To put our bdp to be smaller than or equal to twice the real BDP, - // we should multiply our current sample with 4/3, however to round things out - // we use 2 as the multiplication factor. - gamma = 2 -) - -// Adding arbitrary data to ping so that its ack can be identified. -// Easter-egg: what does the ping message say? -var bdpPing = &ping{data: [8]byte{2, 4, 16, 16, 9, 14, 7, 7}} - -type bdpEstimator struct { - // sentAt is the time when the ping was sent. - sentAt time.Time - - mu sync.Mutex - // bdp is the current bdp estimate. - bdp uint32 - // sample is the number of bytes received in one measurement cycle. - sample uint32 - // bwMax is the maximum bandwidth noted so far (bytes/sec). - bwMax float64 - // bool to keep track of the beginning of a new measurement cycle. - isSent bool - // Callback to update the window sizes. - updateFlowControl func(n uint32) - // sampleCount is the number of samples taken so far. - sampleCount uint64 - // round trip time (seconds) - rtt float64 -} - -// timesnap registers the time bdp ping was sent out so that -// network rtt can be calculated when its ack is received. -// It is called (by controller) when the bdpPing is -// being written on the wire. -func (b *bdpEstimator) timesnap(d [8]byte) { - if bdpPing.data != d { - return - } - b.sentAt = time.Now() -} - -// add adds bytes to the current sample for calculating bdp. -// It returns true only if a ping must be sent. This can be used -// by the caller (handleData) to make decision about batching -// a window update with it. -func (b *bdpEstimator) add(n uint32) bool { - b.mu.Lock() - defer b.mu.Unlock() - if b.bdp == bdpLimit { - return false - } - if !b.isSent { - b.isSent = true - b.sample = n - b.sentAt = time.Time{} - b.sampleCount++ - return true - } - b.sample += n - return false -} - -// calculate is called when an ack for a bdp ping is received. -// Here we calculate the current bdp and bandwidth sample and -// decide if the flow control windows should go up. -func (b *bdpEstimator) calculate(d [8]byte) { - // Check if the ping acked for was the bdp ping. - if bdpPing.data != d { - return - } - b.mu.Lock() - rttSample := time.Since(b.sentAt).Seconds() - if b.sampleCount < 10 { - // Bootstrap rtt with an average of first 10 rtt samples. - b.rtt += (rttSample - b.rtt) / float64(b.sampleCount) - } else { - // Heed to the recent past more. - b.rtt += (rttSample - b.rtt) * float64(alpha) - } - b.isSent = false - // The number of bytes accumulated so far in the sample is smaller - // than or equal to 1.5 times the real BDP on a saturated connection. - bwCurrent := float64(b.sample) / (b.rtt * float64(1.5)) - if bwCurrent > b.bwMax { - b.bwMax = bwCurrent - } - // If the current sample (which is smaller than or equal to the 1.5 times the real BDP) is - // greater than or equal to 2/3rd our perceived bdp AND this is the maximum bandwidth seen so far, we - // should update our perception of the network BDP. - if float64(b.sample) >= beta*float64(b.bdp) && bwCurrent == b.bwMax && b.bdp != bdpLimit { - sampleFloat := float64(b.sample) - b.bdp = uint32(gamma * sampleFloat) - if b.bdp > bdpLimit { - b.bdp = bdpLimit - } - bdp := b.bdp - b.mu.Unlock() - b.updateFlowControl(bdp) - return - } - b.mu.Unlock() -} |