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Diffstat (limited to 'vendor/google.golang.org/grpc/transport/control.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/transport/control.go | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/transport/control.go b/vendor/google.golang.org/grpc/transport/control.go new file mode 100644 index 0000000..7e9bdf3 --- /dev/null +++ b/vendor/google.golang.org/grpc/transport/control.go @@ -0,0 +1,210 @@ +/* + * + * Copyright 2014, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +package transport + +import ( + "fmt" + "sync" + + "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 + initialConnWindowSize = defaultWindowSize * 16 // for a connection +) + +// 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 +} + +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 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 := "aPool{ + c: make(chan int, 1), + } + if q > 0 { + qb.c <- q + } else { + qb.quota = q + } + return qb +} + +// add adds n to the available quota and tries to send it on acquire. +func (qb *quotaPool) add(n int) { + qb.mu.Lock() + defer qb.mu.Unlock() + qb.quota += n + if qb.quota <= 0 { + return + } + select { + case qb.c <- qb.quota: + qb.quota = 0 + default: + } +} + +// cancel cancels the pending quota sent on acquire, if any. +func (qb *quotaPool) cancel() { + qb.mu.Lock() + defer qb.mu.Unlock() + select { + case n := <-qb.c: + qb.quota += n + default: + } +} + +// reset cancels the pending quota sent on acquired, incremented by v and sends +// it back on acquire. +func (qb *quotaPool) reset(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 + } + 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 { + // The inbound flow control limit for pending data. + limit uint32 + + mu sync.Mutex + // 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 +} + +// 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 { + 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 + f.pendingUpdate += n + if f.pendingUpdate >= f.limit/4 { + wu := f.pendingUpdate + f.pendingUpdate = 0 + return wu + } + return 0 +} + +func (f *inFlow) resetPendingData() uint32 { + f.mu.Lock() + defer f.mu.Unlock() + n := f.pendingData + f.pendingData = 0 + return n +} |