diff --git a/go.mod b/go.mod index 9735fb01..f42ec630 100644 --- a/go.mod +++ b/go.mod @@ -8,6 +8,7 @@ require ( github.com/nats-io/nuid v1.0.1 golang.org/x/crypto v0.0.0-20200323165209-0ec3e9974c59 golang.org/x/sys v0.0.0-20191022100944-742c48ecaeb7 + golang.org/x/time v0.0.0-20200416051211-89c76fbcd5d1 ) go 1.13 diff --git a/go.sum b/go.sum index 43fe0de5..e517d146 100644 --- a/go.sum +++ b/go.sum @@ -39,6 +39,8 @@ golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7w golang.org/x/sys v0.0.0-20191022100944-742c48ecaeb7 h1:HmbHVPwrPEKPGLAcHSrMe6+hqSUlvZU0rab6x5EXfGU= golang.org/x/sys v0.0.0-20191022100944-742c48ecaeb7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs= golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= +golang.org/x/time v0.0.0-20200416051211-89c76fbcd5d1 h1:NusfzzA6yGQ+ua51ck7E3omNUX/JuqbFSaRGqU8CcLI= +golang.org/x/time v0.0.0-20200416051211-89c76fbcd5d1/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ= golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4= golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0= google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8= diff --git a/server/client.go b/server/client.go index 41407f0a..09a7c403 100644 --- a/server/client.go +++ b/server/client.go @@ -868,7 +868,7 @@ func (c *client) flushClients(budget time.Duration) time.Time { continue } - if budget > 0 && cp.flushOutbound() { + if budget > 0 && cp.out.lft < 2*budget && cp.flushOutbound() { budget -= cp.out.lft } else { cp.flushSignal() diff --git a/server/const.go b/server/const.go index 976b73ac..fe09dad4 100644 --- a/server/const.go +++ b/server/const.go @@ -92,7 +92,7 @@ const ( LEN_CR_LF = len(CR_LF) // DEFAULT_FLUSH_DEADLINE is the write/flush deadlines. - DEFAULT_FLUSH_DEADLINE = 2 * time.Second + DEFAULT_FLUSH_DEADLINE = 10 * time.Second // DEFAULT_HTTP_PORT is the default monitoring port. DEFAULT_HTTP_PORT = 8222 diff --git a/server/reload_test.go b/server/reload_test.go index fd7623e2..a5ad4f22 100644 --- a/server/reload_test.go +++ b/server/reload_test.go @@ -149,7 +149,7 @@ func TestConfigReloadUnsupported(t *testing.T) { MaxConn: 65536, PingInterval: 2 * time.Minute, MaxPingsOut: 2, - WriteDeadline: 2 * time.Second, + WriteDeadline: 10 * time.Second, Cluster: ClusterOpts{ Name: "abc", Host: "127.0.0.1", @@ -223,7 +223,7 @@ func TestConfigReloadInvalidConfig(t *testing.T) { MaxConn: 65536, PingInterval: 2 * time.Minute, MaxPingsOut: 2, - WriteDeadline: 2 * time.Second, + WriteDeadline: 10 * time.Second, Cluster: ClusterOpts{ Name: "abc", Host: "127.0.0.1", @@ -289,7 +289,7 @@ func TestConfigReload(t *testing.T) { MaxConn: 65536, PingInterval: 2 * time.Minute, MaxPingsOut: 2, - WriteDeadline: 2 * time.Second, + WriteDeadline: 10 * time.Second, Cluster: ClusterOpts{ Name: "abc", Host: "127.0.0.1", diff --git a/test/norace_test.go b/test/norace_test.go index c147fdb5..8c9617a8 100644 --- a/test/norace_test.go +++ b/test/norace_test.go @@ -20,6 +20,7 @@ import ( "encoding/json" "fmt" "io/ioutil" + "math/rand" "net" "net/url" "os" @@ -718,3 +719,61 @@ func TestNoRaceLeafNodeSmapUpdate(t *testing.T) { // Expect that many LS- checkLS("LS- ", ns) } + +func TestNoRaceSlowProxy(t *testing.T) { + t.Skip() + + opts := DefaultTestOptions + opts.Port = -1 + s := RunServer(&opts) + defer s.Shutdown() + + rttTarget := 22 * time.Millisecond + bwTarget := 10 * 1024 * 1024 / 8 // 10mbit + + sp := newSlowProxy(rttTarget, bwTarget, bwTarget, &opts) + defer sp.Stop() + + nc, err := nats.Connect(sp.ClientURL()) + if err != nil { + t.Fatalf("Unexpected error: %v", err) + } + defer nc.Close() + + doRTT := func() time.Duration { + t.Helper() + const samples = 5 + var total time.Duration + for i := 0; i < samples; i++ { + rtt, _ := nc.RTT() + total += rtt + } + return total / samples + } + + rtt := doRTT() + if rtt < rttTarget || rtt > (rttTarget*3/2) { + t.Fatalf("rtt is out of range, target of %v, actual %v", rttTarget, rtt) + } + + // Now test send BW. + const payloadSize = 64 * 1024 + var payload [payloadSize]byte + rand.Read(payload[:]) + + // 5MB total. + bytesSent := (5 * 1024 * 1024) + toSend := bytesSent / payloadSize + + start := time.Now() + for i := 0; i < toSend; i++ { + nc.Publish("z", payload[:]) + } + nc.Flush() + tt := time.Since(start) + bps := float64(bytesSent) / tt.Seconds() + min, max := float64(bwTarget)*0.8, float64(bwTarget)*1.25 + if bps < min || bps > max { + t.Fatalf("bps is off, target is %v, actual is %v", bwTarget, bps) + } +} diff --git a/test/service_latency_test.go b/test/service_latency_test.go index 831056be..b8b07c76 100644 --- a/test/service_latency_test.go +++ b/test/service_latency_test.go @@ -340,10 +340,11 @@ func TestServiceLatencyClientRTTSlowerVsServiceRTT(t *testing.T) { } rtt := 10 * time.Millisecond - sp, opts := newSlowProxy(rtt+5*time.Millisecond, sopts) + bw := 1024 * 1024 + sp := newSlowProxy(rtt+5*time.Millisecond, bw, bw, sopts) defer sp.Stop() - nc2 := clientConnect(t, opts, "bar") + nc2 := clientConnect(t, sp.Opts(), "bar") defer nc2.Close() start := time.Now() diff --git a/test/test_test.go b/test/test_test.go index 81c99b9a..46d2d599 100644 --- a/test/test_test.go +++ b/test/test_test.go @@ -1,4 +1,4 @@ -// Copyright 2016-2018 The NATS Authors +// Copyright 2016-2020 The NATS 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 @@ -14,6 +14,7 @@ package test import ( + "context" "fmt" "net" "strconv" @@ -23,6 +24,7 @@ import ( "time" "github.com/nats-io/nats-server/v2/server" + "golang.org/x/time/rate" ) func checkFor(t *testing.T, totalWait, sleepDur time.Duration, f func() error) { @@ -41,13 +43,15 @@ func checkFor(t *testing.T, totalWait, sleepDur time.Duration, f func() error) { } } -// Slow Proxy - really crude but works for introducing simple RTT delays. +// Slow Proxy - For introducing RTT and BW constraints. type slowProxy struct { listener net.Listener conns []net.Conn + opts *server.Options + u string } -func newSlowProxy(latency time.Duration, opts *server.Options) (*slowProxy, *server.Options) { +func newSlowProxy(rtt time.Duration, up, down int, opts *server.Options) *slowProxy { saddr := net.JoinHostPort(opts.Host, strconv.Itoa(opts.Port)) hp := net.JoinHostPort("127.0.0.1", "0") l, e := net.Listen("tcp", hp) @@ -66,22 +70,44 @@ func newSlowProxy(latency time.Duration, opts *server.Options) (*slowProxy, *ser panic("Can't connect to server") } sp.conns = append(sp.conns, client, server) - go sp.loop(latency, client, server) - go sp.loop(latency, server, client) + go sp.loop(rtt, up, client, server) + go sp.loop(rtt, down, server, client) }() - sopts := &server.Options{Host: "127.0.0.1", Port: port} - return sp, sopts + sp.opts = &server.Options{Host: "127.0.0.1", Port: port} + sp.u = fmt.Sprintf("nats://%s:%d", sp.opts.Host, sp.opts.Port) + return sp } -func (sp *slowProxy) loop(latency time.Duration, r, w net.Conn) { - delay := latency / 2 - for { - var buf [1024]byte +func (sp *slowProxy) Opts() *server.Options { + return sp.opts +} + +func (sp *slowProxy) ClientURL() string { + return sp.u +} + +func (sp *slowProxy) loop(rtt time.Duration, tbw int, r, w net.Conn) { + delay := rtt / 2 + const rbl = 1024 + var buf [rbl]byte + ctx := context.Background() + + rl := rate.NewLimiter(rate.Limit(tbw), rbl) + + for fr := true; ; { + sr := time.Now() n, err := r.Read(buf[:]) if err != nil { return } - time.Sleep(delay) + // RTT delays + if fr || time.Since(sr) > 2*time.Millisecond { + fr = false + time.Sleep(delay) + } + if err := rl.WaitN(ctx, n); err != nil { + return + } if _, err = w.Write(buf[:n]); err != nil { return } diff --git a/vendor/golang.org/x/time/AUTHORS b/vendor/golang.org/x/time/AUTHORS new file mode 100644 index 00000000..15167cd7 --- /dev/null +++ b/vendor/golang.org/x/time/AUTHORS @@ -0,0 +1,3 @@ +# This source code refers to The Go Authors for copyright purposes. +# The master list of authors is in the main Go distribution, +# visible at http://tip.golang.org/AUTHORS. diff --git a/vendor/golang.org/x/time/CONTRIBUTORS b/vendor/golang.org/x/time/CONTRIBUTORS new file mode 100644 index 00000000..1c4577e9 --- /dev/null +++ b/vendor/golang.org/x/time/CONTRIBUTORS @@ -0,0 +1,3 @@ +# This source code was written by the Go contributors. +# The master list of contributors is in the main Go distribution, +# visible at http://tip.golang.org/CONTRIBUTORS. diff --git a/vendor/golang.org/x/time/LICENSE b/vendor/golang.org/x/time/LICENSE new file mode 100644 index 00000000..6a66aea5 --- /dev/null +++ b/vendor/golang.org/x/time/LICENSE @@ -0,0 +1,27 @@ +Copyright (c) 2009 The Go Authors. 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. diff --git a/vendor/golang.org/x/time/PATENTS b/vendor/golang.org/x/time/PATENTS new file mode 100644 index 00000000..73309904 --- /dev/null +++ b/vendor/golang.org/x/time/PATENTS @@ -0,0 +1,22 @@ +Additional IP Rights Grant (Patents) + +"This implementation" means the copyrightable works distributed by +Google as part of the Go project. + +Google hereby grants to You a perpetual, worldwide, non-exclusive, +no-charge, royalty-free, irrevocable (except as stated in this section) +patent license to make, have made, use, offer to sell, sell, import, +transfer and otherwise run, modify and propagate the contents of this +implementation of Go, where such license applies only to those patent +claims, both currently owned or controlled by Google and acquired in +the future, licensable by Google that are necessarily infringed by this +implementation of Go. This grant does not include claims that would be +infringed only as a consequence of further modification of this +implementation. If you or your agent or exclusive licensee institute or +order or agree to the institution of patent litigation against any +entity (including a cross-claim or counterclaim in a lawsuit) alleging +that this implementation of Go or any code incorporated within this +implementation of Go constitutes direct or contributory patent +infringement, or inducement of patent infringement, then any patent +rights granted to you under this License for this implementation of Go +shall terminate as of the date such litigation is filed. diff --git a/vendor/golang.org/x/time/rate/rate.go b/vendor/golang.org/x/time/rate/rate.go new file mode 100644 index 00000000..a114b1aa --- /dev/null +++ b/vendor/golang.org/x/time/rate/rate.go @@ -0,0 +1,400 @@ +// Copyright 2015 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package rate provides a rate limiter. +package rate + +import ( + "context" + "fmt" + "math" + "sync" + "time" +) + +// Limit defines the maximum frequency of some events. +// Limit is represented as number of events per second. +// A zero Limit allows no events. +type Limit float64 + +// Inf is the infinite rate limit; it allows all events (even if burst is zero). +const Inf = Limit(math.MaxFloat64) + +// Every converts a minimum time interval between events to a Limit. +func Every(interval time.Duration) Limit { + if interval <= 0 { + return Inf + } + return 1 / Limit(interval.Seconds()) +} + +// A Limiter controls how frequently events are allowed to happen. +// It implements a "token bucket" of size b, initially full and refilled +// at rate r tokens per second. +// Informally, in any large enough time interval, the Limiter limits the +// rate to r tokens per second, with a maximum burst size of b events. +// As a special case, if r == Inf (the infinite rate), b is ignored. +// See https://en.wikipedia.org/wiki/Token_bucket for more about token buckets. +// +// The zero value is a valid Limiter, but it will reject all events. +// Use NewLimiter to create non-zero Limiters. +// +// Limiter has three main methods, Allow, Reserve, and Wait. +// Most callers should use Wait. +// +// Each of the three methods consumes a single token. +// They differ in their behavior when no token is available. +// If no token is available, Allow returns false. +// If no token is available, Reserve returns a reservation for a future token +// and the amount of time the caller must wait before using it. +// If no token is available, Wait blocks until one can be obtained +// or its associated context.Context is canceled. +// +// The methods AllowN, ReserveN, and WaitN consume n tokens. +type Limiter struct { + limit Limit + burst int + + mu sync.Mutex + tokens float64 + // last is the last time the limiter's tokens field was updated + last time.Time + // lastEvent is the latest time of a rate-limited event (past or future) + lastEvent time.Time +} + +// Limit returns the maximum overall event rate. +func (lim *Limiter) Limit() Limit { + lim.mu.Lock() + defer lim.mu.Unlock() + return lim.limit +} + +// Burst returns the maximum burst size. Burst is the maximum number of tokens +// that can be consumed in a single call to Allow, Reserve, or Wait, so higher +// Burst values allow more events to happen at once. +// A zero Burst allows no events, unless limit == Inf. +func (lim *Limiter) Burst() int { + return lim.burst +} + +// NewLimiter returns a new Limiter that allows events up to rate r and permits +// bursts of at most b tokens. +func NewLimiter(r Limit, b int) *Limiter { + return &Limiter{ + limit: r, + burst: b, + } +} + +// Allow is shorthand for AllowN(time.Now(), 1). +func (lim *Limiter) Allow() bool { + return lim.AllowN(time.Now(), 1) +} + +// AllowN reports whether n events may happen at time now. +// Use this method if you intend to drop / skip events that exceed the rate limit. +// Otherwise use Reserve or Wait. +func (lim *Limiter) AllowN(now time.Time, n int) bool { + return lim.reserveN(now, n, 0).ok +} + +// A Reservation holds information about events that are permitted by a Limiter to happen after a delay. +// A Reservation may be canceled, which may enable the Limiter to permit additional events. +type Reservation struct { + ok bool + lim *Limiter + tokens int + timeToAct time.Time + // This is the Limit at reservation time, it can change later. + limit Limit +} + +// OK returns whether the limiter can provide the requested number of tokens +// within the maximum wait time. If OK is false, Delay returns InfDuration, and +// Cancel does nothing. +func (r *Reservation) OK() bool { + return r.ok +} + +// Delay is shorthand for DelayFrom(time.Now()). +func (r *Reservation) Delay() time.Duration { + return r.DelayFrom(time.Now()) +} + +// InfDuration is the duration returned by Delay when a Reservation is not OK. +const InfDuration = time.Duration(1<<63 - 1) + +// DelayFrom returns the duration for which the reservation holder must wait +// before taking the reserved action. Zero duration means act immediately. +// InfDuration means the limiter cannot grant the tokens requested in this +// Reservation within the maximum wait time. +func (r *Reservation) DelayFrom(now time.Time) time.Duration { + if !r.ok { + return InfDuration + } + delay := r.timeToAct.Sub(now) + if delay < 0 { + return 0 + } + return delay +} + +// Cancel is shorthand for CancelAt(time.Now()). +func (r *Reservation) Cancel() { + r.CancelAt(time.Now()) + return +} + +// CancelAt indicates that the reservation holder will not perform the reserved action +// and reverses the effects of this Reservation on the rate limit as much as possible, +// considering that other reservations may have already been made. +func (r *Reservation) CancelAt(now time.Time) { + if !r.ok { + return + } + + r.lim.mu.Lock() + defer r.lim.mu.Unlock() + + if r.lim.limit == Inf || r.tokens == 0 || r.timeToAct.Before(now) { + return + } + + // calculate tokens to restore + // The duration between lim.lastEvent and r.timeToAct tells us how many tokens were reserved + // after r was obtained. These tokens should not be restored. + restoreTokens := float64(r.tokens) - r.limit.tokensFromDuration(r.lim.lastEvent.Sub(r.timeToAct)) + if restoreTokens <= 0 { + return + } + // advance time to now + now, _, tokens := r.lim.advance(now) + // calculate new number of tokens + tokens += restoreTokens + if burst := float64(r.lim.burst); tokens > burst { + tokens = burst + } + // update state + r.lim.last = now + r.lim.tokens = tokens + if r.timeToAct == r.lim.lastEvent { + prevEvent := r.timeToAct.Add(r.limit.durationFromTokens(float64(-r.tokens))) + if !prevEvent.Before(now) { + r.lim.lastEvent = prevEvent + } + } + + return +} + +// Reserve is shorthand for ReserveN(time.Now(), 1). +func (lim *Limiter) Reserve() *Reservation { + return lim.ReserveN(time.Now(), 1) +} + +// ReserveN returns a Reservation that indicates how long the caller must wait before n events happen. +// The Limiter takes this Reservation into account when allowing future events. +// The returned Reservation’s OK() method returns false if n exceeds the Limiter's burst size. +// Usage example: +// r := lim.ReserveN(time.Now(), 1) +// if !r.OK() { +// // Not allowed to act! Did you remember to set lim.burst to be > 0 ? +// return +// } +// time.Sleep(r.Delay()) +// Act() +// Use this method if you wish to wait and slow down in accordance with the rate limit without dropping events. +// If you need to respect a deadline or cancel the delay, use Wait instead. +// To drop or skip events exceeding rate limit, use Allow instead. +func (lim *Limiter) ReserveN(now time.Time, n int) *Reservation { + r := lim.reserveN(now, n, InfDuration) + return &r +} + +// Wait is shorthand for WaitN(ctx, 1). +func (lim *Limiter) Wait(ctx context.Context) (err error) { + return lim.WaitN(ctx, 1) +} + +// WaitN blocks until lim permits n events to happen. +// It returns an error if n exceeds the Limiter's burst size, the Context is +// canceled, or the expected wait time exceeds the Context's Deadline. +// The burst limit is ignored if the rate limit is Inf. +func (lim *Limiter) WaitN(ctx context.Context, n int) (err error) { + lim.mu.Lock() + burst := lim.burst + limit := lim.limit + lim.mu.Unlock() + + if n > burst && limit != Inf { + return fmt.Errorf("rate: Wait(n=%d) exceeds limiter's burst %d", n, lim.burst) + } + // Check if ctx is already cancelled + select { + case <-ctx.Done(): + return ctx.Err() + default: + } + // Determine wait limit + now := time.Now() + waitLimit := InfDuration + if deadline, ok := ctx.Deadline(); ok { + waitLimit = deadline.Sub(now) + } + // Reserve + r := lim.reserveN(now, n, waitLimit) + if !r.ok { + return fmt.Errorf("rate: Wait(n=%d) would exceed context deadline", n) + } + // Wait if necessary + delay := r.DelayFrom(now) + if delay == 0 { + return nil + } + t := time.NewTimer(delay) + defer t.Stop() + select { + case <-t.C: + // We can proceed. + return nil + case <-ctx.Done(): + // Context was canceled before we could proceed. Cancel the + // reservation, which may permit other events to proceed sooner. + r.Cancel() + return ctx.Err() + } +} + +// SetLimit is shorthand for SetLimitAt(time.Now(), newLimit). +func (lim *Limiter) SetLimit(newLimit Limit) { + lim.SetLimitAt(time.Now(), newLimit) +} + +// SetLimitAt sets a new Limit for the limiter. The new Limit, and Burst, may be violated +// or underutilized by those which reserved (using Reserve or Wait) but did not yet act +// before SetLimitAt was called. +func (lim *Limiter) SetLimitAt(now time.Time, newLimit Limit) { + lim.mu.Lock() + defer lim.mu.Unlock() + + now, _, tokens := lim.advance(now) + + lim.last = now + lim.tokens = tokens + lim.limit = newLimit +} + +// SetBurst is shorthand for SetBurstAt(time.Now(), newBurst). +func (lim *Limiter) SetBurst(newBurst int) { + lim.SetBurstAt(time.Now(), newBurst) +} + +// SetBurstAt sets a new burst size for the limiter. +func (lim *Limiter) SetBurstAt(now time.Time, newBurst int) { + lim.mu.Lock() + defer lim.mu.Unlock() + + now, _, tokens := lim.advance(now) + + lim.last = now + lim.tokens = tokens + lim.burst = newBurst +} + +// reserveN is a helper method for AllowN, ReserveN, and WaitN. +// maxFutureReserve specifies the maximum reservation wait duration allowed. +// reserveN returns Reservation, not *Reservation, to avoid allocation in AllowN and WaitN. +func (lim *Limiter) reserveN(now time.Time, n int, maxFutureReserve time.Duration) Reservation { + lim.mu.Lock() + + if lim.limit == Inf { + lim.mu.Unlock() + return Reservation{ + ok: true, + lim: lim, + tokens: n, + timeToAct: now, + } + } + + now, last, tokens := lim.advance(now) + + // Calculate the remaining number of tokens resulting from the request. + tokens -= float64(n) + + // Calculate the wait duration + var waitDuration time.Duration + if tokens < 0 { + waitDuration = lim.limit.durationFromTokens(-tokens) + } + + // Decide result + ok := n <= lim.burst && waitDuration <= maxFutureReserve + + // Prepare reservation + r := Reservation{ + ok: ok, + lim: lim, + limit: lim.limit, + } + if ok { + r.tokens = n + r.timeToAct = now.Add(waitDuration) + } + + // Update state + if ok { + lim.last = now + lim.tokens = tokens + lim.lastEvent = r.timeToAct + } else { + lim.last = last + } + + lim.mu.Unlock() + return r +} + +// advance calculates and returns an updated state for lim resulting from the passage of time. +// lim is not changed. +func (lim *Limiter) advance(now time.Time) (newNow time.Time, newLast time.Time, newTokens float64) { + last := lim.last + if now.Before(last) { + last = now + } + + // Avoid making delta overflow below when last is very old. + maxElapsed := lim.limit.durationFromTokens(float64(lim.burst) - lim.tokens) + elapsed := now.Sub(last) + if elapsed > maxElapsed { + elapsed = maxElapsed + } + + // Calculate the new number of tokens, due to time that passed. + delta := lim.limit.tokensFromDuration(elapsed) + tokens := lim.tokens + delta + if burst := float64(lim.burst); tokens > burst { + tokens = burst + } + + return now, last, tokens +} + +// durationFromTokens is a unit conversion function from the number of tokens to the duration +// of time it takes to accumulate them at a rate of limit tokens per second. +func (limit Limit) durationFromTokens(tokens float64) time.Duration { + seconds := tokens / float64(limit) + return time.Nanosecond * time.Duration(1e9*seconds) +} + +// tokensFromDuration is a unit conversion function from a time duration to the number of tokens +// which could be accumulated during that duration at a rate of limit tokens per second. +func (limit Limit) tokensFromDuration(d time.Duration) float64 { + // Split the integer and fractional parts ourself to minimize rounding errors. + // See golang.org/issues/34861. + sec := float64(d/time.Second) * float64(limit) + nsec := float64(d%time.Second) * float64(limit) + return sec + nsec/1e9 +} diff --git a/vendor/modules.txt b/vendor/modules.txt index 6a05436b..0da14cfa 100644 --- a/vendor/modules.txt +++ b/vendor/modules.txt @@ -22,3 +22,5 @@ golang.org/x/sys/windows/registry golang.org/x/sys/windows/svc golang.org/x/sys/windows/svc/eventlog golang.org/x/sys/windows/svc/mgr +# golang.org/x/time v0.0.0-20200416051211-89c76fbcd5d1 +golang.org/x/time/rate