Initial checkin from CRI-O repo

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

2 files changed, 297 insertions, 0 deletions

diff --git a/vendor/k8s.io/kubernetes/pkg/util/async/bounded_frequency_runner.go b/vendor/k8s.io/kubernetes/pkg/util/async/bounded_frequency_runner.go
new file mode 100644
index 000000000..da6fc2a4f
--- /dev/null
+++ b/vendor/k8s.io/kubernetes/pkg/util/async/bounded_frequency_runner.go
@@ -0,0 +1,239 @@
+/*
+Copyright 2017 The Kubernetes 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 async
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"k8s.io/client-go/util/flowcontrol"
+
+	"github.com/golang/glog"
+)
+
+// BoundedFrequencyRunner manages runs of a user-provided function.
+// See NewBoundedFrequencyRunner for examples.
+type BoundedFrequencyRunner struct {
+	name        string        // the name of this instance
+	minInterval time.Duration // the min time between runs, modulo bursts
+	maxInterval time.Duration // the max time between runs
+
+	run chan struct{} // try an async run
+
+	mu      sync.Mutex  // guards runs of fn and all mutations
+	fn      func()      // function to run
+	lastRun time.Time   // time of last run
+	timer   timer       // timer for deferred runs
+	limiter rateLimiter // rate limiter for on-demand runs
+}
+
+// designed so that flowcontrol.RateLimiter satisfies
+type rateLimiter interface {
+	TryAccept() bool
+	Stop()
+}
+
+type nullLimiter struct{}
+
+func (nullLimiter) TryAccept() bool {
+	return true
+}
+
+func (nullLimiter) Stop() {}
+
+var _ rateLimiter = nullLimiter{}
+
+// for testing
+type timer interface {
+	// C returns the timer's selectable channel.
+	C() <-chan time.Time
+
+	// See time.Timer.Reset.
+	Reset(d time.Duration) bool
+
+	// See time.Timer.Stop.
+	Stop() bool
+
+	// See time.Now.
+	Now() time.Time
+
+	// See time.Since.
+	Since(t time.Time) time.Duration
+
+	// See time.Sleep.
+	Sleep(d time.Duration)
+}
+
+// implement our timer in terms of std time.Timer.
+type realTimer struct {
+	*time.Timer
+}
+
+func (rt realTimer) C() <-chan time.Time {
+	return rt.Timer.C
+}
+
+func (rt realTimer) Now() time.Time {
+	return time.Now()
+}
+
+func (rt realTimer) Since(t time.Time) time.Duration {
+	return time.Since(t)
+}
+
+func (rt realTimer) Sleep(d time.Duration) {
+	time.Sleep(d)
+}
+
+var _ timer = realTimer{}
+
+// NewBoundedFrequencyRunner creates a new BoundedFrequencyRunner instance,
+// which will manage runs of the specified function.
+//
+// All runs will be async to the caller of BoundedFrequencyRunner.Run, but
+// multiple runs are serialized. If the function needs to hold locks, it must
+// take them internally.
+//
+// Runs of the funtion will have at least minInterval between them (from
+// completion to next start), except that up to bursts may be allowed.  Burst
+// runs are "accumulated" over time, one per minInterval up to burstRuns total.
+// This can be used, for example, to mitigate the impact of expensive operations
+// being called in response to user-initiated operations. Run requests that
+// would violate the minInterval are coallesced and run at the next opportunity.
+//
+// The function will be run at least once per maxInterval. For example, this can
+// force periodic refreshes of state in the absence of anyone calling Run.
+//
+// Examples:
+//
+// NewBoundedFrequencyRunner("name", fn, time.Second, 5*time.Second, 1)
+// - fn will have at least 1 second between runs
+// - fn will have no more than 5 seconds between runs
+//
+// NewBoundedFrequencyRunner("name", fn, 3*time.Second, 10*time.Second, 3)
+// - fn will have at least 3 seconds between runs, with up to 3 burst runs
+// - fn will have no more than 10 seconds between runs
+//
+// The maxInterval must be greater than or equal to the minInterval,  If the
+// caller passes a maxInterval less than minInterval, this function will panic.
+func NewBoundedFrequencyRunner(name string, fn func(), minInterval, maxInterval time.Duration, burstRuns int) *BoundedFrequencyRunner {
+	timer := realTimer{Timer: time.NewTimer(0)} // will tick immediately
+	<-timer.C()                                 // consume the first tick
+	return construct(name, fn, minInterval, maxInterval, burstRuns, timer)
+}
+
+// Make an instance with dependencies injected.
+func construct(name string, fn func(), minInterval, maxInterval time.Duration, burstRuns int, timer timer) *BoundedFrequencyRunner {
+	if maxInterval < minInterval {
+		panic(fmt.Sprintf("%s: maxInterval (%v) must be >= minInterval (%v)", name, minInterval, maxInterval))
+	}
+	if timer == nil {
+		panic(fmt.Sprintf("%s: timer must be non-nil", name))
+	}
+
+	bfr := &BoundedFrequencyRunner{
+		name:        name,
+		fn:          fn,
+		minInterval: minInterval,
+		maxInterval: maxInterval,
+		run:         make(chan struct{}, 1),
+		timer:       timer,
+	}
+	if minInterval == 0 {
+		bfr.limiter = nullLimiter{}
+	} else {
+		// allow burst updates in short succession
+		qps := float32(time.Second) / float32(minInterval)
+		bfr.limiter = flowcontrol.NewTokenBucketRateLimiterWithClock(qps, burstRuns, timer)
+	}
+	return bfr
+}
+
+// Loop handles the periodic timer and run requests.  This is expected to be
+// called as a goroutine.
+func (bfr *BoundedFrequencyRunner) Loop(stop <-chan struct{}) {
+	glog.V(3).Infof("%s Loop running", bfr.name)
+	bfr.timer.Reset(bfr.maxInterval)
+	for {
+		select {
+		case <-stop:
+			bfr.stop()
+			glog.V(3).Infof("%s Loop stopping", bfr.name)
+			return
+		case <-bfr.timer.C():
+			bfr.tryRun()
+		case <-bfr.run:
+			bfr.tryRun()
+		}
+	}
+}
+
+// Run the function as soon as possible.  If this is called while Loop is not
+// running, the call may be deferred indefinitely.
+// If there is already a queued request to call the underlying function, it
+// may be dropped - it is just guaranteed that we will try calling the
+// underlying function as soon as possible starting from now.
+func (bfr *BoundedFrequencyRunner) Run() {
+	// If it takes a lot of time to run the underlying function, noone is really
+	// processing elements from <run> channel. So to avoid blocking here on the
+	// putting element to it, we simply skip it if there is already an element
+	// in it.
+	select {
+	case bfr.run <- struct{}{}:
+	default:
+	}
+}
+
+// assumes the lock is not held
+func (bfr *BoundedFrequencyRunner) stop() {
+	bfr.mu.Lock()
+	defer bfr.mu.Unlock()
+	bfr.limiter.Stop()
+	bfr.timer.Stop()
+}
+
+// assumes the lock is not held
+func (bfr *BoundedFrequencyRunner) tryRun() {
+	bfr.mu.Lock()
+	defer bfr.mu.Unlock()
+
+	if bfr.limiter.TryAccept() {
+		// We're allowed to run the function right now.
+		bfr.fn()
+		bfr.lastRun = bfr.timer.Now()
+		bfr.timer.Stop()
+		bfr.timer.Reset(bfr.maxInterval)
+		glog.V(3).Infof("%s: ran, next possible in %v, periodic in %v", bfr.name, bfr.minInterval, bfr.maxInterval)
+		return
+	}
+
+	// It can't run right now, figure out when it can run next.
+
+	elapsed := bfr.timer.Since(bfr.lastRun)    // how long since last run
+	nextPossible := bfr.minInterval - elapsed  // time to next possible run
+	nextScheduled := bfr.maxInterval - elapsed // time to next periodic run
+	glog.V(4).Infof("%s: %v since last run, possible in %v, scheduled in %v", bfr.name, elapsed, nextPossible, nextScheduled)
+
+	if nextPossible < nextScheduled {
+		// Set the timer for ASAP, but don't drain here.  Assuming Loop is running,
+		// it might get a delivery in the mean time, but that is OK.
+		bfr.timer.Stop()
+		bfr.timer.Reset(nextPossible)
+		glog.V(3).Infof("%s: throttled, scheduling run in %v", bfr.name, nextPossible)
+	}
+}
diff --git a/vendor/k8s.io/kubernetes/pkg/util/async/runner.go b/vendor/k8s.io/kubernetes/pkg/util/async/runner.go
new file mode 100644
index 000000000..924f1d168
--- /dev/null
+++ b/vendor/k8s.io/kubernetes/pkg/util/async/runner.go
@@ -0,0 +1,58 @@
+/*
+Copyright 2014 The Kubernetes 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 async
+
+import (
+	"sync"
+)
+
+// Runner is an abstraction to make it easy to start and stop groups of things that can be
+// described by a single function which waits on a channel close to exit.
+type Runner struct {
+	lock      sync.Mutex
+	loopFuncs []func(stop chan struct{})
+	stop      *chan struct{}
+}
+
+// NewRunner makes a runner for the given function(s). The function(s) should loop until
+// the channel is closed.
+func NewRunner(f ...func(stop chan struct{})) *Runner {
+	return &Runner{loopFuncs: f}
+}
+
+// Start begins running.
+func (r *Runner) Start() {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+	if r.stop == nil {
+		c := make(chan struct{})
+		r.stop = &c
+		for i := range r.loopFuncs {
+			go r.loopFuncs[i](*r.stop)
+		}
+	}
+}
+
+// Stop stops running.
+func (r *Runner) Stop() {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+	if r.stop != nil {
+		close(*r.stop)
+		r.stop = nil
+	}
+}