feat: kubesphere 4.0 (#6115)

* feat: kubesphere 4.0

Signed-off-by: ci-bot <ci-bot@kubesphere.io>

* feat: kubesphere 4.0

Signed-off-by: ci-bot <ci-bot@kubesphere.io>

---------

Signed-off-by: ci-bot <ci-bot@kubesphere.io>
Co-authored-by: ks-ci-bot <ks-ci-bot@example.com>
Co-authored-by: joyceliu <joyceliu@yunify.com>

vendor/k8s.io/apiserver/pkg/storage/cacher/ready.go

@@ -17,6 +17,7 @@ limitations under the License.
 package cacher
 
 import (
+	"context"
 	"fmt"
 	"sync"
 )
@@ -30,67 +31,127 @@ const (
 )
 
 // ready is a three state condition variable that blocks until is Ready if is not Stopped.
-// Its initial state is Pending.
+// Its initial state is Pending and its state machine diagram is as follow.
+//
+// Pending <------> Ready -----> Stopped
+//
+//	|                           ^
+//	└---------------------------┘
 type ready struct {
-	state status
-	c     *sync.Cond
+	state       status        // represent the state of the variable
+	generation  int           // represent the number of times we have transtioned to ready
+	lock        sync.RWMutex  // protect the state and generation variables
+	restartLock sync.Mutex    // protect the transition from ready to pending where the channel is recreated
+	waitCh      chan struct{} // blocks until is ready or stopped
 }
 
 func newReady() *ready {
 	return &ready{
-		c:     sync.NewCond(&sync.RWMutex{}),
-		state: Pending,
+		waitCh: make(chan struct{}),
+		state:  Pending,
 	}
 }
 
+// done close the channel once the state is Ready or Stopped
+func (r *ready) done() chan struct{} {
+	r.restartLock.Lock()
+	defer r.restartLock.Unlock()
+	return r.waitCh
+}
+
 // wait blocks until it is Ready or Stopped, it returns an error if is Stopped.
-func (r *ready) wait() error {
-	r.c.L.Lock()
-	defer r.c.L.Unlock()
-	for r.state == Pending {
-		r.c.Wait()
-	}
-	switch r.state {
-	case Ready:
-		return nil
-	case Stopped:
-		return fmt.Errorf("apiserver cacher is stopped")
-	default:
-		return fmt.Errorf("unexpected apiserver cache state: %v", r.state)
+func (r *ready) wait(ctx context.Context) error {
+	_, err := r.waitAndReadGeneration(ctx)
+	return err
+}
+
+// waitAndReadGenration blocks until it is Ready or Stopped and returns number
+// of times we entered ready state if Ready and error otherwise.
+func (r *ready) waitAndReadGeneration(ctx context.Context) (int, error) {
+	for {
+		// r.done() only blocks if state is Pending
+		select {
+		case <-ctx.Done():
+			return 0, ctx.Err()
+		case <-r.done():
+		}
+
+		r.lock.RLock()
+		switch r.state {
+		case Pending:
+			// since we allow to switch between the states Pending and Ready
+			// if there is a quick transition from Pending -> Ready -> Pending
+			// a process that was waiting can get unblocked and see a Pending
+			// state again. If the state is Pending we have to wait again to
+			// avoid an inconsistent state on the system, with some processes not
+			// waiting despite the state moved back to Pending.
+			r.lock.RUnlock()
+		case Ready:
+			generation := r.generation
+			r.lock.RUnlock()
+			return generation, nil
+		case Stopped:
+			r.lock.RUnlock()
+			return 0, fmt.Errorf("apiserver cacher is stopped")
+		default:
+			r.lock.RUnlock()
+			return 0, fmt.Errorf("unexpected apiserver cache state: %v", r.state)
+		}
 	}
 }
 
 // check returns true only if it is Ready.
 func (r *ready) check() bool {
-	// TODO: Make check() function more sophisticated, in particular
-	// allow it to behave as "waitWithTimeout".
-	rwMutex := r.c.L.(*sync.RWMutex)
-	rwMutex.RLock()
-	defer rwMutex.RUnlock()
-	return r.state == Ready
+	_, ok := r.checkAndReadGeneration()
+	return ok
+}
+
+// checkAndReadGeneration returns the current generation and whether it is Ready.
+func (r *ready) checkAndReadGeneration() (int, bool) {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
+	return r.generation, r.state == Ready
 }
 
 // set the state to Pending (false) or Ready (true), it does not have effect if the state is Stopped.
 func (r *ready) set(ok bool) {
-	r.c.L.Lock()
-	defer r.c.L.Unlock()
+	r.lock.Lock()
+	defer r.lock.Unlock()
 	if r.state == Stopped {
 		return
 	}
-	if ok {
+	if ok && r.state == Pending {
 		r.state = Ready
-	} else {
+		r.generation++
+		select {
+		case <-r.waitCh:
+		default:
+			close(r.waitCh)
+		}
+	} else if !ok && r.state == Ready {
+		// creating the waitCh can be racy if
+		// something enter the wait() method
+		select {
+		case <-r.waitCh:
+			r.restartLock.Lock()
+			r.waitCh = make(chan struct{})
+			r.restartLock.Unlock()
+		default:
+		}
 		r.state = Pending
 	}
-	r.c.Broadcast()
 }
 
 // stop the condition variable and set it as Stopped. This state is irreversible.
 func (r *ready) stop() {
-	r.c.L.Lock()
-	defer r.c.L.Unlock()
+	r.lock.Lock()
+	defer r.lock.Unlock()
 	if r.state != Stopped {
 		r.state = Stopped
-		r.c.Broadcast()
+	}
+	select {
+	case <-r.waitCh:
+	default:
+		close(r.waitCh)
 	}
 }