Cond

package sync

import (
   "sync/atomic"
   "unsafe"
)

// Cond implements a condition variable, a rendezvous point
// for goroutines waiting for or announcing the occurrence
// of an event.
//
// Each Cond has an associated Locker L (often a *Mutex or *RWMutex),
// which must be held when changing the condition and
// when calling the Wait method.
//
// A Cond must not be copied after first use.
type Cond struct {
   noCopy noCopy

   // L is held while observing or changing the condition
   L Locker

   notify  notifyList
   checker copyChecker
}

// NewCond returns a new Cond with Locker l.
func NewCond(l Locker) *Cond {
   return &Cond{L: l}
}

Go/src/sync/cond.go:5

// Server is a gRPC server to serve RPC requests.
type Server struct {
   opts serverOptions

   mu  sync.Mutex // guards following
   lis map[net.Listener]bool
   // conns contains all active server transports. It is a map keyed on a
   // listener address with the value being the set of active transports
   // belonging to that listener.
   conns    map[string]map[transport.ServerTransport]bool
   serve    bool
   drain    bool
   cv       *sync.Cond              // signaled when connections close for GracefulStop
   services map[string]*serviceInfo // service name -> service info
   events   trace.EventLog

   quit               *grpcsync.Event
   done               *grpcsync.Event
   channelzRemoveOnce sync.Once
   serveWG            sync.WaitGroup // counts active Serve goroutines for GracefulStop

   channelzID int64 // channelz unique identification number
   czData     *channelzData

   serverWorkerChannels []chan *serverWorkerData
}

google.golang.org/grpc@v1.43.0/server.go:128