github.com/mirantis/virtlet@v1.5.2-0.20191204181327-1659b8a48e9b/pkg/utils/wait.go (about)

     1  /*
     2  Copyright 2016 Mirantis
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package utils
    18  
    19  import (
    20  	"fmt"
    21  	"time"
    22  
    23  	"github.com/jonboulle/clockwork"
    24  )
    25  
    26  // WaitLoop executes test func in loop until it returns error, true, or the timeout elapses.
    27  // clock argument denotes a clock object to use for waiting.
    28  // When clock is nil, WaitLoop uses clockwork.NewRealClock()
    29  func WaitLoop(test func() (bool, error), retryPeriod time.Duration, timeout time.Duration, clock clockwork.Clock) error {
    30  	if clock == nil {
    31  		clock = clockwork.NewRealClock()
    32  	}
    33  	for start := clock.Now(); clock.Since(start) < timeout; clock.Sleep(retryPeriod) {
    34  		result, err := test()
    35  		if err != nil {
    36  			return err
    37  		}
    38  		if result {
    39  			return nil
    40  		}
    41  	}
    42  
    43  	return fmt.Errorf("timeout reached")
    44  }