github.com/containerd/nerdctl@v1.7.7/pkg/eventutil/eventutil.go (about)

     1  /*
     2     Copyright The containerd Authors.
     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 eventutil
    18  
    19  import (
    20  	"sync"
    21  
    22  	"github.com/containerd/containerd/events"
    23  )
    24  
    25  type eventHandler struct {
    26  	handlers map[string]func(events.Envelope)
    27  	mu       sync.Mutex
    28  }
    29  
    30  // InitEventHandler initializes and returns an eventHandler
    31  func InitEventHandler() *eventHandler { //nolint:revive
    32  	return &eventHandler{handlers: make(map[string]func(events.Envelope))}
    33  }
    34  
    35  func (w *eventHandler) Handle(action string, h func(events.Envelope)) {
    36  	w.mu.Lock()
    37  	w.handlers[action] = h
    38  	w.mu.Unlock()
    39  }
    40  
    41  // Watch ranges over the passed in event chan and processes the events based on the
    42  // handlers created for a given action.
    43  // To stop watching, close the event chan.
    44  func (w *eventHandler) Watch(c <-chan *events.Envelope) {
    45  	for e := range c {
    46  		w.mu.Lock()
    47  		h, exists := w.handlers[e.Topic]
    48  		w.mu.Unlock()
    49  		if !exists {
    50  			continue
    51  		}
    52  		go h(*e)
    53  	}
    54  }