github.com/livekit/protocol@v1.39.3/utils/configobserver.go (about)

     1  // Copyright 2024 LiveKit, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package utils
    16  
    17  import (
    18  	"fmt"
    19  	"os"
    20  
    21  	"github.com/fsnotify/fsnotify"
    22  	"go.uber.org/atomic"
    23  	"gopkg.in/yaml.v3"
    24  
    25  	"github.com/livekit/protocol/logger"
    26  	"github.com/livekit/protocol/utils/events"
    27  )
    28  
    29  type ConfigBuilder[T any] interface {
    30  	New() (*T, error)
    31  }
    32  
    33  type ConfigDefaulter[T any] interface {
    34  	InitDefaults(*T) error
    35  }
    36  
    37  type ConfigObserver[T any] struct {
    38  	builder   ConfigBuilder[T]
    39  	watcher   *fsnotify.Watcher
    40  	observers *events.ObserverList[*T]
    41  	conf      atomic.Pointer[T]
    42  }
    43  
    44  func NewConfigObserver[T any](path string, builder ConfigBuilder[T]) (*ConfigObserver[T], *T, error) {
    45  	c := &ConfigObserver[T]{
    46  		builder:   builder,
    47  		observers: events.NewObserverList[*T](events.WithBlocking()),
    48  	}
    49  
    50  	conf, err := c.load(path)
    51  	if err != nil {
    52  		return nil, nil, err
    53  	}
    54  
    55  	if path != "" {
    56  		c.watcher, err = fsnotify.NewWatcher()
    57  		if err != nil {
    58  			return nil, nil, err
    59  		}
    60  		if err := c.watcher.Add(path); err != nil {
    61  			c.watcher.Close()
    62  			return nil, nil, err
    63  		}
    64  		go c.watch()
    65  	}
    66  
    67  	return c, conf, nil
    68  }
    69  
    70  func (c *ConfigObserver[T]) Close() {
    71  	if c != nil && c.watcher != nil {
    72  		c.watcher.Close()
    73  	}
    74  }
    75  
    76  func (c *ConfigObserver[T]) EmitConfigUpdate(conf *T) {
    77  	c.observers.Emit(conf)
    78  }
    79  
    80  func (c *ConfigObserver[T]) Observe(cb func(*T)) func() {
    81  	if c == nil {
    82  		return func() {}
    83  	}
    84  	return c.observers.On(cb)
    85  }
    86  
    87  func (c *ConfigObserver[T]) Load() *T {
    88  	return c.conf.Load()
    89  }
    90  
    91  func (c *ConfigObserver[T]) watch() {
    92  	for {
    93  		select {
    94  		case event, ok := <-c.watcher.Events:
    95  			if !ok {
    96  				return
    97  			}
    98  			if event.Has(fsnotify.Remove) {
    99  				if err := c.watcher.Add(event.Name); err != nil {
   100  					logger.Errorw("unable to rewatch config file", err, "file", event.Name)
   101  				}
   102  			}
   103  			if event.Has(fsnotify.Write | fsnotify.Remove) {
   104  				if err := c.reload(event.Name); err != nil {
   105  					logger.Errorw("unable to update config file", err, "file", event.Name)
   106  				} else {
   107  					logger.Infow("config file has been updated", "file", event.Name)
   108  				}
   109  			}
   110  		case err, ok := <-c.watcher.Errors:
   111  			if !ok {
   112  				return
   113  			}
   114  			logger.Errorw("config file watcher error", err)
   115  		}
   116  	}
   117  }
   118  
   119  func (c *ConfigObserver[T]) reload(path string) error {
   120  	conf, err := c.load(path)
   121  	if err != nil {
   122  		return err
   123  	}
   124  
   125  	c.EmitConfigUpdate(conf)
   126  	return nil
   127  }
   128  
   129  func (c *ConfigObserver[T]) load(path string) (*T, error) {
   130  	conf, err := c.builder.New()
   131  	if err != nil {
   132  		return nil, err
   133  	}
   134  
   135  	if path != "" {
   136  		b, err := os.ReadFile(path)
   137  		if err != nil {
   138  			return nil, err
   139  		}
   140  
   141  		if len(b) == 0 {
   142  			return nil, fmt.Errorf("cannot parse config: file empty")
   143  		}
   144  
   145  		if err := yaml.Unmarshal(b, conf); err != nil {
   146  			return nil, fmt.Errorf("cannot parse config: %v", err)
   147  		}
   148  	}
   149  
   150  	if d, ok := c.builder.(ConfigDefaulter[T]); ok {
   151  		d.InitDefaults(conf)
   152  	}
   153  
   154  	c.conf.Store(conf)
   155  
   156  	return conf, err
   157  }