github.com/m3db/m3@v1.5.0/src/aggregator/runtime/options_manager.go (about)

     1  // Copyright (c) 2017 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package runtime
    22  
    23  import (
    24  	xresource "github.com/m3db/m3/src/x/resource"
    25  	"github.com/m3db/m3/src/x/watch"
    26  )
    27  
    28  // OptionsManager manages runtime options.
    29  type OptionsManager interface {
    30  	// SetRuntimeOptions sets the runtime options.
    31  	SetRuntimeOptions(value Options)
    32  
    33  	// RuntimeOptions returns the current runtime options.
    34  	RuntimeOptions() Options
    35  
    36  	// RegisterWatcher registers a watcher that watches updates to runtime options.
    37  	// When an update arrives, the manager will deliver the update to all registered
    38  	// watchers.
    39  	RegisterWatcher(l OptionsWatcher) xresource.SimpleCloser
    40  
    41  	// Close closes the watcher and all descendent watches
    42  	Close()
    43  }
    44  
    45  // OptionsWatcher watches for updates to runtime options.
    46  type OptionsWatcher interface {
    47  	// SetRuntimeOptions is called for registerer watchers when the runtime options
    48  	// are updated, passing in the updated options as the argument.
    49  	SetRuntimeOptions(value Options)
    50  }
    51  
    52  type optionsManager struct {
    53  	watchable watch.Watchable
    54  }
    55  
    56  // NewOptionsManager creates a new runtime options manager.
    57  func NewOptionsManager(initialValue Options) OptionsManager {
    58  	watchable := watch.NewWatchable()
    59  	watchable.Update(initialValue)
    60  	return &optionsManager{
    61  		watchable: watchable,
    62  	}
    63  }
    64  
    65  func (w *optionsManager) SetRuntimeOptions(value Options) {
    66  	w.watchable.Update(value)
    67  }
    68  
    69  func (w *optionsManager) RuntimeOptions() Options {
    70  	return w.watchable.Get().(Options)
    71  }
    72  
    73  func (w *optionsManager) RegisterWatcher(
    74  	watcher OptionsWatcher,
    75  ) xresource.SimpleCloser {
    76  	_, watch, _ := w.watchable.Watch()
    77  
    78  	// The watchable is always initialized so it's okay to do a blocking read.
    79  	<-watch.C()
    80  
    81  	// Deliver the current runtime options.
    82  	watcher.SetRuntimeOptions(watch.Get().(Options))
    83  
    84  	// Spawn a new goroutine that will terminate when the
    85  	// watchable terminates on the close of the runtime options manager.
    86  	go func() {
    87  		for range watch.C() {
    88  			watcher.SetRuntimeOptions(watch.Get().(Options))
    89  		}
    90  	}()
    91  
    92  	return watch
    93  }
    94  
    95  func (w *optionsManager) Close() {
    96  	w.watchable.Close()
    97  }