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ConfigStore: clarify intended use

This commit is contained in:
Shivaram Lingamneni 2022-05-03 23:27:24 -04:00
parent c603d41d08
commit 34ad3a2dc1

View File

@ -11,22 +11,23 @@ import (
/*
This can be used to implement the following pattern:
1. Load and munge a config (this can be arbitrarily expensive)
2. Use Set() to install the config
3. Use Get() to access the config
4. As long as any individual config is not modified (by any goroutine)
after the initial call to Set(), this is free of data races, and Get()
1. Prepare a config object (this can be arbitrarily expensive)
2. Take a pointer to the config object and use Set() to install it
3. Use Get() to access the config from any goroutine
4. To update the config, call Set() again with a new prepared config object
5. As long as any individual config object is not modified (by any goroutine)
after it is installed with Set(), this is free of data races, and Get()
is extremely cheap (on amd64 it compiles down to plain MOV instructions).
*/
type ConfigStore[T any] struct {
type ConfigStore[Config any] struct {
ptr unsafe.Pointer
}
func (c *ConfigStore[T]) Get() *T {
return (*T)(atomic.LoadPointer(&c.ptr))
func (c *ConfigStore[Config]) Get() *Config {
return (*Config)(atomic.LoadPointer(&c.ptr))
}
func (c *ConfigStore[T]) Set(ptr *T) {
func (c *ConfigStore[Config]) Set(ptr *Config) {
atomic.StorePointer(&c.ptr, unsafe.Pointer(ptr))
}