store

type Store interface {
	Init(conf string) error

	// AppGetConfig is used by the app to get the value of the key in APP.
	//
	// If the time is 0 or negative, it should return the latest value.
	// Or it should return the value at the provided time.
	AppGetConfig(dc, env, app, key string, _time int64) (v string, err error)

	// CreateDcAndEnv creates the new dc and env.
	//
	// If the dc and evn has existed, it either returns ErrExist or do nothing,
	// Which is determined by the implementation.
	CreateDcAndEnv(dc, env string) error

	// DeleteConfig deletes the config by the provided information.
	//
	//   1. dc must not be empty.
	//   2. If env is "", it should delete the whole dc.
	//   3. If app is "", it should delete the whole env.
	//   4. If key is "", it should delete the whole app.
	//   5. If _time is 0 or negative, it should delete the whole key.
	//
	// Notice: you can consider them as "/dc/env/app/key/_time".
	DeleteConfig(dc, env, app, key string, _time int64) error

	// GetAllDcAndEnvs returns all dc and env. The key is dc, and the value is
	// the all envs in the dc.
	GetAllDcAndEnvs() (map[string][]string, error)

	// SetKeyValue sets the key-value in dc, evn and app.
	//
	// If the key has not existed, it will create it; Or append it with a new
	// timestamp.
	SetKeyValue(dc, env, app, key, value string) error

	// GetAllApps returns the names of all apps in dc and env.
	//
	// If search is not "", it will return those apps the name of which contains
	// search.
	//
	// page is the ith page, and number the number of the apps in one page.
	GetAllApps(dc, env, search string, page, number int64) (int64, []string, error)

	// GetAllKeys returns the names of all keys in dc, env and app.
	//
	// If search is not "", it will return those keys the name of which contains
	// search.
	//
	// page is the ith page, and number the number of the apps in one page.
	GetAllKeys(dc, env, app, search string, page, number int64) (int64, []string, error)

	// GetAllValues returns the values of all keys in dc, env and app.
	//
	// page is the ith page, and number the number of the apps in one page.
	//
	// from and to is the start and end time to filte the values.
	GetAllValues(dc, env, app, key string, page, number, from, to int64) (int64, map[int64]string, error)

	// AddCallback adds a callback notification for a certain key of app
	// in dc and env.
	AddCallback(dc, env, app, key, id, callback string) error

	// GetCallback returns all the callback notifications of a key of app
	// in dc and env.
	//
	// The result is a map, the key of which is the registered id,
	// and the value of that is the callback value.
	GetCallback(dc, env, app, key string) (map[string]string, error)

	// DeleteCallback deletes all the callback notifications of the key of app
	// in dc and env.
	//
	// If id is not "", only delete the callback notification identified by id.
	DeleteCallback(dc, env, app, key, id string) error

	// AddCallbackResult adds the callback result into the store.
	//
	// If the callback is successful, result is "". Or it's the error string.
	//
	// Notice: when adding the callback result, the implementation must record
	// the time.
	AddCallbackResult(dc, env, app, key, id, callback, result string) error

	// GetCallbackResult returns the callback result.
	//
	// The result is an array, each element of which is three-tuples. The first
	// is the unixstamp time, the second is the callback address, and the second
	// is the result. If the callback is successful, the result is "".
	// Or it is the error string.
	//
	// Notice: There may be hundreds of the callback results. But they all are
	// not returned overall. The number is decided by the implementation.
	// In general, suggest most recent 20.
	GetCallbackResult(dc, env, app, key, id string) ([][3]string, error)
}

type ZkLoggerFunc func(string, ...interface{})