rclone/vendor/github.com/spacemonkeygo/monkit/v3/task.go
2020-05-12 15:56:50 +00:00

75 lines
2.3 KiB
Go

// Copyright (C) 2015 Space Monkey, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package monkit
import (
"time"
)
type taskKey int
const taskGetFunc taskKey = 0
type taskSecretT struct{}
func (*taskSecretT) Value(key interface{}) interface{} { return nil }
func (*taskSecretT) Done() <-chan struct{} { return nil }
func (*taskSecretT) Err() error { return nil }
func (*taskSecretT) Deadline() (time.Time, bool) {
return time.Time{}, false
}
// Func returns the Func associated with the Task
func (f Task) Func() (out *Func) {
// we're doing crazy things to make a function have methods that do other
// things with internal state. basically, we have a secret argument we can
// pass to the function that is only checked if ctx is taskSecret (
// which it should never be) that controls what other behavior we want.
// in this case, if arg[0] is taskGetFunc, then f will place the func in the
// out location.
// since someone can cast any function of this signature to a lazy task,
// let's make sure we got roughly expected behavior and panic otherwise
if f(&taskSecret, taskGetFunc, &out) != nil || out == nil {
panic("Func() called on a non-Task function")
}
return out
}
func taskArgs(f *Func, args []interface{}) bool {
// this function essentially does method dispatch for Tasks. returns true
// if a method got dispatched and normal behavior should be aborted
if len(args) != 2 {
return false
}
val, ok := args[0].(taskKey)
if !ok {
return false
}
switch val {
case taskGetFunc:
*(args[1].(**Func)) = f
return true
}
return false
}
// TaskNamed is like Task except you can choose the name of the associated
// Func.
//
// You may also include any SeriesTags which should be included with the Task.
func (s *Scope) TaskNamed(name string, tags ...SeriesTag) Task {
return s.FuncNamed(name, tags...).Task
}