126 lines
4.0 KiB
Go
126 lines
4.0 KiB
Go
// Mgmt
|
|
// Copyright (C) James Shubin and the project contributors
|
|
// Written by James Shubin <james@shubin.ca> and the project contributors
|
|
//
|
|
// This program is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// This program is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with this program. If not, see <https://www.gnu.org/licenses/>.
|
|
//
|
|
// Additional permission under GNU GPL version 3 section 7
|
|
//
|
|
// If you modify this program, or any covered work, by linking or combining it
|
|
// with embedded mcl code and modules (and that the embedded mcl code and
|
|
// modules which link with this program, contain a copy of their source code in
|
|
// the authoritative form) containing parts covered by the terms of any other
|
|
// license, the licensors of this program grant you additional permission to
|
|
// convey the resulting work. Furthermore, the licensors of this program grant
|
|
// the original author, James Shubin, additional permission to update this
|
|
// additional permission if he deems it necessary to achieve the goals of this
|
|
// additional permission.
|
|
|
|
package structs
|
|
|
|
import (
|
|
"context"
|
|
"fmt"
|
|
|
|
"github.com/purpleidea/mgmt/lang/interfaces"
|
|
"github.com/purpleidea/mgmt/lang/types"
|
|
)
|
|
|
|
// ChannelBasedSourceFunc is a Func which receives values from a golang channel
|
|
// and emits them to the downstream nodes.
|
|
type ChannelBasedSourceFunc struct {
|
|
Name string
|
|
Source interfaces.Func // for drawing dashed edges in the Graphviz visualization
|
|
|
|
Chan chan types.Value
|
|
Type *types.Type
|
|
|
|
init *interfaces.Init
|
|
last types.Value // last value received to use for diff
|
|
}
|
|
|
|
// String returns a simple name for this function. This is needed so this struct
|
|
// can satisfy the pgraph.Vertex interface.
|
|
func (obj *ChannelBasedSourceFunc) String() string {
|
|
return "ChannelBasedSourceFunc"
|
|
}
|
|
|
|
// ArgGen returns the Nth arg name for this function.
|
|
func (obj *ChannelBasedSourceFunc) ArgGen(index int) (string, error) {
|
|
return "", fmt.Errorf("the ChannelBasedSourceFunc doesn't have any arguments")
|
|
}
|
|
|
|
// Validate makes sure we've built our struct properly. It is usually unused for
|
|
// normal functions that users can use directly.
|
|
func (obj *ChannelBasedSourceFunc) Validate() error {
|
|
if obj.Chan == nil {
|
|
return fmt.Errorf("the Chan was not set")
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Info returns some static info about itself.
|
|
func (obj *ChannelBasedSourceFunc) Info() *interfaces.Info {
|
|
return &interfaces.Info{
|
|
Pure: false,
|
|
Memo: false,
|
|
Sig: types.NewType(fmt.Sprintf("func() %s", obj.Type)),
|
|
Err: obj.Validate(),
|
|
}
|
|
}
|
|
|
|
// Init runs some startup code for this function.
|
|
func (obj *ChannelBasedSourceFunc) Init(init *interfaces.Init) error {
|
|
obj.init = init
|
|
return nil
|
|
}
|
|
|
|
// Stream returns the changing values that this func has over time.
|
|
func (obj *ChannelBasedSourceFunc) Stream(ctx context.Context) error {
|
|
defer close(obj.init.Output) // the sender closes
|
|
|
|
for {
|
|
select {
|
|
case input, ok := <-obj.Chan:
|
|
if !ok {
|
|
return nil // can't output any more
|
|
}
|
|
|
|
//if obj.last != nil && input.Cmp(obj.last) == nil {
|
|
// continue // value didn't change, skip it
|
|
//}
|
|
obj.last = input // store so we can send after this select
|
|
|
|
case <-ctx.Done():
|
|
return nil
|
|
}
|
|
|
|
select {
|
|
case obj.init.Output <- obj.last: // send
|
|
case <-ctx.Done():
|
|
return nil
|
|
}
|
|
}
|
|
}
|
|
|
|
// XXX: Is it correct to implement this here for this particular function?
|
|
// XXX: tricky since this really receives input from a secret channel...
|
|
// XXX: ADD A MUTEX AROUND READING obj.last ???
|
|
//func (obj *ChannelBasedSourceFunc) Call(ctx context.Context, args []types.Value) (types.Value, error) {
|
|
// if obj.last == nil {
|
|
// return nil, fmt.Errorf("programming error")
|
|
// }
|
|
// return obj.last, nil
|
|
//}
|