5d664855de
This adds the requirement that all function implementations provider a String() string method so that these can be used as vertices in the pgraph library. If we eventually move to generics for the pgraph DAG, then this might not matter, but it's not bad that these have names either.
109 lines
3.2 KiB
Go
109 lines
3.2 KiB
Go
// Mgmt
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// Copyright (C) 2013-2022+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package coreexample
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import (
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"time"
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"github.com/purpleidea/mgmt/lang/funcs/facts"
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"github.com/purpleidea/mgmt/lang/types"
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)
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const (
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// FlipFlopFuncName is the name this fact is registered as. It's still a
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// Func Name because this is the name space the fact is actually using.
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FlipFlopFuncName = "flipflop"
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)
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func init() {
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facts.ModuleRegister(ModuleName, FlipFlopFuncName, func() facts.Fact { return &FlipFlopFact{} }) // must register the fact and name
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}
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// FlipFlopFact is a fact which flips a bool repeatedly. This is an example fact
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// and is not meant for serious computing. This would be better served by a flip
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// function which you could specify an interval for.
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type FlipFlopFact struct {
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init *facts.Init
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value bool
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closeChan chan struct{}
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}
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// String returns a simple name for this fact. This is needed so this struct can
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// satisfy the pgraph.Vertex interface.
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func (obj *FlipFlopFact) String() string {
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return FlipFlopFuncName
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}
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// Validate makes sure we've built our struct properly. It is usually unused for
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// normal facts that users can use directly.
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//func (obj *FlipFlopFact) Validate() error {
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// return nil
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//}
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// Info returns some static info about itself.
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func (obj *FlipFlopFact) Info() *facts.Info {
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return &facts.Info{
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Output: types.NewType("bool"),
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}
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}
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// Init runs some startup code for this fact.
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func (obj *FlipFlopFact) Init(init *facts.Init) error {
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obj.init = init
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obj.closeChan = make(chan struct{})
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return nil
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}
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// Stream returns the changing values that this fact has over time.
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func (obj *FlipFlopFact) Stream() error {
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defer close(obj.init.Output) // always signal when we're done
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// TODO: don't hard code 5 sec interval
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ticker := time.NewTicker(time.Duration(5) * time.Second)
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// streams must generate an initial event on startup
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startChan := make(chan struct{}) // start signal
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close(startChan) // kick it off!
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defer ticker.Stop()
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for {
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select {
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case <-startChan: // kick the loop once at start
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startChan = nil // disable
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case <-ticker.C: // received the timer event
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// pass
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case <-obj.closeChan:
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return nil
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}
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select {
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case obj.init.Output <- &types.BoolValue{ // flip
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V: obj.value,
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}:
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case <-obj.closeChan:
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return nil
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}
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obj.value = !obj.value // flip it
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}
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}
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// Close runs some shutdown code for this fact and turns off the stream.
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func (obj *FlipFlopFact) Close() error {
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close(obj.closeChan)
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return nil
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}
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