b134c4b778
This removes the `Close() error` and replaces it with a more modern Stream API that takes a context. This removes boilerplate and makes integration with concurrent code easier. The only downside is that there isn't an explicit cleanup step, but only one function was even using that and it was possible to switch it to a defer in Stream. This also renames the functions from polyfunc to just func which we determine by API not naming.
114 lines
3.3 KiB
Go
114 lines
3.3 KiB
Go
// Mgmt
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// Copyright (C) 2013-2023+ 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 coresys
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import (
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"context"
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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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"github.com/purpleidea/mgmt/util/errwrap"
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)
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const (
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// LoadFuncName 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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LoadFuncName = "load"
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loadSignature = "struct{x1 float; x5 float; x15 float}"
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)
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func init() {
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facts.ModuleRegister(ModuleName, LoadFuncName, func() facts.Fact { return &LoadFact{} }) // must register the fact and name
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}
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// LoadFact is a fact which returns the current system load.
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type LoadFact struct {
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init *facts.Init
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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 *LoadFact) String() string {
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return LoadFuncName
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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 *LoadFact) 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 *LoadFact) Info() *facts.Info {
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return &facts.Info{
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Output: types.NewType(loadSignature),
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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 *LoadFact) Init(init *facts.Init) error {
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obj.init = init
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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 *LoadFact) Stream(ctx context.Context) error {
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defer close(obj.init.Output) // always signal when we're done
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// it seems the different values only update once every 5
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// seconds, so that's as often as we need to refresh this!
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// TODO: lookup this value if it's something configurable
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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 <-ctx.Done():
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return nil
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}
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x1, x5, x15, err := load()
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if err != nil {
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return errwrap.Wrapf(err, "could not read load values")
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}
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st := types.NewStruct(types.NewType(loadSignature))
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for k, v := range map[string]float64{"x1": x1, "x5": x5, "x15": x15} {
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if err := st.Set(k, &types.FloatValue{V: v}); err != nil {
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return errwrap.Wrapf(err, "struct could not set key: `%s`", k)
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}
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}
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select {
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case obj.init.Output <- st:
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// send
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case <-ctx.Done():
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return nil
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}
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}
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}
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