88 lines
3.2 KiB
Go
88 lines
3.2 KiB
Go
// Mgmt
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// Copyright (C) 2013-2018+ 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 facts provides a framework for language values that change over time.
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package facts
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import (
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"fmt"
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"github.com/purpleidea/mgmt/engine"
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"github.com/purpleidea/mgmt/lang/funcs"
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"github.com/purpleidea/mgmt/lang/interfaces"
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"github.com/purpleidea/mgmt/lang/types"
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)
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// RegisteredFacts is a global map of all possible facts which can be used. You
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// should never touch this map directly. Use methods like Register instead.
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var RegisteredFacts = make(map[string]func() Fact) // must initialize
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// Register takes a fact and its name and makes it available for use. It is
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// commonly called in the init() method of the fact at program startup. There is
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// no matching Unregister function.
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func Register(name string, fn func() Fact) {
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if _, ok := RegisteredFacts[name]; ok {
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panic(fmt.Sprintf("a fact named %s is already registered", name))
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}
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//gob.Register(fn())
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funcs.Register(name, func() interfaces.Func { // implement in terms of func interface
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return &FactFunc{
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Fact: fn(),
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}
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})
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RegisteredFacts[name] = fn
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}
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// ModuleRegister is exactly like Register, except that it registers within a
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// named module. This is a helper function.
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func ModuleRegister(module, name string, fn func() Fact) {
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Register(module+funcs.ModuleSep+name, fn)
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}
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// Info is a static representation of some information about the fact. It is
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// used for static analysis and type checking. If you break this contract, you
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// might cause a panic.
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type Info struct {
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Output *types.Type // output value type (must not change over time!)
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Err error // did this fact validate?
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}
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// Init is the structure of values and references which is passed into all
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// facts on initialization.
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type Init struct {
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Hostname string // uuid for the host
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//Noop bool
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Output chan types.Value // Stream must close `output` chan
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World engine.World
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Debug bool
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Logf func(format string, v ...interface{})
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}
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// Fact is the interface that any valid fact must fulfill. It is very simple,
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// but still event driven. Facts should attempt to only send values when they
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// have changed.
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// TODO: should we support a static version of this interface for facts that
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// never change to avoid the overhead of the goroutine and channel listener?
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// TODO: should we move this to the interface package?
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type Fact interface {
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//Validate() error // currently not needed since no facts are internal
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Info() *Info
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Init(*Init) error
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Stream() error
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Close() error
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}
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