lang: core: Remove the unnecessary func suffix
We don't really need these, it's clear what things are.
This commit is contained in:
James Shubin
340
lang/core/value/get.go
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340
lang/core/value/get.go
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@@ -0,0 +1,340 @@
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// Mgmt
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// Copyright (C) 2013-2024+ 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 <https://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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package corevalue
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import (
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"context"
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"fmt"
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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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"github.com/purpleidea/mgmt/util/errwrap"
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)
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const (
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// GetFuncName is the name this function is registered as. This variant
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// is the fanciest version, although type unification is much more
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// difficult when using this.
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// XXX: type unification doesn't work perfectly here yet... maybe a bug with returned structs?
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GetFuncName = "get"
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// GetBoolFuncName is the name this function is registered as. This
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// variant can only pull in values of type bool.
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GetBoolFuncName = "get_bool"
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// GetStrFuncName is the name this function is registered as. This
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// variant can only pull in values of type str.
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GetStrFuncName = "get_str"
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// GetIntFuncName is the name this function is registered as. This
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// variant can only pull in values of type int.
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GetIntFuncName = "get_int"
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// GetFloatFuncName is the name this function is registered as. This
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// variant can only pull in values of type float.
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GetFloatFuncName = "get_float"
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// arg names...
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getArgNameKey = "key"
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// struct field names...
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getFieldNameValue = "value"
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getFieldNameReady = "ready"
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)
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func init() {
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funcs.ModuleRegister(ModuleName, GetFuncName, func() interfaces.Func { return &GetFunc{} })
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funcs.ModuleRegister(ModuleName, GetBoolFuncName, func() interfaces.Func { return &GetFunc{Type: types.TypeBool} })
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funcs.ModuleRegister(ModuleName, GetStrFuncName, func() interfaces.Func { return &GetFunc{Type: types.TypeStr} })
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funcs.ModuleRegister(ModuleName, GetIntFuncName, func() interfaces.Func { return &GetFunc{Type: types.TypeInt} })
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funcs.ModuleRegister(ModuleName, GetFloatFuncName, func() interfaces.Func { return &GetFunc{Type: types.TypeFloat} })
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}
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// GetFunc is special function which looks up the stored `Any` field in the
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// value resource that it gets it from. If it is initialized with a fixed Type
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// field, then it becomes a statically typed version that can only return keys
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// of that type. It is instead recommended to use the Get* functions that are
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// more strictly typed.
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type GetFunc struct {
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// Type is the actual type being used for the value we are looking up.
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Type *types.Type
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init *interfaces.Init
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key string
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last types.Value
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result types.Value // last calculated output
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watchChan chan struct{}
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}
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// String returns a simple name for this function. This is needed so this struct
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// can satisfy the pgraph.Vertex interface.
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func (obj *GetFunc) String() string {
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return GetFuncName
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}
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// ArgGen returns the Nth arg name for this function.
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func (obj *GetFunc) ArgGen(index int) (string, error) {
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seq := []string{getArgNameKey}
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if l := len(seq); index >= l {
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return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
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}
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return seq[index], nil
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}
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// helper
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func (obj *GetFunc) sig() *types.Type {
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// func(key str) struct{value ?1; ready bool}
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typ := "?1"
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if obj.Type != nil {
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typ = obj.Type.String()
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}
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// output is a struct with two fields:
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// value is the zero value if not ready. A bool for that in other field.
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return types.NewType(fmt.Sprintf("func(%s str) struct{%s %s; %s bool}", getArgNameKey, getFieldNameValue, typ, getFieldNameReady))
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}
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// Build is run to turn the polymorphic, undetermined function, into the
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// specific statically typed version. It is usually run after Unify completes,
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// and must be run before Info() and any of the other Func interface methods are
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// used. This function is idempotent, as long as the arg isn't changed between
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// runs.
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func (obj *GetFunc) Build(typ *types.Type) (*types.Type, error) {
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// typ is the KindFunc signature we're trying to build...
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if typ.Kind != types.KindFunc {
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return nil, fmt.Errorf("input type must be of kind func")
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}
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if typ.Map == nil {
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return nil, fmt.Errorf("invalid input type")
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}
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if len(typ.Ord) != 1 {
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return nil, fmt.Errorf("the function needs exactly one arg")
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}
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if typ.Out == nil {
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return nil, fmt.Errorf("return type of function must be specified")
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}
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tKey, exists := typ.Map[typ.Ord[0]]
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if !exists || tKey == nil {
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return nil, fmt.Errorf("first arg must be specified")
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}
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if tKey.Kind != types.KindStr {
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return nil, fmt.Errorf("key must be str kind")
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}
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if typ.Out.Kind != types.KindStruct {
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return nil, fmt.Errorf("return must be kind struct")
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}
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if typ.Out.Map == nil {
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return nil, fmt.Errorf("invalid return type")
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}
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if len(typ.Out.Ord) != 2 {
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return nil, fmt.Errorf("invalid return type")
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}
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tValue, exists := typ.Out.Map[typ.Out.Ord[0]]
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if !exists || tValue == nil {
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return nil, fmt.Errorf("first struct field must be specified")
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}
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tReady, exists := typ.Out.Map[typ.Out.Ord[1]]
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if !exists || tReady == nil {
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return nil, fmt.Errorf("second struct field must be specified")
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}
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if tReady.Kind != types.KindBool {
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return nil, fmt.Errorf("second struct field must be bool kind")
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}
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obj.Type = tValue // type of our value
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return obj.sig(), nil
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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 functions that users can use directly.
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func (obj *GetFunc) 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 *GetFunc) Info() *interfaces.Info {
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var sig *types.Type
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if obj.Type != nil { // don't panic if called speculatively
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sig = obj.sig() // helper
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}
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return &interfaces.Info{
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Pure: false, // definitely false
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Memo: false,
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Sig: sig,
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Err: obj.Validate(),
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}
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}
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// Init runs some startup code for this function.
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func (obj *GetFunc) Init(init *interfaces.Init) error {
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obj.init = init
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obj.watchChan = make(chan struct{}) // sender closes this when Stream ends
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return nil
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}
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// Stream returns the changing values that this func has over time.
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func (obj *GetFunc) Stream(ctx context.Context) error {
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defer close(obj.init.Output) // the sender closes
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ctx, cancel := context.WithCancel(ctx)
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defer cancel() // important so that we cleanup the watch when exiting
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for {
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select {
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// TODO: should this first chan be run as a priority channel to
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// avoid some sort of glitch? is that even possible? can our
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// hostname check with reality (below) fix that?
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case input, ok := <-obj.init.Input:
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if !ok {
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obj.init.Input = nil // don't infinite loop back
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continue // no more inputs, but don't return!
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}
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//if err := input.Type().Cmp(obj.Info().Sig.Input); err != nil {
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// return errwrap.Wrapf(err, "wrong function input")
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//}
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if obj.last != nil && input.Cmp(obj.last) == nil {
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continue // value didn't change, skip it
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}
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obj.last = input // store for next
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key := input.Struct()[getArgNameKey].Str()
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if key == "" {
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return fmt.Errorf("can't use an empty key")
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}
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if obj.init.Debug {
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obj.init.Logf("key: %s", key)
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}
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// We don't support changing the key over time, since it
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// might cause the type to need to be changed.
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if obj.key == "" {
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obj.key = key // store it
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var err error
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// Don't send a value right away, wait for the
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// first ValueWatch startup event to get one!
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obj.watchChan, err = obj.init.Local.ValueWatch(ctx, obj.key) // watch for var changes
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if err != nil {
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return err
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}
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} else if obj.key != key {
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return fmt.Errorf("can't change key, previously: `%s`", obj.key)
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}
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continue // we get values on the watch chan, not here!
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case _, ok := <-obj.watchChan:
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if !ok { // closed
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return nil
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}
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//if err != nil {
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// return errwrap.Wrapf(err, "channel watch failed on `%s`", obj.key)
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//}
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result, err := obj.getValue(ctx) // get the value...
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if err != nil {
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return err
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}
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// if the result is still the same, skip sending an update...
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if obj.result != nil && result.Cmp(obj.result) == nil {
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continue // result didn't change
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}
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obj.result = result // store new result
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case <-ctx.Done():
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return nil
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}
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select {
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case obj.init.Output <- obj.result: // send
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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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}
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}
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// getValue gets the value we're looking for.
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func (obj *GetFunc) getValue(ctx context.Context) (types.Value, error) {
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typ, exists := obj.Info().Sig.Out.Map[getFieldNameValue] // type of value field
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if !exists || typ == nil {
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// programming error
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return nil, fmt.Errorf("missing type for %s field", getFieldNameValue)
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}
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// The API will pull from the on-disk stored cache if present... This
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// value comes from the field in the Value resource... We only have an
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// on-disk cache because since functions load before resources do, we'd
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// like to warm the cache with the right value before the resource can
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// issue a new one to our in-memory store. This avoids a re-provisioning
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// step that might be needed if the value started out empty...
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// TODO: We could even add a stored: bool field in the returned struct!
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isReady := true // assume true
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val, err := obj.init.Local.ValueGet(ctx, obj.key)
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if err != nil {
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return nil, errwrap.Wrapf(err, "channel read failed on `%s`", obj.key)
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}
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if val == nil { // val doesn't exist
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isReady = false
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}
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ready := &types.BoolValue{V: isReady}
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value := typ.New() // new zero value of that typ
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if isReady {
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value, err = types.ValueOfGolang(val) // interface{} -> types.Value
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if err != nil {
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// programming error
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return nil, errwrap.Wrapf(err, "invalid value")
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}
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if err := value.Type().Cmp(typ); err != nil {
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// XXX: when we run get_int, but the resource value is
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// an str for example, this error happens... Do we want
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// to: (1) coerce? -- no; (2) error? -- yep for now; (3)
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// improve type unification? -- if it's possible, yes.
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return nil, errwrap.Wrapf(err, "type mismatch, check type in Value[%s]", obj.key)
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}
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}
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st := types.NewStruct(obj.Info().Sig.Out)
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if err := st.Set(getFieldNameValue, value); err != nil {
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return nil, errwrap.Wrapf(err, "struct could not add field `%s`, val: `%s`", getFieldNameValue, value)
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}
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if err := st.Set(getFieldNameReady, ready); err != nil {
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return nil, errwrap.Wrapf(err, "struct could not add field `%s`, val: `%s`", getFieldNameReady, ready)
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}
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return st, nil // put struct into interface type
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}
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