58998f9cab
Since we'll want to use them elsewhere, we should make these helper functions. It also makes the code look a lot neater. Unfortunately, it adds a bit more indirection, but this isn't a critical flaw here.
103 lines
4.1 KiB
Go
103 lines
4.1 KiB
Go
// Mgmt
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// Copyright (C) 2013-2021+ 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 engine
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// SendableRes is the interface a resource must implement to support sending
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// named parameters. You must specify to the engine what kind of values (and
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// with their types) you will be sending. This is used for static type checking.
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// Formerly, you had to make sure not to overwrite omitted parameters, otherwise
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// it will be as if you've now declared a fixed state for that param. For that
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// example, if a parameter `Foo string` had the zero value to mean that it was
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// undefined, and you learned that the value is actually `up`, then sending on
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// that param would cause that state to be managed, when it was previously not.
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// This new interface actually provides a different namespace for sending keys.
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type SendableRes interface {
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Res // implement everything in Res but add the additional requirements
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// Sends returns a struct containing the defaults of the type we send.
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Sends() interface{}
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// Send is used in CheckApply to send the desired data. It returns an
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// error if the data is malformed or doesn't type check. You should use
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// the GenerateSendFunc helper function to build this function for use
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// in the resource internal state handle.
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Send(st interface{}) error
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// Sent returns the most recently sent data. This is used by the engine.
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Sent() interface{}
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}
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// RecvableRes is the interface a resource must implement to support receiving
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// on public parameters. The resource only has to include the correct trait for
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// this interface to be fulfilled, as no additional methods need to be added. To
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// get information about received changes, you can use the Recv method from the
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// input API that comes in via Init.
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type RecvableRes interface {
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Res
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// SetRecv stores the map of sendable data which should arrive here. It
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// is called by the GAPI when building the resource.
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SetRecv(recv map[string]*Send)
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// Recv is used by the resource to get information on changes. This data
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// can be used to invalidate caches, restart watches, or it can be
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// ignored entirely. You should use the GenerateRecvFunc helper function
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// to build this function for use in the resource internal state handle.
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Recv() map[string]*Send
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}
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// Send points to a value that a resource will send.
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type Send struct {
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Res SendableRes // a handle to the resource which is sending a value
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Key string // the key in the resource that we're sending
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Changed bool // set to true if this key was updated, read only!
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}
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// GenerateSendFunc generates the Send function using the resource of our choice
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// for use in the resource internal state handle.
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func GenerateSendFunc(res Res) func(interface{}) error {
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return func(st interface{}) error {
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//fmt.Printf("from: %+v\n", res)
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//fmt.Printf("send: %+v\n", st)
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r, ok := res.(SendableRes)
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if !ok {
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panic("res does not support the Sendable trait")
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}
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// XXX: type check this
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//expected := r.Sends()
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//if err := XXX_TYPE_CHECK(expected, st); err != nil {
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// return err
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//}
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return r.Send(st) // send the struct
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}
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}
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// GenerateRecvFunc generates the Recv function using the resource of our choice
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// for use in the resource internal state handle.
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func GenerateRecvFunc(res Res) func() map[string]*Send {
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return func() map[string]*Send { // TODO: change this API?
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r, ok := res.(RecvableRes)
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if !ok {
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panic("res does not support the Recvable trait")
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}
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return r.Recv()
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}
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}
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