pulumi/sdk/go/pulumix/combinators.go

137 lines
3.8 KiB
Go

// Copyright 2016-2023, Pulumi Corporation.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pulumix
import (
"context"
"github.com/pulumi/pulumi/sdk/v3/go/internal"
)
// applyNState helps implement the ApplyN combinators
// without excessive code duplication.
// O is the final type of the output.
//
// Intended usage:
//
// // Start a new ApplyN operation.
// st := newApplyNState[O](outputState)
//
// // For each Output[A], declare a variable for the value (A),
// // and call applyNStep. It will await, fill the value,
// // and update internal state as needed.
// var a A
// applyNStep(ctx, &st, a, &a)
// ...
//
// // Once all the steps are done, consume the recorded values
// // and call st.finish -- if the applyn hasn't already failed.
// if st.ok {
// st.finish(f(a, b, c, ...))
// }
type applyNState[O any] struct {
ok bool
zero O
known bool
secret bool
deps []internal.Resource
outputState *internal.OutputState
}
func newApplyNState[O any](outputState *internal.OutputState) applyNState[O] {
return applyNState[O]{
ok: true,
known: true,
secret: false,
outputState: outputState,
}
}
// applyNStep takes a single step in an ApplyN computation.
// It awwaits the given output, stores the value in the given pointer,
// and updates the internal state accordingly.
//
// If the applyN has already failed, this is a no-op.
func applyNStep[A, O any](ctx context.Context, st *applyNState[O], o Output[A], dst *A) {
if !st.ok {
return
}
v, known, secret, deps, err := await(ctx, o)
st.secret = st.secret || secret
st.known = st.known && known
st.deps = append(st.deps, deps...)
if err != nil || !known {
st.ok = false
internal.FulfillOutput(st.outputState, st.zero, false, st.secret, st.deps, err)
return
}
*dst = v
}
// finish finishes the applyN computation.
// Call it with the result of the function passed to Apply.
func (st *applyNState[O]) finish(v O, err error) {
if err != nil {
internal.RejectOutput(st.outputState, err)
} else {
internal.FulfillOutput(st.outputState, v, st.known, st.secret, st.deps, nil)
}
}
// JoinContext unpacks an Output stored inside another input,
// returning an output containing the underlying value.
func JoinContext[A any, I Input[A]](ctx context.Context, i Input[I]) Output[A] {
outputOutputA := i.ToOutput(ctx)
stateOutputOutputA := internal.GetOutputState(outputOutputA)
stateA := internal.NewOutputState(
internal.OutputJoinGroup(stateOutputOutputA),
typeOf[A](),
internal.OutputDependencies(stateOutputOutputA)...,
)
go func() {
var outputA I
var a A
applier := newApplyNState[A](stateA)
applyNStep(ctx, &applier, outputOutputA, &outputA)
applyNStep(ctx, &applier, outputA.ToOutput(ctx), &a)
if applier.ok {
applier.finish(a, nil /* err */)
}
}()
return Output[A]{OutputState: stateA}
}
// Join unpacks the Output stored inside another input,
// returning an output containing the underlying value.
//
// This is a variant of JoinContext
// that uses the background context.
func Join[A any, I Input[A]](i Input[I]) Output[A] {
return JoinContext[A, I](context.Background(), i)
}
// All combines multiple inputs into a single output
// that produces a list of all the input values.
func All(args ...Input[any]) Output[[]any] {
return Array[any](args).ToOutput(context.Background())
}