pulumi/sdk/go/pulumix/apply_state.go

111 lines
3.2 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/common/util/contract"
"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 awaits 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)
}
}
// await is a type-safe variant of OutputState.await.
//
// It disables unwrapping of nested Output values.
// Otherwise, await `Output[Output[T]]` would return `T`, not `Output[T]`,
// which will then panic.
func await[T any](ctx context.Context, o Output[T]) (value T, known, secret bool, deps []internal.Resource, err error) {
iface, known, secret, deps, err := internal.AwaitOutputNoUnwrap(ctx, o)
if known && err == nil {
var ok bool
value, ok = iface.(T)
contract.Assertf(ok, "await expected %v, got %T", typeOf[T](), iface)
}
return value, known, secret, deps, err
}