157 lines
5.3 KiB
Go
157 lines
5.3 KiB
Go
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// Copyright (c) 2022 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package fx
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import (
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"fmt"
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"reflect"
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"strings"
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"go.uber.org/dig"
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"go.uber.org/fx/internal/fxreflect"
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)
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// Provide registers any number of constructor functions, teaching the
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// application how to instantiate various types. The supplied constructor
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// function(s) may depend on other types available in the application, must
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// return one or more objects, and may return an error. For example:
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//
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// // Constructs type *C, depends on *A and *B.
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// func(*A, *B) *C
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//
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// // Constructs type *C, depends on *A and *B, and indicates failure by
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// // returning an error.
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// func(*A, *B) (*C, error)
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//
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// // Constructs types *B and *C, depends on *A, and can fail.
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// func(*A) (*B, *C, error)
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//
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// The order in which constructors are provided doesn't matter, and passing
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// multiple Provide options appends to the application's collection of
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// constructors. Constructors are called only if one or more of their returned
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// types are needed, and their results are cached for reuse (so instances of a
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// type are effectively singletons within an application). Taken together,
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// these properties make it perfectly reasonable to Provide a large number of
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// constructors even if only a fraction of them are used.
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//
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// See the documentation of the In and Out types for advanced features,
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// including optional parameters and named instances.
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//
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// Constructor functions should perform as little external interaction as
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// possible, and should avoid spawning goroutines. Things like server listen
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// loops, background timer loops, and background processing goroutines should
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// instead be managed using Lifecycle callbacks.
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func Provide(constructors ...interface{}) Option {
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return provideOption{
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Targets: constructors,
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Stack: fxreflect.CallerStack(1, 0),
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}
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}
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type provideOption struct {
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Targets []interface{}
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Stack fxreflect.Stack
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}
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func (o provideOption) apply(mod *module) {
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for _, target := range o.Targets {
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mod.provides = append(mod.provides, provide{
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Target: target,
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Stack: o.Stack,
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})
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}
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}
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func (o provideOption) String() string {
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items := make([]string, len(o.Targets))
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for i, c := range o.Targets {
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items[i] = fxreflect.FuncName(c)
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}
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return fmt.Sprintf("fx.Provide(%s)", strings.Join(items, ", "))
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}
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func runProvide(c container, p provide, opts ...dig.ProvideOption) error {
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constructor := p.Target
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if _, ok := constructor.(Option); ok {
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return fmt.Errorf("fx.Option should be passed to fx.New directly, "+
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"not to fx.Provide: fx.Provide received %v from:\n%+v",
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constructor, p.Stack)
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}
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switch constructor := constructor.(type) {
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case annotationError:
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// fx.Annotate failed. Turn it into an Fx error.
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return fmt.Errorf(
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"encountered error while applying annotation using fx.Annotate to %s: %+v",
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fxreflect.FuncName(constructor.target), constructor.err)
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case annotated:
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ctor, err := constructor.Build()
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if err != nil {
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return fmt.Errorf("fx.Provide(%v) from:\n%+vFailed: %v", constructor, p.Stack, err)
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}
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opts = append(opts, dig.LocationForPC(constructor.FuncPtr))
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if err := c.Provide(ctor, opts...); err != nil {
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return fmt.Errorf("fx.Provide(%v) from:\n%+vFailed: %v", constructor, p.Stack, err)
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}
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case Annotated:
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ann := constructor
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switch {
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case len(ann.Group) > 0 && len(ann.Name) > 0:
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return fmt.Errorf(
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"fx.Annotated may specify only one of Name or Group: received %v from:\n%+v",
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ann, p.Stack)
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case len(ann.Name) > 0:
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opts = append(opts, dig.Name(ann.Name))
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case len(ann.Group) > 0:
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opts = append(opts, dig.Group(ann.Group))
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}
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if err := c.Provide(ann.Target, opts...); err != nil {
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return fmt.Errorf("fx.Provide(%v) from:\n%+vFailed: %v", ann, p.Stack, err)
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}
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default:
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if reflect.TypeOf(constructor).Kind() == reflect.Func {
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ft := reflect.ValueOf(constructor).Type()
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for i := 0; i < ft.NumOut(); i++ {
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t := ft.Out(i)
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if t == reflect.TypeOf(Annotated{}) {
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return fmt.Errorf(
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"fx.Annotated should be passed to fx.Provide directly, "+
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"it should not be returned by the constructor: "+
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"fx.Provide received %v from:\n%+v",
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fxreflect.FuncName(constructor), p.Stack)
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}
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}
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}
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if err := c.Provide(constructor, opts...); err != nil {
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return fmt.Errorf("fx.Provide(%v) from:\n%+vFailed: %v", fxreflect.FuncName(constructor), p.Stack, err)
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}
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}
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return nil
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}
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