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package waiter
import (
"fmt"
"reflect"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/awsutil"
"github.com/aws/aws-sdk-go/aws/request"
)
// A Config provides a collection of configuration values to setup a generated
// waiter code with.
type Config struct {
Name string
Delay int
MaxAttempts int
Operation string
Acceptors []WaitAcceptor
}
// A WaitAcceptor provides the information needed to wait for an API operation
// to complete.
type WaitAcceptor struct {
Expected interface{}
Matcher string
State string
Argument string
}
// A Waiter provides waiting for an operation to complete.
type Waiter struct {
Config
Client interface{}
Input interface{}
}
// Wait waits for an operation to complete, expire max attempts, or fail. Error
// is returned if the operation fails.
func (w *Waiter) Wait() error {
client := reflect.ValueOf(w.Client)
in := reflect.ValueOf(w.Input)
method := client.MethodByName(w.Config.Operation + "Request")
for i := 0; i < w.MaxAttempts; i++ {
res := method.Call([]reflect.Value{in})
req := res[0].Interface().(*request.Request)
req.Handlers.Build.PushBack(request.MakeAddToUserAgentFreeFormHandler("Waiter"))
err := req.Send()
for _, a := range w.Acceptors {
result := false
var vals []interface{}
switch a.Matcher {
case "pathAll", "path":
// Require all matches to be equal for result to match
vals, _ = awsutil.ValuesAtPath(req.Data, a.Argument)
if len(vals) == 0 {
break
}
result = true
for _, val := range vals {
if !awsutil.DeepEqual(val, a.Expected) {
result = false
break
}
}
case "pathAny":
// Only a single match needs to equal for the result to match
vals, _ = awsutil.ValuesAtPath(req.Data, a.Argument)
for _, val := range vals {
if awsutil.DeepEqual(val, a.Expected) {
result = true
break
}
}
case "status":
s := a.Expected.(int)
result = s == req.HTTPResponse.StatusCode
case "error":
if aerr, ok := err.(awserr.Error); ok {
result = aerr.Code() == a.Expected.(string)
}
case "pathList":
// ignored matcher
default:
logf(client, "WARNING: Waiter for %s encountered unexpected matcher: %s",
w.Config.Operation, a.Matcher)
}
if !result {
// If there was no matching result found there is nothing more to do
// for this response, retry the request.
continue
}
switch a.State {
case "success":
// waiter completed
return nil
case "failure":
// Waiter failure state triggered
return awserr.New("ResourceNotReady",
fmt.Sprintf("failed waiting for successful resource state"), err)
case "retry":
// clear the error and retry the operation
err = nil
default:
logf(client, "WARNING: Waiter for %s encountered unexpected state: %s",
w.Config.Operation, a.State)
}
}
if err != nil {
return err
}
time.Sleep(time.Second * time.Duration(w.Delay))
}
return awserr.New("ResourceNotReady",
fmt.Sprintf("exceeded %d wait attempts", w.MaxAttempts), nil)
}
func logf(client reflect.Value, msg string, args ...interface{}) {
cfgVal := client.FieldByName("Config")
if !cfgVal.IsValid() {
return
}
if cfg, ok := cfgVal.Interface().(*aws.Config); ok && cfg.Logger != nil {
cfg.Logger.Log(fmt.Sprintf(msg, args...))
}
}
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