fix: only add arn patterns to list if not already contained

[cfstras]

I found a case where dynamoDB requests would create infinite (or just very very large) lists. This led to iamlive pinning one CPU at 100%, and not making progress on the request being processed.

See below an output from my dlv session:

> github.com/iann0036/iamlive/iamlivecore.subARNParameters() ./iamlivecore/logger.go:658 (PC: 0x100bdec38)
   653:		// parameter substitution
   654:		for paramVarName, params := range call.Parameters {
   655:			newArns := []string{}
   656:			for _, param := range params {
   657:				for _, arn := range arns {
=> 658:					newArns = append(newArns, regexp.MustCompile(`\$\{`+strings.ReplaceAll(strings.ReplaceAll(paramVarName, "[", "\\["), "]", "\\]")+`\}`).ReplaceAllString(arn, param)) // might have dupes but resolved out later
   659:				}
   660:			}
   661:			arns = newArns
   662:		}
   663:
(dlv) p arns
[]string len: 524288, cap: 568320, [
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",
	"arn:${Partition}:dynamodb:${Region}:${Account}:table/${TableName...+1 more",

I slightly refactored this section in the code, and added a set along with the list. If the ordering is not important here, we could also remove the list entirely, or simplify the code further (I didn't look too hard, just removed the dupes situation for now.

With this fix, my requests run fine.

[iann0036]

Hey @cfstras,

Thanks for this contribution and your brief testing!

I'll include this in the next release today or tomorrow.

[cfstras]

Glad to have helped, thanks for merging 😊