Be more careful to try to grab the message after a heartbeat failure more quickly

Rather than waiting for the whole length of a visibility timeout,
in which time another process may grab the message, instead wait
a short amount of time, each time the message is searched for.

Also add a bit more logging.

2 files changed, 8 insertions, 4 deletions

diff --git a/bookpipeline/aws.go b/bookpipeline/aws.go
index d51e4ea..4d32f3d 100644
--- a/bookpipeline/aws.go
+++ b/bookpipeline/aws.go
@@ -16,6 +16,7 @@ import (
 )
 
 const PreprocPattern = `_bin[0-9].[0-9].png`
+const heartbeatRetry = 10
 
 type Qmsg struct {
 	Id, Handle, Body string
@@ -132,10 +133,11 @@ func (a *AwsConn) QueueHeartbeat(msg Qmsg, qurl string, duration int64) (Qmsg, e
 		// Check if the visibility timeout has exceeded the maximum allowed,
 		// and if so try to find the message again to get a new handle.
 		if ok && aerr.Code() == "InvalidParameterValue" {
-			// Wait for existing visibilitytimeout to expire
-			time.Sleep(time.Duration(duration) * time.Second)
-			// Try 3 times to find the message
-			for range [3]bool{} {
+			// Try heartbeatRetry times to find the message
+			for range [heartbeatRetry]bool{} {
+				// Wait a little in case existing visibilitytimeout needs to expire
+				time.Sleep((time.Duration(duration) / heartbeatRetry) * time.Second)
+
 				msgResult, err := a.sqssvc.ReceiveMessage(&sqs.ReceiveMessageInput{
 					MaxNumberOfMessages: aws.Int64(10),
 					VisibilityTimeout:   &duration,
diff --git a/bookpipeline/cmd/bookpipeline/main.go b/bookpipeline/cmd/bookpipeline/main.go
index f1309ca..f8b0b68 100644
--- a/bookpipeline/cmd/bookpipeline/main.go
+++ b/bookpipeline/cmd/bookpipeline/main.go
@@ -322,8 +322,10 @@ func processBook(msg bookpipeline.Qmsg, conn Pipeliner, process func(chan string
 	case m, ok := <-msgc :
 		if ok {
 			msg = m
+			conn.GetLogger().Println("Using new message handle to delete message from old queue")
 		}
 	default:
+		conn.GetLogger().Println("Using original message handle to delete message from old queue")
 	}
 
 	conn.GetLogger().Println("Deleting original message from queue", fromQueue)