delegating locking to SetRank

src/engines/google/google.go

@@ -132,17 +132,20 @@ func setResultResponse(link string, response *colly.Response, relay *structures.
 	log.Trace().Msgf("Got Response %v", link)
 
 	relay.Mutex.Lock()
-	defer relay.Mutex.Unlock()
-
 	mapRes, exists := relay.ResultMap[link]
 
 	if !exists {
 		log.Error().Msgf("URL not in map when adding response! Should not be possible. URL: %v", link)
+		relay.Mutex.Unlock()
 		return
 	}
 
 	mapRes.Response = response
-	rank.SetRank(mapRes) //IF I PASS COPY HERE, THAN I CAN UNLOCK EARLIER (MAYBE)
+
+	resCopy := *mapRes
+	rankAddr := &(mapRes.Rank)
+	relay.Mutex.Unlock()
+	rank.SetRank(&resCopy, rankAddr, &(relay.Mutex)) //copy contains pointer to response
 }
 
 func getPageNum(uri string) int {

src/rank/rank.go

@@ -1,12 +1,32 @@
 package rank
 
 import (
+	"sync"
+
 	"github.com/rs/zerolog/log"
 	"github.com/tminaorg/brzaguza/src/structures"
 )
 
-func SetRank(result *structures.Result) {
-	result.Rank = result.SEPage*100 + result.SEPageRank
+// only one call for setResultResponse for a page will ever be performed, so there will never be a read and a write to result.Response at the same time
+// thus not locking relay.ResultMap[result.URL] in this function, because the result parameter is a copy is safe. It may, however, read memory that the map sees,
+// at the same time that the map is being written to, while this should be fine in this use-case, go may throw an error.
+// TLDR: you must mutex.Lock when changing *rankAddr, you probably dont need to mutex.RLock() when reading result
+// (in reality even *rankAddr shouldnt need a lock, but go would definately complain about simultanious read/write because of it)
+func SetRank(result *structures.Result, rankAddr *int, mutex *sync.RWMutex) {
+
+	mutex.RLock()
+	reqUrl := result.Response.Request.URL.String() //dummy code
+	mutex.RUnlock()
+
+	if reqUrl != result.URL { //dummy code
+		log.Trace().Msg("Request URL not same as result.URL \\/")
+	}
+
+	rrank := result.SEPage*100 + result.SEPageRank
+
+	mutex.Lock()
+	*rankAddr = rrank
+	mutex.Unlock()
 
-	log.Trace().Msgf("Set rank to %v for %v: %v", result.Rank, result.Title, result.URL)
+	log.Trace().Msgf("Set rank to %v for %v: %v", rrank, result.Title, result.URL)
 }