From 8161d932a1c23cea2db63cc7cccbc00e78de48f2 Mon Sep 17 00:00:00 2001
From: Dave Clendenan <dclendenan@salesforce.com>
Date: Mon, 28 Nov 2016 14:47:38 -0800
Subject: [PATCH] performance: precompile regex before iterating

---
 entry.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/entry.go b/entry.go
index 1e721ce..290232a 100644
--- a/entry.go
+++ b/entry.go
@@ -96,6 +96,11 @@ func getCaller() (method string) {
 	// Restrict the lookback to 25 frames - if it's further than that, report UNKNOWN
 	pcs := make([]uintptr, 25)
 
+	matchesLogrus, err := regexp.Compile("logrus.*")
+	if err != nil {
+		return "CALLER_LOOKUP_FAILED"
+	}
+
 	// the first non-logrus caller is at least three frames away
 	depth := runtime.Callers(3, pcs)
 	for i := 0; i < depth; i++ {
@@ -105,10 +110,7 @@ func getCaller() (method string) {
 			fullFuncName = fullFuncName[idx:]
 		}
 
-		matched, err := regexp.MatchString("logrus.*", fullFuncName)
-		if err != nil {
-			return "CALLER_LOOKUP_FAILED"
-		}
+		matched := matchesLogrus.MatchString(fullFuncName)
 
 		// If the caller isn't part of logrus, we're done
 		if !matched {