From 8aa12d3cb043859229810947da6c52e600d34b55 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Thu, 26 Jan 2023 13:59:35 -0700
Subject: struct.go: Cache structIndexes

This should help save some CPU time and avoid some memory churn.
---
 struct.go | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'struct.go')

diff --git a/struct.go b/struct.go
index b7fc287..8a664c6 100644
--- a/struct.go
+++ b/struct.go
@@ -7,6 +7,8 @@ package lowmemjson
 import (
 	"reflect"
 
+	"git.lukeshu.com/go/typedsync"
+
 	"git.lukeshu.com/go/lowmemjson/internal"
 )
 
@@ -25,9 +27,19 @@ type structIndex struct {
 	byName map[string]int
 }
 
+var structIndexCache typedsync.CacheMap[reflect.Type, structIndex]
+
 // indexStruct takes a struct Type, and indexes its fields for use by
-// Decoder.Decode() and Encoder.Encode().
+// Decoder.Decode() and Encoder.Encode().  indexStruct caches its
+// results.
 func indexStruct(typ reflect.Type) structIndex {
+	ret, _ := structIndexCache.LoadOrCompute(typ, indexStructReal)
+	return ret
+}
+
+// indexStructReal is like indexStruct, but is the real indexer,
+// bypassing the cache.
+func indexStructReal(typ reflect.Type) structIndex {
 	var byPos []structField
 	byName := make(map[string][]int)
 
-- 
cgit v1.2.3-2-g168b