From 6b3f653c9159d8685f9f014cc307cfc3db7f1931 Mon Sep 17 00:00:00 2001
From: Ravi Shekhar Jethani <rsjethani@gmail.com>
Date: Fri, 6 Sep 2019 00:39:16 +0200
Subject: [PATCH] Implement simplelru.InvalidSize error

---
 2q.go            |  2 ++
 simplelru/lru.go | 13 +++++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/2q.go b/2q.go
index fdc3cae..a325c26 100644
--- a/2q.go
+++ b/2q.go
@@ -70,7 +70,9 @@ func New2QParams(size int, recentRatio float64, ghostRatio float64) (*TwoQueueCa
 	}
 	recentEvict, err := simplelru.NewLRU(evictSize, nil)
 	if err != nil {
+	    if _, ok := err.(*simplelru.InvalidSize); ok {
 		return nil, fmt.Errorf("Failed to create Evict cache, please choose a higher 'ghostRatio' or increase cache 'size'")
+	    }
 	}
 
 	// Initialize the cache
diff --git a/simplelru/lru.go b/simplelru/lru.go
index a86c853..1fcc4a9 100644
--- a/simplelru/lru.go
+++ b/simplelru/lru.go
@@ -2,9 +2,18 @@ package simplelru
 
 import (
 	"container/list"
-	"errors"
 )
 
+// InvalidSize error is returned when a size <= 0 is given while creting simplelru
+type InvalidSize struct {
+    errMsg string
+}
+
+// Error implements the error interface for type InvalidSize
+func (e *InvalidSize) Error() string {
+    return "Must provide a positive size"
+}
+
 // EvictCallback is used to get a callback when a cache entry is evicted
 type EvictCallback func(key interface{}, value interface{})
 
@@ -25,7 +34,7 @@ type entry struct {
 // NewLRU constructs an LRU of the given size
 func NewLRU(size int, onEvict EvictCallback) (*LRU, error) {
 	if size <= 0 {
-		return nil, errors.New("Must provide a positive size")
+		return nil, &InvalidSize{}
 	}
 	c := &LRU{
 		size:      size,