From 6a70f27f59602e31ebfba6ee3d9cdc820d2deb2a Mon Sep 17 00:00:00 2001
From: Todd Gruben <tgruben@umbel.com>
Date: Mon, 28 Aug 2017 13:46:18 -0500
Subject: [PATCH 1/3] account for all same values in rank

---
 cache.go      |  5 +++++
 cache_test.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 cache_test.go

diff --git a/cache.go b/cache.go
index 242e5a6ab..ba33fe258 100644
--- a/cache.go
+++ b/cache.go
@@ -273,6 +273,11 @@ func (c *RankCache) recalculate() {
 			if cnt <= c.thresholdValue {
 				delete(c.entries, id)
 			}
+			// prevent from deleting the whole cache if all the same value
+			if len(c.entries) <= int(c.maxEntries) {
+				break
+			}
+
 		}
 	}
 }
diff --git a/cache_test.go b/cache_test.go
new file mode 100644
index 000000000..21d8acf07
--- /dev/null
+++ b/cache_test.go
@@ -0,0 +1,35 @@
+// Copyright 2017 Pilosa Corp.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pilosa_test
+
+import (
+	"testing"
+
+	"github.com/pilosa/pilosa"
+)
+
+// Ensure a bitmap query can be executed.
+func TestCache_Rank(t *testing.T) {
+	cacheSize := uint32(3)
+	cache := pilosa.NewRankCache(cacheSize)
+	for i := 1; i < int(2*cacheSize); i++ {
+		cache.Add(uint64(i), 3)
+	}
+	cache.Recalculate()
+	if cache.Len() != int(cacheSize) {
+		t.Fatalf("unexpected cache Size: %d!=%d expected\n", cache.Len(), cacheSize)
+	}
+
+}

From 60ee6dcfdda3a3e112c3f9c317dd9100f9bbba64 Mon Sep 17 00:00:00 2001
From: Todd Gruben <tgruben@umbel.com>
Date: Mon, 28 Aug 2017 14:12:31 -0500
Subject: [PATCH 2/3] constant cache removal

---
 cache.go | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/cache.go b/cache.go
index ba33fe258..890a38e0b 100644
--- a/cache.go
+++ b/cache.go
@@ -256,8 +256,10 @@ func (c *RankCache) recalculate() {
 	length := len(c.rankings)
 	c.stats.Gauge("RankCache", float64(length), 1.0)
 
+	var remove_items []BitmapPair // cached, ordered list
 	if length > int(c.maxEntries) {
 		c.thresholdValue = rankings[c.maxEntries].Count
+		remove_items = c.rankings[c.maxEntries:]
 		c.rankings = c.rankings[0:c.maxEntries]
 	} else {
 		c.thresholdValue = 1
@@ -269,15 +271,8 @@ func (c *RankCache) recalculate() {
 	// If size is larger than the threshold then trim it.
 	if len(c.entries) > c.thresholdBuffer {
 		c.stats.Count("cache.threshold", 1, 1.0)
-		for id, cnt := range c.entries {
-			if cnt <= c.thresholdValue {
-				delete(c.entries, id)
-			}
-			// prevent from deleting the whole cache if all the same value
-			if len(c.entries) <= int(c.maxEntries) {
-				break
-			}
-
+		for _, pair := range remove_items {
+			delete(c.entries, pair.ID)
 		}
 	}
 }

From 773019a0f33fc8d6b80742cec81f58bb5c80f341 Mon Sep 17 00:00:00 2001
From: Todd Gruben <tgruben@umbel.com>
Date: Mon, 28 Aug 2017 14:15:59 -0500
Subject: [PATCH 3/3] corrected nameing

---
 cache.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cache.go b/cache.go
index 890a38e0b..2e66d35b9 100644
--- a/cache.go
+++ b/cache.go
@@ -256,10 +256,10 @@ func (c *RankCache) recalculate() {
 	length := len(c.rankings)
 	c.stats.Gauge("RankCache", float64(length), 1.0)
 
-	var remove_items []BitmapPair // cached, ordered list
+	var removeItems []BitmapPair // cached, ordered list
 	if length > int(c.maxEntries) {
 		c.thresholdValue = rankings[c.maxEntries].Count
-		remove_items = c.rankings[c.maxEntries:]
+		removeItems = c.rankings[c.maxEntries:]
 		c.rankings = c.rankings[0:c.maxEntries]
 	} else {
 		c.thresholdValue = 1
@@ -271,7 +271,7 @@ func (c *RankCache) recalculate() {
 	// If size is larger than the threshold then trim it.
 	if len(c.entries) > c.thresholdBuffer {
 		c.stats.Count("cache.threshold", 1, 1.0)
-		for _, pair := range remove_items {
+		for _, pair := range removeItems {
 			delete(c.entries, pair.ID)
 		}
 	}