From a3812a67d95651c70c801cbea5ed1ff2e39ee051 Mon Sep 17 00:00:00 2001
From: rustamhsmv <rustam.hashimov@outlook.com>
Date: Fri, 16 Dec 2016 15:34:47 -0800
Subject: [PATCH 1/2] make CountSlotArrAcc internal array reusable

---
 .../solr/search/facet/FacetProcessor.java     |  1 +
 .../solr/search/facet/FacetRequest.java       | 23 +++++++++++++++++++
 .../org/apache/solr/search/facet/SlotAcc.java | 11 ++++++++-
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/solr/core/src/java/org/apache/solr/search/facet/FacetProcessor.java b/solr/core/src/java/org/apache/solr/search/facet/FacetProcessor.java
index 4a839a29ccf0..c2c04c533bfc 100644
--- a/solr/core/src/java/org/apache/solr/search/facet/FacetProcessor.java
+++ b/solr/core/src/java/org/apache/solr/search/facet/FacetProcessor.java
@@ -419,6 +419,7 @@ void processSubs(SimpleOrderedMap<Object> response, Query filter, DocSet domain)
 
       // make a new context for each sub-facet since they can change the domain
       FacetContext subContext = fcontext.sub(filter, domain);
+      subContext.sequentialProcessing = true;
       FacetProcessor subProcessor = subRequest.createFacetProcessor(subContext);
 
       if (fcontext.getDebugInfo() != null) {   // if fcontext.debugInfo != null, it means rb.debug() == true
diff --git a/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java b/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java
index 636460f7e60b..e7235251da3c 100644
--- a/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java
+++ b/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java
@@ -18,6 +18,7 @@
 
 import java.util.ArrayList;
 import java.util.EnumSet;
+import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -178,6 +179,15 @@ class FacetContext {
   int flags;
   FacetDebugInfo debugInfo;
   
+  int level; // level of the context
+  boolean sequentialProcessing; // indicates if execution of facet processors happens sequentially 
+  private Map<String, Object> reusables;
+  
+  public FacetContext() {
+    level = 0;
+    reusables = new HashMap<>();
+  }
+  
   public void setDebugInfo(FacetDebugInfo debugInfo) {
     this.debugInfo = debugInfo;
   }
@@ -190,6 +200,16 @@ public boolean isShard() {
     return (flags & IS_SHARD) != 0;
   }
 
+  public Object getReusable(String key) {
+    return sequentialProcessing ? reusables.get(key) : null;
+  }
+  
+  public void addReusable(String key, Object obj) {
+    if (sequentialProcessing) {
+      reusables.put(key, obj);
+    }
+  }
+  
   /**
    * @param filter The filter for the bucket that resulted in this context/domain.  Can be null if this is the root context.
    * @param domain The resulting set of documents for this facet.
@@ -205,6 +225,9 @@ public FacetContext sub(Query filter, DocSet domain) {
     ctx.qcontext = qcontext;
     ctx.req = req;
     ctx.searcher = searcher;
+    ctx.reusables = reusables;
+    
+    ctx.level = level + 1;
 
     return ctx;
   }
diff --git a/solr/core/src/java/org/apache/solr/search/facet/SlotAcc.java b/solr/core/src/java/org/apache/solr/search/facet/SlotAcc.java
index 4f4851bbb602..ae5347733ec4 100644
--- a/solr/core/src/java/org/apache/solr/search/facet/SlotAcc.java
+++ b/solr/core/src/java/org/apache/solr/search/facet/SlotAcc.java
@@ -394,7 +394,16 @@ class CountSlotArrAcc extends CountSlotAcc {
   int[] result;
   public CountSlotArrAcc(FacetContext fcontext, int numSlots) {
     super(fcontext);
-    result = new int[numSlots];
+    
+    String key = fcontext.level + this.getClass().getSimpleName();
+    result = (int[]) fcontext.getReusable(key);
+    if (result == null || result.length < numSlots) {
+      result = new int[numSlots];
+      fcontext.addReusable(key, result);
+    }
+    else {
+      Arrays.fill(result, 0);
+    }
   }
 
   @Override

From 1c069cc6e0fdc084bb1b88591dae32143d4ebdba Mon Sep 17 00:00:00 2001
From: rustamhsmv <rustam.hashimov@outlook.com>
Date: Sat, 17 Dec 2016 13:51:21 -0800
Subject: [PATCH 2/2] Comments

---
 .../src/java/org/apache/solr/search/facet/FacetRequest.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java b/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java
index e7235251da3c..8f847b86f5ab 100644
--- a/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java
+++ b/solr/core/src/java/org/apache/solr/search/facet/FacetRequest.java
@@ -179,8 +179,9 @@ class FacetContext {
   int flags;
   FacetDebugInfo debugInfo;
   
-  int level; // level of the context
+  // Parameters for reusable
   boolean sequentialProcessing; // indicates if execution of facet processors happens sequentially 
+  int level; // level of facet processor
   private Map<String, Object> reusables;
   
   public FacetContext() {