# HG changeset patch
# User igerasim
# Date 1530325828 25200
#      Fri Jun 29 19:30:28 2018 -0700
# Node ID 030b673b3fa962e9069a6ecd237448b800bfbf6b
# Parent  9f62267e79df8fd87172aa08971ba66701286f90
imported patch 8206122-Use-Queue-in-place-of-ArrayList-when-need-to-remove-first-element

diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/api/JavacTaskPool.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/api/JavacTaskPool.java
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/api/JavacTaskPool.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/api/JavacTaskPool.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,9 +27,10 @@
 
 import java.io.PrintStream;
 import java.io.Writer;
+import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
+import java.util.Deque;
 import java.util.HashMap;
 
 import com.sun.source.tree.ClassTree;
@@ -101,9 +102,10 @@
 public class JavacTaskPool {
 
     private static final JavacTool systemProvider = JavacTool.create();
+    private static final Deque<ReusableContext> EMPTY_DEQUE = new ArrayDeque<>(0);
 
     private final int maxPoolSize;
-    private final Map<List<String>, List<ReusableContext>> options2Contexts = new HashMap<>();
+    private final Map<List<String>, Deque<ReusableContext>> options2Contexts = new HashMap<>();
     private int id;
 
     private int statReused = 0;
@@ -159,14 +161,14 @@
         ReusableContext ctx;
 
         synchronized (this) {
-            List<ReusableContext> cached =
-                    options2Contexts.getOrDefault(opts, Collections.emptyList());
+            Deque<ReusableContext> cached =
+                    options2Contexts.getOrDefault(opts, EMPTY_DEQUE);
 
             if (cached.isEmpty()) {
                 ctx = new ReusableContext(opts);
                 statNew++;
             } else {
-                ctx = cached.remove(0);
+                ctx = cached.remove();
                 statReused++;
             }
         }
@@ -200,7 +202,7 @@
                     options2Contexts.get(toRemove.arguments).remove(toRemove);
                     statRemoved++;
                 }
-                options2Contexts.computeIfAbsent(ctx.arguments, x -> new ArrayList<>()).add(ctx);
+                options2Contexts.computeIfAbsent(ctx.arguments, x -> new ArrayDeque<>()).add(ctx);
                 ctx.timeStamp = id++;
             }
         }
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Analyzer.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Analyzer.java
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Analyzer.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Analyzer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,7 +25,8 @@
 
 package com.sun.tools.javac.comp;
 
-import java.util.ArrayList;
+import java.util.ArrayDeque;
+import java.util.Queue;
 
 import com.sun.source.tree.LambdaExpressionTree;
 import com.sun.tools.javac.code.Source;
@@ -521,11 +522,11 @@
      */
     DeferredAnalysisHelper queueDeferredHelper = new DeferredAnalysisHelper() {
 
-        Map<ClassSymbol, ArrayList<RewritingContext>> Q = new HashMap<>();
+        Map<ClassSymbol, Queue<RewritingContext>> Q = new HashMap<>();
 
         @Override
         public void queue(RewritingContext rewriting) {
-            ArrayList<RewritingContext> s = Q.computeIfAbsent(rewriting.env.enclClass.sym.outermostClass(), k -> new ArrayList<>());
+            Queue<RewritingContext> s = Q.computeIfAbsent(rewriting.env.enclClass.sym.outermostClass(), k -> new ArrayDeque<>());
             s.add(rewriting);
         }
 
@@ -535,9 +536,9 @@
                 DeferredAnalysisHelper prevHelper = deferredAnalysisHelper;
                 try {
                     deferredAnalysisHelper = flushDeferredHelper;
-                    ArrayList<RewritingContext> rewritings = Q.get(flushEnv.enclClass.sym.outermostClass());
+                    Queue<RewritingContext> rewritings = Q.get(flushEnv.enclClass.sym.outermostClass());
                     while (rewritings != null && !rewritings.isEmpty()) {
-                        doAnalysis(rewritings.remove(0));
+                        doAnalysis(rewritings.remove());
                     }
                 } finally {
                     deferredAnalysisHelper = prevHelper;