From 54503f09ec0279ff2c2830459c84176c49654db3 Mon Sep 17 00:00:00 2001
From: Ben Manes <ben.manes@gmail.com>
Date: Sun, 30 Aug 2015 23:44:13 -0700
Subject: [PATCH] Fix warmup of HIR blocks in LIRS policy

When comparing against the output from the C reference version I discovered
that the warmup for HIR was incorrectly followed. This change results in the
same output for a small sample.

There is still a mistake as verified by running a large sample, multi1, and
seeing that S, Q, evictions, and statistics are askew. While this has a very
small impact on the hit rate, we should still try to find the subtle bug
remaining.

For ease of comparing outputs, the debug format now matches the reference's.
---
 .../simulator/policy/irr/LirsPolicy.java      | 43 ++++++++++++-------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/irr/LirsPolicy.java b/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/irr/LirsPolicy.java
index fe1fbede19..faa53c9708 100644
--- a/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/irr/LirsPolicy.java
+++ b/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/irr/LirsPolicy.java
@@ -140,14 +140,16 @@ private void onResidentHir(Node node) {
   }
 
   private void onNonResidentHir(Node node) {
-    // When LIR block set is not full, all the referenced blocks are given an LIR status until its
-    // size reaches Llirs. After that, HIR status is given to any blocks that are referenced for the
-    // first time, and to the blocks that have not been referenced for a long time so that they are
-    // not in stack S any longer.
+    // When an LIR block set is not full, all the accessed blocks are given LIR status until its
+    // size reaches Llirs. After that, HIR status is given to any blocks that are accessed for the
+    // first time and to blocks that have not been accessed for a long time so that currently they
+    // are not in stack S.
     policyStats.recordMiss();
 
     if (sizeHot < maximumHotSize) {
-      onWarmupMiss(node);
+      onLirWarmupMiss(node);
+    } else if (residentSize < maximumSize) {
+      onHirWarmupMiss(node);
     } else {
       onFullMiss(node);
     }
@@ -155,12 +157,18 @@ private void onNonResidentHir(Node node) {
   }
 
   /** Records a miss when the hot set is not full. */
-  private void onWarmupMiss(Node node) {
+  private void onLirWarmupMiss(Node node) {
     node.moveToTop(StackType.S);
     node.status = Status.LIR;
     sizeHot++;
   }
 
+  /** Records a miss when the cold set is not full. */
+  private void onHirWarmupMiss(Node node) {
+    node.status = Status.HIR_RESIDENT;
+    node.moveToTop(StackType.Q);
+  }
+
   /** Records a miss when the hot set is full. */
   private void onFullMiss(Node node) {
     // Upon accessing an HIR non-resident block X. This is a miss. We remove the HIR resident block
@@ -265,27 +273,30 @@ public void finished() {
 
   /** Prints out the internal state of the policy. */
   private void printLirs() {
-    List<Object> stack = new ArrayList<>(sizeS);
-    List<Object> queue = new ArrayList<>(sizeQ);
-
+    System.out.println("** LIRS stack TOP **");
     for (Node n = headS.nextS; n != headS; n = n.nextS) {
       checkState(n.isInS);
       if (n.status == Status.HIR_NON_RESIDENT) {
-        stack.add("NR_" + n.key);
+        System.out.println("<NR> " + n.key);
       } else if (n.status == Status.HIR_RESIDENT) {
-        stack.add("RH_" + n.key);
+        System.out.println("<RH> " + n.key);
       } else {
-        stack.add("RL_" + n.key);
+        System.out.println("<RL> " + n.key);
       }
     }
+    System.out.println("** LIRS stack BOTTOM **");
+
+    System.out.println("\n** LIRS queue END **");
     for (Node n = headQ.nextQ; n != headQ; n = n.nextQ) {
       checkState(n.isInQ);
-      queue.add(n.key);
+      System.out.println(n.key);
     }
+    System.out.println("** LIRS queue front **");
 
-    System.out.println("Stack: " + stack);
-    System.out.println("Queue: " + queue);
-    System.out.println("Evicted: " + evicted);
+    System.out.println("\nLIRS EVICTED PAGE sequence:");
+    for (int i = 0; i < evicted.size(); i++) {
+      System.out.println("<" + i + "> " + evicted.get(i));
+    }
   }
 
   enum Status {