From 8064c669fe02cf90995dc82b1c67c8f434860dc5 Mon Sep 17 00:00:00 2001
From: Kurt Partridge <kep@google.com>
Date: Fri, 19 Apr 2013 16:02:02 -0700
Subject: [PATCH] Fix looping logic bugs.

shiftOut() is getting called once too often through these for loops.

Change-Id: I9a68b49e6cc1469bcddd673ab1567e238cf192b8
---
 .../inputmethod/research/FixedLogBuffer.java  | 23 +++++++------
 .../inputmethod/research/MainLogBuffer.java   | 33 +++++++++++--------
 2 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/java/src/com/android/inputmethod/research/FixedLogBuffer.java b/java/src/com/android/inputmethod/research/FixedLogBuffer.java
index 4249af544..8b64de8ae 100644
--- a/java/src/com/android/inputmethod/research/FixedLogBuffer.java
+++ b/java/src/com/android/inputmethod/research/FixedLogBuffer.java
@@ -65,6 +65,7 @@ public class FixedLogBuffer extends LogBuffer {
         final int numWordsIncoming = newLogUnit.getNumWords();
         if (mNumActualWords >= mWordCapacity) {
             // Give subclass a chance to handle the buffer full condition by shifting out logUnits.
+            // TODO: Tell onBufferFull() how much space it needs to make to avoid forced eviction.
             onBufferFull();
             // If still full, evict.
             if (mNumActualWords >= mWordCapacity) {
@@ -119,21 +120,19 @@ public class FixedLogBuffer extends LogBuffer {
     /**
      * Remove LogUnits from the front of the LogBuffer until {@code numWords} have been removed.
      *
-     * If there are less than {@code numWords} word-containing {@link LogUnit}s, shifts out
-     * all {@code LogUnit}s in the buffer.
+     * If there are less than {@code numWords} in the buffer, shifts out all {@code LogUnit}s.
      *
-     * @param numWords the minimum number of word-containing {@link LogUnit}s to shift out
-     * @return the number of actual {@code LogUnit}s shifted out
+     * @param numWords the minimum number of words in {@link LogUnit}s to shift out
+     * @return the number of actual words LogUnit}s shifted out
      */
     protected int shiftOutWords(final int numWords) {
-        int numWordContainingLogUnitsShiftedOut = 0;
-        for (LogUnit logUnit = shiftOut(); logUnit != null
-                && numWordContainingLogUnitsShiftedOut < numWords; logUnit = shiftOut()) {
-            if (logUnit.hasOneOrMoreWords()) {
-                numWordContainingLogUnitsShiftedOut += logUnit.getNumWords();
-            }
-        }
-        return numWordContainingLogUnitsShiftedOut;
+        int numWordsShiftedOut = 0;
+        do {
+            final LogUnit logUnit = shiftOut();
+            if (logUnit == null) break;
+            numWordsShiftedOut += logUnit.getNumWords();
+        } while (numWordsShiftedOut < numWords);
+        return numWordsShiftedOut;
     }
 
     public void shiftOutAll() {
diff --git a/java/src/com/android/inputmethod/research/MainLogBuffer.java b/java/src/com/android/inputmethod/research/MainLogBuffer.java
index 42ef5d3b6..9bdedbf6d 100644
--- a/java/src/com/android/inputmethod/research/MainLogBuffer.java
+++ b/java/src/com/android/inputmethod/research/MainLogBuffer.java
@@ -190,22 +190,30 @@ public abstract class MainLogBuffer extends FixedLogBuffer {
     }
 
     protected final void publishLogUnitsAtFrontOfBuffer() {
+        // TODO: Refactor this method to require fewer passes through the LogUnits.  Should really
+        // require only one pass.
         ArrayList<LogUnit> logUnits = peekAtFirstNWords(N_GRAM_SIZE);
         if (isSafeNGram(logUnits, N_GRAM_SIZE)) {
             // Good n-gram at the front of the buffer.  Publish it, disclosing details.
             publish(logUnits, true /* canIncludePrivateData */);
             shiftOutWords(N_GRAM_SIZE);
             mNumWordsUntilSafeToSample = mNumWordsBetweenNGrams;
-        } else {
-            // No good n-gram at front, and buffer is full.  Shift out up through the first logUnit
-            // with associated words (or if there is none, all the existing logUnits).
-            logUnits.clear();
-            for (LogUnit logUnit = shiftOut(); logUnit != null && !logUnit.hasOneOrMoreWords();
-                    logUnit = shiftOut()) {
-                logUnits.add(logUnit);
-            }
-            publish(logUnits, false /* canIncludePrivateData */);
+            return;
         }
+        // No good n-gram at front, and buffer is full.  Shift out up through the first logUnit
+        // with associated words (or if there is none, all the existing logUnits).
+        logUnits.clear();
+        LogUnit logUnit = shiftOut();
+        while (logUnit != null) {
+            logUnits.add(logUnit);
+            final int numWords = logUnit.getNumWords();
+            if (numWords > 0) {
+                mNumWordsUntilSafeToSample = Math.max(0, mNumWordsUntilSafeToSample - numWords);
+                break;
+            }
+            logUnit = shiftOut();
+        }
+        publish(logUnits, false /* canIncludePrivateData */);
     }
 
     /**
@@ -222,12 +230,11 @@ public abstract class MainLogBuffer extends FixedLogBuffer {
 
     @Override
     protected int shiftOutWords(final int numWords) {
-        final int numWordContainingLogUnitsShiftedOut = super.shiftOutWords(numWords);
-        mNumWordsUntilSafeToSample = Math.max(0, mNumWordsUntilSafeToSample
-                - numWordContainingLogUnitsShiftedOut);
+        final int numWordsShiftedOut = super.shiftOutWords(numWords);
+        mNumWordsUntilSafeToSample = Math.max(0, mNumWordsUntilSafeToSample - numWordsShiftedOut);
         if (DEBUG) {
             Log.d(TAG, "wordsUntilSafeToSample now at " + mNumWordsUntilSafeToSample);
         }
-        return numWordContainingLogUnitsShiftedOut;
+        return numWordsShiftedOut;
     }
 }