Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b7edebc8 authored by Yohei Yukawa's avatar Yohei Yukawa
Browse files

Fix inefficient CursorAnchorInfo#hashCode(). 

It turns out that the current CursorAnchorInfo#equals() is quite
inefficient because our CursorAnchorInfo#hashCode() tries to use almost
all the fields.  Even worse, as Matrix#hashCode() is hard-coded to 44,
we get the same hashCode() when comparing two CursorAnchorInfo objects
that are different only in transformation Matrix after such a complex
hash calculation.

In the real world scenarios, most likely calculation hash code only from
Matrix and composing text would be good enough for our use case, because
the former can cover UI scrolling scenario and the latter can cover the
text typing scenario.  More complex hash calculation is probably
inefficient.

With this CL, CursorAnchorInfo#hashCode() is pre-calculated only from
those two fields, and carefully reorder comparisons in
CursorAnchorInfo#equals() to improve the likelihood of returning false
with fewer comparisons.

Bug: 28105733
Change-Id: Id896adeab5ffe87ceddb2c2762d6d91475e28ec4
parent cf45224a

core/java/android/view/inputmethod/CursorAnchorInfo.java

+58 −32
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


package android.view.inputmethod;



import android.annotation.NonNull;

import android.graphics.Matrix;

import android.graphics.RectF;

import android.os.Parcel;
@@ -25,6 +26,7 @@ import android.text.SpannedString; 
import android.text.TextUtils;

import android.view.inputmethod.SparseRectFArray.SparseRectFArrayBuilder;



import java.util.Arrays;

import java.util.Objects;



/**
@@ -35,6 +37,11 @@ import java.util.Objects; 
 * actually inserted.</p>

 */

public final class CursorAnchorInfo implements Parcelable {

    /**

     * The pre-computed hash code.

     */

    private final int mHashCode;



    /**

     * The index of the first character of the selected text (inclusive). {@code -1} when there is

     * no text selection.
@@ -100,7 +107,8 @@ public final class CursorAnchorInfo implements Parcelable { 
     * Transformation matrix that is applied to any positional information of this class to

     * transform local coordinates into screen coordinates.

     */

    private final Matrix mMatrix;

    @NonNull

    private final float[] mMatrixValues;



    /**

     * Flag for {@link #getInsertionMarkerFlags()} and {@link #getCharacterBoundsFlags(int)}: the
@@ -121,6 +129,7 @@ public final class CursorAnchorInfo implements Parcelable { 
    public static final int FLAG_IS_RTL = 0x04;



    public CursorAnchorInfo(final Parcel source) {

        mHashCode = source.readInt();

        mSelectionStart = source.readInt();

        mSelectionEnd = source.readInt();

        mComposingTextStart = source.readInt();
@@ -131,8 +140,7 @@ public final class CursorAnchorInfo implements Parcelable { 
        mInsertionMarkerBaseline = source.readFloat();

        mInsertionMarkerBottom = source.readFloat();

        mCharacterBoundsArray = source.readParcelable(SparseRectFArray.class.getClassLoader());

        mMatrix = new Matrix();

        mMatrix.setValues(source.createFloatArray());

        mMatrixValues = source.createFloatArray();

    }



    /**
@@ -143,6 +151,7 @@ public final class CursorAnchorInfo implements Parcelable { 
     */

    @Override

    public void writeToParcel(Parcel dest, int flags) {

        dest.writeInt(mHashCode);

        dest.writeInt(mSelectionStart);

        dest.writeInt(mSelectionEnd);

        dest.writeInt(mComposingTextStart);
@@ -153,27 +162,12 @@ public final class CursorAnchorInfo implements Parcelable { 
        dest.writeFloat(mInsertionMarkerBaseline);

        dest.writeFloat(mInsertionMarkerBottom);

        dest.writeParcelable(mCharacterBoundsArray, flags);

        final float[] matrixArray = new float[9];

        mMatrix.getValues(matrixArray);

        dest.writeFloatArray(matrixArray);

        dest.writeFloatArray(mMatrixValues);

    }



    @Override

    public int hashCode(){

        final float floatHash = mInsertionMarkerHorizontal + mInsertionMarkerTop

                + mInsertionMarkerBaseline + mInsertionMarkerBottom;

        int hash = floatHash > 0 ? (int) floatHash : (int)(-floatHash);

        hash *= 31;

        hash += mInsertionMarkerFlags;

        hash *= 31;

        hash += mSelectionStart + mSelectionEnd + mComposingTextStart;

        hash *= 31;

        hash += Objects.hashCode(mComposingText);

        hash *= 31;

        hash += Objects.hashCode(mCharacterBoundsArray);

        hash *= 31;

        hash += Objects.hashCode(mMatrix);

        return hash;

        return mHashCode;

    }



    /**
@@ -202,13 +196,13 @@ public final class CursorAnchorInfo implements Parcelable { 
        if (hashCode() != that.hashCode()) {

            return false;

        }



        // Check fields that are not covered by hashCode() first.



        if (mSelectionStart != that.mSelectionStart || mSelectionEnd != that.mSelectionEnd) {

            return false;

        }

        if (mComposingTextStart != that.mComposingTextStart

                || !Objects.equals(mComposingText, that.mComposingText)) {

            return false;

        }



        if (mInsertionMarkerFlags != that.mInsertionMarkerFlags

                || !areSameFloatImpl(mInsertionMarkerHorizontal, that.mInsertionMarkerHorizontal)

                || !areSameFloatImpl(mInsertionMarkerTop, that.mInsertionMarkerTop)
@@ -216,18 +210,35 @@ public final class CursorAnchorInfo implements Parcelable { 
                || !areSameFloatImpl(mInsertionMarkerBottom, that.mInsertionMarkerBottom)) {

            return false;

        }



        if (!Objects.equals(mCharacterBoundsArray, that.mCharacterBoundsArray)) {

            return false;

        }

        if (!Objects.equals(mMatrix, that.mMatrix)) {



        // Following fields are (partially) covered by hashCode().



        if (mComposingTextStart != that.mComposingTextStart

                || !Objects.equals(mComposingText, that.mComposingText)) {

            return false;

        }



        // We do not use Arrays.equals(float[], float[]) to keep the previous behavior regarding

        // NaN, 0.0f, and -0.0f.

        if (mMatrixValues.length != that.mMatrixValues.length) {

            return false;

        }

        for (int i = 0; i < mMatrixValues.length; ++i) {

            if (mMatrixValues[i] != that.mMatrixValues[i]) {

                return false;

            }

        }

        return true;

    }



    @Override

    public String toString() {

        return "SelectionInfo{mSelection=" + mSelectionStart + "," + mSelectionEnd

        return "CursorAnchorInfo{mHashCode=" + mHashCode

                + " mSelection=" + mSelectionStart + "," + mSelectionEnd

                + " mComposingTextStart=" + mComposingTextStart

                + " mComposingText=" + Objects.toString(mComposingText)

                + " mInsertionMarkerFlags=" + mInsertionMarkerFlags
@@ -236,7 +247,7 @@ public final class CursorAnchorInfo implements Parcelable { 
                + " mInsertionMarkerBaseline=" + mInsertionMarkerBaseline

                + " mInsertionMarkerBottom=" + mInsertionMarkerBottom

                + " mCharacterBoundsArray=" + Objects.toString(mCharacterBoundsArray)

                + " mMatrix=" + Objects.toString(mMatrix)

                + " mMatrix=" + Arrays.toString(mMatrixValues)

                + "}";

    }
@@ -254,7 +265,7 @@ public final class CursorAnchorInfo implements Parcelable { 
        private float mInsertionMarkerBottom = Float.NaN;

        private int mInsertionMarkerFlags = 0;

        private SparseRectFArrayBuilder mCharacterBoundsArrayBuilder = null;

        private final Matrix mMatrix = new Matrix(Matrix.IDENTITY_MATRIX);

        private float[] mMatrixValues = null;

        private boolean mMatrixInitialized = false;



        /**
@@ -349,7 +360,10 @@ public final class CursorAnchorInfo implements Parcelable { 
         * is interpreted as an identity matrix.

         */

        public Builder setMatrix(final Matrix matrix) {

            mMatrix.set(matrix != null ? matrix : Matrix.IDENTITY_MATRIX);

            if (mMatrixValues == null) {

                mMatrixValues = new float[9];

            }

            (matrix != null ? matrix : Matrix.IDENTITY_MATRIX).getValues(mMatrixValues);

            mMatrixInitialized = true;

            return this;

        }
@@ -391,7 +405,6 @@ public final class CursorAnchorInfo implements Parcelable { 
            mInsertionMarkerTop = Float.NaN;

            mInsertionMarkerBaseline = Float.NaN;

            mInsertionMarkerBottom = Float.NaN;

            mMatrix.set(Matrix.IDENTITY_MATRIX);

            mMatrixInitialized = false;

            if (mCharacterBoundsArrayBuilder != null) {

                mCharacterBoundsArrayBuilder.reset();
@@ -411,7 +424,18 @@ public final class CursorAnchorInfo implements Parcelable { 
        mInsertionMarkerBottom = builder.mInsertionMarkerBottom;

        mCharacterBoundsArray = builder.mCharacterBoundsArrayBuilder != null ?

                builder.mCharacterBoundsArrayBuilder.build() : null;

        mMatrix = new Matrix(builder.mMatrix);

        mMatrixValues = new float[9];

        if (builder.mMatrixInitialized) {

            System.arraycopy(builder.mMatrixValues, 0, mMatrixValues, 0, 9);

        } else {

            Matrix.IDENTITY_MATRIX.getValues(mMatrixValues);

        }



        // To keep hash function simple, we only use some complex objects for hash.

        int hash = Objects.hashCode(mComposingText);

        hash *= 31;

        hash += Arrays.hashCode(mMatrixValues);

        mHashCode = hash;

    }



    /**
@@ -527,7 +551,9 @@ public final class CursorAnchorInfo implements Parcelable { 
     * @return a new instance (copy) of the transformation matrix.

     */

    public Matrix getMatrix() {

        return new Matrix(mMatrix);

        final Matrix matrix = new Matrix();

        matrix.setValues(mMatrixValues);

        return matrix;

    }



    /**