Hi,
please give your comments on the attached patch. It tries to reduce the
size of char[] for strings used to hold numbers. It changes Float/Double
equals to use bit based comparisons rather than division. It increases
the use of valueOf methods. It adds a cache of values from -128 to 127
for Long. It adds a cache of the values of zero and one to Float and Double.
The string size is an estimate. For decimal numbers it will divide the
value repeatedly by 8, causing the string length to be over estimated by
a character for values like 999. This string size is still better than
the current estimate of 33 characters. It also avoids the use of
division (shifts are used) and/or lookup tables.
Regards,
Ian
Index: ChangeLog
===================================================================
RCS file: /sources/classpath/classpath/ChangeLog,v
retrieving revision 1.9572
diff -u -r1.9572 ChangeLog
--- ChangeLog 9 Apr 2008 20:23:11 -0000 1.9572
+++ ChangeLog 14 Apr 2008 13:54:25 -0000
@@ -1,3 +1,50 @@
+2008-04-14 Ian Rogers <[EMAIL PROTECTED]>
+
+ * java/lang/Byte.java (static): initialize byteCache.
+ (valueOf(String,int)): use valueOf(byte) rather than new.
+ (valueOf(String)): likewise.
+ (valueOf(byte)): remove synchronization.
+ (decode): use valueOf(byte) rather than new.
+ * java/lang/Character.java (static): initialize charCache.
+ (valueOf): remove synchronization.
+ * java/lang/Double.java (ZERO): new private field.
+ (ONE): likewise.
+ (valueOf(double)): don't create new doubles for the case of 0 and 1.
+ (valueOf(String)): use valueOf(double) rather than new.
+ (equals): use raw bits for comparison to avoid division.
+ * java/lang/Float.java (ZERO): new private field.
+ (ONE): likewise.
+ (valueOf(double)): don't create new floats for the case of 0 and 1.
+ (valueOf(String)): use valueOf(float) rather than new.
+ (equals): use raw bits for comparison to avoid division.
+ * java/lang/Integer.java (static): initialize intCache.
+ (stringSize): new private method to estimate size of string for an int.
+ (toString): reuse digits for single character strings, for multiple
+ character strings estimate their length using string size method.
+ (valueOf(String,int)): use valueOf(int) rather than new.
+ (valueOf(String)): likewise.
+ (valueOf(int)): remove synchronization.
+ (getInteger): use valueOf(int) rather than new.
+ (decode): use valueOf(int) rather than new.
+ (signum): use shift and subtract to compute value.
+ (toUnsignedString): calculate string size rather than using 32 chars.
+ * java/lang/Long.java (longCache): new private field.
+ (stringSize): new private method to estimate size of string for a long.
+ (toString): reuse digits for single character strings, for multiple
+ character strings estimate their length using string size method.
+ (valueOf(String,int)): use valueOf(long) rather than new.
+ (valueOf(String)): likewise.
+ (valueOf(long)): use cache.
+ (decode): use valueOf(long) rather than new.
+ (getLong): likewise.
+ (signum): use shift and subtract to compute value.
+ (toUnsignedString): calculate string size rather than using 64 chars.
+ * java/lang/Short.java (static): initialize shortCache.
+ (valueOf(String,int)): use valueOf(short) rather than new.
+ (valueOf(String)): likewise.
+ (valueOf(short)): remove synchronization.
+ (decode): use valueOf(short) rather than new.
+
2008-04-09 Mario Torre <[EMAIL PROTECTED]>
* java/io/File.java (canWrite): use canWriteDirectory(String).
Index: java/lang/Byte.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Byte.java,v
retrieving revision 1.26
diff -u -r1.26 Byte.java
--- java/lang/Byte.java 10 Dec 2006 20:25:44 -0000 1.26
+++ java/lang/Byte.java 14 Apr 2008 13:54:25 -0000
@@ -88,6 +88,11 @@
// This caches Byte values, and is used by boxing conversions via
// valueOf(). We're required to cache all possible values here.
private static Byte[] byteCache = new Byte[MAX_VALUE - MIN_VALUE + 1];
+ static
+ {
+ for (byte i=MIN_VALUE; i <= MAX_VALUE; i++)
+ byteCache[i - MIN_VALUE] = new Byte(i);
+ }
/**
@@ -185,7 +190,7 @@
*/
public static Byte valueOf(String s, int radix)
{
- return new Byte(parseByte(s, radix));
+ return valueOf(parseByte(s, radix));
}
/**
@@ -201,7 +206,7 @@
*/
public static Byte valueOf(String s)
{
- return new Byte(parseByte(s, 10));
+ return valueOf(parseByte(s, 10));
}
/**
@@ -214,12 +219,7 @@
*/
public static Byte valueOf(byte val)
{
- synchronized (byteCache)
- {
- if (byteCache[val - MIN_VALUE] == null)
- byteCache[val - MIN_VALUE] = new Byte(val);
- return byteCache[val - MIN_VALUE];
- }
+ return byteCache[val - MIN_VALUE];
}
/**
@@ -258,7 +258,7 @@
int i = Integer.parseInt(s, 10, true);
if ((byte) i != i)
throw new NumberFormatException();
- return new Byte((byte) i);
+ return valueOf((byte) i);
}
/**
Index: java/lang/Character.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Character.java,v
retrieving revision 1.48
diff -u -r1.48 Character.java
--- java/lang/Character.java 19 Dec 2006 01:14:23 -0000 1.48
+++ java/lang/Character.java 14 Apr 2008 13:54:25 -0000
@@ -2055,6 +2055,11 @@
// this constant controls how much we actually cache.
private static final int MAX_CACHE = 127;
private static Character[] charCache = new Character[MAX_CACHE + 1];
+ static
+ {
+ for (char i=0; i <= MAX_CACHE; i++)
+ charCache[i] = new Character(i);
+ }
/**
* Lu = Letter, Uppercase (Informative).
@@ -4208,12 +4213,8 @@
{
if (val > MAX_CACHE)
return new Character(val);
- synchronized (charCache)
- {
- if (charCache[val - MIN_VALUE] == null)
- charCache[val - MIN_VALUE] = new Character(val);
- return charCache[val - MIN_VALUE];
- }
+ else
+ return charCache[val - MIN_VALUE];
}
/**
Index: java/lang/Double.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Double.java,v
retrieving revision 1.45
diff -u -r1.45 Double.java
--- java/lang/Double.java 16 Mar 2008 22:04:50 -0000 1.45
+++ java/lang/Double.java 14 Apr 2008 13:54:25 -0000
@@ -104,6 +104,16 @@
public static final Class<Double> TYPE = (Class<Double>)
VMClassLoader.getPrimitiveClass('D');
/**
+ * Cache representation of 0
+ */
+ private static final Double ZERO = new Double(0.0d);
+
+ /**
+ * Cache representation of 1
+ */
+ private static final Double ONE = new Double(1.0d);
+
+ /**
* The immutable value of this Double.
*
* @serial the wrapped double
@@ -261,8 +271,12 @@
*/
public static Double valueOf(double val)
{
- // We don't actually cache, but we could.
- return new Double(val);
+ if ((val == 0.0) && (doubleToRawLongBits(val) == 0L))
+ return ZERO;
+ else if (val == 1.0)
+ return ONE;
+ else
+ return new Double(val);
}
/**
@@ -277,7 +291,7 @@
*/
public static Double valueOf(String s)
{
- return new Double(parseDouble(s));
+ return valueOf(parseDouble(s));
}
/**
@@ -490,17 +504,13 @@
*/
public boolean equals(Object obj)
{
- if (! (obj instanceof Double))
- return false;
-
- double d = ((Double) obj).value;
-
- // Avoid call to native method. However, some implementations, like gcj,
- // are better off using floatToIntBits(value) == floatToIntBits(f).
- // Check common case first, then check NaN and 0.
- if (value == d)
- return (value != 0) || (1 / value == 1 / d);
- return isNaN(value) && isNaN(d);
+ if (obj instanceof Double)
+ {
+ double d = ((Double) obj).value;
+ return (doubleToRawLongBits(value) == doubleToRawLongBits(d)) ||
+ (isNaN(value) && isNaN(d));
+ }
+ return false;
}
/**
Index: java/lang/Float.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Float.java,v
retrieving revision 1.39
diff -u -r1.39 Float.java
--- java/lang/Float.java 16 Mar 2008 22:04:50 -0000 1.39
+++ java/lang/Float.java 14 Apr 2008 13:54:25 -0000
@@ -104,6 +104,16 @@
public static final int SIZE = 32;
/**
+ * Cache representation of 0
+ */
+ private static final Float ZERO = new Float(0.0f);
+
+ /**
+ * Cache representation of 1
+ */
+ private static final Float ONE = new Float(1.0f);
+
+ /**
* The immutable value of this Float.
*
* @serial the wrapped float
@@ -275,7 +285,7 @@
*/
public static Float valueOf(String s)
{
- return new Float(parseFloat(s));
+ return valueOf(parseFloat(s));
}
/**
@@ -289,8 +299,12 @@
*/
public static Float valueOf(float val)
{
- // We don't actually cache, but we could.
- return new Float(val);
+ if ((val == 0.0) && (floatToRawIntBits(val) == 0))
+ return ZERO;
+ else if (val == 1.0)
+ return ONE;
+ else
+ return new Float(val);
}
/**
@@ -500,17 +514,13 @@
*/
public boolean equals(Object obj)
{
- if (! (obj instanceof Float))
- return false;
-
- float f = ((Float) obj).value;
-
- // Avoid call to native method. However, some implementations, like gcj,
- // are better off using floatToIntBits(value) == floatToIntBits(f).
- // Check common case first, then check NaN and 0.
- if (value == f)
- return (value != 0) || (1 / value == 1 / f);
- return isNaN(value) && isNaN(f);
+ if (obj instanceof Float)
+ {
+ float f = ((Float) obj).value;
+ return (floatToRawIntBits(value) == floatToRawIntBits(f)) ||
+ (isNaN(value) && isNaN(f));
+ }
+ return false;
}
/**
Index: java/lang/Integer.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Integer.java,v
retrieving revision 1.36
diff -u -r1.36 Integer.java
--- java/lang/Integer.java 3 Jul 2007 14:59:00 -0000 1.36
+++ java/lang/Integer.java 14 Apr 2008 13:54:25 -0000
@@ -52,6 +52,7 @@
* @author Eric Blake ([EMAIL PROTECTED])
* @author Tom Tromey ([EMAIL PROTECTED])
* @author Andrew John Hughes ([EMAIL PROTECTED])
+ * @author Ian Rogers
* @since 1.0
* @status updated to 1.5
*/
@@ -92,7 +93,12 @@
// these constants control how much we actually cache.
private static final int MIN_CACHE = -128;
private static final int MAX_CACHE = 127;
- private static Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE + 1];
+ private static final Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE
+ 1];
+ static
+ {
+ for (int i=MIN_CACHE; i <= MAX_CACHE; i++)
+ intCache[i - MIN_CACHE] = new Integer(i);
+ }
/**
* The immutable value of this Integer.
@@ -126,6 +132,45 @@
}
/**
+ * Return the size of a string large enough to hold the given number
+ *
+ * @param num the number we want the string length for (must be positive)
+ * @param radix the radix (base) that will be used for the string
+ * @return a size sufficient for a string of num
+ */
+ private static int stringSize(int num, int radix) {
+ int exp;
+ if (radix < 4)
+ {
+ exp = 1;
+ }
+ else if (radix < 8)
+ {
+ exp = 2;
+ }
+ else if (radix < 16)
+ {
+ exp = 3;
+ }
+ else if (radix < 32)
+ {
+ exp = 4;
+ }
+ else
+ {
+ exp = 5;
+ }
+ int size=0;
+ do
+ {
+ num >>>= exp;
+ size++;
+ }
+ while(num != 0);
+ return size;
+ }
+
+ /**
* Converts the <code>int</code> to a <code>String</code> using
* the specified radix (base). If the radix exceeds
* <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10
@@ -142,22 +187,40 @@
if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
radix = 10;
- // For negative numbers, print out the absolute value w/ a leading '-'.
- // Use an array large enough for a binary number.
- char[] buffer = new char[33];
- int i = 33;
- boolean isNeg = false;
- if (num < 0)
+ // Is the value negative?
+ boolean isNeg = num < 0;
+
+ // Is the string a single character?
+ if (!isNeg && num < radix)
+ return new String(digits, num, 1, true);
+
+ // Compute string size and allocate buffer
+ // account for a leading '-' if the value is negative
+ int size;
+ int i;
+ char[] buffer;
+ if (isNeg)
{
- isNeg = true;
num = -num;
// When the value is MIN_VALUE, it overflows when made positive
if (num < 0)
{
+ i = size = stringSize(MAX_VALUE, radix) + 2;
+ buffer = new char[size];
buffer[--i] = digits[(int) (-(num + radix) % radix)];
num = -(num / radix);
}
+ else
+ {
+ i = size = stringSize(num, radix) + 1;
+ buffer = new char[size];
+ }
+ }
+ else
+ {
+ i = size = stringSize(num, radix);
+ buffer = new char[size];
}
do
@@ -171,7 +234,7 @@
buffer[--i] = '-';
// Package constructor avoids an array copy.
- return new String(buffer, i, 33 - i, true);
+ return new String(buffer, i, size - i, true);
}
/**
@@ -275,7 +338,7 @@
*/
public static Integer valueOf(String s, int radix)
{
- return new Integer(parseInt(s, radix, false));
+ return valueOf(parseInt(s, radix, false));
}
/**
@@ -291,7 +354,7 @@
*/
public static Integer valueOf(String s)
{
- return new Integer(parseInt(s, 10, false));
+ return valueOf(parseInt(s, 10, false));
}
/**
@@ -306,12 +369,8 @@
{
if (val < MIN_CACHE || val > MAX_CACHE)
return new Integer(val);
- synchronized (intCache)
- {
- if (intCache[val - MIN_CACHE] == null)
- intCache[val - MIN_CACHE] = new Integer(val);
- return intCache[val - MIN_CACHE];
- }
+ else
+ return intCache[val - MIN_CACHE];
}
/**
@@ -440,7 +499,7 @@
public static Integer getInteger(String nm, int val)
{
Integer result = getInteger(nm, null);
- return result == null ? new Integer(val) : result;
+ return result == null ? valueOf(val) : result;
}
/**
@@ -506,7 +565,7 @@
*/
public static Integer decode(String str)
{
- return new Integer(parseInt(str, 10, true));
+ return valueOf(parseInt(str, 10, true));
}
/**
@@ -628,7 +687,7 @@
*/
public static int signum(int x)
{
- return x < 0 ? -1 : (x > 0 ? 1 : 0);
+ return (x >> 31) - (-x >> 31);
}
/**
@@ -666,10 +725,22 @@
// Package visible for use by Long.
static String toUnsignedString(int num, int exp)
{
- // Use an array large enough for a binary number.
+ // Compute string length
+ int size = 1;
+ int copy = num >>> exp;
+ while (copy != 0)
+ {
+ size++;
+ copy >>>= exp;
+ }
+ // Quick path for single character strings
+ if (size == 1)
+ return new String(digits, num, 1, true);
+
+ // Encode into buffer
int mask = (1 << exp) - 1;
- char[] buffer = new char[32];
- int i = 32;
+ char[] buffer = new char[size];
+ int i = size;
do
{
buffer[--i] = digits[num & mask];
@@ -678,7 +749,7 @@
while (num != 0);
// Package constructor avoids an array copy.
- return new String(buffer, i, 32 - i, true);
+ return new String(buffer, i, size - i, true);
}
/**
Index: java/lang/Long.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Long.java,v
retrieving revision 1.25
diff -u -r1.25 Long.java
--- java/lang/Long.java 23 Nov 2007 14:50:53 -0000 1.25
+++ java/lang/Long.java 14 Apr 2008 13:54:25 -0000
@@ -51,6 +51,7 @@
* @author Eric Blake ([EMAIL PROTECTED])
* @author Tom Tromey ([EMAIL PROTECTED])
* @author Andrew John Hughes ([EMAIL PROTECTED])
+ * @author Ian Rogers
* @since 1.0
* @status updated to 1.5
*/
@@ -86,6 +87,18 @@
*/
public static final int SIZE = 64;
+ // This caches some Long values, and is used by boxing
+ // conversions via valueOf(). We cache at least -128..127;
+ // these constants control how much we actually cache.
+ private static final int MIN_CACHE = -128;
+ private static final int MAX_CACHE = 127;
+ private static final Long[] longCache = new Long[MAX_CACHE - MIN_CACHE + 1];
+ static
+ {
+ for (int i=MIN_CACHE; i <= MAX_CACHE; i++)
+ longCache[i - MIN_CACHE] = new Long(i);
+ }
+
/**
* The immutable value of this Long.
*
@@ -118,6 +131,45 @@
}
/**
+ * Return the size of a string large enough to hold the given number
+ *
+ * @param num the number we want the string length for (must be positive)
+ * @param radix the radix (base) that will be used for the string
+ * @return a size sufficient for a string of num
+ */
+ private static int stringSize(long num, int radix) {
+ int exp;
+ if (radix < 4)
+ {
+ exp = 1;
+ }
+ else if (radix < 8)
+ {
+ exp = 2;
+ }
+ else if (radix < 16)
+ {
+ exp = 3;
+ }
+ else if (radix < 32)
+ {
+ exp = 4;
+ }
+ else
+ {
+ exp = 5;
+ }
+ int size=0;
+ do
+ {
+ num >>>= exp;
+ size++;
+ }
+ while(num != 0);
+ return size;
+ }
+
+ /**
* Converts the <code>long</code> to a <code>String</code> using
* the specified radix (base). If the radix exceeds
* <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10
@@ -131,29 +183,43 @@
*/
public static String toString(long num, int radix)
{
- // Use the Integer toString for efficiency if possible.
- if ((int) num == num)
- return Integer.toString((int) num, radix);
-
if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
radix = 10;
- // For negative numbers, print out the absolute value w/ a leading '-'.
- // Use an array large enough for a binary number.
- char[] buffer = new char[65];
- int i = 65;
- boolean isNeg = false;
- if (num < 0)
+ // Is the value negative?
+ boolean isNeg = num < 0;
+
+ // Is the string a single character?
+ if (!isNeg && num < radix)
+ return new String(digits, (int)num, 1, true);
+
+ // Compute string size and allocate buffer
+ // account for a leading '-' if the value is negative
+ int size;
+ int i;
+ char[] buffer;
+ if (isNeg)
{
- isNeg = true;
num = -num;
// When the value is MIN_VALUE, it overflows when made positive
if (num < 0)
- {
- buffer[--i] = digits[(int) (-(num + radix) % radix)];
- num = -(num / radix);
- }
+ {
+ i = size = stringSize(MAX_VALUE, radix) + 2;
+ buffer = new char[size];
+ buffer[--i] = digits[(int) (-(num + radix) % radix)];
+ num = -(num / radix);
+ }
+ else
+ {
+ i = size = stringSize(num, radix) + 1;
+ buffer = new char[size];
+ }
+ }
+ else
+ {
+ i = size = stringSize(num, radix);
+ buffer = new char[size];
}
do
@@ -167,7 +233,7 @@
buffer[--i] = '-';
// Package constructor avoids an array copy.
- return new String(buffer, i, 65 - i, true);
+ return new String(buffer, i, size - i, true);
}
/**
@@ -270,7 +336,7 @@
*/
public static Long valueOf(String s, int radix)
{
- return new Long(parseLong(s, radix, false));
+ return valueOf(parseLong(s, radix, false));
}
/**
@@ -286,7 +352,7 @@
*/
public static Long valueOf(String s)
{
- return new Long(parseLong(s, 10, false));
+ return valueOf(parseLong(s, 10, false));
}
/**
@@ -298,9 +364,10 @@
*/
public static Long valueOf(long val)
{
- // We aren't required to cache here. We could, though perhaps we
- // ought to consider that as an empirical question.
- return new Long(val);
+ if (val < MIN_CACHE || val > MAX_CACHE)
+ return new Long(val);
+ else
+ return longCache[((int)val) - MIN_CACHE];
}
/**
@@ -337,7 +404,7 @@
*/
public static Long decode(String str)
{
- return new Long(parseLong(str, 10, true));
+ return valueOf(parseLong(str, 10, true));
}
/**
@@ -467,7 +534,7 @@
public static Long getLong(String nm, long val)
{
Long result = getLong(nm, null);
- return result == null ? new Long(val) : result;
+ return result == null ? valueOf(val) : result;
}
/**
@@ -622,7 +689,7 @@
*/
public static int signum(long x)
{
- return x < 0 ? -1 : (x > 0 ? 1 : 0);
+ return (int)(x >> 63) - (int)(-x >> 63);
}
/**
@@ -655,16 +722,22 @@
*/
private static String toUnsignedString(long num, int exp)
{
- // Use the Integer toUnsignedString for efficiency if possible.
- // If NUM<0 then this particular optimization doesn't work
- // properly.
- if (num >= 0 && (int) num == num)
- return Integer.toUnsignedString((int) num, exp);
+ // Compute string length
+ int size = 1;
+ long copy = num >>> exp;
+ while (copy != 0)
+ {
+ size++;
+ copy >>>= exp;
+ }
+ // Quick path for single character strings
+ if (size == 1)
+ return new String(digits, (int)num, 1, true);
- // Use an array large enough for a binary number.
+ // Encode into buffer
int mask = (1 << exp) - 1;
- char[] buffer = new char[64];
- int i = 64;
+ char[] buffer = new char[size];
+ int i = size;
do
{
buffer[--i] = digits[(int) num & mask];
@@ -673,7 +746,7 @@
while (num != 0);
// Package constructor avoids an array copy.
- return new String(buffer, i, 64 - i, true);
+ return new String(buffer, i, size - i, true);
}
/**
Index: java/lang/Short.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/Short.java,v
retrieving revision 1.20
diff -u -r1.20 Short.java
--- java/lang/Short.java 10 Dec 2006 20:25:44 -0000 1.20
+++ java/lang/Short.java 14 Apr 2008 13:54:25 -0000
@@ -90,6 +90,11 @@
private static final int MIN_CACHE = -128;
private static final int MAX_CACHE = 127;
private static Short[] shortCache = new Short[MAX_CACHE - MIN_CACHE + 1];
+ static
+ {
+ for (short i=MIN_CACHE; i <= MAX_CACHE; i++)
+ shortCache[i - MIN_CACHE] = new Short(i);
+ }
/**
* The immutable value of this Short.
@@ -184,7 +189,7 @@
*/
public static Short valueOf(String s, int radix)
{
- return new Short(parseShort(s, radix));
+ return valueOf(parseShort(s, radix));
}
/**
@@ -200,7 +205,7 @@
*/
public static Short valueOf(String s)
{
- return new Short(parseShort(s, 10));
+ return valueOf(parseShort(s, 10));
}
/**
@@ -216,12 +221,8 @@
{
if (val < MIN_CACHE || val > MAX_CACHE)
return new Short(val);
- synchronized (shortCache)
- {
- if (shortCache[val - MIN_CACHE] == null)
- shortCache[val - MIN_CACHE] = new Short(val);
- return shortCache[val - MIN_CACHE];
- }
+ else
+ return shortCache[val - MIN_CACHE];
}
/**
@@ -260,7 +261,7 @@
int i = Integer.parseInt(s, 10, true);
if ((short) i != i)
throw new NumberFormatException();
- return new Short((short) i);
+ return valueOf((short) i);
}
/**
