Partial application of the patch in Bugzilla 41044:

 * addition of a generic PropertyCache to be used by all Property
   types that can be safely canonicalized
 * modified EnumProperty, StringProperty, NumberProperty, EnumNumber
   and FixedLength to make use of the cache infrastructure



git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@554251 13f79535-47bb-0310-9956-ffa450edef68

9 files changed, 218 insertions, 53 deletions

diff --git a/src/java/org/apache/fop/fo/properties/EnumNumber.java b/src/java/org/apache/fop/fo/properties/EnumNumber.java
index a5679cbcc..f8e940b01 100755
--- a/src/java/org/apache/fop/fo/properties/EnumNumber.java
+++ b/src/java/org/apache/fop/fo/properties/EnumNumber.java
@@ -19,30 +19,34 @@
  
 package org.apache.fop.fo.properties;
 
-import java.util.Map;
-import java.util.WeakHashMap;
-
 /**
  * A number quantity in XSL which is specified as an enum, such as "no-limit".
  */
 public class EnumNumber extends NumberProperty {
 
-    private static final Map cache = new WeakHashMap();
+    /** cache holding all canonical EnumNumber instances */
+    private static final PropertyCache cache = new PropertyCache();
 
     private final EnumProperty enumProperty;
     
-    private EnumNumber(EnumProperty enumProperty) {
+    /**
+     * Constructor
+     * @param enumProperty  the base EnumProperty
+     */
+    private EnumNumber(Property enumProperty) {
         super(null);
-        this.enumProperty = enumProperty;
+        this.enumProperty = (EnumProperty) enumProperty;
     }
 
+    /**
+     * Returns the canonical EnumNumber instance corresponding
+     * to the given Property
+     * @param enumProperty  the base EnumProperty
+     * @return  the canonical instance
+     */
     public static EnumNumber getInstance(Property enumProperty) {
-        EnumNumber en = (EnumNumber)cache.get(enumProperty);
-        if (en == null) {
-            en = new EnumNumber((EnumProperty)enumProperty);
-            cache.put(enumProperty, en);
-        }
-        return en;
+        return (EnumNumber)cache.fetch(
+                new EnumNumber((EnumProperty) enumProperty));
     }
 
     public int getEnum() {
@@ -81,5 +85,22 @@ public class EnumNumber extends NumberProperty {
         return enumProperty.getObject();
     }
 
+    /**
+     * @see java.lang.Object#equals(Object)
+     */
+    public boolean equals(Object obj) {
+        if (obj instanceof EnumNumber) {
+            return (((EnumNumber)obj).enumProperty == this.enumProperty);
+        } else {
+            return false;
+        }
+    }
 
+    /**
+     * @see java.lang.Object#hashCode()
+     */
+    public int hashCode() {
+        return enumProperty.hashCode();
+    }
+    
 }
diff --git a/src/java/org/apache/fop/fo/properties/EnumProperty.java b/src/java/org/apache/fop/fo/properties/EnumProperty.java
index 533ebd64f..f9801e222 100644
--- a/src/java/org/apache/fop/fo/properties/EnumProperty.java
+++ b/src/java/org/apache/fop/fo/properties/EnumProperty.java
@@ -23,13 +23,13 @@ import org.apache.fop.fo.FObj;
 import org.apache.fop.fo.PropertyList;
 import org.apache.fop.fo.expr.PropertyException;
 
-import java.util.Map;
-import java.util.WeakHashMap;
-
 /**
  * Superclass for properties that wrap an enumeration value
  */
 public class EnumProperty extends Property {
+    
+    /** cache holding all canonical EnumProperty instances */
+    private static final PropertyCache cache = new PropertyCache();
 
     /**
      * Inner class for creating EnumProperty instances
@@ -65,8 +65,6 @@ public class EnumProperty extends Property {
         }
     }
 
-    private static final Map propertyCache = new WeakHashMap();
-
     private final int value;
     private final String text;
 
@@ -80,14 +78,8 @@ public class EnumProperty extends Property {
     }
 
     public static EnumProperty getInstance(int explicitValue, String text) {
-        EnumProperty ep = new EnumProperty(explicitValue, text);
-        EnumProperty cacheEntry = (EnumProperty)propertyCache.get(ep);
-        if (cacheEntry == null) {
-            propertyCache.put(ep, ep);
-            return ep;
-        } else {
-            return cacheEntry;
-        }
+        return (EnumProperty) cache.fetch(
+                        new EnumProperty(explicitValue, text));
     }
 
     /**
@@ -119,6 +111,9 @@ public class EnumProperty extends Property {
         }
     }
 
+    /**
+     * @see java.lang.Object#hashCode()
+     */
     public int hashCode() {
         return value + text.hashCode();
     }
diff --git a/src/java/org/apache/fop/fo/properties/FixedLength.java b/src/java/org/apache/fop/fo/properties/FixedLength.java
index a043d803e..80016ba2e 100644
--- a/src/java/org/apache/fop/fo/properties/FixedLength.java
+++ b/src/java/org/apache/fop/fo/properties/FixedLength.java
@@ -25,26 +25,34 @@ import org.apache.fop.datatypes.PercentBaseContext;
  * An absolute length quantity in XSL
  */
 public class FixedLength extends LengthProperty {
+    
+    /** cache holding all canonical FixedLength instances */
+    private static final PropertyCache cache = new PropertyCache();
+    
     private int millipoints;
 
     /**
-     * Set the length given
-     * @param numRelUnits the number of relative units
-     * @param iCurFontSize the current font size in base units.
-     */
-    public FixedLength(double numRelUnits, int iCurFontSize) {
-        millipoints = (int) (numRelUnits * (double)iCurFontSize);
-    }
-
-    /**
      * Set the length given a number of units and a unit name.
      * @param numUnits quantity of input units
      * @param units input unit specifier (in, cm, etc.)
      */
-    public FixedLength(double numUnits, String units) {
+    private FixedLength(double numUnits, String units) {
         convert(numUnits, units);
     }
-
+    
+    /**
+     * Return the canonical FixedLength instance corresponding
+     * to the computed value
+     * @param numUnits  input units
+     * @param units     unit specifier
+     * @return
+     */
+    public static FixedLength getInstance(double numUnits, String units) {
+        return (FixedLength) cache.fetch(
+                    new FixedLength(numUnits, units));
+        
+    }
+    
     /**
      * @param baseUnits the length as a number of base units (millipoints)
      */
@@ -139,5 +147,22 @@ public class FixedLength extends LengthProperty {
         return millipoints + "mpt";
     }
 
+    /**
+     * @see java.lang.Object#equals(Object)
+     */
+    public boolean equals(Object obj) {
+        if (obj instanceof EnumProperty) {
+            return (((FixedLength)obj).millipoints == this.millipoints);
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * @see java.lang.Object#hashCode()
+     */
+    public int hashCode() {
+        return millipoints;
+    }
 }
 
diff --git a/src/java/org/apache/fop/fo/properties/FontFamilyProperty.java b/src/java/org/apache/fop/fo/properties/FontFamilyProperty.java
index 62263a02c..58cbc6402 100644
--- a/src/java/org/apache/fop/fo/properties/FontFamilyProperty.java
+++ b/src/java/org/apache/fop/fo/properties/FontFamilyProperty.java
@@ -86,7 +86,7 @@ public class FontFamilyProperty extends ListProperty {
                                         + tmpVal.substring(dblSpaceIndex + 1);
                             dblSpaceIndex = tmpVal.indexOf("  ");
                         }
-                        prop.addProperty(new StringProperty(tmpVal));
+                        prop.addProperty(StringProperty.getInstance(tmpVal));
                     }
                 }
                 return prop;
diff --git a/src/java/org/apache/fop/fo/properties/LengthProperty.java b/src/java/org/apache/fop/fo/properties/LengthProperty.java
index 79f9cfba7..8b5565e68 100644
--- a/src/java/org/apache/fop/fo/properties/LengthProperty.java
+++ b/src/java/org/apache/fop/fo/properties/LengthProperty.java
@@ -59,7 +59,7 @@ public abstract class LengthProperty extends Property
             }
             if (p instanceof NumberProperty) {
                 //Assume pixels (like in HTML) when there's no unit
-                return new FixedLength(p.getNumeric().getNumericValue(), "px");
+                return FixedLength.getInstance(p.getNumeric().getNumericValue(), "px");
             }
             Length val = p.getLength();
             if (val != null) {
diff --git a/src/java/org/apache/fop/fo/properties/NumberProperty.java b/src/java/org/apache/fop/fo/properties/NumberProperty.java
index 21ffd32e7..55206cff7 100644
--- a/src/java/org/apache/fop/fo/properties/NumberProperty.java
+++ b/src/java/org/apache/fop/fo/properties/NumberProperty.java
@@ -69,13 +69,16 @@ public class NumberProperty extends Property implements Numeric {
 
     }
 
-    private Number number;
+    /** cache holding all canonical NumberProperty instances */
+    private static final PropertyCache cache = new PropertyCache();
+    
+    private final Number number;
 
     /**
      * Constructor for Number input
      * @param num Number object value for property
      */
-    public NumberProperty(Number num) {
+    protected NumberProperty(Number num) {
         this.number = num;
     }
 
@@ -83,7 +86,7 @@ public class NumberProperty extends Property implements Numeric {
      * Constructor for double input
      * @param num double numeric value for property
      */
-    public NumberProperty(double num) {
+    protected NumberProperty(double num) {
         this.number = new Double(num);
     }
 
@@ -91,11 +94,44 @@ public class NumberProperty extends Property implements Numeric {
      * Constructor for integer input
      * @param num integer numeric value for property
      */
-    public NumberProperty(int num) {
+    protected NumberProperty(int num) {
         this.number = new Integer(num);
     }
     
     /**
+     * Returns the canonical NumberProperty instance
+     * corresponding to the given Number
+     * @param num   the base Number
+     * @return  the canonical NumberProperty
+     */
+    public static NumberProperty getInstance(Number num) {
+        return (NumberProperty)cache.fetch(
+                    new NumberProperty(num));
+    }
+    
+    /**
+     * Returns the canonical NumberProperty instance
+     * corresponding to the given double
+     * @param num   the base double value
+     * @return  the canonical NumberProperty
+     */
+    public static NumberProperty getInstance(double num) {
+        return (NumberProperty)cache.fetch(
+                    new NumberProperty(num));
+    }
+
+    /**
+     * Returns the canonical NumberProperty instance
+     * corresponding to the given int
+     * @param num   the base int value
+     * @return  the canonical NumberProperty
+     */
+    public static NumberProperty getInstance(int num) {
+        return (NumberProperty)cache.fetch(
+                    new NumberProperty(num));
+    }
+    
+    /**
      * Plain number always has a dimension of 0.
      * @return a dimension of 0.
      * @see Numeric#getDimension()
@@ -172,7 +208,7 @@ public class NumberProperty extends Property implements Numeric {
     /** @see org.apache.fop.fo.properties.Property#getLength() */
     public Length getLength() {
         //Assume pixels (like in HTML) when there's no unit
-        return new FixedLength(getNumericValue(), "px");
+        return FixedLength.getInstance(getNumericValue(), "px");
     }
 
     /**
diff --git a/src/java/org/apache/fop/fo/properties/PropertyCache.java b/src/java/org/apache/fop/fo/properties/PropertyCache.java
new file mode 100644
index 000000000..176cdd4aa
--- /dev/null
+++ b/src/java/org/apache/fop/fo/properties/PropertyCache.java
@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* $Id$ */
+
+package org.apache.fop.fo.properties;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.WeakHashMap;
+
+/**
+ *  Thin wrapper around a HashMap to implement the property caching idiom
+ *  in which a new Property instance is created then tested against cached
+ *  instances created previously. If an existing property is found, this is
+ *  retained and the newly created one is instantly eligible for garbage
+ *  collection.
+ */
+public class PropertyCache {
+
+    private Map propCache = Collections.synchronizedMap(new WeakHashMap());
+    
+    
+    /**
+     *  Checks if the given property is present in the cache - if so, returns
+     *  a reference to the cached value. Otherwise the given object is added
+     *  to the cache and returned.
+     *  @param obj
+     *  @return the cached instance
+     */
+    public Property fetch(Property prop) {
+        
+        Property cacheEntry = (Property) propCache.get(prop);
+        if (cacheEntry != null) {
+            return cacheEntry;
+        } else {
+            propCache.put(prop, prop);
+            return prop;
+        }
+    }
+}
diff --git a/src/java/org/apache/fop/fo/properties/StringProperty.java b/src/java/org/apache/fop/fo/properties/StringProperty.java
index 1b1699c5a..691942d78 100644
--- a/src/java/org/apache/fop/fo/properties/StringProperty.java
+++ b/src/java/org/apache/fop/fo/properties/StringProperty.java
@@ -77,17 +77,31 @@ public class StringProperty extends Property {
 
     }    // end String.Maker
 
-    private String str;
+    /** cache containing all canonical StringProperty instances */
+    private static final PropertyCache cache = new PropertyCache();
+    
+    private final String str;
 
     /**
+     * Constructor
      * @param str String value to place in this object
      */
-    public StringProperty(String str) {
+    private StringProperty(String str) {
         this.str = str;
-        // log.debug("Set StringProperty: " + str);
     }
 
     /**
+     * Return the canonical StringProperty instance 
+     * corresponding to the given string value
+     * @param str   the base String
+     * @return  the canonical instance
+     */
+    public static StringProperty getInstance(String str) {
+        return (StringProperty)cache.fetch(
+                   new StringProperty(str));
+    }
+    
+    /**
      * @return the Object equivalent of this property
      */
     public Object getObject() {
@@ -101,4 +115,23 @@ public class StringProperty extends Property {
         return this.str;
     }
 
+    /**
+     * @see java.lang.Object#hashCode()
+     */
+    public boolean equals(Object obj) {
+        if (obj instanceof StringProperty) {
+            StringProperty sp = (StringProperty)obj;
+            return (sp.str == this.str
+                    || sp.str.equals(this.str));
+        } else {
+            return false;
+        }
+    }
+    
+    /**
+     * @see java.lang.Object#hashCode()
+     */
+    public int hashCode() {
+        return str.hashCode();
+    }
 }
diff --git a/src/java/org/apache/fop/fo/properties/TableBorderPrecedence.java b/src/java/org/apache/fop/fo/properties/TableBorderPrecedence.java
index 9c094840e..dff9626a1 100644
--- a/src/java/org/apache/fop/fo/properties/TableBorderPrecedence.java
+++ b/src/java/org/apache/fop/fo/properties/TableBorderPrecedence.java
@@ -25,13 +25,13 @@ import org.apache.fop.fo.PropertyList;
 import org.apache.fop.fo.expr.PropertyException;
 
 public class TableBorderPrecedence extends NumberProperty.Maker{
-    private static Property num0 = new NumberProperty(0);
-    private static Property num1 = new NumberProperty(1);
-    private static Property num2 = new NumberProperty(2);
-    private static Property num3 = new NumberProperty(3);
-    private static Property num4 = new NumberProperty(4);
-    private static Property num5 = new NumberProperty(5);
-    private static Property num6 = new NumberProperty(6);
+    private static Property num0 = NumberProperty.getInstance(0);
+    private static Property num1 = NumberProperty.getInstance(1);
+    private static Property num2 = NumberProperty.getInstance(2);
+    private static Property num3 = NumberProperty.getInstance(3);
+    private static Property num4 = NumberProperty.getInstance(4);
+    private static Property num5 = NumberProperty.getInstance(5);
+    private static Property num6 = NumberProperty.getInstance(6);
 
     public TableBorderPrecedence(int propId) {
         super(propId);