Changeset 8574 in josm for trunk/src/org/openstreetmap/josm/tools

Timestamp:

2015-07-05T22:14:49+02:00 (10 years ago)

Author:

bastiK

Message:

applied #11655 - memory optimization (patch by shinigami, modified)

Location:

trunk/src/org/openstreetmap/josm/tools

Files:

• Utils.java (modified) (1 diff)
• date/DateUtils.java (modified) (4 diffs)

trunk/src/org/openstreetmap/josm/tools/Utils.java

@@ -1366 +1366 @@
         }
     }
+
+    /**
+     * Returns the initial capacity to pass to the HashMap / HashSet constructor
+     * when it is initialized with a known number of entries.
+     * 
+     * When a HashMap is filled with entries, the underlying array is copied over
+     * to a larger one multiple times. To avoid this process when the number of
+     * entries is known in advance, the initial capacity of the array can be
+     * given to the HashMap constructor. This method returns a suitable value
+     * that avoids rehashing but doesn't waste memory.
+     * @param nEntries the number of entries expected
+     * @param loadFactor the load factor
+     * @return the initial capacity for the HashMap constructor
+     */
+    public static int hashMapInitialCapacity(int nEntries, float loadFactor) {
+        return (int) Math.ceil(nEntries / loadFactor);
+    }
+
+    /**
+     * Returns the initial capacity to pass to the HashMap / HashSet constructor
+     * when it is initialized with a known number of entries.
+     * 
+     * When a HashMap is filled with entries, the underlying array is copied over
+     * to a larger one multiple times. To avoid this process when the number of
+     * entries is known in advance, the initial capacity of the array can be
+     * given to the HashMap constructor. This method returns a suitable value
+     * that avoids rehashing but doesn't waste memory.
+     * 
+     * Assumes default load factor (0.75).
+     * @param nEntries the number of entries expected
+     * @return the initial capacity for the HashMap constructor
+     */
+    public static int hashMapInitialCapacity(int nEntries) {
+        return hashMapInitialCapacity(nEntries, 0.75f);
+    }
 }

trunk/src/org/openstreetmap/josm/tools/date/DateUtils.java

@@ -66 +66 @@
      */
     public static synchronized Date fromString(String str) {
+        return new Date(tsFromString(str));
+    }
+
+    /**
+     * Parses XML date quickly, regardless of current locale.
+     * @param str The XML date as string
+     * @return The date in milliseconds since epoch
+     */
+    public static synchronized long tsFromString(String str) {
         // "2007-07-25T09:26:24{Z|{+|-}01:00}"
         if (checkLayout(str, "xxxx-xx-xxTxx:xx:xxZ") ||
@@ -83 +92 @@
                 int plusHr = parsePart2(str, 20);
                 int mul = str.charAt(19) == '+' ? -3600000 : 3600000;
-                calendar.setTimeInMillis(calendar.getTimeInMillis()+plusHr*mul);
+                return calendar.getTimeInMillis()+plusHr*mul;
             }
 
-            return calendar.getTime();
+            return calendar.getTimeInMillis();
         } else if (checkLayout(str, "xxxx-xx-xxTxx:xx:xx.xxxZ") ||
                 checkLayout(str, "xxxx-xx-xxTxx:xx:xx.xxx") ||
@@ -99 +108 @@
                 parsePart2(str, 17));
             long millis = parsePart3(str, 20);
-            if (str.length() == 29)
+            if (str.length() == 29){
                 millis += parsePart2(str, 24) * (str.charAt(23) == '+' ? -3600000 : 3600000);
-            calendar.setTimeInMillis(calendar.getTimeInMillis()+millis);
-
-            return calendar.getTime();
+            }
+
+            return calendar.getTimeInMillis() + millis;
         } else {
             // example date format "18-AUG-08 13:33:03"
@@ -109 +118 @@
             Date d = f.parse(str, new ParsePosition(0));
             if (d != null)
-                return d;
+                return d.getTime();
         }
 
         try {
-            return XML_DATE.newXMLGregorianCalendar(str).toGregorianCalendar().getTime();
+            return XML_DATE.newXMLGregorianCalendar(str).toGregorianCalendar().getTimeInMillis();
         } catch (Exception ex) {
-            return new Date();
+            return System.currentTimeMillis();
         }
     }