001 // VTMemory.java, created by wbeebee
002 // Copyright (C) 2001 Wes Beebee <wbeebee@mit.edu>
003 // Licensed under the terms of the GNU GPL; see COPYING for details.
004 package javax.realtime;
005
006 /**
007 * @author Wes Beebee <<a href="mailto:wbeebee@mit.edu">wbeebee@mit.edu</a>>
008 */
009
010 /** The execution time of an allocation from a <code>VTMemory</code> area may
011 * take a variable amount of time. However, since <code>VTMemory</code> areas
012 * are not subject to garbage collection and objects within it may not be moved,
013 * these areas can be used by instances of <code>NoHeapRealtimeThread</code>.
014 */
015 public class VTMemory extends ScopedMemory {
016
017 /** The logic associated with <code>this</code> */
018 Runnable logic;
019
020 /** Creates a <code>VTMemory</code> with the given parameters.
021 *
022 * @param initial The size in bytes of the memory to initially allocate for
023 * this area.
024 * @param maximum The maximum size in bytes of this memory area to which
025 * the size may grow.
026 */
027 public VTMemory(long initialSizeInBytes, long maxSizeInBytes) {
028 super(maxSizeInBytes);
029 }
030
031 /** Creates a <code>VTMemory</code> with the given parameters.
032 *
033 * @param initial The size in bytes of the memory to initially allocate for
034 * this area.
035 * @param maximum The maximum size in bytes of this memory area to which
036 * the size may grow.
037 * @param logic An instance of <code>java.lang.Runnable</code> whose
038 * <code>run()</code> method will use <code>this</code> as its
039 * initial memory area.
040 */
041 public VTMemory(long initialSizeInBytes, long maxSizeInBytes,
042 Runnable logic) {
043 this(initialSizeInBytes, maxSizeInBytes);
044 this.logic = logic;
045 }
046
047 /** Creates a <code>VTMemory</code> with the given parameters.
048 *
049 * @param initial The size in bytes of the memory to initially allocate for
050 * this area.
051 * @param maximum The maximum size in bytes of this memory area to which
052 * the size may grow estimated by an instance of
053 * <code>SizeEstimator</code>.
054 */
055 public VTMemory(SizeEstimator initial, SizeEstimator maximum) {
056 this(initial.getEstimate(), maximum.getEstimate());
057 }
058
059 /** Creates a <code>VTMemory</code> with the given parameters.
060 *
061 * @param initial The size in bytes of the memory to initially allocate for
062 * this area.
063 * @param maximum The maximum size in bytes of this memory area to which
064 * the size may grow estimated by an instance of
065 * <code>SizeEstimator</code>.
066 * @param logic An instance of <code>java.lang.Runnable</code> whose
067 * <code>run()</code> method will use <code>this<code> as its
068 * initial memory area.
069 */
070 public VTMemory(SizeEstimator initial, SizeEstimator maximum,
071 Runnable logic) {
072 this(initial, maximum);
073 this.logic = logic;
074 }
075
076 /** Alternate constructor, with no limits */
077 public VTMemory() {
078 super(0);
079 }
080
081 /** Gets the value of the maximum size to which <code>this</code> can grow.
082 *
083 * @return The maximum size value.
084 */
085 public long getMaximumSize() {
086 return size;
087 }
088
089 /** Create a string representing the name of <code>this</code>.
090 *
091 * @return A string representing the name of <code>this</code>.
092 */
093 public String toString() {
094 return "VTMemory: " + super.toString();
095 }
096
097 /** Initialize the native component of this VTMemory. */
098 protected native void initNative(long sizeInBytes);
099 }