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java.lang.Objectcom.danga.MemCached.NativeHandler
public class NativeHandler
Handle encoding standard Java types directly which can result in significant memory savings: Currently the Memcached driver for Java supports the setSerialize() option. This can increase performance in some situations but has a few issues: Code that performs class casting will throw ClassCastExceptions when setSerialize is enabled. For example: mc.set( "foo", new Integer( 1 ) ); Integer output = (Integer)mc.get("foo"); Will work just file when setSerialize is true but when its false will just throw a ClassCastException. Also internally it doesn't support Boolean and since toString is called wastes a lot of memory and causes additional performance issue. For example an Integer can take anywhere from 1 byte to 10 bytes. Due to the way the memcached slab allocator works it seems like a LOT of wasted memory to store primitive types as serialized objects (from a performance and memory perspective). In our applications we have millions of small objects and wasted memory would become a big problem. For example a Serialized Boolean takes 47 bytes which means it will fit into the 64byte LRU. Using 1 byte means it will fit into the 8 byte LRU thus saving 8x the memory. This also saves the CPU performance since we don't have to serialize bytes back and forth and we can compute the byte[] value directly. One problem would be when the user calls get() because doing so would require the app to know the type of the object stored as a bytearray inside memcached (since the user will probably cast). If we assume the basic types are interned we could use the first byte as the type with the remaining bytes as the value. Then on get() we could read the first byte to determine the type and then construct the correct object for it. This would prevent the ClassCastException I talked about above. We could remove the setSerialize() option and just assume that standard VM types are always internd in this manner. mc.set( "foo", new Boolean.TRUE ); Boolean b = (Boolean)mc.get( "foo" ); And the type casts would work because internally we would create a new Boolean to return back to the client. This would reduce memory footprint and allow for a virtual implementation of the Externalizable interface which is much faster than Serialzation. Currently the memory improvements would be: java.lang.Boolean - 8x performance improvement (now just two bytes) java.lang.Integer - 16x performance improvement (now just 5 bytes) Most of the other primitive types would benefit from this optimization. java.lang.Character being another obvious example. I know it seems like I'm being really picky here but for our application I'd save 1G of memory right off the bat. We'd go down from 1.152G of memory used down to 144M of memory used which is much better IMO. http://java.sun.com/docs/books/tutorial/native1.1/integrating/types.html
Field Summary | |
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private static Logger |
log
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Constructor Summary | |
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NativeHandler()
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Method Summary | |
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static java.lang.Object |
decode(byte[] b,
int flag)
Decodes byte array using memcache flag to determine type. |
protected static java.lang.Boolean |
decodeBoolean(byte[] b)
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protected static java.lang.Byte |
decodeByte(byte[] b)
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protected static byte[] |
decodeByteArr(byte[] b)
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protected static java.lang.Character |
decodeCharacter(byte[] b)
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protected static java.util.Date |
decodeDate(byte[] b)
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protected static java.lang.Double |
decodeDouble(byte[] b)
|
protected static java.lang.Float |
decodeFloat(byte[] b)
|
protected static java.lang.Integer |
decodeInteger(byte[] b)
|
protected static java.lang.Long |
decodeLong(byte[] b)
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protected static java.lang.Short |
decodeShort(byte[] b)
|
protected static java.lang.String |
decodeString(byte[] b)
|
protected static java.lang.StringBuffer |
decodeStringBuffer(byte[] b)
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protected static java.lang.StringBuilder |
decodeStringBuilder(byte[] b)
|
protected static byte[] |
encode(java.lang.Boolean value)
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protected static byte[] |
encode(java.lang.Byte value)
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protected static byte[] |
encode(byte[] value)
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protected static byte[] |
encode(java.lang.Character value)
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protected static byte[] |
encode(java.util.Date value)
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protected static byte[] |
encode(double value)
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protected static byte[] |
encode(float value)
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protected static byte[] |
encode(int value)
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protected static byte[] |
encode(long value)
|
static byte[] |
encode(java.lang.Object value)
Encodes supported types |
protected static byte[] |
encode(java.lang.Short value)
|
protected static byte[] |
encode(java.lang.String value)
|
protected static byte[] |
encode(java.lang.StringBuffer value)
|
protected static byte[] |
encode(java.lang.StringBuilder value)
|
protected static byte[] |
getBytes(int value)
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protected static byte[] |
getBytes(long value)
|
static int |
getMarkerFlag(java.lang.Object value)
Returns the flag for marking the type of the byte array. |
static boolean |
isHandled(java.lang.Object value)
Detemine of object can be natively serialized by this class. |
protected static int |
toInt(byte[] b)
This works by taking each of the bit patterns and converting them to ints taking into account 2s complement and then adding them.. |
protected static long |
toLong(byte[] b)
|
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private static Logger log
Constructor Detail |
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public NativeHandler()
Method Detail |
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public static boolean isHandled(java.lang.Object value)
value
- Object to test.
public static int getMarkerFlag(java.lang.Object value)
value
- Object we are storing.
public static byte[] encode(java.lang.Object value) throws java.lang.Exception
value
- Object to encode.
java.lang.Exception
- If fail to encode.protected static byte[] encode(java.lang.Byte value)
protected static byte[] encode(java.lang.Boolean value)
protected static byte[] encode(int value)
protected static byte[] encode(long value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(java.util.Date value)
protected static byte[] encode(java.lang.Character value)
protected static byte[] encode(java.lang.String value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(java.lang.StringBuffer value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(float value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(java.lang.Short value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(double value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(java.lang.StringBuilder value) throws java.lang.Exception
java.lang.Exception
protected static byte[] encode(byte[] value)
protected static byte[] getBytes(long value)
protected static byte[] getBytes(int value)
public static java.lang.Object decode(byte[] b, int flag) throws java.lang.Exception
b
- marker
-
java.lang.Exception
protected static java.lang.Byte decodeByte(byte[] b)
protected static java.lang.Boolean decodeBoolean(byte[] b)
protected static java.lang.Integer decodeInteger(byte[] b)
protected static java.lang.Long decodeLong(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static java.lang.Character decodeCharacter(byte[] b)
protected static java.lang.String decodeString(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static java.lang.StringBuffer decodeStringBuffer(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static java.lang.Float decodeFloat(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static java.lang.Short decodeShort(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static java.lang.Double decodeDouble(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static java.util.Date decodeDate(byte[] b)
protected static java.lang.StringBuilder decodeStringBuilder(byte[] b) throws java.lang.Exception
java.lang.Exception
protected static byte[] decodeByteArr(byte[] b)
protected static int toInt(byte[] b)
b
-
protected static long toLong(byte[] b)
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