Package org.apache.geode

Class CopyHelper

java.lang.Object
org.apache.geode.CopyHelper
public final class CopyHelper extends Object
A static helper for optimally creating copies. Creating copies of cache values provides improved concurrency as well as isolation. For transactions, creating a copy is the guaranteed way to enforce "Read Committed" isolation on changes to cache Entries.

Here is a simple example of how to use CopyHelper.copy 

 Object o = r.get("stringBuf");
 StringBuilder s = (StringBuilder) CopyHelper.copy(o);
 s.append("... and they lived happily ever after.  The End.");
 r.put("stringBuf", s);
Since:
GemFire 4.0
See Also:

  • Method Details

    • isWellKnownImmutableInstance

      public static boolean isWellKnownImmutableInstance(Object o)
      Return true if the given object is an instance of a well known immutable class. The well known classes are:
      • String
      • Byte
      • Character
      • Short
      • Integer
      • Long
      • Float
      • Double
      • BigInteger
      • BigDecimal
      • UUID
      • PdxInstance but not WritablePdxInstance
      Parameters:
      o - the object to check
      Returns:
      true if o is an instance of a well known immutable class.
      Since:
      GemFire 6.6.2

    • copy

      public static <T> T copy(T o)

      Makes a copy of the specified object. The object returned is not guaranteed to be a deep copy of the original object, as explained below.

      Copies can only be made if the original is a Cloneable or serializable by GemFire. If o is a well known immutable instance then it will be returned without copying it.

      If the argument o is an instance of Cloneable, a copy is made by invoking clone on it. Note that not all implementations of clone make deep copies (e.g. HashMap.clone). Otherwise, if the argument is not an instance of Cloneable, a copy is made using serialization: if GemFire serialization is implemented, it is used; otherwise, java serialization is used.

      The difference between this method and deepCopy, is that this method uses clone if available, whereas deepCopy does not. As a result, for Cloneable objects copied using this method, how deep a copy the returned object is depends on its implementation of clone.

      Type Parameters:
      T - the type of the object to be copied
      Parameters:
      o - the original object that a copy is needed of
      Returns:
      the new instance that is a copy of of the original
      Throws:
      CopyException - if copying fails because a class could not be found or could not be serialized.
      Since:
      GemFire 4.0
      See Also:

    • deepCopy

      public static <T> T deepCopy(T o)
      Makes a deep copy of the specified object o using serialization, so the object has to be serializable by GemFire.

      If o is a well known immutable instance then it will be returned without copying it.

      The passed in object is serialized in memory, and then deserialized into a new instance, which is returned. If GemFire serialization is implemented for the object, it is used; otherwise, java serialization is used.

      Type Parameters:
      T - the type of the object to be copied
      Parameters:
      o - the original object to be copied
      Returns:
      the new instance that is a copy of the original
      Throws:
      CopyException - if copying fails because a class could not be found or could not be serialized
      See Also: