Package org.apache.geode

Class CopyHelper

  • java.lang.Object
    • org.apache.geode.CopyHelper
  • public final class CopyHelper
extends java.lang.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:
    Cloneable, Serializable, DataSerializer, GemFireCache.setCopyOnRead(boolean), CacheTransactionManager

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static <T> T copy​(T o)
      Makes a copy of the specified object.
      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.
      static boolean isWellKnownImmutableInstance​(java.lang.Object o)
      Return true if the given object is an instance of a well known immutable class.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • isWellKnownImmutableInstance

        public static boolean isWellKnownImmutableInstance​(java.lang.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(Object)

      • 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:
        copy(Object)