11.4. Hot Rod Hash Functions

JBoss Data Grid uses a consistent hash function to place nodes and, subsequently, their corresponding keys on a hash wheel to determine where entries live.

The hash space value is constant and limited to the maximum 32-bit positive integer value (Integer.MAX_INT). This value is returned to the client using the Hot Rod protocol each time a hash-topology change is detected to prevent Hot Rod clients assuming a specific hash space as a default. The hash space can only contain positive numbers ranging from 0 to Integer.MAX_INT.

When the Hot Rod protocol is used to interact with JBoss Data Grid, the keys (and their values) must be byte arrays to ensure platform neutral behavior. Smart clients (which are aware of hash distribution in the background) must be able to recalculate hash codes of such byte array keys in this platform-neutral manner. To accommodate this, version information for hash functions used in JBoss Data Grid is saved for implementation by non-Java clients, if required.