Class CompositeIdRouter


  • public class CompositeIdRouter
    extends HashBasedRouter
    CompositeIdRouter partitions ids based on a SEPARATOR, hashes each partition and merges the hashes together to map the id to a slice. This allows bucketing of like groups of ids. Allows basic separation split between 32 bits as example given below, or using bitsSeparator can specify exact bits
     Example inputs:
     user!uniqueid
     app!user!uniqueid
     user/4!uniqueid
     app/2!user/4!uniqueid
     
    Lets say you had a set of records you want to index together such as a contact in a database, using a prefix of contact!contactid would allow all contact ids to be bucketed together.
     An Example:
     If the id "contact!0000000KISS is passed 😘
     Take "contact"" and hash it with murmurhash3_x86_32
     result: -541354036
     bits: 11011111101110111001011111001100
    
     Take 0000000KISS and hash it with murmurhash3_x86_32
     result: 2099700320
     bits: 01111101001001101110001001100000
    
     Now we take the bits and apply a mask, since this is 32 bits the mask is the first 16 bits or the last 16 bits
     So uppermask = 0xFFFF0000  11111111111111110000000000000000
     So we bitwise AND to get half the original hash and only the upper 16 bits for 00T
     11011111101110111001011111001100
     11111111111111110000000000000000
     ________________________________
     11011111101110110000000000000000
    
     lowermask = 0x0000FFFF 00000000000000001111111111111111
     So we bitwise AND and get the lower 16 bits of the original hash for 0000000KISS
     01111101001001101110001001100000
     00000000000000001111111111111111
     ________________________________
     00000000000000001110001001100000
    
     Now we combine the hashes with a bitwise OR
     11011111101110110000000000000000
     00000000000000001110001001100000
     ________________________________
     11011111101110111110001001100000
    
     11011111101110111110001001100000 is the hash we return, bucketing the suffixed by prefix type prefix!suffix