Method hash

lib/tokenizer.js:138–240

* @param {Buffer} value * @return {Murmur3Token}

(value)

   * @return {Murmur3Token}
   */
  hash(value) {
    // This is an adapted version of the MurmurHash.hash3_x64_128 from Cassandra used
    // for M3P. Compared to that methods, there's a few inlining of arguments and we
    // only return the first 64-bits of the result since that's all M3 partitioner uses.

    const data = value;
    let offset = 0;
    const length = data.length;

    const nblocks = length >> 4; // Process as 128-bit blocks.

    const h1 = new MutableLong();
    const h2 = new MutableLong();
    let k1 = new MutableLong();
    let k2 = new MutableLong();

    for (let i = 0; i < nblocks; i++) {
      k1 = this.getBlock(data, offset, i * 2);
      k2 = this.getBlock(data, offset, i * 2 + 1);

      k1.multiply(mconst1);
      this.rotl64(k1, 31);
      k1.multiply(mconst2);

      h1.xor(k1);
      this.rotl64(h1, 27);
      h1.add(h2);
      h1.multiply(mlongFive).add(mconst5);

      k2.multiply(mconst2);
      this.rotl64(k2, 33);
      k2.multiply(mconst1);
      h2.xor(k2);
      this.rotl64(h2, 31);
      h2.add(h1);
      h2.multiply(mlongFive).add(mconst6);
    }
    //----------
    // tail

    // Advance offset to the unprocessed tail of the data.
    offset += nblocks * 16;

    k1 = new MutableLong();
    k2 = new MutableLong();

    /* eslint-disable no-fallthrough */
    switch(length & 15) {
      case 15:
        k2.xor(fromSignedByte(data[offset+14]).shiftLeft(48));
      case 14:
        k2.xor(fromSignedByte(data[offset+13]).shiftLeft(40));
      case 13:
        k2.xor(fromSignedByte(data[offset+12]).shiftLeft(32));
      case 12:
        k2.xor(fromSignedByte(data[offset+11]).shiftLeft(24));
      case 11:
        k2.xor(fromSignedByte(data[offset+10]).shiftLeft(16));