Different results from Murmur3 from Scala and Guava
scala,guava,consistent-hashing,murmurhash
It looks to me like Scala's hashString converts pairs of UTF-16 chars to ints differently than Guava's hashUnencodedChars (hashString with no Charset was renamed to that). Scala: val data = (str.charAt(i) << 16) + str.charAt(i + 1) Guava: int k1 = input.charAt(i - 1) | (input.charAt(i) << 16); In Guava,...
Is there any Delphi implementation of MurMurHash3?
I have a murmurhash3 implementation in my FastDefaults unit at https://github.com/JBontes/FastCode Here's the sourcecode for Murmurhash3: {$pointermath on} function MurmurHash3(const [ref] HashData; Len: integer; Seed: integer = 0): integer; const c1 = $CC9E2D51; c2 = $1B873593; r1 = 15; r2 = 13; m = 5; n = $E6546B64; f1 =...
Murmurhash3 between Java and C++ is not aligning
There are two problems I can see. First, C++ is using uint32_t, and giving you a value of 3,297,211,900. This number is larger than can fit in a signed 32-bit int, and Java uses only signed integers. However, -1,868,221,715 is not equal to 3,297,211,900, even accounting for the difference between...
Cassandra hashing algorithm with composite keys
algorithm,hash,cassandra,murmurhash
Thanks for giving me more details about the algorithm. I wrote a sample code in order to share the solution. byte[] keyBytes; try(ByteArrayOutputStream bos = new ByteArrayOutputStream(); DataOutputStream out = new DataOutputStream(bos)) { String[] keys = new String[] {"key1", "key2"}; for(String key : keys) { byte[] arr = key.getBytes("UTF-8"); out.writeShort(arr.length);...
Murmur3 hash different result between Python and Java implementation
Here's how to get the same result from both: byte[] mm3_le = Hashing.murmur3_128().hashString("abc", UTF_8).asBytes(); byte[] mm3_be = Bytes.toArray(Lists.reverse(Bytes.asList(mm3_le))); assertEquals("79267961763742113019008347020647561319", new BigInteger(mm3_be).toString()); The hash code's bytes need to be treated as little endian but BigInteger interprets bytes as big endian. You were presumably using new BigInteger(hex, 16) to create the BigInteger,...
how to have different source code when cross-compiling Scala with sbt? (changes in MurmurHash)
scala,sbt,cross-compiling,murmurhash
You can append to unmanagedSourceDirectories: lazy val commonSettings = Seq( scalaVersion := "2.10.4", unmanagedSourceDirectories in Compile += (sourceDirectory in Compile).value / ("scala_" + (scalaBinaryVersion.value match { case v if v startsWith "2.9." => "2.9" case v => v })) ) lazy val root = (project in file(".")). aggregate(app). settings(commonSettings: _*)...