Added a 64bit string hash function.

1 files changed, 21 insertions, 0 deletions

diff --git a/graph/src/main/scala/spark/graph/util/HashUtils.scala b/graph/src/main/scala/spark/graph/util/HashUtils.scala
new file mode 100644
index 0000000000..0dfaef4c48
--- /dev/null
+++ b/graph/src/main/scala/spark/graph/util/HashUtils.scala
@@ -0,0 +1,21 @@
+package spark.graph.util
+
+
+object HashUtils {
+
+  /**
+   * Compute a 64-bit hash value for the given string.
+   * See http://stackoverflow.com/questions/1660501/what-is-a-good-64bit-hash-function-in-java-for-textual-strings
+   */
+  def hash(str: String): Long = {
+    var h = 1125899906842597L
+    val len = str.length
+    var i = 0
+
+    while (i < len) {
+      h = 31 * h + str(i)
+      i += 1
+    }
+    h
+  }
+}