From 4743e7a61ef751dd69b41fef67b148b9fd6556c5 Mon Sep 17 00:00:00 2001
From: Isaac Whitfield <iw@whitfin.io>
Date: Sat, 26 Sep 2020 10:57:54 -0700
Subject: [PATCH] Migrate to a Rust xxHash implementation

---
 Cargo.toml     |  1 +
 src/filters.rs | 27 +++++++++++++++++++--------
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index e65a0e4..94b538a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,3 +19,4 @@ clap = "2.33"
 fnv = "1.0"
 scalable_bloom_filter = "0.1"
 xxhash2 = "0.1"
+twox-hash = "1.5.0"
diff --git a/src/filters.rs b/src/filters.rs
index 50fe29a..d832232 100644
--- a/src/filters.rs
+++ b/src/filters.rs
@@ -8,8 +8,10 @@
 use clap::*;
 use fnv::FnvHashSet;
 use scalable_bloom_filter::ScalableBloomFilter;
+use twox_hash::XxHash64;
+
 use std::collections::HashSet;
-use xxhash2;
+use std::hash::Hasher;
 
 // Enumerable filters for clap-rs.
 arg_enum! {
@@ -108,11 +110,8 @@ impl Filter for DigestFilter {
     /// Detects a unique value.
     #[inline]
     fn detect(&mut self, input: &[u8]) -> bool {
-        // hash to u64 always, for collisions
-        let digest = xxhash2::hash64(input, 0);
-
-        // insert the new digest
-        self.inner.insert(digest)
+        // insert as a hashed digest
+        self.inner.insert(hash(input))
     }
 }
 
@@ -180,8 +179,8 @@ impl Filter for BloomFilter {
     /// Detects a unique value.
     #[inline]
     fn detect(&mut self, input: &[u8]) -> bool {
-        // // create a digest from the input
-        let digest = xxhash2::hash64(input, 0);
+        // create a digest from the input
+        let digest = hash(input);
 
         // short circuit if duplicated
         if self.inner.contains(&digest) {
@@ -194,6 +193,18 @@ impl Filter for BloomFilter {
     }
 }
 
+/// Small hash binding around `Hasher`.
+fn hash(input: &[u8]) -> u64 {
+    // create a new default hasher
+    let mut hasher = XxHash64::default();
+
+    // write the bytes to the hasher
+    hasher.write(input);
+
+    // finish the hash
+    hasher.finish()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;