From dcc92d287ebb488854a95aa1f00455e6de3428dd Mon Sep 17 00:00:00 2001
From: Paul Masurel <paul.masurel@gmail.com>
Date: Mon, 17 Dec 2018 19:08:48 +0900
Subject: [PATCH] Facet remove unsafe (#456)

* Removing some unsafe

* Removing some unsafe (2)

* Remove murmurhash
---
 Cargo.toml                           |  1 +
 src/postings/stacker/mod.rs          |  2 -
 src/postings/stacker/murmurhash2.rs  | 87 ----------------------------
 src/postings/stacker/term_hashmap.rs |  7 ++-
 4 files changed, 6 insertions(+), 91 deletions(-)
 delete mode 100644 src/postings/stacker/murmurhash2.rs

diff --git a/Cargo.toml b/Cargo.toml
index 558ce4607..d4f1a9ed0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -49,6 +49,7 @@ failure = "0.1"
 htmlescape = "0.3.1"
 fail = "0.2"
 scoped-pool = "1.0"
+murmurhash32 = "0.1"
 
 [target.'cfg(windows)'.dependencies]
 winapi = "0.2"
diff --git a/src/postings/stacker/mod.rs b/src/postings/stacker/mod.rs
index 3fdf3e850..78fbf456c 100644
--- a/src/postings/stacker/mod.rs
+++ b/src/postings/stacker/mod.rs
@@ -1,9 +1,7 @@
 mod expull;
 mod memory_arena;
-mod murmurhash2;
 mod term_hashmap;
 
 pub use self::expull::ExpUnrolledLinkedList;
 pub use self::memory_arena::{Addr, ArenaStorable, MemoryArena};
-use self::murmurhash2::murmurhash2;
 pub use self::term_hashmap::{compute_table_size, TermHashMap};
diff --git a/src/postings/stacker/murmurhash2.rs b/src/postings/stacker/murmurhash2.rs
deleted file mode 100644
index 9626dcb53..000000000
--- a/src/postings/stacker/murmurhash2.rs
+++ /dev/null
@@ -1,87 +0,0 @@
-use std::ptr;
-const SEED: u32 = 3_242_157_231u32;
-const M: u32 = 0x5bd1_e995;
-
-#[inline(always)]
-pub fn murmurhash2(key: &[u8]) -> u32 {
-    #[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
-    let mut key_ptr: *const u32 = key.as_ptr() as *const u32;
-    let len = key.len() as u32;
-    let mut h: u32 = SEED ^ len;
-
-    let num_blocks = len >> 2;
-    for _ in 0..num_blocks {
-        let mut k: u32 = unsafe { ptr::read_unaligned(key_ptr) }; // ok because of num_blocks definition
-        k = k.wrapping_mul(M);
-        k ^= k >> 24;
-        k = k.wrapping_mul(M);
-        h = h.wrapping_mul(M);
-        h ^= k;
-        key_ptr = key_ptr.wrapping_offset(1);
-    }
-
-    // Handle the last few bytes of the input array
-    let remaining: &[u8] = &key[key.len() & !3..];
-    match remaining.len() {
-        3 => {
-            h ^= u32::from(remaining[2]) << 16;
-            h ^= u32::from(remaining[1]) << 8;
-            h ^= u32::from(remaining[0]);
-            h = h.wrapping_mul(M);
-        }
-        2 => {
-            h ^= u32::from(remaining[1]) << 8;
-            h ^= u32::from(remaining[0]);
-            h = h.wrapping_mul(M);
-        }
-        1 => {
-            h ^= u32::from(remaining[0]);
-            h = h.wrapping_mul(M);
-        }
-        _ => {}
-    }
-    h ^= h >> 13;
-    h = h.wrapping_mul(M);
-    h ^ (h >> 15)
-}
-
-#[cfg(test)]
-mod test {
-
-    use super::murmurhash2;
-    use std::collections::HashSet;
-
-    #[test]
-    fn test_murmur() {
-        let s1 = "abcdef";
-        let s2 = "abcdeg";
-        for i in 0..5 {
-            assert_eq!(
-                murmurhash2(&s1[i..5].as_bytes()),
-                murmurhash2(&s2[i..5].as_bytes())
-            );
-        }
-    }
-
-    #[test]
-    fn test_murmur_against_reference_impl() {
-        assert_eq!(murmurhash2("".as_bytes()), 3632506080);
-        assert_eq!(murmurhash2("a".as_bytes()), 455683869);
-        assert_eq!(murmurhash2("ab".as_bytes()), 2448092234);
-        assert_eq!(murmurhash2("abc".as_bytes()), 2066295634);
-        assert_eq!(murmurhash2("abcd".as_bytes()), 2588571162);
-        assert_eq!(murmurhash2("abcde".as_bytes()), 2988696942);
-        assert_eq!(murmurhash2("abcdefghijklmnop".as_bytes()), 2350868870);
-    }
-
-    #[test]
-    fn test_murmur_collisions() {
-        let mut set: HashSet<u32> = HashSet::default();
-        for i in 0..10_000 {
-            let s = format!("hash{}", i);
-            let hash = murmurhash2(s.as_bytes());
-            set.insert(hash);
-        }
-        assert_eq!(set.len(), 10_000);
-    }
-}
diff --git a/src/postings/stacker/term_hashmap.rs b/src/postings/stacker/term_hashmap.rs
index 47ee3d5c7..2ec71de05 100644
--- a/src/postings/stacker/term_hashmap.rs
+++ b/src/postings/stacker/term_hashmap.rs
@@ -1,4 +1,7 @@
-use super::murmurhash2;
+extern crate murmurhash32;
+
+use self::murmurhash32::murmurhash2;
+
 use super::{Addr, ArenaStorable, MemoryArena};
 use std::iter;
 use std::mem;
@@ -206,7 +209,7 @@ impl TermHashMap {
             self.resize();
         }
         let key_bytes: &[u8] = key.as_ref();
-        let hash = murmurhash2::murmurhash2(key.as_ref());
+        let hash = murmurhash2(key.as_ref());
         let mut probe = self.probe(hash);
         loop {
             let bucket = probe.next_probe();