support bkdrabscrc32

sharding/src/hash/bkdrabscrc32.rs

@@ -0,0 +1,46 @@
+use super::{bkdr::Bkdr, crc32::Crc32, Hash};
+
+/// key：${num}#suffix，对数字部分进行 bkdr + abs + crc32；属小众业务算法。
+/// 对于i32溢出，一般有类型提升 vs abs两种策略，bkdr自身是有abs，但考虑避免后面bkdr符号变化的影响，此处仍然进行abs；
+#[derive(Debug, Clone)]
+pub struct BkdrAbsCrc32 {
+    bkdr: Bkdr,
+    crc32: Crc32,
+}
+
+impl Default for BkdrAbsCrc32 {
+    fn default() -> Self {
+        Self {
+            bkdr: Default::default(),
+            crc32: Default::default(),
+        }
+    }
+}
+
+impl Hash for BkdrAbsCrc32 {
+    fn hash<S: super::HashKey>(&self, key: &S) -> i64 {
+        // 定位到num结束的位置，拿到hashkey
+        let mut hash_key = String::with_capacity(key.len());
+        for i in 0..key.len() {
+            let c = key.at(i);
+            if c.is_ascii_digit() {
+                hash_key.push(c as char);
+            } else {
+                // 遇到第一个非数字停止
+                break;
+            }
+        }
+
+        if hash_key.len() == 0 {
+            log::warn!("found malformed bkdrabscrc32 key:{:?}", key);
+            return 0;
+        }
+
+        // bkdr
+        let hash = self.bkdr.hash(&hash_key.as_bytes());
+        // abs + string
+        let hash_abs = hash.abs().to_string();
+        // crc32
+        self.crc32.hash(&hash_abs.as_bytes())
+    }
+}

sharding/src/hash/mod.rs

@@ -1,4 +1,5 @@
 pub mod bkdr;
+pub mod bkdrabscrc32;
 pub mod bkdrsub;
 pub mod crc32;
 pub mod crc32local;
@@ -11,6 +12,7 @@ pub mod rawcrc32local;
 pub mod rawsuffix;
 
 pub use bkdr::Bkdr;
+pub use bkdrabscrc32::BkdrAbsCrc32;
 pub use crc32::*;
 pub use crc32local::*;
 pub use lbcrc32local::LBCrc32localDelimiter;
@@ -66,6 +68,7 @@ pub enum Hasher {
     Raw(Raw), // redis raw, long型字符串直接用数字作为hash
     Bkdr(Bkdr),
     Bkdrsub(Bkdrsub),
+    BkdrAbsCrc32(BkdrAbsCrc32), // 混合三种hash：先bkdr，再abs，最后进行crc32计算
     Crc32(Crc32),
     Crc32Short(Crc32Short),         // mc short crc32
     Crc32Num(Crc32Num),             // crc32 for a hash key whick is a num,
@@ -114,6 +117,7 @@ impl Hasher {
                 HASH_PADDING => Self::Padding(Default::default()),
                 "bkdr" => Self::Bkdr(Default::default()),
                 "bkdrsub" => Self::Bkdrsub(Default::default()),
+                "bkdrabscrc32" => Self::BkdrAbsCrc32(Default::default()),
                 "raw" => Self::Raw(Raw::from(Default::default())),
                 "crc32" => Self::Crc32(Default::default()),
                 "crc32local" => Self::Crc32local(Default::default()),

tests/src/hash_test.rs

@@ -101,4 +101,16 @@ mod hash_test {
         println!("key:{}, crc64: {}, dist: {}", key, crc, idx);
         assert_eq!(-7536761181773004100_i64, crc);
     }
+
+    #[test]
+    fn bkdrabscrc32() {
+        let hasher = Hasher::from("bkdrabscrc32");
+        let key1 = "1234567890#123";
+        let key2 = "1234567890Abc";
+
+        let hash1 = hasher.hash(&key1.as_bytes());
+        let hash2 = hasher.hash(&key2.as_bytes());
+        println!("bkdrabscrc32: {} : {}", hash1, hash2);
+        assert_eq!(hash1, hash2);
+    }
 }