Auto merge of #37312 - arthurprs:sip-smaller, r=alexcrichton

Small improvement to SipHasher

Very small but constant improvement, the objective is to lower latency for u16, u32 and small strings.

CC #35735

```
➜  siphash-bench git:(master) ✗ sudo nice -n -20 target/release/foo-648738a54f390643 --bench | tee benches.txt
[sudo] password for arthurprs:

running 62 tests
test _same                       ... bench:           0 ns/iter (+/- 0)
test _warmup                     ... bench:           0 ns/iter (+/- 0)
test rust_siphash13::int_u16     ... bench:          12 ns/iter (+/- 1)
test rust_siphash13::int_u32     ... bench:          14 ns/iter (+/- 0)
test rust_siphash13::int_u64     ... bench:          11 ns/iter (+/- 1)
test rust_siphash13::int_u8      ... bench:          11 ns/iter (+/- 1)
test rust_siphash13::slice::_10  ... bench:          18 ns/iter (+/- 1)
test rust_siphash13::slice::_100 ... bench:          42 ns/iter (+/- 2)
test rust_siphash13::slice::_11  ... bench:          19 ns/iter (+/- 1)
test rust_siphash13::slice::_12  ... bench:          21 ns/iter (+/- 3)
test rust_siphash13::slice::_2   ... bench:          16 ns/iter (+/- 2)
test rust_siphash13::slice::_200 ... bench:          68 ns/iter (+/- 3)
test rust_siphash13::slice::_3   ... bench:          17 ns/iter (+/- 3)
test rust_siphash13::slice::_4   ... bench:          18 ns/iter (+/- 1)
test rust_siphash13::slice::_5   ... bench:          19 ns/iter (+/- 4)
test rust_siphash13::slice::_6   ... bench:          19 ns/iter (+/- 1)
test rust_siphash13::slice::_7   ... bench:          20 ns/iter (+/- 1)
test rust_siphash13::slice::_8   ... bench:          16 ns/iter (+/- 1)
test rust_siphash13::slice::_9   ... bench:          18 ns/iter (+/- 2)
test rust_siphash13::str_::_10   ... bench:          18 ns/iter (+/- 1)
test rust_siphash13::str_::_100  ... bench:          41 ns/iter (+/- 2)
test rust_siphash13::str_::_11   ... bench:          19 ns/iter (+/- 1)
test rust_siphash13::str_::_12   ... bench:          20 ns/iter (+/- 2)
test rust_siphash13::str_::_2    ... bench:          16 ns/iter (+/- 1)
test rust_siphash13::str_::_200  ... bench:          68 ns/iter (+/- 3)
test rust_siphash13::str_::_3    ... bench:          17 ns/iter (+/- 1)
test rust_siphash13::str_::_4    ... bench:          18 ns/iter (+/- 2)
test rust_siphash13::str_::_5    ... bench:          19 ns/iter (+/- 6)
test rust_siphash13::str_::_6    ... bench:          20 ns/iter (+/- 5)
test rust_siphash13::str_::_7    ... bench:          23 ns/iter (+/- 1)
test rust_siphash13::str_::_8    ... bench:          15 ns/iter (+/- 1)
test rust_siphash13::str_::_9    ... bench:          17 ns/iter (+/- 1)
test sip1b::int_u16              ... bench:          10 ns/iter (+/- 1)
test sip1b::int_u32              ... bench:           9 ns/iter (+/- 1)
test sip1b::int_u64              ... bench:          12 ns/iter (+/- 1)
test sip1b::int_u8               ... bench:           7 ns/iter (+/- 0)
test sip1b::slice::_10           ... bench:          12 ns/iter (+/- 1)
test sip1b::slice::_100          ... bench:          33 ns/iter (+/- 2)
test sip1b::slice::_11           ... bench:          13 ns/iter (+/- 0)
test sip1b::slice::_12           ... bench:          12 ns/iter (+/- 1)
test sip1b::slice::_2            ... bench:          10 ns/iter (+/- 0)
test sip1b::slice::_200          ... bench:          62 ns/iter (+/- 2)
test sip1b::slice::_3            ... bench:          10 ns/iter (+/- 1)
test sip1b::slice::_4            ... bench:           9 ns/iter (+/- 0)
test sip1b::slice::_5            ... bench:          10 ns/iter (+/- 1)
test sip1b::slice::_6            ... bench:          10 ns/iter (+/- 0)
test sip1b::slice::_7            ... bench:          11 ns/iter (+/- 0)
test sip1b::slice::_8            ... bench:          11 ns/iter (+/- 1)
test sip1b::slice::_9            ... bench:          12 ns/iter (+/- 1)
test sip1b::str_::_10            ... bench:          15 ns/iter (+/- 1)
test sip1b::str_::_100           ... bench:          37 ns/iter (+/- 3)
test sip1b::str_::_11            ... bench:          16 ns/iter (+/- 1)
test sip1b::str_::_12            ... bench:          14 ns/iter (+/- 1)
test sip1b::str_::_2             ... bench:          13 ns/iter (+/- 1)
test sip1b::str_::_200           ... bench:          67 ns/iter (+/- 5)
test sip1b::str_::_3             ... bench:          14 ns/iter (+/- 2)
test sip1b::str_::_4             ... bench:          12 ns/iter (+/- 1)
test sip1b::str_::_5             ... bench:          13 ns/iter (+/- 1)
test sip1b::str_::_6             ... bench:          13 ns/iter (+/- 0)
test sip1b::str_::_7             ... bench:          16 ns/iter (+/- 1)
test sip1b::str_::_8             ... bench:          14 ns/iter (+/- 1)
test sip1b::str_::_9             ... bench:          15 ns/iter (+/- 1)

test result: ok. 0 passed; 0 failed; 0 ignored; 62 measured

➜  siphash-bench git:(master) ✗ cargo benchcmp rust_siphash13:: sip1b:: benches.txt
 name         rust_siphash13:: ns/iter  sip1b:: ns/iter  diff ns/iter   diff %
 int_u16      12                        10                         -2  -16.67%
 int_u32      14                        9                          -5  -35.71%
 int_u64      11                        12                          1    9.09%
 int_u8       11                        7                          -4  -36.36%
 slice::_10   18                        12                         -6  -33.33%
 slice::_100  42                        33                         -9  -21.43%
 slice::_11   19                        13                         -6  -31.58%
 slice::_12   21                        12                         -9  -42.86%
 slice::_2    16                        10                         -6  -37.50%
 slice::_200  68                        62                         -6   -8.82%
 slice::_3    17                        10                         -7  -41.18%
 slice::_4    18                        9                          -9  -50.00%
 slice::_5    19                        10                         -9  -47.37%
 slice::_6    19                        10                         -9  -47.37%
 slice::_7    20                        11                         -9  -45.00%
 slice::_8    16                        11                         -5  -31.25%
 slice::_9    18                        12                         -6  -33.33%
 str_::_10    18                        15                         -3  -16.67%
 str_::_100   41                        37                         -4   -9.76%
 str_::_11    19                        16                         -3  -15.79%
 str_::_12    20                        14                         -6  -30.00%
 str_::_2     16                        13                         -3  -18.75%
 str_::_200   68                        67                         -1   -1.47%
 str_::_3     17                        14                         -3  -17.65%
 str_::_4     18                        12                         -6  -33.33%
 str_::_5     19                        13                         -6  -31.58%
 str_::_6     20                        13                         -7  -35.00%
 str_::_7     23                        16                         -7  -30.43%
 str_::_8     15                        14                         -1   -6.67%
 str_::_9     17                        15                         -2  -11.76%

```

from a modified hash-rs suite (preallocating maps and adding having slice/str variants)

graph version: http://imgur.com/a/DuoI4

```
➜  hash-rs git:(rfc-extend-hasher) ✗ cargo benchcmp sip13:: sip13opt:: benches.txt
 name                             sip13:: ns/iter      sip13opt:: ns/iter   diff ns/iter   diff %
 slice::mapcountdense_000000001   27,343 (36 MB/s)     26,401 (37 MB/s)             -942   -3.45%
 slice::mapcountdense_000000002   28,982 (69 MB/s)     26,807 (74 MB/s)           -2,175   -7.50%
 slice::mapcountdense_000000003   29,304 (102 MB/s)    27,360 (109 MB/s)          -1,944   -6.63%
 slice::mapcountdense_000000004   30,411 (131 MB/s)    25,888 (154 MB/s)          -4,523  -14.87%
 slice::mapcountdense_000000005   32,625 (153 MB/s)    27,486 (181 MB/s)          -5,139  -15.75%
 slice::mapcountdense_000000006   34,920 (171 MB/s)    27,204 (220 MB/s)          -7,716  -22.10%
 slice::mapcountdense_000000007   33,497 (208 MB/s)    28,330 (247 MB/s)          -5,167  -15.43%
 slice::mapcountdense_000000008   31,153 (256 MB/s)    28,617 (279 MB/s)          -2,536   -8.14%
 slice::mapcountdense_000000009   30,745 (292 MB/s)    29,666 (303 MB/s)          -1,079   -3.51%
 slice::mapcountdense_000000010   31,509 (317 MB/s)    29,804 (335 MB/s)          -1,705   -5.41%
 slice::mapcountdense_000000011   32,526 (338 MB/s)    30,520 (360 MB/s)          -2,006   -6.17%
 slice::mapcountdense_000000012   32,981 (363 MB/s)    28,739 (417 MB/s)          -4,242  -12.86%
 slice::mapcountdense_000000013   34,713 (374 MB/s)    30,348 (428 MB/s)          -4,365  -12.57%
 slice::mapcountdense_000000014   34,635 (404 MB/s)    29,974 (467 MB/s)          -4,661  -13.46%
 slice::mapcountdense_000000015   35,924 (417 MB/s)    30,584 (490 MB/s)          -5,340  -14.86%
 slice::mapcountdense_000000016   31,939 (500 MB/s)    30,564 (523 MB/s)          -1,375   -4.31%
 slice::mapcountdense_000000032   36,545 (875 MB/s)    34,833 (918 MB/s)          -1,712   -4.68%
 slice::mapcountdense_000000064   44,691 (1432 MB/s)   43,912 (1457 MB/s)           -779   -1.74%
 slice::mapcountdense_000000128   67,210 (1904 MB/s)   64,630 (1980 MB/s)         -2,580   -3.84%
 slice::mapcountdense_000000256   110,320 (2320 MB/s)  108,713 (2354 MB/s)        -1,607   -1.46%
 slice::mapcountsparse_000000001  29,686 (33 MB/s)     28,673 (34 MB/s)           -1,013   -3.41%
 slice::mapcountsparse_000000002  32,073 (62 MB/s)     30,519 (65 MB/s)           -1,554   -4.85%
 slice::mapcountsparse_000000003  33,184 (90 MB/s)     31,208 (96 MB/s)           -1,976   -5.95%
 slice::mapcountsparse_000000004  34,344 (116 MB/s)    30,242 (132 MB/s)          -4,102  -11.94%
 slice::mapcountsparse_000000005  34,536 (144 MB/s)    30,552 (163 MB/s)          -3,984  -11.54%
 slice::mapcountsparse_000000006  35,791 (167 MB/s)    30,813 (194 MB/s)          -4,978  -13.91%
 slice::mapcountsparse_000000007  36,773 (190 MB/s)    31,362 (223 MB/s)          -5,411  -14.71%
 slice::mapcountsparse_000000008  33,101 (241 MB/s)    32,399 (246 MB/s)            -702   -2.12%
 slice::mapcountsparse_000000009  34,025 (264 MB/s)    33,065 (272 MB/s)            -960   -2.82%
 slice::mapcountsparse_000000010  34,755 (287 MB/s)    33,152 (301 MB/s)          -1,603   -4.61%
 slice::mapcountsparse_000000011  35,682 (308 MB/s)    33,631 (327 MB/s)          -2,051   -5.75%
 slice::mapcountsparse_000000012  36,422 (329 MB/s)    32,604 (368 MB/s)          -3,818  -10.48%
 slice::mapcountsparse_000000013  37,561 (346 MB/s)    32,978 (394 MB/s)          -4,583  -12.20%
 slice::mapcountsparse_000000014  38,476 (363 MB/s)    33,376 (419 MB/s)          -5,100  -13.26%
 slice::mapcountsparse_000000015  39,202 (382 MB/s)    33,750 (444 MB/s)          -5,452  -13.91%
 slice::mapcountsparse_000000016  34,898 (458 MB/s)    33,621 (475 MB/s)          -1,277   -3.66%
 slice::mapcountsparse_000000032  39,767 (804 MB/s)    38,013 (841 MB/s)          -1,754   -4.41%
 slice::mapcountsparse_000000064  47,810 (1338 MB/s)   46,332 (1381 MB/s)         -1,478   -3.09%
 slice::mapcountsparse_000000128  64,519 (1983 MB/s)   63,322 (2021 MB/s)         -1,197   -1.86%
 slice::mapcountsparse_000000256  101,042 (2533 MB/s)  99,754 (2566 MB/s)         -1,288   -1.27%
 str_::mapcountdense_000000001    27,183 (36 MB/s)     24,007 (41 MB/s)           -3,176  -11.68%
 str_::mapcountdense_000000002    28,940 (69 MB/s)     24,574 (81 MB/s)           -4,366  -15.09%
 str_::mapcountdense_000000003    29,000 (103 MB/s)    24,687 (121 MB/s)          -4,313  -14.87%
 str_::mapcountdense_000000004    29,822 (134 MB/s)    24,377 (164 MB/s)          -5,445  -18.26%
 str_::mapcountdense_000000005    31,962 (156 MB/s)    25,184 (198 MB/s)          -6,778  -21.21%
 str_::mapcountdense_000000006    32,218 (186 MB/s)    25,020 (239 MB/s)          -7,198  -22.34%
 str_::mapcountdense_000000007    35,482 (197 MB/s)    27,705 (252 MB/s)          -7,777  -21.92%
 str_::mapcountdense_000000008    28,643 (279 MB/s)    25,563 (312 MB/s)          -3,080  -10.75%
 str_::mapcountdense_000000009    30,112 (298 MB/s)    26,773 (336 MB/s)          -3,339  -11.09%
 str_::mapcountdense_000000010    31,554 (316 MB/s)    27,607 (362 MB/s)          -3,947  -12.51%
 str_::mapcountdense_000000011    32,062 (343 MB/s)    27,770 (396 MB/s)          -4,292  -13.39%
 str_::mapcountdense_000000012    32,258 (372 MB/s)    25,612 (468 MB/s)          -6,646  -20.60%
 str_::mapcountdense_000000013    33,544 (387 MB/s)    26,908 (483 MB/s)          -6,636  -19.78%
 str_::mapcountdense_000000014    34,681 (403 MB/s)    27,267 (513 MB/s)          -7,414  -21.38%
 str_::mapcountdense_000000015    37,883 (395 MB/s)    30,226 (496 MB/s)          -7,657  -20.21%
 str_::mapcountdense_000000016    30,299 (528 MB/s)    27,960 (572 MB/s)          -2,339   -7.72%
 str_::mapcountdense_000000032    34,372 (930 MB/s)    32,736 (977 MB/s)          -1,636   -4.76%
 str_::mapcountdense_000000048    38,610 (1243 MB/s)   36,437 (1317 MB/s)         -2,173   -5.63%
 str_::mapcountdense_000000064    43,052 (1486 MB/s)   41,269 (1550 MB/s)         -1,783   -4.14%
 str_::mapcountdense_000000128    64,059 (1998 MB/s)   62,007 (2064 MB/s)         -2,052   -3.20%
 str_::mapcountdense_000000256    109,608 (2335 MB/s)  107,184 (2388 MB/s)        -2,424   -2.21%
 str_::mapcountsparse_000000001   29,155 (34 MB/s)     26,151 (38 MB/s)           -3,004  -10.30%
 str_::mapcountsparse_000000002   31,536 (63 MB/s)     27,787 (71 MB/s)           -3,749  -11.89%
 str_::mapcountsparse_000000003   32,524 (92 MB/s)     27,861 (107 MB/s)          -4,663  -14.34%
 str_::mapcountsparse_000000004   33,535 (119 MB/s)    27,585 (145 MB/s)          -5,950  -17.74%
 str_::mapcountsparse_000000005   34,239 (146 MB/s)    27,520 (181 MB/s)          -6,719  -19.62%
 str_::mapcountsparse_000000006   35,485 (169 MB/s)    27,437 (218 MB/s)          -8,048  -22.68%
 str_::mapcountsparse_000000007   39,098 (179 MB/s)    30,465 (229 MB/s)          -8,633  -22.08%
 str_::mapcountsparse_000000008   30,882 (259 MB/s)    29,215 (273 MB/s)          -1,667   -5.40%
 str_::mapcountsparse_000000009   33,375 (269 MB/s)    29,301 (307 MB/s)          -4,074  -12.21%
 str_::mapcountsparse_000000010   33,531 (298 MB/s)    29,008 (344 MB/s)          -4,523  -13.49%
 str_::mapcountsparse_000000011   34,607 (317 MB/s)    29,800 (369 MB/s)          -4,807  -13.89%
 str_::mapcountsparse_000000012   35,700 (336 MB/s)    28,380 (422 MB/s)          -7,320  -20.50%
 str_::mapcountsparse_000000013   36,692 (354 MB/s)    29,350 (442 MB/s)          -7,342  -20.01%
 str_::mapcountsparse_000000014   37,326 (375 MB/s)    29,285 (478 MB/s)          -8,041  -21.54%
 str_::mapcountsparse_000000015   41,098 (364 MB/s)    33,073 (453 MB/s)          -8,025  -19.53%
 str_::mapcountsparse_000000016   33,046 (484 MB/s)    30,717 (520 MB/s)          -2,329   -7.05%
 str_::mapcountsparse_000000032   37,471 (853 MB/s)    35,542 (900 MB/s)          -1,929   -5.15%
 str_::mapcountsparse_000000048   41,324 (1161 MB/s)   39,332 (1220 MB/s)         -1,992   -4.82%
 str_::mapcountsparse_000000064   45,858 (1395 MB/s)   43,802 (1461 MB/s)         -2,056   -4.48%
 str_::mapcountsparse_000000128   62,471 (2048 MB/s)   60,683 (2109 MB/s)         -1,788   -2.86%
 str_::mapcountsparse_000000256   101,283 (2527 MB/s)  97,655 (2621 MB/s)         -3,628   -3.58%
```
This commit is contained in:
bors 2016-10-26 08:15:07 -07:00 committed by GitHub
commit a5b6a9fa8a
2 changed files with 118 additions and 50 deletions

View File

@ -14,6 +14,8 @@
use marker::PhantomData;
use ptr;
use cmp;
use mem;
/// An implementation of SipHash 1-3.
///
@ -78,45 +80,6 @@ struct State {
v3: u64,
}
// sadly, these macro definitions can't appear later,
// because they're needed in the following defs;
// this design could be improved.
macro_rules! u8to64_le {
($buf:expr, $i:expr) =>
($buf[0+$i] as u64 |
($buf[1+$i] as u64) << 8 |
($buf[2+$i] as u64) << 16 |
($buf[3+$i] as u64) << 24 |
($buf[4+$i] as u64) << 32 |
($buf[5+$i] as u64) << 40 |
($buf[6+$i] as u64) << 48 |
($buf[7+$i] as u64) << 56);
($buf:expr, $i:expr, $len:expr) =>
({
let mut t = 0;
let mut out = 0;
while t < $len {
out |= ($buf[t+$i] as u64) << t*8;
t += 1;
}
out
});
}
/// Load a full u64 word from a byte stream, in LE order. Use
/// `copy_nonoverlapping` to let the compiler generate the most efficient way
/// to load u64 from a possibly unaligned address.
///
/// Unsafe because: unchecked indexing at i..i+8
#[inline]
unsafe fn load_u64_le(buf: &[u8], i: usize) -> u64 {
debug_assert!(i + 8 <= buf.len());
let mut data = 0u64;
ptr::copy_nonoverlapping(buf.get_unchecked(i), &mut data as *mut _ as *mut u8, 8);
data.to_le()
}
macro_rules! compress {
($state:expr) => ({
compress!($state.v0, $state.v1, $state.v2, $state.v3)
@ -132,6 +95,47 @@ macro_rules! compress {
});
}
/// Load an integer of the desired type from a byte stream, in LE order. Uses
/// `copy_nonoverlapping` to let the compiler generate the most efficient way
/// to load it from a possibly unaligned address.
///
/// Unsafe because: unchecked indexing at i..i+size_of(int_ty)
macro_rules! load_int_le {
($buf:expr, $i:expr, $int_ty:ident) =>
({
debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len());
let mut data = 0 as $int_ty;
ptr::copy_nonoverlapping($buf.get_unchecked($i),
&mut data as *mut _ as *mut u8,
mem::size_of::<$int_ty>());
data.to_le()
});
}
/// Load an u64 using up to 7 bytes of a byte slice.
///
/// Unsafe because: unchecked indexing at start..start+len
#[inline]
unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 {
debug_assert!(len < 8);
let mut i = 0; // current byte index (from LSB) in the output u64
let mut out = 0;
if i + 3 < len {
out = load_int_le!(buf, start + i, u32) as u64;
i += 4;
}
if i + 1 < len {
out |= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
i += 2
}
if i < len {
out |= (*buf.get_unchecked(start + i) as u64) << (i * 8);
i += 1;
}
debug_assert_eq!(i, len);
out
}
impl SipHasher {
/// Creates a new `SipHasher` with the two initial keys set to 0.
#[inline]
@ -220,6 +224,37 @@ impl<S: Sip> Hasher<S> {
self.state.v3 = self.k1 ^ 0x7465646279746573;
self.ntail = 0;
}
// Specialized write function that is only valid for buffers with len <= 8.
// It's used to force inlining of write_u8 and write_usize, those would normally be inlined
// except for composite types (that includes slices and str hashing because of delimiter).
// Without this extra push the compiler is very reluctant to inline delimiter writes,
// degrading performance substantially for the most common use cases.
#[inline(always)]
fn short_write(&mut self, msg: &[u8]) {
debug_assert!(msg.len() <= 8);
let length = msg.len();
self.length += length;
let needed = 8 - self.ntail;
let fill = cmp::min(length, needed);
if fill == 8 {
self.tail = unsafe { load_int_le!(msg, 0, u64) };
} else {
self.tail |= unsafe { u8to64_le(msg, 0, fill) } << (8 * self.ntail);
if length < needed {
self.ntail += length;
return;
}
}
self.state.v3 ^= self.tail;
S::c_rounds(&mut self.state);
self.state.v0 ^= self.tail;
// Buffered tail is now flushed, process new input.
self.ntail = length - needed;
self.tail = unsafe { u8to64_le(msg, needed, self.ntail) };
}
}
#[stable(feature = "rust1", since = "1.0.0")]
@ -262,6 +297,21 @@ impl super::Hasher for SipHasher24 {
}
impl<S: Sip> super::Hasher for Hasher<S> {
// see short_write comment for explanation
#[inline]
fn write_usize(&mut self, i: usize) {
let bytes = unsafe {
::slice::from_raw_parts(&i as *const usize as *const u8, mem::size_of::<usize>())
};
self.short_write(bytes);
}
// see short_write comment for explanation
#[inline]
fn write_u8(&mut self, i: u8) {
self.short_write(&[i]);
}
#[inline]
fn write(&mut self, msg: &[u8]) {
let length = msg.len();
@ -271,19 +321,16 @@ impl<S: Sip> super::Hasher for Hasher<S> {
if self.ntail != 0 {
needed = 8 - self.ntail;
self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << 8 * self.ntail;
if length < needed {
self.tail |= u8to64_le!(msg, 0, length) << 8 * self.ntail;
self.ntail += length;
return
} else {
self.state.v3 ^= self.tail;
S::c_rounds(&mut self.state);
self.state.v0 ^= self.tail;
self.ntail = 0;
}
let m = self.tail | u8to64_le!(msg, 0, needed) << 8 * self.ntail;
self.state.v3 ^= m;
S::c_rounds(&mut self.state);
self.state.v0 ^= m;
self.ntail = 0;
}
// Buffered tail is now flushed, process new input.
@ -292,7 +339,7 @@ impl<S: Sip> super::Hasher for Hasher<S> {
let mut i = needed;
while i < len - left {
let mi = unsafe { load_u64_le(msg, i) };
let mi = unsafe { load_int_le!(msg, i, u64) };
self.state.v3 ^= mi;
S::c_rounds(&mut self.state);
@ -301,7 +348,7 @@ impl<S: Sip> super::Hasher for Hasher<S> {
i += 8;
}
self.tail = u8to64_le!(msg, i, left);
self.tail = unsafe { u8to64_le(msg, i, left) };
self.ntail = left;
}

View File

@ -14,6 +14,7 @@ use test::{Bencher, black_box};
use core::hash::{Hash, Hasher};
use core::hash::{SipHasher, SipHasher13, SipHasher24};
use core::{slice, mem};
// Hash just the bytes of the slice, without length prefix
struct Bytes<'a>(&'a [u8]);
@ -327,6 +328,26 @@ fn test_hash_no_concat_alias() {
assert!(hash(&v) != hash(&w));
}
#[test]
fn test_write_short_works() {
let test_usize = 0xd0c0b0a0usize;
let mut h1 = SipHasher24::new();
h1.write_usize(test_usize);
h1.write(b"bytes");
h1.write(b"string");
h1.write_u8(0xFFu8);
h1.write_u8(0x01u8);
let mut h2 = SipHasher24::new();
h2.write(unsafe {
slice::from_raw_parts(&test_usize as *const _ as *const u8,
mem::size_of::<usize>())
});
h2.write(b"bytes");
h2.write(b"string");
h2.write(&[0xFFu8, 0x01u8]);
assert_eq!(h1.finish(), h2.finish());
}
#[bench]
fn bench_str_under_8_bytes(b: &mut Bencher) {
let s = "foo";