    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358

    #[cfg(all(feature = "runtime-rng", not(all(feature = "compile-time-rng", test))))]
    use crate::convert::Convert;
    #[cfg(feature = "specialize")]
    use crate::BuildHasherExt;

    #[cfg(any(
        all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "aes", not(miri)),
        all(any(target_arch = "arm", target_arch = "aarch64"), target_feature = "crypto", not(miri), feature = "stdsimd")
    ))]
    pub use crate::aes_hash::*;

    #[cfg(not(any(
        all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "aes", not(miri)),
        all(any(target_arch = "arm", target_arch = "aarch64"), target_feature = "crypto", not(miri), feature = "stdsimd")
    )))]
    pub use crate::fallback_hash::*;

    #[cfg(all(feature = "compile-time-rng", any(not(feature = "runtime-rng"), test)))]
    use const_random::const_random;
    use core::any::{Any, TypeId};
    use core::fmt;
    use core::hash::BuildHasher;
    #[cfg(feature = "specialize")]
    use core::hash::Hash;
    use core::hash::Hasher;

    #[cfg(not(feature = "std"))]
    extern crate alloc;
    #[cfg(feature = "std")]
    extern crate std as alloc;

    use alloc::boxed::Box;
    use core::sync::atomic::{AtomicUsize, Ordering};
    #[cfg(not(all(target_arch = "arm", target_os = "none")))]
    use once_cell::race::OnceBox;

    #[cfg(any(
        all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "aes", not(miri)),
        all(any(target_arch = "arm", target_arch = "aarch64"), target_feature = "crypto", not(miri), feature = "stdsimd")
    ))]
    use crate::aes_hash::*;
    #[cfg(not(any(
        all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "aes", not(miri)),
        all(any(target_arch = "arm", target_arch = "aarch64"), target_feature = "crypto", not(miri), feature = "stdsimd")
    )))]
    use crate::fallback_hash::*;

    #[cfg(not(all(target_arch = "arm", target_os = "none")))]
    static RAND_SOURCE: OnceBox<Box<dyn RandomSource + Send + Sync>> = OnceBox::new();

    /// A supplier of Randomness used for different hashers.
    /// See [RandomState.set_random_source].
    pub trait RandomSource {

        fn get_fixed_seeds(&self) -> &'static [[u64; 4]; 2];

        fn gen_hasher_seed(&self) -> usize;

    }

    pub(crate) const PI: [u64; 4] = [
        0x243f_6a88_85a3_08d3,
        0x1319_8a2e_0370_7344,
        0xa409_3822_299f_31d0,
        0x082e_fa98_ec4e_6c89,
    ];

    pub(crate) const PI2: [u64; 4] = [
        0x4528_21e6_38d0_1377,
        0xbe54_66cf_34e9_0c6c,
        0xc0ac_29b7_c97c_50dd,
        0x3f84_d5b5_b547_0917,
    ];

    struct DefaultRandomSource {
        counter: AtomicUsize,
    }

    impl DefaultRandomSource {
        fn new() -> DefaultRandomSource {
            DefaultRandomSource {
                counter: AtomicUsize::new(&PI as *const _ as usize),
            }
        }

        const fn default() -> DefaultRandomSource {
            DefaultRandomSource {
                counter: AtomicUsize::new(PI[3] as usize),
            }
        }
    }

    impl RandomSource for DefaultRandomSource {

        #[cfg(all(feature = "runtime-rng", not(all(feature = "compile-time-rng", test))))]
        fn get_fixed_seeds(&self) -> &'static [[u64; 4]; 2] {
            static SEEDS: OnceBox<[[u64; 4]; 2]> = OnceBox::new();

            SEEDS.get_or_init(|| {
                let mut result: [u8; 64] = [0; 64];
                getrandom::getrandom(&mut result).expect("getrandom::getrandom() failed.");
                Box::new(result.convert())
            })
        }

        #[cfg(all(feature = "compile-time-rng", any(not(feature = "runtime-rng"), test)))]
        fn get_fixed_seeds(&self) -> &'static [[u64; 4]; 2] {
            const RAND: [[u64; 4]; 2] = [
                [
                    const_random!(u64),
                    const_random!(u64),
                    const_random!(u64),
                    const_random!(u64),
                ], [
                    const_random!(u64),
                    const_random!(u64),
                    const_random!(u64),
                    const_random!(u64),
                ]
            ];
            &RAND
        }

        #[cfg(all(not(feature = "runtime-rng"), not(feature = "compile-time-rng")))]
        fn get_fixed_seeds(&self) -> &'static [[u64; 4]; 2] {
            &[PI, PI2]
        }

        #[cfg(not(all(target_arch = "arm", target_os = "none")))]
        fn gen_hasher_seed(&self) -> usize {
            let stack = self as *const _ as usize;
            self.counter.fetch_add(stack, Ordering::Relaxed)
        }

        #[cfg(all(target_arch = "arm", target_os = "none"))]
        fn gen_hasher_seed(&self) -> usize {
            let stack = self as *const _ as usize;
            let previous = self.counter.load(Ordering::Relaxed);
            let new = previous.wrapping_add(stack);
            self.counter.store(new, Ordering::Relaxed);
            new
        }
    }

    /// Provides a [Hasher] factory. This is typically used (e.g. by [HashMap]) to create
    /// [AHasher]s in order to hash the keys of the map. See `build_hasher` below.
    ///
    /// [build_hasher]: ahash::
    /// [Hasher]: std::hash::Hasher
    /// [BuildHasher]: std::hash::BuildHasher
    /// [HashMap]: std::collections::HashMap
    #[derive(Clone)]
    pub struct RandomState {
        pub(crate) k0: u64,
        pub(crate) k1: u64,
        pub(crate) k2: u64,
        pub(crate) k3: u64,
    }

    impl fmt::Debug for RandomState {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            f.pad("RandomState { .. }")
        }
    }

    impl RandomState {

        /// Provides an optional way to manually supply a source of randomness for Hasher keys.
        ///
        /// The provided [RandomSource] will be used to be used as a source of randomness by [RandomState] to generate new states.
        /// If this method is not invoked the standard source of randomness is used as described in the Readme.
        ///
        /// The source of randomness can only be set once, and must be set before the first RandomState is created.
        /// If the source has already been specified `Err` is returned with a `bool` indicating if the set failed because
        /// method was previously invoked (true) or if the default source is already being used (false).
        #[cfg(not(all(target_arch = "arm", target_os = "none")))]
        pub fn set_random_source(source: impl RandomSource + Send + Sync + 'static) -> Result<(), bool> {
            RAND_SOURCE.set(Box::new(Box::new(source))).map_err(|s| s.as_ref().type_id() != TypeId::of::<&DefaultRandomSource>())
        }

        #[inline]
        #[cfg(not(all(target_arch = "arm", target_os = "none")))]
        fn get_src() -> &'static dyn RandomSource {
            RAND_SOURCE.get_or_init(|| Box::new(Box::new(DefaultRandomSource::new()))).as_ref()
        }

        #[inline]
        #[cfg(all(target_arch = "arm", target_os = "none"))]
        fn get_src() -> &'static dyn RandomSource {
            static RAND_SOURCE: DefaultRandomSource = DefaultRandomSource::default();
            &RAND_SOURCE
        }

        /// Use randomly generated keys
        #[inline]
        pub fn new() -> RandomState {
            let src = Self::get_src();
            let fixed = src.get_fixed_seeds();
            Self::from_keys(&fixed[0], &fixed[1], src.gen_hasher_seed())
        }

        /// Allows for supplying seeds, but each time it is called the resulting state will be different.
        /// This is done using a static counter, so it can safely be used with a fixed keys.
        #[inline]
        pub fn generate_with(k0: u64, k1: u64, k2: u64, k3: u64) -> RandomState {
            let src = Self::get_src();
            let fixed = src.get_fixed_seeds();
            RandomState::from_keys(&fixed[0], &[k0, k1, k2, k3], src.gen_hasher_seed())
        }

        fn from_keys(a: &[u64; 4], b: &[u64; 4], c: usize) -> RandomState {
            let &[k0, k1, k2, k3] = a;
            let mut hasher = AHasher::from_random_state(&RandomState { k0, k1, k2, k3 });
            hasher.write_usize(c);
            let mix = |k: u64| {
                let mut h = hasher.clone();
                h.write_u64(k);
                h.finish()
            };
            RandomState {
                k0: mix(b[0]),
                k1: mix(b[1]),
                k2: mix(b[2]),
                k3: mix(b[3]),
            }
        }

        /// Internal. Used by Default.
        #[inline]
        pub(crate) fn with_fixed_keys() -> RandomState {
            let [k0, k1, k2, k3] = Self::get_src().get_fixed_seeds()[0];
            RandomState { k0, k1, k2, k3 }
        }

        /// Allows for explicitly setting a seed to used.
        ///
        /// Note: This method does not require the provided seed to be strong.
        #[inline]
        pub fn with_seed(key: usize) -> RandomState {
            let fixed = Self::get_src().get_fixed_seeds();
            RandomState::from_keys(&fixed[0], &fixed[1], key)
        }

        /// Allows for explicitly setting the seeds to used.
        ///
        /// Note: This method is robust against 0s being passed for one or more of the parameters
        /// or the same value being passed for more than one parameter.
        #[inline]
        pub const fn with_seeds(k0: u64, k1: u64, k2: u64, k3: u64) -> RandomState {
            RandomState { k0: k0 ^ PI2[0], k1: k1 ^ PI2[1], k2: k2 ^ PI2[2], k3: k3 ^ PI2[3] }
        }
    }

    impl Default for RandomState {
        #[inline]
        fn default() -> Self {
            Self::new()
        }
    }

    impl BuildHasher for RandomState {
        type Hasher = AHasher;

        /// Constructs a new [AHasher] with keys based on this [RandomState] object.
        /// This means that two different [RandomState]s will will generate
        /// [AHasher]s that will return different hashcodes, but [Hasher]s created from the same [BuildHasher]
        /// will generate the same hashes for the same input data.
        ///
        /// # Examples
        ///
        /// ```
        /// use ahash::{AHasher, RandomState};
        /// use std::hash::{Hasher, BuildHasher};
        ///
        /// let build_hasher = RandomState::new();
        /// let mut hasher_1 = build_hasher.build_hasher();
        /// let mut hasher_2 = build_hasher.build_hasher();
        ///
        /// hasher_1.write_u32(1234);
        /// hasher_2.write_u32(1234);
        ///
        /// assert_eq!(hasher_1.finish(), hasher_2.finish());
        ///
        /// let other_build_hasher = RandomState::new();
        /// let mut different_hasher = other_build_hasher.build_hasher();
        /// different_hasher.write_u32(1234);
        /// assert_ne!(different_hasher.finish(), hasher_1.finish());
        /// ```
        /// [Hasher]: std::hash::Hasher
        /// [BuildHasher]: std::hash::BuildHasher
        /// [HashMap]: std::collections::HashMap
        #[inline]
        fn build_hasher(&self) -> AHasher {
            AHasher::from_random_state(self)
        }
    }

    #[cfg(feature = "specialize")]
    impl BuildHasherExt for RandomState {
        #[inline]
        fn hash_as_u64<T: Hash + ?Sized>(&self, value: &T) -> u64 {
            let mut hasher = AHasherU64 {
                buffer: self.k0,
                pad: self.k1,
            };
            value.hash(&mut hasher);
            hasher.finish()
        }

        #[inline]
        fn hash_as_fixed_length<T: Hash + ?Sized>(&self, value: &T) -> u64 {
            let mut hasher = AHasherFixed(self.build_hasher());
            value.hash(&mut hasher);
            hasher.finish()
        }

        #[inline]
        fn hash_as_str<T: Hash + ?Sized>(&self, value: &T) -> u64 {
            let mut hasher = AHasherStr(self.build_hasher());
            value.hash(&mut hasher);
            hasher.finish()
        }
    }

    #[cfg(test)]
    mod test {
        use super::*;

        #[test]
        fn test_unique() {
            let a = RandomState::new();
            let b = RandomState::new();
            assert_ne!(a.build_hasher().finish(), b.build_hasher().finish());
        }

        #[cfg(all(feature = "runtime-rng", not(all(feature = "compile-time-rng", test))))]
        #[test]
        fn test_not_pi() {
            assert_ne!(PI, RandomState::get_src().get_fixed_seeds()[0]);
        }

        #[cfg(all(feature = "compile-time-rng", any(not(feature = "runtime-rng"), test)))]
        #[test]
        fn test_not_pi_const() {
            assert_ne!(PI, RandomState::get_src().get_fixed_seeds()[0]);
        }

        #[cfg(all(not(feature = "runtime-rng"), not(feature = "compile-time-rng")))]
        #[test]
        fn test_pi() {
            assert_eq!(PI, RandomState::get_src().get_fixed_seeds()[0]);
        }

        #[test]
        fn test_with_seeds_const() {
            const _CONST_RANDOM_STATE: RandomState = RandomState::with_seeds(17, 19, 21, 23);
        }
    }