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added unsafe code to remove ranks.len() (spares 8 byte) #12

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added unsafe code to remove ranks.len() (spares 8 byte) #12

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27 changes: 21 additions & 6 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,7 @@ fn hashmod<T: Hash>(iter: u64, v: &T, n: usize) -> u64 {
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Mphf<T> {
bitvecs: Box<[BitVector]>,
ranks: Box<[Box<[u64]>]>,
ranks: *const Box<[u64]>,
phantom: PhantomData<T>,
}

Expand All @@ -119,6 +119,14 @@ impl<T> HeapSizeOf for Mphf<T> {
}
}

impl<T> Drop for Mphf<T> {
fn drop(&mut self) {
unsafe {
Box::from_raw(std::slice::from_raw_parts_mut(self.ranks as *mut Box<[u64]>, self.bitvecs.len()));
}
}
}

const MAX_ITERS: u64 = 100;

impl<'a, T: 'a + Hash + Clone + Debug> Mphf<T> {
Expand Down Expand Up @@ -239,9 +247,10 @@ impl<'a, T: 'a + Hash + Clone + Debug> Mphf<T> {
}

let ranks = Self::compute_ranks(&bitvecs);
debug_assert!(ranks.len() == bitvecs.len());
let r = Mphf {
bitvecs: bitvecs.into_boxed_slice(),
ranks: ranks,
ranks: Box::into_raw(ranks) as *const Box<[u64]>,
phantom: PhantomData,
};

Expand Down Expand Up @@ -316,9 +325,10 @@ impl<T: Hash + Clone + Debug> Mphf<T> {
}

let ranks = Self::compute_ranks(&bitvecs);
debug_assert!(ranks.len() == bitvecs.len());
let r = Mphf {
bitvecs: bitvecs.into_boxed_slice(),
ranks: ranks,
ranks: Box::into_raw(ranks) as *const Box<[u64]>,
phantom: PhantomData,
};

Expand Down Expand Up @@ -366,7 +376,10 @@ impl<T: Hash + Clone + Debug> Mphf<T> {
fn get_rank(&self, hash: u64, i: usize) -> u64 {
let idx = hash as usize;
let bv = self.bitvecs.get(i).expect("that level doesn't exist");
let ranks = self.ranks.get(i).expect("that level doesn't exist");

assert!(i <= isize::max_value() as usize);
// Here you need no check while self.ranks.len() == self.bitvecs.len()
let ranks = &unsafe { &*self.ranks.add(i) };

// Last pre-computed rank
let mut rank = ranks[idx / 512];
Expand Down Expand Up @@ -494,9 +507,10 @@ impl<T: Hash + Clone + Debug + Sync + Send> Mphf<T> {
}

let ranks = Self::compute_ranks(&bitvecs);
debug_assert!(ranks.len() == bitvecs.len());
let r = Mphf {
bitvecs: bitvecs.into_boxed_slice(),
ranks: ranks,
ranks: Box::into_raw(ranks) as *const Box<[u64]>,
phantom: PhantomData,
};

Expand Down Expand Up @@ -728,9 +742,10 @@ impl<'a, T: 'a + Hash + Clone + Debug + Send + Sync> Mphf<T> {
}

let ranks = Self::compute_ranks(&bitvecs);
debug_assert!(ranks.len() == bitvecs.len());
let r = Mphf {
bitvecs: bitvecs.into_boxed_slice(),
ranks: ranks,
ranks: Box::into_raw(ranks) as *const Box<[u64]>,
phantom: PhantomData,
};

Expand Down