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use std::hash::{Hash};
use spin::{RwLockReadGuard, RwLockWriteGuard};
use std::ptr;
use std::mem;
use std::cmp::{max};
use std::mem::{align_of, size_of, drop};
use std::marker::{Send, Sync};
use alloc::heap::{allocate, deallocate, EMPTY};
const MIN_CAPACITY: usize = 1 << 5;
const MAX_CAPACITY: u64 = (1 << 48) - 1;
const HASH_MASK: u64 = 0x0000FFFFFFFFFFFF;
const TOMBSTONE: u64 = 0x0001000000000000;
const PRESENT: u64 = 0x1000000000000000;
unsafe fn alloc<T>(count: usize, zero: bool) -> *mut T {
if count == 0 {
return ptr::null_mut();
}
if size_of::<T>() == 0 {
return EMPTY as *mut T;
}
let alloc_size = match count.checked_mul(size_of::<T>()) {
None => panic!("allocation size overflow"),
Some(s) => s
};
let p = allocate(alloc_size, align_of::<T>());
if p.is_null() {
::alloc::oom()
}
let ret = p as *mut T;
if zero {
ptr::write_bytes(ret, 0, count);
}
return ret;
}
unsafe fn dealloc<T>(p: *mut T, count: usize) {
if p.is_null() || count == 0 || p as *mut () == EMPTY {
return;
}
let size = count * size_of::<T>();
deallocate(p as *mut u8, size, align_of::<T>());
}
pub struct Table<K, V> {
hashes: *mut u64,
keys: *mut K,
values: *mut V,
capacity: usize,
len: usize,
}
pub struct Accessor<'a, K: 'a, V: 'a> {
table: RwLockReadGuard<'a, Table<K, V>>,
idx: usize
}
pub struct MutAccessor<'a, K: 'a, V: 'a> {
table: RwLockWriteGuard<'a, Table<K, V>>,
idx: usize
}
impl <'a, K, V> Accessor<'a, K, V> {
pub fn new(table: RwLockReadGuard<'a, Table<K, V>>, idx: usize) -> Accessor<'a, K, V> {
Accessor {
table: table,
idx: idx
}
}
pub fn get(&self) -> &'a V {
debug_assert!(self.table.is_present(self.idx));
unsafe {
&*self.table.values.offset(self.idx as isize)
}
}
}
impl <'a, K, V> MutAccessor<'a, K, V> {
pub fn new(table: RwLockWriteGuard<'a, Table<K, V>>, idx: usize) -> MutAccessor<'a, K, V> {
MutAccessor {
table: table,
idx: idx
}
}
pub fn get(&mut self) -> &'a mut V {
debug_assert!(self.table.is_present(self.idx));
unsafe {
&mut *self.table.values.offset(self.idx as isize)
}
}
}
impl <K, V> Table<K, V> where K: Hash + Eq {
pub fn new(capacity: usize) -> Table<K, V> {
assert!(size_of::<K>() > 0 && size_of::<V>() > 0, "zero-size types not yet supported");
let capacity = if capacity == 0 { 0 } else { capacity.next_power_of_two() };
Table {
capacity: capacity,
len: 0,
hashes: unsafe { alloc(capacity, true) },
keys: unsafe { alloc(capacity, false) },
values: unsafe { alloc(capacity, false) }
}
}
pub fn lookup<C>(&self, hash: u64, eq: C) -> Option<usize> where C: Fn(&K) -> bool {
let len = self.capacity;
if len == 0 {
return None;
}
let mask = len - 1;
let hash = hash & HASH_MASK;
let mut i = hash as usize & mask;
let mut j = 0;
loop {
if self.is_present(i) && self.compare_key_at(&eq, i) {
return Some(i);
}
if !self.is_present(i) && !self.is_deleted(i) {
return None;
}
if i == len - 1 { return None; }
j += 1;
i = (i + j) & mask;
}
}
pub fn put<T, U: Fn(&mut V, V)-> T>(&mut self, key: K, value: V, hash: u64, update: U) -> Option<T> {
if self.capacity == 0 {
self.resize();
}
loop {
let len = self.capacity;
let hash = hash & HASH_MASK;
let mask = len - 1;
let mut i = (hash as usize) & mask;
let mut j = 0;
loop {
if !self.is_present(i) {
unsafe { self.put_at_empty(i, key, value, hash); }
self.len += 1;
return None;
} else if self.compare_key_at(&|k| k == &key, i) {
let old_value = unsafe { &mut *self.values.offset(i as isize) };
return Some(update(old_value, value));
}
if i == len - 1 { break; }
j += 1;
i = (i + j) & mask;
}
self.resize();
}
}
pub fn remove<C>(&mut self, hash: u64, eq: C) -> Option<V> where C: Fn(&K) -> bool {
let i = match self.lookup(hash, eq) {
Some(i) => i,
None => return None
};
unsafe {
drop::<K>(ptr::read(self.keys.offset(i as isize)));
*self.hashes.offset(i as isize) = TOMBSTONE;
self.len -= 1;
let value = ptr::read(self.values.offset(i as isize));
return Some(value);
}
}
#[inline]
fn compare_key_at<C>(&self, eq: &C, idx: usize) -> bool where C: Fn(&K) -> bool {
assert!(self.is_present(idx));
unsafe { eq(&*self.keys.offset(idx as isize)) }
}
unsafe fn put_at_empty(&mut self, idx: usize, key: K, value: V, hash: u64) {
let i = idx as isize;
*self.hashes.offset(i) = hash | PRESENT;
ptr::write(self.keys.offset(i), key);
ptr::write(self.values.offset(i), value);
}
fn resize(&mut self) {
let new_capacity = max(self.capacity.checked_add(self.capacity).expect("size overflow"), MIN_CAPACITY);
if new_capacity as u64 > MAX_CAPACITY {
panic!("requested size: {}, max size: {}", new_capacity, MAX_CAPACITY);
}
let mut new_table = Table::new(new_capacity);
unsafe {
self.foreach_present_idx(|i| {
let hash: u64 = *self.hashes.offset(i as isize);
new_table.put(ptr::read(self.keys.offset(i as isize)),
ptr::read(self.values.offset(i as isize)),
hash, |_, _| { });
});
dealloc(self.hashes, self.capacity);
dealloc(self.keys, self.capacity);
dealloc(self.values, self.capacity);
self.hashes = ptr::null_mut();
}
mem::swap(self, &mut new_table);
}
}
impl <K, V> Table<K, V> {
pub fn capacity(&self) -> usize { self.capacity }
pub fn iter_advance<'a>(&'a self, idx: &mut usize) -> Option<(&'a K, &'a V)> {
if *idx >= self.capacity {
return None;
}
for i in *idx..self.capacity {
if self.is_present(i) {
*idx = i + 1;
let entry = unsafe {
let key = self.keys.offset(i as isize);
let value = self.values.offset(i as isize);
(&*key, &*value)
};
return Some(entry);
}
}
*idx = self.capacity;
return None;
}
pub fn clear(&mut self) {
self.foreach_present_idx(|i| {
unsafe {
drop::<K>(ptr::read(self.keys.offset(i as isize)));
drop::<V>(ptr::read(self.values.offset(i as isize)));
}
});
unsafe {
ptr::write_bytes(self.hashes, 0, self.capacity);
}
self.len = 0;
}
fn is_present(&self, idx: usize) -> bool {
assert!(idx < self.capacity);
self.hash_at(idx) & PRESENT != 0
}
fn is_deleted(&self, idx: usize) -> bool {
assert!(idx < self.capacity);
!self.is_present(idx) && self.hash_at(idx) & TOMBSTONE != 0
}
fn hash_at(&self, idx: usize) -> u64 {
assert!(idx < self.capacity);
unsafe { *self.hashes.offset(idx as isize) }
}
fn foreach_present_idx<F>(&self, mut f: F) where F: FnMut(usize) {
let mut seen = 0;
for i in 0..self.capacity {
if seen == self.len {
return;
}
if self.is_present(i) {
seen += 1;
f(i);
}
}
}
}
impl <K, V> Drop for Table<K, V> {
fn drop(&mut self) {
if self.hashes.is_null() {
return;
}
self.foreach_present_idx(|i| {
unsafe {
drop::<K>(ptr::read(self.keys.offset(i as isize)));
drop::<V>(ptr::read(self.values.offset(i as isize)));
}
});
unsafe {
dealloc(self.hashes, self.capacity);
dealloc(self.keys, self.capacity);
dealloc(self.values, self.capacity);
}
}
}
unsafe impl <K, V> Sync for Table<K, V> where K: Send + Sync, V: Send + Sync { }
unsafe impl <K, V> Send for Table<K, V> where K: Send, V: Send { }