410 lines
14 KiB
Rust
410 lines
14 KiB
Rust
#![allow(dead_code)]
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use {
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crate::{
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bucket_storage::{BucketOccupied, BucketStorage, IncludeHeader},
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RefCount,
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},
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bv::BitVec,
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modular_bitfield::prelude::*,
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solana_sdk::{clock::Slot, pubkey::Pubkey},
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std::{fmt::Debug, marker::PhantomData},
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};
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/// allocated in `contents` in a BucketStorage
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pub struct BucketWithBitVec {
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pub occupied: BitVec,
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}
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impl BucketOccupied for BucketWithBitVec {
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fn occupy(&mut self, element: &mut [u8], ix: usize) {
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assert!(self.is_free(element, ix));
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self.occupied.set(ix as u64, true);
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}
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fn free(&mut self, element: &mut [u8], ix: usize) {
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assert!(!self.is_free(element, ix));
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self.occupied.set(ix as u64, false);
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}
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fn is_free(&self, _element: &[u8], ix: usize) -> bool {
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!self.occupied.get(ix as u64)
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}
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fn offset_to_first_data() -> usize {
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// no header, nothing stored in data stream
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0
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}
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fn new(num_elements: usize) -> Self {
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Self {
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occupied: BitVec::new_fill(false, num_elements as u64),
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}
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}
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}
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#[derive(Debug, Default)]
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pub struct IndexBucketUsingRefCountBits<T: 'static> {
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_phantom: PhantomData<&'static T>,
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}
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impl<T: Copy> BucketOccupied for IndexBucketUsingRefCountBits<T> {
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fn occupy(&mut self, element: &mut [u8], ix: usize) {
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assert!(self.is_free(element, ix));
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let entry: &mut IndexEntry<T> =
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BucketStorage::<IndexBucketUsingRefCountBits<T>>::get_mut_from_parts(element);
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entry.set_slot_count_enum_value(OccupiedEnum::ZeroSlots);
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}
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fn free(&mut self, element: &mut [u8], ix: usize) {
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assert!(!self.is_free(element, ix));
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let entry: &mut IndexEntry<T> =
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BucketStorage::<IndexBucketUsingRefCountBits<T>>::get_mut_from_parts(element);
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entry.set_slot_count_enum_value(OccupiedEnum::Free);
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}
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fn is_free(&self, element: &[u8], _ix: usize) -> bool {
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let entry: &IndexEntry<T> =
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BucketStorage::<IndexBucketUsingRefCountBits<T>>::get_from_parts(element);
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matches!(entry.get_slot_count_enum(), OccupiedEnum::Free)
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}
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fn offset_to_first_data() -> usize {
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0
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}
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fn new(_num_elements: usize) -> Self {
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Self {
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_phantom: PhantomData,
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}
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}
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}
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pub type DataBucket = BucketWithBitVec;
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pub type IndexBucket<T> = IndexBucketUsingRefCountBits<T>;
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/// contains the index of an entry in the index bucket.
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/// This type allows us to call methods to interact with the index entry on this type.
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pub struct IndexEntryPlaceInBucket<T: 'static> {
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pub ix: u64,
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_phantom: PhantomData<&'static T>,
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}
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#[repr(C)]
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#[derive(Copy, Clone)]
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/// one instance of this per item in the index
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/// stored in the index bucket
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pub struct IndexEntry<T: Clone + Copy> {
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pub(crate) key: Pubkey, // can this be smaller if we have reduced the keys into buckets already?
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packed_ref_count: PackedRefCount,
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/// depends on the contents of ref_count.slot_count_enum
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contents: SingleElementOrMultipleSlots<T>,
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}
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/// 62 bits available for ref count
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pub(crate) const MAX_LEGAL_REFCOUNT: RefCount = RefCount::MAX >> 2;
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/// hold a big `RefCount` while leaving room for extra bits to be used for things like 'Occupied'
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#[bitfield(bits = 64)]
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#[repr(C)]
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#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
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struct PackedRefCount {
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/// tag for Enum
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slot_count_enum: B2,
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/// ref_count of this entry. We don't need any where near 62 bits for this value
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ref_count: B62,
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}
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/// required fields when an index element references the data file
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#[repr(C)]
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#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
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pub(crate) struct MultipleSlots {
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// if the bucket doubled, the index can be recomputed using storage_cap_and_offset.create_bucket_capacity_pow2
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storage_cap_and_offset: PackedStorage,
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/// num elements in the slot list
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num_slots: Slot,
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}
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impl MultipleSlots {
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pub(crate) fn set_storage_capacity_when_created_pow2(
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&mut self,
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storage_capacity_when_created_pow2: u8,
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) {
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self.storage_cap_and_offset
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.set_capacity_when_created_pow2(storage_capacity_when_created_pow2)
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}
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pub(crate) fn set_storage_offset(&mut self, storage_offset: u64) {
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self.storage_cap_and_offset
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.set_offset_checked(storage_offset)
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.expect("New storage offset must fit into 7 bytes!")
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}
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fn storage_capacity_when_created_pow2(&self) -> u8 {
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self.storage_cap_and_offset.capacity_when_created_pow2()
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}
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fn storage_offset(&self) -> u64 {
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self.storage_cap_and_offset.offset()
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}
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pub(crate) fn num_slots(&self) -> Slot {
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self.num_slots
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}
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pub(crate) fn set_num_slots(&mut self, num_slots: Slot) {
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self.num_slots = num_slots;
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}
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pub(crate) fn data_bucket_ix(&self) -> u64 {
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Self::data_bucket_from_num_slots(self.num_slots())
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}
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/// return closest bucket index fit for the slot slice.
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/// Since bucket size is 2^index, the return value is
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/// min index, such that 2^index >= num_slots
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/// index = ceiling(log2(num_slots))
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/// special case, when slot slice empty, return 0th index.
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pub(crate) fn data_bucket_from_num_slots(num_slots: Slot) -> u64 {
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// Compute the ceiling of log2 for integer
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if num_slots == 0 {
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0
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} else {
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(Slot::BITS - (num_slots - 1).leading_zeros()) as u64
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}
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}
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/// This function maps the original data location into an index in the current bucket storage.
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/// This is coupled with how we resize bucket storages.
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pub(crate) fn data_loc(&self, storage: &BucketStorage<DataBucket>) -> u64 {
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self.storage_offset() << (storage.capacity_pow2 - self.storage_capacity_when_created_pow2())
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}
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}
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#[repr(C)]
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#[derive(Copy, Clone)]
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pub(crate) union SingleElementOrMultipleSlots<T: Clone + Copy> {
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/// the slot list contains a single element. No need for an entry in the data file.
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/// The element itself is stored in place in the index entry
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pub(crate) single_element: T,
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/// the slot list ocntains more than one element. This contains the reference to the data file.
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pub(crate) multiple_slots: MultipleSlots,
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}
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#[repr(u8)]
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#[derive(Debug, Eq, PartialEq)]
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pub(crate) enum OccupiedEnum<'a, T> {
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/// this spot is not occupied.
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/// ALL other enum values ARE occupied.
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Free = 0,
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/// zero slots in the slot list
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ZeroSlots = 1,
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/// one slot in the slot list, it is stored in the index
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OneSlotInIndex(&'a T) = 2,
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/// data is stored in data file
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MultipleSlots(&'a MultipleSlots) = 3,
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}
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impl<T: Copy> IndexEntry<T> {
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pub(crate) fn get_slot_count_enum(&self) -> OccupiedEnum<'_, T> {
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unsafe {
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match self.packed_ref_count.slot_count_enum() {
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0 => OccupiedEnum::Free,
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1 => OccupiedEnum::ZeroSlots,
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2 => OccupiedEnum::OneSlotInIndex(&self.contents.single_element),
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3 => OccupiedEnum::MultipleSlots(&self.contents.multiple_slots),
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_ => {
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panic!("unexpected value");
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}
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}
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}
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}
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pub(crate) fn get_multiple_slots_mut(&mut self) -> Option<&mut MultipleSlots> {
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unsafe {
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match self.packed_ref_count.slot_count_enum() {
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3 => Some(&mut self.contents.multiple_slots),
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_ => None,
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}
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}
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}
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pub(crate) fn set_slot_count_enum_value<'a>(&'a mut self, value: OccupiedEnum<'a, T>) {
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self.packed_ref_count.set_slot_count_enum(match value {
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OccupiedEnum::Free => 0,
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OccupiedEnum::ZeroSlots => 1,
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OccupiedEnum::OneSlotInIndex(single_element) => {
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self.contents.single_element = *single_element;
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2
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}
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OccupiedEnum::MultipleSlots(multiple_slots) => {
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self.contents.multiple_slots = *multiple_slots;
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3
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}
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});
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}
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}
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/// Pack the storage offset and capacity-when-crated-pow2 fields into a single u64
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#[bitfield(bits = 64)]
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#[repr(C)]
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#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
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struct PackedStorage {
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capacity_when_created_pow2: B8,
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offset: B56,
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}
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impl<T: Copy> IndexEntryPlaceInBucket<T> {
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pub fn init(&self, index_bucket: &mut BucketStorage<IndexBucket<T>>, pubkey: &Pubkey) {
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self.set_slot_count_enum_value(index_bucket, OccupiedEnum::ZeroSlots);
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let index_entry = index_bucket.get_mut::<IndexEntry<T>>(self.ix);
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index_entry.key = *pubkey;
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index_entry.packed_ref_count.set_ref_count(0);
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}
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/// return Some(MultipleSlots) if this item's data is stored in the data file
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pub(crate) fn get_multiple_slots_mut<'a>(
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&self,
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index_bucket: &'a mut BucketStorage<IndexBucket<T>>,
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) -> Option<&'a mut MultipleSlots> {
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let index_entry = index_bucket.get_mut::<IndexEntry<T>>(self.ix);
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index_entry.get_multiple_slots_mut()
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}
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pub(crate) fn get_slot_count_enum<'a>(
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&self,
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index_bucket: &'a BucketStorage<IndexBucket<T>>,
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) -> OccupiedEnum<'a, T> {
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let index_entry = index_bucket.get::<IndexEntry<T>>(self.ix);
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index_entry.get_slot_count_enum()
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}
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/// make this index entry reflect `value`
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pub(crate) fn set_slot_count_enum_value<'a>(
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&self,
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index_bucket: &'a mut BucketStorage<IndexBucket<T>>,
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value: OccupiedEnum<'a, T>,
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) {
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let index_entry = index_bucket.get_mut::<IndexEntry<T>>(self.ix);
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index_entry.set_slot_count_enum_value(value);
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}
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fn ref_count(&self, index_bucket: &BucketStorage<IndexBucket<T>>) -> RefCount {
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let index_entry = index_bucket.get::<IndexEntry<T>>(self.ix);
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index_entry.packed_ref_count.ref_count()
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}
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pub(crate) fn read_value<'a>(
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&self,
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index_bucket: &'a BucketStorage<IndexBucket<T>>,
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data_buckets: &'a [BucketStorage<DataBucket>],
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) -> (&'a [T], RefCount) {
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(
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match self.get_slot_count_enum(index_bucket) {
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OccupiedEnum::ZeroSlots => {
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// num_slots is 0. This means we don't have an actual allocation.
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&[]
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}
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OccupiedEnum::OneSlotInIndex(single_element) => {
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// only element is stored in the index entry
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// Note that the lifetime comes from `index_bucket` here.
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std::slice::from_ref(single_element)
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}
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OccupiedEnum::MultipleSlots(multiple_slots) => {
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// data is in data file, so return a ref to that data
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let data_bucket_ix = multiple_slots.data_bucket_ix();
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let data_bucket = &data_buckets[data_bucket_ix as usize];
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let loc = multiple_slots.data_loc(data_bucket);
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assert!(!data_bucket.is_free(loc));
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data_bucket.get_cell_slice::<T>(
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loc,
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multiple_slots.num_slots,
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IncludeHeader::NoHeader,
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)
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}
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_ => {
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panic!("trying to read data from a free entry");
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}
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},
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self.ref_count(index_bucket),
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)
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}
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pub fn new(ix: u64) -> Self {
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Self {
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ix,
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_phantom: PhantomData,
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}
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}
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pub fn key<'a>(&self, index_bucket: &'a BucketStorage<IndexBucket<T>>) -> &'a Pubkey {
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let entry: &IndexEntry<T> = index_bucket.get(self.ix);
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&entry.key
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}
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pub fn set_ref_count(
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&self,
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index_bucket: &mut BucketStorage<IndexBucket<T>>,
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ref_count: RefCount,
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) {
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let index_entry = index_bucket.get_mut::<IndexEntry<T>>(self.ix);
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index_entry
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.packed_ref_count
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.set_ref_count_checked(ref_count)
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.expect("ref count must fit into 62 bits!");
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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/// verify that accessors for storage_offset and capacity_when_created are
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/// correct and independent
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#[test]
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fn test_api() {
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for offset in [0, 1, u32::MAX as u64] {
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let mut multiple_slots = MultipleSlots::default();
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if offset != 0 {
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multiple_slots.set_storage_offset(offset);
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}
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assert_eq!(multiple_slots.storage_offset(), offset);
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assert_eq!(multiple_slots.storage_capacity_when_created_pow2(), 0);
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for pow in [1, 255, 0] {
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multiple_slots.set_storage_capacity_when_created_pow2(pow);
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assert_eq!(multiple_slots.storage_offset(), offset);
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assert_eq!(multiple_slots.storage_capacity_when_created_pow2(), pow);
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}
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}
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}
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#[test]
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fn test_size() {
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assert_eq!(std::mem::size_of::<PackedStorage>(), 1 + 7);
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assert_eq!(std::mem::size_of::<IndexEntry<u64>>(), 32 + 8 + 8 + 8);
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}
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#[test]
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#[should_panic(expected = "New storage offset must fit into 7 bytes!")]
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fn test_set_storage_offset_value_too_large() {
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let too_big = 1 << 56;
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let mut multiple_slots = MultipleSlots::default();
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multiple_slots.set_storage_offset(too_big);
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}
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#[test]
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fn test_data_bucket_from_num_slots() {
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for n in 0..512 {
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assert_eq!(
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MultipleSlots::data_bucket_from_num_slots(n),
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(n as f64).log2().ceil() as u64
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);
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}
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assert_eq!(
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MultipleSlots::data_bucket_from_num_slots(u32::MAX as u64),
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32
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);
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assert_eq!(
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MultipleSlots::data_bucket_from_num_slots(u32::MAX as u64 + 1),
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32
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);
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assert_eq!(
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MultipleSlots::data_bucket_from_num_slots(u32::MAX as u64 + 2),
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33
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);
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}
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}
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