introduce bucket map (#19848)

* introduce bucket map

* rename BucketMap bits to num_buckets_pow2

* use u64::BITS

* Store the number of buckets in BucketMapConfig as a regular number

* remove redundant type aliases

* use Slot from sdk

* use Arc::clone() instead

* fixup erase drives

* rename num_buckets to max_buckets

* add doc to BucketMapConfig::new()

* add more documentation

* rename to DEFAULT_CAPACITY_POW2

* doc

* add more traits while we can

* rename capacity to capacity_pow2

* fix a naming for max_buckets_pow2

* remove unused/incorrect DataBucket::bytes

* rework benches a bit

* fixup bench docs

* rename create_bucket_capacity_pow2 to bucket_capacity_when_created_pow2

* rename BucketMapKeyValue to BucketItem

* rename to items_in_range

* remove values()

* remove addref and unref

* remove more addref and unref

* resurect addref and unref since tests use 'em for now

* rename to BucketStorage

* move stats in bucket_stats

* remove specializations (i don't think they are needed)

* move MaxSearch and RefCount into lib.rs

* move BucketItem to bucket_item.rs

* add doc

* keys no longer returns an option

* Revert "remove specializations (i don't think they are needed)"

This reverts commit b22f78e072.

Co-authored-by: Brooks Prumo <brooks@solana.com>

Cargo.lock

@@ -854,11 +854,11 @@ dependencies = [
 
 [[package]]
 name = "crc32fast"
-version = "1.2.0"
+version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba125de2af0df55319f41944744ad91c71113bf74a4646efff39afe1f6842db1"
+checksum = "81156fece84ab6a9f2afdb109ce3ae577e42b1228441eded99bd77f627953b1a"
 dependencies = [
- "cfg-if 0.1.10",
+ "cfg-if 1.0.0",
 ]
 
 [[package]]
@@ -2446,6 +2446,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "memmap2"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "723e3ebdcdc5c023db1df315364573789f8857c11b631a2fdfad7c00f5c046b4"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "memmap2"
 version = "0.4.0"
@@ -4308,6 +4317,21 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "solana-bucket-map"
+version = "1.8.0"
+dependencies = [
+ "fs_extra",
+ "log 0.4.14",
+ "memmap2 0.2.3",
+ "rand 0.7.3",
+ "rayon",
+ "solana-logger 1.8.0",
+ "solana-measure",
+ "solana-sdk",
+ "tempfile",
+]
+
 [[package]]
 name = "solana-cargo-build-bpf"
 version = "1.8.0"
@@ -5407,6 +5431,7 @@ dependencies = [
  "rustc_version 0.4.0",
  "serde",
  "serde_derive",
+ "solana-bucket-map",
  "solana-compute-budget-program",
  "solana-config-program",
  "solana-ed25519-program",

Cargo.toml

@@ -8,6 +8,7 @@ members = [
     "banks-client",
     "banks-interface",
     "banks-server",
+    "bucket_map",
     "clap-utils",
     "cli-config",
     "cli-output",

bucket_map/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "solana-bucket-map"
+version = "1.8.0"
+description = "solana-bucket-map"
+homepage = "https://solana.com/"
+documentation = "https://docs.rs/solana-bucket-map"
+readme = "../README.md"
+repository = "https://github.com/solana-labs/solana"
+authors = ["Solana Maintainers <maintainers@solana.foundation>"]
+license = "Apache-2.0"
+edition = "2018"
+
+[dependencies]
+rayon = "1.5.0"
+solana-logger = { path = "../logger", version = "=1.8.0" }
+solana-sdk = { path = "../sdk", version = "=1.8.0" }
+memmap2 = "0.2.3"
+log = { version = "0.4.11" }
+solana-measure = { path = "../measure", version = "=1.8.0" }
+rand = "0.7.0"
+fs_extra = "1.2.0"
+tempfile = "3.2.0"
+
+[lib]
+crate-type = ["lib"]
+name = "solana_bucket_map"
+
+[[bench]]
+name = "bucket_map"

bucket_map/benches/bucket_map.rs

@@ -0,0 +1,76 @@
+#![feature(test)]
+
+macro_rules! DEFINE_NxM_BENCH {
+    ($i:ident, $n:literal, $m:literal) => {
+        mod $i {
+            use super::*;
+
+            #[bench]
+            fn bench_insert_baseline_hashmap(bencher: &mut Bencher) {
+                do_bench_insert_baseline_hashmap(bencher, $n, $m);
+            }
+
+            #[bench]
+            fn bench_insert_bucket_map(bencher: &mut Bencher) {
+                do_bench_insert_bucket_map(bencher, $n, $m);
+            }
+        }
+    };
+}
+
+extern crate test;
+use rayon::prelude::*;
+use solana_bucket_map::bucket_map::{BucketMap, BucketMapConfig};
+use solana_sdk::pubkey::Pubkey;
+use std::collections::hash_map::HashMap;
+use std::sync::RwLock;
+use test::Bencher;
+
+type IndexValue = u64;
+
+DEFINE_NxM_BENCH!(dim_01x02, 1, 2);
+DEFINE_NxM_BENCH!(dim_02x04, 2, 4);
+DEFINE_NxM_BENCH!(dim_04x08, 4, 8);
+DEFINE_NxM_BENCH!(dim_08x16, 8, 16);
+DEFINE_NxM_BENCH!(dim_16x32, 16, 32);
+DEFINE_NxM_BENCH!(dim_32x64, 32, 64);
+
+/// Benchmark insert with Hashmap as baseline for N threads inserting M keys each
+fn do_bench_insert_baseline_hashmap(bencher: &mut Bencher, n: usize, m: usize) {
+    let index = RwLock::new(HashMap::new());
+    (0..n).into_iter().into_par_iter().for_each(|i| {
+        let key = Pubkey::new_unique();
+        index
+            .write()
+            .unwrap()
+            .insert(key, vec![(i, IndexValue::default())]);
+    });
+    bencher.iter(|| {
+        (0..n).into_iter().into_par_iter().for_each(|_| {
+            for j in 0..m {
+                let key = Pubkey::new_unique();
+                index
+                    .write()
+                    .unwrap()
+                    .insert(key, vec![(j, IndexValue::default())]);
+            }
+        })
+    });
+}
+
+/// Benchmark insert with BucketMap with N buckets for N threads inserting M keys each
+fn do_bench_insert_bucket_map(bencher: &mut Bencher, n: usize, m: usize) {
+    let index = BucketMap::new(BucketMapConfig::new(n));
+    (0..n).into_iter().into_par_iter().for_each(|i| {
+        let key = Pubkey::new_unique();
+        index.update(&key, |_| Some((vec![(i, IndexValue::default())], 0)));
+    });
+    bencher.iter(|| {
+        (0..n).into_iter().into_par_iter().for_each(|_| {
+            for j in 0..m {
+                let key = Pubkey::new_unique();
+                index.update(&key, |_| Some((vec![(j, IndexValue::default())], 0)));
+            }
+        })
+    });
+}

bucket_map/src/bucket.rs

@@ -0,0 +1,397 @@
+use crate::bucket_item::BucketItem;
+use crate::bucket_map::BucketMapError;
+use crate::bucket_stats::BucketMapStats;
+use crate::bucket_storage::BucketStorage;
+use crate::index_entry::IndexEntry;
+use crate::{MaxSearch, RefCount};
+use rand::thread_rng;
+use rand::Rng;
+use solana_measure::measure::Measure;
+use solana_sdk::pubkey::Pubkey;
+use std::collections::hash_map::DefaultHasher;
+use std::hash::{Hash, Hasher};
+use std::marker::PhantomData;
+use std::ops::RangeBounds;
+use std::path::PathBuf;
+use std::sync::atomic::Ordering;
+use std::sync::Arc;
+
+// >= 2 instances of BucketStorage per 'bucket' in the bucket map. 1 for index, >= 1 for data
+pub struct Bucket<T> {
+    drives: Arc<Vec<PathBuf>>,
+    //index
+    index: BucketStorage,
+    //random offset for the index
+    random: u64,
+    //storage buckets to store SlotSlice up to a power of 2 in len
+    pub data: Vec<BucketStorage>,
+    _phantom: PhantomData<T>,
+    stats: Arc<BucketMapStats>,
+}
+
+impl<T: Clone + Copy> Bucket<T> {
+    pub fn new(
+        drives: Arc<Vec<PathBuf>>,
+        max_search: MaxSearch,
+        stats: Arc<BucketMapStats>,
+    ) -> Self {
+        let index = BucketStorage::new(
+            Arc::clone(&drives),
+            1,
+            std::mem::size_of::<IndexEntry>() as u64,
+            max_search,
+            Arc::clone(&stats.index),
+        );
+        Self {
+            random: thread_rng().gen(),
+            drives,
+            index,
+            data: vec![],
+            _phantom: PhantomData::default(),
+            stats,
+        }
+    }
+
+    pub fn bucket_len(&self) -> u64 {
+        self.index.used.load(Ordering::Relaxed)
+    }
+
+    pub fn keys(&self) -> Vec<Pubkey> {
+        let mut rv = vec![];
+        for i in 0..self.index.num_cells() {
+            if self.index.uid(i) == 0 {
+                continue;
+            }
+            let ix: &IndexEntry = self.index.get(i);
+            rv.push(ix.key);
+        }
+        rv
+    }
+
+    pub fn items_in_range<R>(&self, range: Option<&R>) -> Vec<BucketItem<T>>
+    where
+        R: RangeBounds<Pubkey>,
+    {
+        let mut result = Vec::with_capacity(self.index.used.load(Ordering::Relaxed) as usize);
+        for i in 0..self.index.num_cells() {
+            let ii = i % self.index.num_cells();
+            if self.index.uid(ii) == 0 {
+                continue;
+            }
+            let ix: &IndexEntry = self.index.get(ii);
+            let key = ix.key;
+            if range.map(|r| r.contains(&key)).unwrap_or(true) {
+                let val = ix.read_value(self);
+                result.push(BucketItem {
+                    pubkey: key,
+                    ref_count: ix.ref_count(),
+                    slot_list: val.map(|(v, _ref_count)| v.to_vec()).unwrap_or_default(),
+                });
+            }
+        }
+        result
+    }
+
+    pub fn find_entry(&self, key: &Pubkey) -> Option<(&IndexEntry, u64)> {
+        Self::bucket_find_entry(&self.index, key, self.random)
+    }
+
+    fn find_entry_mut(&self, key: &Pubkey) -> Option<(&mut IndexEntry, u64)> {
+        Self::bucket_find_entry_mut(&self.index, key, self.random)
+    }
+
+    fn bucket_find_entry_mut<'a>(
+        index: &'a BucketStorage,
+        key: &Pubkey,
+        random: u64,
+    ) -> Option<(&'a mut IndexEntry, u64)> {
+        let ix = Self::bucket_index_ix(index, key, random);
+        for i in ix..ix + index.max_search() {
+            let ii = i % index.num_cells();
+            if index.uid(ii) == 0 {
+                continue;
+            }
+            let elem: &mut IndexEntry = index.get_mut(ii);
+            if elem.key == *key {
+                return Some((elem, ii));
+            }
+        }
+        None
+    }
+
+    fn bucket_find_entry<'a>(
+        index: &'a BucketStorage,
+        key: &Pubkey,
+        random: u64,
+    ) -> Option<(&'a IndexEntry, u64)> {
+        let ix = Self::bucket_index_ix(index, key, random);
+        for i in ix..ix + index.max_search() {
+            let ii = i % index.num_cells();
+            if index.uid(ii) == 0 {
+                continue;
+            }
+            let elem: &IndexEntry = index.get(ii);
+            if elem.key == *key {
+                return Some((elem, ii));
+            }
+        }
+        None
+    }
+
+    fn bucket_create_key(
+        index: &BucketStorage,
+        key: &Pubkey,
+        elem_uid: u64,
+        random: u64,
+        ref_count: u64,
+    ) -> Result<u64, BucketMapError> {
+        let ix = Self::bucket_index_ix(index, key, random);
+        for i in ix..ix + index.max_search() {
+            let ii = i as u64 % index.num_cells();
+            if index.uid(ii) != 0 {
+                continue;
+            }
+            index.allocate(ii, elem_uid).unwrap();
+            let mut elem: &mut IndexEntry = index.get_mut(ii);
+            elem.key = *key;
+            elem.ref_count = ref_count;
+            elem.storage_offset = 0;
+            elem.storage_capacity_when_created_pow2 = 0;
+            elem.num_slots = 0;
+            //debug!(                "INDEX ALLOC {:?} {} {} {}",                key, ii, index.capacity, elem_uid            );
+            return Ok(ii);
+        }
+        Err(BucketMapError::IndexNoSpace(index.capacity_pow2))
+    }
+
+    pub fn addref(&mut self, key: &Pubkey) -> Option<RefCount> {
+        let (elem, _) = self.find_entry_mut(key)?;
+        elem.ref_count += 1;
+        Some(elem.ref_count)
+    }
+
+    pub fn unref(&mut self, key: &Pubkey) -> Option<RefCount> {
+        let (elem, _) = self.find_entry_mut(key)?;
+        elem.ref_count -= 1;
+        Some(elem.ref_count)
+    }
+
+    fn create_key(&self, key: &Pubkey, ref_count: u64) -> Result<u64, BucketMapError> {
+        Self::bucket_create_key(
+            &self.index,
+            key,
+            IndexEntry::key_uid(key),
+            self.random,
+            ref_count,
+        )
+    }
+
+    pub fn read_value(&self, key: &Pubkey) -> Option<(&[T], RefCount)> {
+        //debug!("READ_VALUE: {:?}", key);
+        let (elem, _) = self.find_entry(key)?;
+        elem.read_value(self)
+    }
+
+    pub fn try_write(
+        &mut self,
+        key: &Pubkey,
+        data: &[T],
+        ref_count: u64,
+    ) -> Result<(), BucketMapError> {
+        let index_entry = self.find_entry_mut(key);
+        let (elem, elem_ix) = match index_entry {
+            None => {
+                let ii = self.create_key(key, ref_count)?;
+                let elem = self.index.get_mut(ii); // get_mut here is right?
+                (elem, ii)
+            }
+            Some(res) => {
+                if ref_count != res.0.ref_count {
+                    res.0.ref_count = ref_count;
+                }
+                res
+            }
+        };
+        let elem_uid = self.index.uid(elem_ix);
+        let best_fit_bucket = IndexEntry::data_bucket_from_num_slots(data.len() as u64);
+        if self.data.get(best_fit_bucket as usize).is_none() {
+            //error!("resizing because missing bucket");
+            return Err(BucketMapError::DataNoSpace((best_fit_bucket, 0)));
+        }
+        let bucket_ix = elem.data_bucket_ix();
+        let current_bucket = &self.data[bucket_ix as usize];
+        if best_fit_bucket == bucket_ix && elem.num_slots > 0 {
+            //in place update
+            let elem_loc = elem.data_loc(current_bucket);
+            let slice: &mut [T] = current_bucket.get_mut_cell_slice(elem_loc, data.len() as u64);
+            //let elem: &mut IndexEntry = self.index.get_mut(elem_ix);
+            assert!(current_bucket.uid(elem_loc) == elem_uid);
+            elem.num_slots = data.len() as u64;
+            slice.clone_from_slice(data);
+            Ok(())
+        } else {
+            //need to move the allocation to a best fit spot
+            let best_bucket = &self.data[best_fit_bucket as usize];
+            let cap_power = best_bucket.capacity_pow2;
+            let cap = best_bucket.num_cells();
+            let pos = thread_rng().gen_range(0, cap);
+            for i in pos..pos + self.index.max_search() {
+                let ix = i % cap;
+                if best_bucket.uid(ix) == 0 {
+                    let elem_loc = elem.data_loc(current_bucket);
+                    if elem.num_slots > 0 {
+                        current_bucket.free(elem_loc, elem_uid).unwrap();
+                    }
+                    // elem: &mut IndexEntry = self.index.get_mut(elem_ix);
+                    elem.storage_offset = ix;
+                    elem.storage_capacity_when_created_pow2 = best_bucket.capacity_pow2;
+                    elem.num_slots = data.len() as u64;
+                    //debug!(                        "DATA ALLOC {:?} {} {} {}",                        key, elem.data_location, best_bucket.capacity, elem_uid                    );
+                    if elem.num_slots > 0 {
+                        best_bucket.allocate(ix, elem_uid).unwrap();
+                        let slice = best_bucket.get_mut_cell_slice(ix, data.len() as u64);
+                        slice.copy_from_slice(data);
+                    }
+                    return Ok(());
+                }
+            }
+            Err(BucketMapError::DataNoSpace((best_fit_bucket, cap_power)))
+        }
+    }
+
+    pub fn delete_key(&mut self, key: &Pubkey) {
+        if let Some((elem, elem_ix)) = self.find_entry(key) {
+            let elem_uid = self.index.uid(elem_ix);
+            if elem.num_slots > 0 {
+                let data_bucket = &self.data[elem.data_bucket_ix() as usize];
+                let loc = elem.data_loc(data_bucket);
+                //debug!(                    "DATA FREE {:?} {} {} {}",                    key, elem.data_location, data_bucket.capacity, elem_uid                );
+                data_bucket.free(loc, elem_uid).unwrap();
+            }
+            //debug!("INDEX FREE {:?} {}", key, elem_uid);
+            self.index.free(elem_ix, elem_uid).unwrap();
+        }
+    }
+
+    pub fn grow_index(&mut self, sz: u8) {
+        if self.index.capacity_pow2 == sz {
+            let mut m = Measure::start("");
+            //debug!("GROW_INDEX: {}", sz);
+            let increment = 1;
+            for i in increment.. {
+                //increasing the capacity by ^4 reduces the
+                //likelyhood of a re-index collision of 2^(max_search)^2
+                //1 in 2^32
+                let index = BucketStorage::new_with_capacity(
+                    Arc::clone(&self.drives),
+                    1,
+                    std::mem::size_of::<IndexEntry>() as u64,
+                    self.index.capacity_pow2 + i, // * 2,
+                    self.index.max_search,
+                    Arc::clone(&self.stats.index),
+                );
+                let random = thread_rng().gen();
+                let mut valid = true;
+                for ix in 0..self.index.num_cells() {
+                    let uid = self.index.uid(ix);
+                    if 0 != uid {
+                        let elem: &IndexEntry = self.index.get(ix);
+                        let ref_count = 0; // ??? TODO
+                        let new_ix =
+                            Self::bucket_create_key(&index, &elem.key, uid, random, ref_count);
+                        if new_ix.is_err() {
+                            valid = false;
+                            break;
+                        }
+                        let new_ix = new_ix.unwrap();
+                        let new_elem: &mut IndexEntry = index.get_mut(new_ix);
+                        *new_elem = *elem;
+                        /*
+                        let dbg_elem: IndexEntry = *new_elem;
+                        assert_eq!(
+                            Self::bucket_find_entry(&index, &elem.key, random).unwrap(),
+                            (&dbg_elem, new_ix)
+                        );
+                        */
+                    }
+                }
+                if valid {
+                    self.index = index;
+                    self.random = random;
+                    break;
+                }
+            }
+            m.stop();
+            let sz = 1 << self.index.capacity_pow2;
+            {
+                let mut max = self.stats.index.max_size.lock().unwrap();
+                *max = std::cmp::max(*max, sz);
+            }
+            self.stats.index.resizes.fetch_add(1, Ordering::Relaxed);
+            self.stats
+                .index
+                .resize_us
+                .fetch_add(m.as_us(), Ordering::Relaxed);
+        }
+    }
+
+    pub fn grow_data(&mut self, sz: (u64, u8)) {
+        if self.data.get(sz.0 as usize).is_none() {
+            for i in self.data.len() as u64..(sz.0 + 1) {
+                self.data.push(BucketStorage::new(
+                    Arc::clone(&self.drives),
+                    1 << i,
+                    std::mem::size_of::<T>() as u64,
+                    self.index.max_search,
+                    Arc::clone(&self.stats.data),
+                ))
+            }
+        }
+        if self.data[sz.0 as usize].capacity_pow2 == sz.1 {
+            //debug!("GROW_DATA: {} {}", sz.0, sz.1);
+            self.data[sz.0 as usize].grow();
+        }
+    }
+
+    fn bucket_index_ix(index: &BucketStorage, key: &Pubkey, random: u64) -> u64 {
+        let uid = IndexEntry::key_uid(key);
+        let mut s = DefaultHasher::new();
+        uid.hash(&mut s);
+        //the locally generated random will make it hard for an attacker
+        //to deterministically cause all the pubkeys to land in the same
+        //location in any bucket on all validators
+        random.hash(&mut s);
+        let ix = s.finish();
+        ix % index.num_cells()
+        //debug!(            "INDEX_IX: {:?} uid:{} loc: {} cap:{}",            key,            uid,            location,            index.num_cells()        );
+    }
+
+    pub fn update<F>(&mut self, key: &Pubkey, updatefn: F)
+    where
+        F: Fn(Option<(&[T], RefCount)>) -> Option<(Vec<T>, RefCount)>,
+    {
+        let current = self.read_value(key);
+        let new = updatefn(current);
+        if new.is_none() {
+            self.delete_key(key);
+            return;
+        }
+        let (new, refct) = new.unwrap();
+        loop {
+            let rv = self.try_write(key, &new, refct);
+            match rv {
+                Err(BucketMapError::DataNoSpace(sz)) => {
+                    //debug!("GROWING SPACE {:?}", sz);
+                    self.grow_data(sz);
+                    continue;
+                }
+                Err(BucketMapError::IndexNoSpace(sz)) => {
+                    //debug!("GROWING INDEX {}", sz);
+                    self.grow_index(sz);
+                    continue;
+                }
+                Ok(()) => return,
+            }
+        }
+    }
+}

bucket_map/src/bucket_item.rs

@@ -0,0 +1,9 @@
+use crate::RefCount;
+use solana_sdk::pubkey::Pubkey;
+
+#[derive(Debug, Default, Clone)]
+pub struct BucketItem<T> {
+    pub pubkey: Pubkey,
+    pub ref_count: RefCount,
+    pub slot_list: Vec<T>,
+}

bucket_map/src/bucket_map.rs

@@ -0,0 +1,508 @@
+//! BucketMap is a mostly contention free concurrent map backed by MmapMut
+
+use crate::bucket::Bucket;
+use crate::bucket_item::BucketItem;
+use crate::bucket_stats::BucketMapStats;
+use crate::{MaxSearch, RefCount};
+use solana_sdk::pubkey::Pubkey;
+use std::convert::TryInto;
+use std::fmt::Debug;
+use std::fs;
+use std::ops::RangeBounds;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::RwLock;
+use tempfile::TempDir;
+
+#[derive(Debug, Default, Clone)]
+pub struct BucketMapConfig {
+    pub max_buckets: usize,
+    pub drives: Option<Vec<PathBuf>>,
+    pub max_search: Option<MaxSearch>,
+}
+
+impl BucketMapConfig {
+    /// Create a new BucketMapConfig
+    /// NOTE: BucketMap requires that max_buckets is a power of two
+    pub fn new(max_buckets: usize) -> BucketMapConfig {
+        BucketMapConfig {
+            max_buckets,
+            ..BucketMapConfig::default()
+        }
+    }
+}
+
+pub struct BucketMap<T: Clone + Copy + Debug> {
+    buckets: Vec<RwLock<Option<Bucket<T>>>>,
+    drives: Arc<Vec<PathBuf>>,
+    max_buckets_pow2: u8,
+    max_search: MaxSearch,
+    pub stats: Arc<BucketMapStats>,
+    pub temp_dir: Option<TempDir>,
+}
+
+impl<T: Clone + Copy + Debug> Drop for BucketMap<T> {
+    fn drop(&mut self) {
+        if self.temp_dir.is_none() {
+            BucketMap::<T>::erase_previous_drives(&self.drives);
+        }
+    }
+}
+
+impl<T: Clone + Copy + Debug> std::fmt::Debug for BucketMap<T> {
+    fn fmt(&self, _f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+pub enum BucketMapError {
+    DataNoSpace((u64, u8)),
+    IndexNoSpace(u8),
+}
+
+impl<T: Clone + Copy + Debug> BucketMap<T> {
+    pub fn new(config: BucketMapConfig) -> Self {
+        assert_ne!(
+            config.max_buckets, 0,
+            "Max number of buckets must be non-zero"
+        );
+        assert!(
+            config.max_buckets.is_power_of_two(),
+            "Max number of buckets must be a power of two"
+        );
+        let mut buckets = Vec::with_capacity(config.max_buckets);
+        buckets.resize_with(config.max_buckets, || RwLock::new(None));
+        let stats = Arc::new(BucketMapStats::default());
+        // this should be <= 1 << DEFAULT_CAPACITY or we end up searching the same items over and over - probably not a big deal since it is so small anyway
+        const MAX_SEARCH: MaxSearch = 32;
+        let max_search = config.max_search.unwrap_or(MAX_SEARCH);
+
+        if let Some(drives) = config.drives.as_ref() {
+            Self::erase_previous_drives(drives);
+        }
+        let mut temp_dir = None;
+        let drives = config.drives.unwrap_or_else(|| {
+            temp_dir = Some(TempDir::new().unwrap());
+            vec![temp_dir.as_ref().unwrap().path().to_path_buf()]
+        });
+        let drives = Arc::new(drives);
+
+        // A simple log2 function that is correct if x is a power of two
+        let log2 = |x: usize| usize::BITS - x.leading_zeros() - 1;
+
+        Self {
+            buckets,
+            drives,
+            max_buckets_pow2: log2(config.max_buckets) as u8,
+            stats,
+            max_search,
+            temp_dir,
+        }
+    }
+
+    fn erase_previous_drives(drives: &[PathBuf]) {
+        drives.iter().for_each(|folder| {
+            let _ = fs::remove_dir_all(&folder);
+            let _ = fs::create_dir_all(&folder);
+        })
+    }
+
+    pub fn num_buckets(&self) -> usize {
+        self.buckets.len()
+    }
+
+    pub fn bucket_len(&self, ix: usize) -> u64 {
+        self.buckets[ix]
+            .read()
+            .unwrap()
+            .as_ref()
+            .map(|bucket| bucket.bucket_len())
+            .unwrap_or_default()
+    }
+
+    /// Get the items for bucket `ix` in `range`
+    pub fn items_in_range<R>(&self, ix: usize, range: Option<&R>) -> Option<Vec<BucketItem<T>>>
+    where
+        R: RangeBounds<Pubkey>,
+    {
+        Some(
+            self.buckets[ix]
+                .read()
+                .unwrap()
+                .as_ref()?
+                .items_in_range(range),
+        )
+    }
+
+    /// Get the Pubkeys for bucket `ix`
+    pub fn keys(&self, ix: usize) -> Vec<Pubkey> {
+        self.buckets[ix]
+            .read()
+            .unwrap()
+            .as_ref()
+            .map_or_else(Vec::default, |bucket| bucket.keys())
+    }
+
+    /// Get the values for Pubkey `key`
+    pub fn read_value(&self, key: &Pubkey) -> Option<(Vec<T>, RefCount)> {
+        let ix = self.bucket_ix(key);
+        self.buckets[ix]
+            .read()
+            .unwrap()
+            .as_ref()
+            .and_then(|bucket| {
+                bucket
+                    .read_value(key)
+                    .map(|(value, ref_count)| (value.to_vec(), ref_count))
+            })
+    }
+
+    /// Delete the Pubkey `key`
+    pub fn delete_key(&self, key: &Pubkey) {
+        let ix = self.bucket_ix(key);
+        if let Some(bucket) = self.buckets[ix].write().unwrap().as_mut() {
+            bucket.delete_key(key);
+        }
+    }
+
+    /// Update Pubkey `key`'s value with function `updatefn`
+    pub fn update<F>(&self, key: &Pubkey, updatefn: F)
+    where
+        F: Fn(Option<(&[T], RefCount)>) -> Option<(Vec<T>, RefCount)>,
+    {
+        let ix = self.bucket_ix(key);
+        let mut bucket = self.buckets[ix].write().unwrap();
+        if bucket.is_none() {
+            *bucket = Some(Bucket::new(
+                Arc::clone(&self.drives),
+                self.max_search,
+                Arc::clone(&self.stats),
+            ));
+        }
+        let bucket = bucket.as_mut().unwrap();
+        bucket.update(key, updatefn)
+    }
+
+    /// Get the bucket index for Pubkey `key`
+    pub fn bucket_ix(&self, key: &Pubkey) -> usize {
+        if self.max_buckets_pow2 > 0 {
+            let location = read_be_u64(key.as_ref());
+            (location >> (u64::BITS - self.max_buckets_pow2 as u32)) as usize
+        } else {
+            0
+        }
+    }
+
+    /// Increment the refcount for Pubkey `key`
+    pub fn addref(&self, key: &Pubkey) -> Option<RefCount> {
+        let ix = self.bucket_ix(key);
+        let mut bucket = self.buckets[ix].write().unwrap();
+        bucket.as_mut()?.addref(key)
+    }
+
+    /// Decrement the refcount for Pubkey `key`
+    pub fn unref(&self, key: &Pubkey) -> Option<RefCount> {
+        let ix = self.bucket_ix(key);
+        let mut bucket = self.buckets[ix].write().unwrap();
+        bucket.as_mut()?.unref(key)
+    }
+}
+
+/// Look at the first 8 bytes of the input and reinterpret them as a u64
+fn read_be_u64(input: &[u8]) -> u64 {
+    assert!(input.len() >= std::mem::size_of::<u64>());
+    u64::from_be_bytes(input[0..std::mem::size_of::<u64>()].try_into().unwrap())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rand::thread_rng;
+    use rand::Rng;
+    use std::collections::HashMap;
+
+    #[test]
+    fn bucket_map_test_insert() {
+        let key = Pubkey::new_unique();
+        let config = BucketMapConfig::new(1 << 1);
+        let index = BucketMap::new(config);
+        index.update(&key, |_| Some((vec![0], 0)));
+        assert_eq!(index.read_value(&key), Some((vec![0], 0)));
+    }
+
+    #[test]
+    fn bucket_map_test_update() {
+        let key = Pubkey::new_unique();
+        let config = BucketMapConfig::new(1 << 1);
+        let index = BucketMap::new(config);
+        index.update(&key, |_| Some((vec![0], 0)));
+        assert_eq!(index.read_value(&key), Some((vec![0], 0)));
+        index.update(&key, |_| Some((vec![1], 0)));
+        assert_eq!(index.read_value(&key), Some((vec![1], 0)));
+    }
+
+    #[test]
+    fn bucket_map_test_update_to_0_len() {
+        solana_logger::setup();
+        let key = Pubkey::new_unique();
+        let config = BucketMapConfig::new(1 << 1);
+        let index = BucketMap::new(config);
+        index.update(&key, |_| Some((vec![0], 1)));
+        assert_eq!(index.read_value(&key), Some((vec![0], 1)));
+        // sets len to 0, updates in place
+        index.update(&key, |_| Some((vec![], 1)));
+        assert_eq!(index.read_value(&key), Some((vec![], 1)));
+        // sets len to 0, doesn't update in place - finds a new place, which causes us to no longer have an allocation in data
+        index.update(&key, |_| Some((vec![], 2)));
+        assert_eq!(index.read_value(&key), Some((vec![], 2)));
+        // sets len to 1, doesn't update in place - finds a new place
+        index.update(&key, |_| Some((vec![1], 2)));
+        assert_eq!(index.read_value(&key), Some((vec![1], 2)));
+    }
+
+    #[test]
+    fn bucket_map_test_delete() {
+        let config = BucketMapConfig::new(1 << 1);
+        let index = BucketMap::new(config);
+        for i in 0..10 {
+            let key = Pubkey::new_unique();
+            assert_eq!(index.read_value(&key), None);
+
+            index.update(&key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(&key), Some((vec![i], 0)));
+
+            index.delete_key(&key);
+            assert_eq!(index.read_value(&key), None);
+
+            index.update(&key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(&key), Some((vec![i], 0)));
+            index.delete_key(&key);
+        }
+    }
+
+    #[test]
+    fn bucket_map_test_delete_2() {
+        let config = BucketMapConfig::new(1 << 2);
+        let index = BucketMap::new(config);
+        for i in 0..100 {
+            let key = Pubkey::new_unique();
+            assert_eq!(index.read_value(&key), None);
+
+            index.update(&key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(&key), Some((vec![i], 0)));
+
+            index.delete_key(&key);
+            assert_eq!(index.read_value(&key), None);
+
+            index.update(&key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(&key), Some((vec![i], 0)));
+            index.delete_key(&key);
+        }
+    }
+
+    #[test]
+    fn bucket_map_test_n_drives() {
+        let config = BucketMapConfig::new(1 << 2);
+        let index = BucketMap::new(config);
+        for i in 0..100 {
+            let key = Pubkey::new_unique();
+            index.update(&key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(&key), Some((vec![i], 0)));
+        }
+    }
+    #[test]
+    fn bucket_map_test_grow_read() {
+        let config = BucketMapConfig::new(1 << 2);
+        let index = BucketMap::new(config);
+        let keys: Vec<Pubkey> = (0..100).into_iter().map(|_| Pubkey::new_unique()).collect();
+        for k in 0..keys.len() {
+            let key = &keys[k];
+            let i = read_be_u64(key.as_ref());
+            index.update(key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(key), Some((vec![i], 0)));
+            for (ix, key) in keys.iter().enumerate() {
+                let i = read_be_u64(key.as_ref());
+                //debug!("READ: {:?} {}", key, i);
+                let expected = if ix <= k { Some((vec![i], 0)) } else { None };
+                assert_eq!(index.read_value(key), expected);
+            }
+        }
+    }
+
+    #[test]
+    fn bucket_map_test_n_delete() {
+        let config = BucketMapConfig::new(1 << 2);
+        let index = BucketMap::new(config);
+        let keys: Vec<Pubkey> = (0..20).into_iter().map(|_| Pubkey::new_unique()).collect();
+        for key in keys.iter() {
+            let i = read_be_u64(key.as_ref());
+            index.update(key, |_| Some((vec![i], 0)));
+            assert_eq!(index.read_value(key), Some((vec![i], 0)));
+        }
+        for key in keys.iter() {
+            let i = read_be_u64(key.as_ref());
+            //debug!("READ: {:?} {}", key, i);
+            assert_eq!(index.read_value(key), Some((vec![i], 0)));
+        }
+        for k in 0..keys.len() {
+            let key = &keys[k];
+            index.delete_key(key);
+            assert_eq!(index.read_value(key), None);
+            for key in keys.iter().skip(k + 1) {
+                let i = read_be_u64(key.as_ref());
+                assert_eq!(index.read_value(key), Some((vec![i], 0)));
+            }
+        }
+    }
+
+    #[test]
+    fn hashmap_compare() {
+        use std::sync::Mutex;
+        solana_logger::setup();
+        let maps = (0..2)
+            .into_iter()
+            .map(|max_buckets_pow2| {
+                let config = BucketMapConfig::new(1 << max_buckets_pow2);
+                BucketMap::new(config)
+            })
+            .collect::<Vec<_>>();
+        let hash_map = RwLock::new(HashMap::<Pubkey, (Vec<(usize, usize)>, RefCount)>::new());
+        let max_slot_list_len = 3;
+        let all_keys = Mutex::new(vec![]);
+
+        let gen_rand_value = || {
+            let count = thread_rng().gen_range(0, max_slot_list_len);
+            let v = (0..count)
+                .into_iter()
+                .map(|x| (x as usize, x as usize /*thread_rng().gen::<usize>()*/))
+                .collect::<Vec<_>>();
+            let rc = thread_rng().gen::<RefCount>();
+            (v, rc)
+        };
+
+        let get_key = || {
+            let mut keys = all_keys.lock().unwrap();
+            if keys.is_empty() {
+                return None;
+            }
+            let len = keys.len();
+            Some(keys.remove(thread_rng().gen_range(0, len)))
+        };
+        let return_key = |key| {
+            let mut keys = all_keys.lock().unwrap();
+            keys.push(key);
+        };
+
+        let verify = || {
+            let mut maps = maps
+                .iter()
+                .map(|map| {
+                    let mut r = vec![];
+                    for bin in 0..map.num_buckets() {
+                        r.append(
+                            &mut map
+                                .items_in_range(bin, None::<&std::ops::RangeInclusive<Pubkey>>)
+                                .unwrap_or_default(),
+                        );
+                    }
+                    r
+                })
+                .collect::<Vec<_>>();
+            let hm = hash_map.read().unwrap();
+            for (k, v) in hm.iter() {
+                for map in maps.iter_mut() {
+                    for i in 0..map.len() {
+                        if k == &map[i].pubkey {
+                            assert_eq!(map[i].slot_list, v.0);
+                            assert_eq!(map[i].ref_count, v.1);
+                            map.remove(i);
+                            break;
+                        }
+                    }
+                }
+            }
+            for map in maps.iter() {
+                assert!(map.is_empty());
+            }
+        };
+        let mut initial = 100; // put this many items in to start
+
+        // do random operations: insert, update, delete, add/unref in random order
+        // verify consistency between hashmap and all bucket maps
+        for i in 0..10000 {
+            if initial > 0 {
+                initial -= 1;
+            }
+            if initial > 0 || thread_rng().gen_range(0, 5) == 0 {
+                // insert
+                let k = solana_sdk::pubkey::new_rand();
+                let v = gen_rand_value();
+                hash_map.write().unwrap().insert(k, v.clone());
+                maps.iter().for_each(|map| {
+                    map.update(&k, |current| {
+                        assert!(current.is_none());
+                        Some(v.clone())
+                    })
+                });
+                return_key(k);
+            }
+            if thread_rng().gen_range(0, 10) == 0 {
+                // update
+                if let Some(k) = get_key() {
+                    let hm = hash_map.read().unwrap();
+                    let (v, rc) = gen_rand_value();
+                    let v_old = hm.get(&k);
+                    maps.iter().for_each(|map| {
+                        map.update(&k, |current| {
+                            assert_eq!(current, v_old.map(|(v, rc)| (&v[..], *rc)), "{}", k);
+                            Some((v.clone(), rc))
+                        })
+                    });
+                    drop(hm);
+                    hash_map.write().unwrap().insert(k, (v, rc));
+                    return_key(k);
+                }
+            }
+            if thread_rng().gen_range(0, 20) == 0 {
+                // delete
+                if let Some(k) = get_key() {
+                    let mut hm = hash_map.write().unwrap();
+                    hm.remove(&k);
+                    maps.iter().for_each(|map| {
+                        map.delete_key(&k);
+                    });
+                }
+            }
+            if thread_rng().gen_range(0, 10) == 0 {
+                // add/unref
+                if let Some(k) = get_key() {
+                    let mut inc = thread_rng().gen_range(0, 2) == 0;
+                    let mut hm = hash_map.write().unwrap();
+                    let (v, mut rc) = hm.get(&k).map(|(v, rc)| (v.to_vec(), *rc)).unwrap();
+                    if !inc && rc == 0 {
+                        // can't decrement rc=0
+                        inc = true;
+                    }
+                    rc = if inc { rc + 1 } else { rc - 1 };
+                    hm.insert(k, (v.to_vec(), rc));
+                    maps.iter().for_each(|map| {
+                        if thread_rng().gen_range(0, 2) == 0 {
+                            map.update(&k, |current| Some((current.unwrap().0.to_vec(), rc)))
+                        } else if inc {
+                            map.addref(&k);
+                        } else {
+                            map.unref(&k);
+                        }
+                    });
+
+                    return_key(k);
+                }
+            }
+            if i % 1000 == 0 {
+                verify();
+            }
+        }
+        verify();
+    }
+}

bucket_map/src/bucket_stats.rs

@@ -0,0 +1,18 @@
+use std::sync::Arc;
+use std::sync::{atomic::AtomicU64, Mutex};
+
+#[derive(Debug, Default)]
+pub struct BucketStats {
+    pub resizes: AtomicU64,
+    pub max_size: Mutex<u64>,
+    pub resize_us: AtomicU64,
+    pub new_file_us: AtomicU64,
+    pub flush_file_us: AtomicU64,
+    pub mmap_us: AtomicU64,
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct BucketMapStats {
+    pub index: Arc<BucketStats>,
+    pub data: Arc<BucketStats>,
+}

bucket_map/src/bucket_storage.rs

@@ -0,0 +1,334 @@
+use crate::bucket_stats::BucketStats;
+use crate::MaxSearch;
+use memmap2::MmapMut;
+use rand::{thread_rng, Rng};
+use solana_measure::measure::Measure;
+use std::fs::{remove_file, OpenOptions};
+use std::io::Seek;
+use std::io::SeekFrom;
+use std::io::Write;
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::Arc;
+
+/*
+1	2
+2	4
+3	8
+4	16
+5	32
+6	64
+7	128
+8	256
+9	512
+10	1,024
+11	2,048
+12	4,096
+13	8,192
+14	16,384
+23  8,388,608
+24  16,777,216
+*/
+const DEFAULT_CAPACITY_POW2: u8 = 5;
+
+#[repr(C)]
+struct Header {
+    lock: AtomicU64,
+}
+
+impl Header {
+    fn try_lock(&self, uid: u64) -> bool {
+        Ok(0)
+            == self
+                .lock
+                .compare_exchange(0, uid, Ordering::Relaxed, Ordering::Relaxed)
+    }
+    fn unlock(&self, uid: u64) -> bool {
+        Ok(uid)
+            == self
+                .lock
+                .compare_exchange(uid, 0, Ordering::Relaxed, Ordering::Relaxed)
+    }
+    fn uid(&self) -> u64 {
+        self.lock.load(Ordering::Relaxed)
+    }
+}
+
+pub struct BucketStorage {
+    drives: Arc<Vec<PathBuf>>,
+    path: PathBuf,
+    mmap: MmapMut,
+    pub cell_size: u64,
+    pub capacity_pow2: u8,
+    pub used: AtomicU64,
+    pub stats: Arc<BucketStats>,
+    pub max_search: MaxSearch,
+}
+
+#[derive(Debug)]
+pub enum BucketStorageError {
+    AlreadyAllocated,
+    InvalidFree,
+}
+
+impl Drop for BucketStorage {
+    fn drop(&mut self) {
+        let _ = remove_file(&self.path);
+    }
+}
+
+impl BucketStorage {
+    pub fn new_with_capacity(
+        drives: Arc<Vec<PathBuf>>,
+        num_elems: u64,
+        elem_size: u64,
+        capacity_pow2: u8,
+        max_search: MaxSearch,
+        mut stats: Arc<BucketStats>,
+    ) -> Self {
+        let cell_size = elem_size * num_elems + std::mem::size_of::<Header>() as u64;
+        let (mmap, path) = Self::new_map(&drives, cell_size as usize, capacity_pow2, &mut stats);
+        Self {
+            path,
+            mmap,
+            drives,
+            cell_size,
+            used: AtomicU64::new(0),
+            capacity_pow2,
+            stats,
+            max_search,
+        }
+    }
+
+    pub fn max_search(&self) -> u64 {
+        self.max_search as u64
+    }
+
+    pub fn new(
+        drives: Arc<Vec<PathBuf>>,
+        num_elems: u64,
+        elem_size: u64,
+        max_search: MaxSearch,
+        stats: Arc<BucketStats>,
+    ) -> Self {
+        Self::new_with_capacity(
+            drives,
+            num_elems,
+            elem_size,
+            DEFAULT_CAPACITY_POW2,
+            max_search,
+            stats,
+        )
+    }
+
+    pub fn uid(&self, ix: u64) -> u64 {
+        if ix >= self.num_cells() {
+            panic!("bad index size");
+        }
+        let ix = (ix * self.cell_size) as usize;
+        let hdr_slice: &[u8] = &self.mmap[ix..ix + std::mem::size_of::<Header>()];
+        unsafe {
+            let hdr = hdr_slice.as_ptr() as *const Header;
+            return hdr.as_ref().unwrap().uid();
+        }
+    }
+
+    pub fn allocate(&self, ix: u64, uid: u64) -> Result<(), BucketStorageError> {
+        if ix >= self.num_cells() {
+            panic!("allocate: bad index size");
+        }
+        if 0 == uid {
+            panic!("allocate: bad uid");
+        }
+        let mut e = Err(BucketStorageError::AlreadyAllocated);
+        let ix = (ix * self.cell_size) as usize;
+        //debug!("ALLOC {} {}", ix, uid);
+        let hdr_slice: &[u8] = &self.mmap[ix..ix + std::mem::size_of::<Header>()];
+        unsafe {
+            let hdr = hdr_slice.as_ptr() as *const Header;
+            if hdr.as_ref().unwrap().try_lock(uid) {
+                e = Ok(());
+                self.used.fetch_add(1, Ordering::Relaxed);
+            }
+        };
+        e
+    }
+
+    pub fn free(&self, ix: u64, uid: u64) -> Result<(), BucketStorageError> {
+        if ix >= self.num_cells() {
+            panic!("free: bad index size");
+        }
+        if 0 == uid {
+            panic!("free: bad uid");
+        }
+        let ix = (ix * self.cell_size) as usize;
+        //debug!("FREE {} {}", ix, uid);
+        let hdr_slice: &[u8] = &self.mmap[ix..ix + std::mem::size_of::<Header>()];
+        let mut e = Err(BucketStorageError::InvalidFree);
+        unsafe {
+            let hdr = hdr_slice.as_ptr() as *const Header;
+            //debug!("FREE uid: {}", hdr.as_ref().unwrap().uid());
+            if hdr.as_ref().unwrap().unlock(uid) {
+                self.used.fetch_sub(1, Ordering::Relaxed);
+                e = Ok(());
+            }
+        };
+        e
+    }
+
+    pub fn get<T: Sized>(&self, ix: u64) -> &T {
+        if ix >= self.num_cells() {
+            panic!("bad index size");
+        }
+        let start = (ix * self.cell_size) as usize + std::mem::size_of::<Header>();
+        let end = start + std::mem::size_of::<T>();
+        let item_slice: &[u8] = &self.mmap[start..end];
+        unsafe {
+            let item = item_slice.as_ptr() as *const T;
+            &*item
+        }
+    }
+
+    pub fn get_empty_cell_slice<T: Sized>(&self) -> &[T] {
+        let len = 0;
+        let item_slice: &[u8] = &self.mmap[0..0];
+        unsafe {
+            let item = item_slice.as_ptr() as *const T;
+            std::slice::from_raw_parts(item, len as usize)
+        }
+    }
+
+    pub fn get_cell_slice<T: Sized>(&self, ix: u64, len: u64) -> &[T] {
+        if ix >= self.num_cells() {
+            panic!("bad index size");
+        }
+        let ix = self.cell_size * ix;
+        let start = ix as usize + std::mem::size_of::<Header>();
+        let end = start + std::mem::size_of::<T>() * len as usize;
+        //debug!("GET slice {} {}", start, end);
+        let item_slice: &[u8] = &self.mmap[start..end];
+        unsafe {
+            let item = item_slice.as_ptr() as *const T;
+            std::slice::from_raw_parts(item, len as usize)
+        }
+    }
+
+    pub fn get_mut<T: Sized>(&self, ix: u64) -> &mut T {
+        if ix >= self.num_cells() {
+            panic!("bad index size");
+        }
+        let start = (ix * self.cell_size) as usize + std::mem::size_of::<Header>();
+        let end = start + std::mem::size_of::<T>();
+        let item_slice: &[u8] = &self.mmap[start..end];
+        unsafe {
+            let item = item_slice.as_ptr() as *mut T;
+            &mut *item
+        }
+    }
+
+    pub fn get_mut_cell_slice<T: Sized>(&self, ix: u64, len: u64) -> &mut [T] {
+        if ix >= self.num_cells() {
+            panic!("bad index size");
+        }
+        let ix = self.cell_size * ix;
+        let start = ix as usize + std::mem::size_of::<Header>();
+        let end = start + std::mem::size_of::<T>() * len as usize;
+        //debug!("GET mut slice {} {}", start, end);
+        let item_slice: &[u8] = &self.mmap[start..end];
+        unsafe {
+            let item = item_slice.as_ptr() as *mut T;
+            std::slice::from_raw_parts_mut(item, len as usize)
+        }
+    }
+
+    fn new_map(
+        drives: &[PathBuf],
+        cell_size: usize,
+        capacity_pow2: u8,
+        stats: &mut Arc<BucketStats>,
+    ) -> (MmapMut, PathBuf) {
+        let mut m0 = Measure::start("");
+        let capacity = 1u64 << capacity_pow2;
+        let r = thread_rng().gen_range(0, drives.len());
+        let drive = &drives[r];
+        let pos = format!("{}", thread_rng().gen_range(0, u128::MAX),);
+        let file = drive.join(pos);
+        let mut data = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .create(true)
+            .open(file.clone())
+            .map_err(|e| {
+                panic!(
+                    "Unable to create data file {} in current dir({:?}): {:?}",
+                    file.display(),
+                    std::env::current_dir(),
+                    e
+                );
+            })
+            .unwrap();
+
+        // Theoretical performance optimization: write a zero to the end of
+        // the file so that we won't have to resize it later, which may be
+        // expensive.
+        //debug!("GROWING file {}", capacity * cell_size as u64);
+        data.seek(SeekFrom::Start(capacity * cell_size as u64 - 1))
+            .unwrap();
+        data.write_all(&[0]).unwrap();
+        data.seek(SeekFrom::Start(0)).unwrap();
+        m0.stop();
+        let mut m1 = Measure::start("");
+        data.flush().unwrap(); // can we skip this?
+        m1.stop();
+        let mut m2 = Measure::start("");
+        let res = (unsafe { MmapMut::map_mut(&data).unwrap() }, file);
+        m2.stop();
+        stats.new_file_us.fetch_add(m0.as_us(), Ordering::Relaxed);
+        stats.flush_file_us.fetch_add(m0.as_us(), Ordering::Relaxed);
+        stats.mmap_us.fetch_add(m0.as_us(), Ordering::Relaxed);
+        res
+    }
+
+    pub fn grow(&mut self) {
+        let mut m = Measure::start("grow");
+        let old_cap = self.num_cells();
+        let old_map = &self.mmap;
+        let old_file = self.path.clone();
+
+        let increment = 1;
+        let index_grow = 1 << increment;
+        let (new_map, new_file) = Self::new_map(
+            &self.drives,
+            self.cell_size as usize,
+            self.capacity_pow2 + increment,
+            &mut self.stats,
+        );
+        (0..old_cap as usize).into_iter().for_each(|i| {
+            let old_ix = i * self.cell_size as usize;
+            let new_ix = old_ix * index_grow;
+            let dst_slice: &[u8] = &new_map[new_ix..new_ix + self.cell_size as usize];
+            let src_slice: &[u8] = &old_map[old_ix..old_ix + self.cell_size as usize];
+
+            unsafe {
+                let dst = dst_slice.as_ptr() as *mut u8;
+                let src = src_slice.as_ptr() as *const u8;
+                std::ptr::copy_nonoverlapping(src, dst, self.cell_size as usize);
+            };
+        });
+        self.mmap = new_map;
+        self.path = new_file;
+        self.capacity_pow2 += increment;
+        remove_file(old_file).unwrap();
+        m.stop();
+        let sz = 1 << self.capacity_pow2;
+        {
+            let mut max = self.stats.max_size.lock().unwrap();
+            *max = std::cmp::max(*max, sz);
+        }
+        self.stats.resizes.fetch_add(1, Ordering::Relaxed);
+        self.stats.resize_us.fetch_add(m.as_us(), Ordering::Relaxed);
+    }
+    pub fn num_cells(&self) -> u64 {
+        1 << self.capacity_pow2
+    }
+}

bucket_map/src/index_entry.rs

@@ -0,0 +1,62 @@
+use crate::bucket::Bucket;
+use crate::bucket_storage::BucketStorage;
+use crate::RefCount;
+use solana_sdk::clock::Slot;
+use solana_sdk::pubkey::Pubkey;
+use std::collections::hash_map::DefaultHasher;
+use std::fmt::Debug;
+use std::hash::{Hash, Hasher};
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, PartialEq)]
+// one instance of this per item in the index
+// stored in the index bucket
+pub struct IndexEntry {
+    pub key: Pubkey, // can this be smaller if we have reduced the keys into buckets already?
+    pub ref_count: RefCount, // can this be smaller? Do we ever need more than 4B refcounts?
+    pub storage_offset: u64, // smaller? since these are variably sized, this could get tricky. well, actually accountinfo is not variable sized...
+    // if the bucket doubled, the index can be recomputed using create_bucket_capacity_pow2
+    pub storage_capacity_when_created_pow2: u8, // see data_location
+    pub num_slots: Slot, // can this be smaller? epoch size should ~ be the max len. this is the num elements in the slot list
+}
+
+impl IndexEntry {
+    pub fn data_bucket_from_num_slots(num_slots: Slot) -> u64 {
+        (num_slots as f64).log2().ceil() as u64 // use int log here?
+    }
+
+    pub fn data_bucket_ix(&self) -> u64 {
+        Self::data_bucket_from_num_slots(self.num_slots)
+    }
+
+    pub fn ref_count(&self) -> RefCount {
+        self.ref_count
+    }
+
+    // This function maps the original data location into an index in the current bucket storage.
+    // This is coupled with how we resize bucket storages.
+    pub fn data_loc(&self, storage: &BucketStorage) -> u64 {
+        self.storage_offset << (storage.capacity_pow2 - self.storage_capacity_when_created_pow2)
+    }
+
+    pub fn read_value<'a, T>(&self, bucket: &'a Bucket<T>) -> Option<(&'a [T], RefCount)> {
+        let data_bucket_ix = self.data_bucket_ix();
+        let data_bucket = &bucket.data[data_bucket_ix as usize];
+        let slice = if self.num_slots > 0 {
+            let loc = self.data_loc(data_bucket);
+            let uid = Self::key_uid(&self.key);
+            assert_eq!(uid, bucket.data[data_bucket_ix as usize].uid(loc));
+            bucket.data[data_bucket_ix as usize].get_cell_slice(loc, self.num_slots)
+        } else {
+            // num_slots is 0. This means we don't have an actual allocation.
+            // can we trust that the data_bucket is even safe?
+            bucket.data[data_bucket_ix as usize].get_empty_cell_slice()
+        };
+        Some((slice, self.ref_count))
+    }
+    pub fn key_uid(key: &Pubkey) -> u64 {
+        let mut s = DefaultHasher::new();
+        key.hash(&mut s);
+        s.finish().max(1u64)
+    }
+}

bucket_map/src/lib.rs

@@ -0,0 +1,12 @@
+#![cfg_attr(RUSTC_WITH_SPECIALIZATION, feature(min_specialization))]
+#![allow(clippy::integer_arithmetic)]
+#![allow(clippy::mut_from_ref)]
+mod bucket;
+mod bucket_item;
+pub mod bucket_map;
+mod bucket_stats;
+mod bucket_storage;
+mod index_entry;
+
+pub type MaxSearch = u8;
+pub type RefCount = u64;

bucket_map/tests/bucket_map.rs

@@ -0,0 +1,46 @@
+use rayon::prelude::*;
+use solana_bucket_map::bucket_map::{BucketMap, BucketMapConfig};
+use solana_measure::measure::Measure;
+use solana_sdk::pubkey::Pubkey;
+use std::path::PathBuf;
+#[test]
+#[ignore]
+fn bucket_map_test_mt() {
+    let threads = 4096;
+    let items = 4096;
+    let tmpdir1 = std::env::temp_dir().join("bucket_map_test_mt");
+    let tmpdir2 = PathBuf::from("/mnt/data/0").join("bucket_map_test_mt");
+    let paths: Vec<PathBuf> = [tmpdir1, tmpdir2]
+        .iter()
+        .filter(|x| std::fs::create_dir_all(x).is_ok())
+        .cloned()
+        .collect();
+    assert!(!paths.is_empty());
+    let index = BucketMap::new(BucketMapConfig {
+        max_buckets: 1 << 12,
+        drives: Some(paths.clone()),
+        ..BucketMapConfig::default()
+    });
+    (0..threads).into_iter().into_par_iter().for_each(|_| {
+        let key = Pubkey::new_unique();
+        index.update(&key, |_| Some((vec![0u64], 0)));
+    });
+    let mut timer = Measure::start("bucket_map_test_mt");
+    (0..threads).into_iter().into_par_iter().for_each(|_| {
+        for _ in 0..items {
+            let key = Pubkey::new_unique();
+            let ix: u64 = index.bucket_ix(&key) as u64;
+            index.update(&key, |_| Some((vec![ix], 0)));
+            assert_eq!(index.read_value(&key), Some((vec![ix], 0)));
+        }
+    });
+    timer.stop();
+    println!("time: {}ns per item", timer.as_ns() / (threads * items));
+    let mut total = 0;
+    for tmpdir in paths.iter() {
+        let folder_size = fs_extra::dir::get_size(tmpdir).unwrap();
+        total += folder_size;
+        std::fs::remove_dir_all(tmpdir).unwrap();
+    }
+    println!("overhead: {}bytes per item", total / (threads * items));
+}

programs/bpf/Cargo.lock

@@ -873,6 +873,12 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "fs_extra"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2022715d62ab30faffd124d40b76f4134a550a87792276512b18d63272333394"
+
 [[package]]
 name = "futures"
 version = "0.3.17"
@@ -1481,6 +1487,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "memmap2"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "723e3ebdcdc5c023db1df315364573789f8857c11b631a2fdfad7c00f5c046b4"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "memmap2"
 version = "0.4.0"
@@ -2784,6 +2799,21 @@ dependencies = [
  "solana-program 1.8.0",
 ]
 
+[[package]]
+name = "solana-bucket-map"
+version = "1.8.0"
+dependencies = [
+ "fs_extra",
+ "log",
+ "memmap2 0.2.3",
+ "rand 0.7.3",
+ "rayon",
+ "solana-logger 1.8.0",
+ "solana-measure",
+ "solana-sdk",
+ "tempfile",
+]
+
 [[package]]
 name = "solana-clap-utils"
 version = "1.8.0"
@@ -3214,6 +3244,7 @@ dependencies = [
  "rustc_version 0.4.0",
  "serde",
  "serde_derive",
+ "solana-bucket-map",
  "solana-compute-budget-program",
  "solana-config-program",
  "solana-ed25519-program",

runtime/Cargo.toml

@@ -40,6 +40,7 @@ solana-frozen-abi-macro = { path = "../frozen-abi/macro", version = "=1.8.0" }
 solana-logger = { path = "../logger", version = "=1.8.0" }
 solana-measure = { path = "../measure", version = "=1.8.0" }
 solana-metrics = { path = "../metrics", version = "=1.8.0" }
+solana-bucket-map = { path = "../bucket_map", version = "=1.8.0" }
 solana-program-runtime = { path = "../program-runtime", version = "=1.8.0" }
 solana-rayon-threadlimit = { path = "../rayon-threadlimit", version = "=1.8.0" }
 solana-sdk = { path = "../sdk", version = "=1.8.0" }