IC Storage

Owned stable allocation and collections for Internet Computer applications. Storage owns the backing interface, codec trait, named allocation directory, namespace admission, exclusive leases and collection implementations. It does not depend on ic-stable-structures. Rust 1.99.1 or later is required.

Supported collections

The map retains its public ordered-map name; its implementation is an AVL tree, not a copy of the upstream B-tree. Stable Log and Min-heap are outside the scope. Map and set iterators support forward/reverse traversal and ordered bounds. Iterators retain bounded pointer stacks after the initial seek, with linear traversal work across a scan and no retained ancestor payloads.

ic_storage::adapter exports these collections, MapIter, SetIter, MapEntry, RegionGrowError, CollectionError, CodecError, and the owned Memory, Storable, Bound and storable interfaces. Backing implementations and runtime types live at the crate root. Collections require non-cloneable RuntimeMemory leases; implementing Memory or Storable does not grant access to an allocation.

use ic_storage::{AllocationGrants, GenericAllocationPolicy, MemoryAuthority,
    MemoryRequest, MemoryRuntime, SealedDeclarationSnapshot, StableKey, VectorMemory};
use ic_storage::adapter::StableBTreeMap;

let mut host = MemoryRuntime::new(VectorMemory::default())?;
let requests = SealedDeclarationSnapshot::new(vec![
    MemoryRequest::new("app", "app.rows.v1")?,
])?;
let grants = AllocationGrants::new(vec![MemoryAuthority::new("app", "app.")?])?;
host.bootstrap(&requests, &grants, &GenericAllocationPolicy)?;
let key = StableKey::parse("app.rows.v1")?;
let mut rows = StableBTreeMap::<u64, u64>::create(host.open_memory(&key)?)?;
rows.insert(7, 11)?;
drop(rows);
let rows = StableBTreeMap::<u64, u64>::load(host.open_memory(&key)?)?;
assert_eq!(rows.get(&7)?, Some(11));
# Ok::<(), Box<dyn std::error::Error>>(())

Current storage contract

This is a hard cut. Previous manager, ledger, map, set, vector and region images are retired. There is no legacy decoder or automatic reset. Hosts must install fresh backing or explicitly retire the complete old storage image; never reset only allocation governance while retaining unmanaged application data. Rebuild consumers against Storage's owned codec and backing traits. Primitive numeric codecs are little-endian; application codecs remain application-owned.

The root directory, map metadata/nodes and vector root use bounded IC Wire. Checksums detect accidental corruption, not hostile changes by linked code. Map node records have a 16 MiB encoded limit. Vector records require a finite Storable::BOUND; each slot reserves its maximum width. Cell supports unbounded values within its u32 envelope length and enforces finite bounds where declared. Cells and vector slots also checksum their payloads. StableCell::load(memory, maximum_bytes) requires a caller-selected ceiling before payload allocation. The cell marker is ICCELL01 with a 24-byte envelope; the vector marker is ICVECC01 with 12 bytes of length/checksum overhead per slot. These formats require fresh/reset storage; earlier cell/vector bytes are not reinterpreted.

Storable encoding, decoding and bound checks return Result<_, CodecError>. Collection creation, loading, lookup and mutation return CollectionError; map/set iterators yield Result entries and fuse after an iteration error. MapEntry value decoding is separately fallible. Handle errors explicitly; Metrics/Logging Storage propagate them through StoreError::Storage. Backing panics and buggy caller codecs remain host failures. Cached length and value observations are not recovery APIs for a poisoned owner.

create requires empty allocation memory. load only reads and never repairs or initializes a replacement. reset explicitly replaces contents in an admitted allocation. Maps also support clear. All collection growth reserves capacity before writes; rejected encoding/bounds or ordinary growth refusal leave prior values intact. Native backing writes are not transactions. A backing failure poisons the shared allocation owner; drop it and its leases before reopening. Installed Wasm traps follow the host's rollback semantics.

Maps stage the affected AVL nodes and allocator metadata before writing, publish the root last, and reuse power-of-two blocks on removal or replacement. clear reuses the allocation from its data start. They do not load the complete map into heap. This implementation has correctness qualification, not a production performance-equivalence claim. Node reads still include encoded values; hosts should measure their large-record and scan workloads. Existing-key replacements skip unchanged ancestors and do not rebalance the tree. Two-child deletion extracts and rebalances the successor path once, without searching for it again.

reserve_pages takes an absolute virtual extent in 65,536-byte pages, not entry capacity. allocated_pages observes that extent while retaining the lease. Satisfied reservations do not grow or write. These APIs grant no raw-memory extraction.

Map regions

BTreeMapRegion::new(Rc<RuntimeMemory<M>>, start..end) selects a disjoint page range within one admitted allocation. Construction performs no IO. initialize requires an empty region. Operations load the current owned root, allowing views to interleave without stale caches. The current marker is ICMAP001; old upstream BTR/BTA framing is unsupported. IcyDB must update its framing admission together with fresh storage for this hard cut.

keys_range_limited(bounds, limit) bounds the collected key count before returning an owned snapshot. Resume using an excluded last key. Regions bound all IO and growth to their selected extent; callers own disjoint application frames and must not reenter collection access from codecs. Drop all views and the last shared lease owner before reopening that allocation.

See allocation and host integration.

Licensed under MIT; see LICENSE.