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 uses private copied ICSS 0.7.2 collection engines, with no production ic-stable-structures dependency. Rust 1.99.1 or later is required.

Supported collections

Map, Set and regions share the copied B-tree, including its node layout, overflow pages and split/borrow/merge algorithms. Vector uses ICSS's fixed-stride slots and scalar iterator; Cell caches its decoded value. Stable Log and Min-heap remain outside the scope.

There are two collection layers: private engine contains the copied algorithms; public adapter wraps them with governed leases and the existing successful-call APIs. Application types continue to implement Storage's Storable; a private bridge translates that contract. The previous competing engines, node cache, record checksums and Vector scan-window implementation have been removed.

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.

Allocation directory encoding and checksums are unchanged. Collection images now use current ICSS framing: Map/Set/regions use BTR version 2 with explicit page-size metadata, Vector uses SVC version 1 with a 64-byte header, and Cell uses SCL version 1 with an eight-byte header. The copied engines contain no readers for retired Storage formats or ICSS version-1 B-trees. Every existing Storage collection must be explicitly rebuilt/reset or placed in fresh admitted allocations. Hosts must update their collection framing checks, including region admission. No reader converts or silently resets old images.

Collection payloads have no Storage integrity checksum. Valid-looking byte changes can pass application decoding. Vector requires a finite Storable::BOUND and reserves its maximum slot width, plus a 1/2/4-byte length for variable records. Cell retains its u32 length envelope; StableCell::load(memory, maximum_bytes) admits a caller-selected ceiling before allocating its payload buffer.

The public codec trait remains fallible, and successful-call Result signatures remain available. Inside collections, codec failures, malformed engine state and engine allocation failures trap, following ICSS behavior. Explicit framing admission and page reservations can still return typed errors. Do not rely on mutation failures returning CollectionError, iterators yielding an error, or an unsuccessful operation leaving native backing intact. MapEntry keeps its owned key/encoded-value API; decoding malformed bytes traps.

create requires empty allocation memory. load never initializes or repairs a replacement. reset explicitly replaces contents in an admitted allocation. Maps also support clear. IC execution rollback supplies atomicity for trapped updates and upgrades. Native writes are not transactions: a mutation panic poisons the shared allocation owner; discard the runtime and all leases, then explicitly recover or replace the backing. Cached lengths and Cell values are not recovery APIs. The native unwind guard is absent on Wasm.

The baseline map caches no routing nodes. set_node_cache_budget remains a ceiling hint satisfied by zero cached bytes; supplying a positive ceiling does not enable caching. Vector reads its durable length and has no custom cached length, scan windows or mutation epochs. See source provenance and deliberate adaptations before changing this baseline.

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 collection marker is BTR version 2, with explicit page-size metadata. Hosts such as IcyDB must update framing admission together with fresh or explicitly rebuilt region 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.

Storage-authored code is MIT; copied engine code is Apache-2.0. See LICENSE, LICENSE-APACHE and the per-file notices. Package metadata declares both licenses.

Native memory metering

Enable test-support and use ic_storage::testing::{MeteredMemory, MemoryIoCounts} for native backing IO observations. The wrapper implements Storage's Memory and delegates MemoryBacking identity to the underlying backing, preserving exclusive runtime custody across raw, wrapped and cloned aliases. Counters are shared by clones; reset() clears observations without clearing bytes. Reads and writes count attempts, while growth counts completed calls and successful requested pages. Counters saturate and set overflowed; reject overflowed results when reporting exact measurements. These observations are native IO counts, not IC instruction or cycle costs. Allocation measurement remains in ic-testkit-native.