Module account 

Account memory architecture.

Hopper supports four account memory styles:

1. Fixed Layout – Classic zero-copy #[repr(C)] overlay with a 16-byte header.
2. Overlay Layout – Multiple typed views over different regions of one account.
3. Segmented Layout – Fixed prefix + dynamic typed segments with a segment table.
4. Arena Layout – Accounts as typed storage arenas (slab allocators, ring buffers).

All styles share the same 16-byte header format for self-description.

Re-exports

pub use registry::segment_id;

pub use registry::SegmentEntry;

pub use registry::SegmentId;

pub use registry::SegmentRegistry;

pub use registry::SegmentRegistryMut;

pub use registry::MAX_REGISTRY_SEGMENTS;

pub use registry::REGISTRY_HEADER_SIZE;

pub use registry::REGISTRY_OFFSET;

pub use registry::SEGMENT_ENTRY_SIZE;

pub use registry::SEG_FLAG_DYNAMIC;

pub use registry::SEG_FLAG_FROZEN;

pub use registry::SEG_FLAG_LOCKED;

pub use segment_role::SegmentRole;

pub use segment_role::SEG_ROLE_AUDIT;

pub use segment_role::SEG_ROLE_CACHE;

pub use segment_role::SEG_ROLE_CORE;

pub use segment_role::SEG_ROLE_EXTENSION;

pub use segment_role::SEG_ROLE_INDEX;

pub use segment_role::SEG_ROLE_JOURNAL;

pub use segment_role::SEG_ROLE_SHARD;

Modules

registry

Segmented Accounts for Hopper.

segment_role

Segment roles – typed semantic classification for account segments.

Structs

AccountHeader

The 16-byte account header, overlay-safe.

AccountReader

Header-aware read-only account reader.

DataWriter

Sequential write cursor over a mutable byte slice.

DynamicView

An inline dynamic view that caches offsets for O(1) field access.

DynamicViewMut

Mutable inline dynamic view for writing dynamic fields.

ReallocGuard

Per-instruction realloc budget guard.

SegmentDescriptor

A single segment descriptor.

SegmentSlice

Type-safe immutable slice over a segment’s elements.

SegmentSliceMut

Type-safe mutable slice over a segment’s elements.

SegmentTable

Read-only segment table.

SegmentTableMut

Mutable segment table.

SliceCursor

Sequential read cursor over a byte slice.

VerifiedAccount

Immutable verified account – proof that validation passed.

VerifiedAccountMut

Mutable verified account – proof that validation passed, with write access.

Constants

CLOSE_SENTINEL

Sentinel byte written to byte 0 when an account is closed. Prevents account revival attacks.

HEADER_FORMAT

Header format version. Bump only if the header wire format itself changes.

HEADER_LEN

Header length in bytes.

MAX_SEGMENTS

Maximum number of segments per account.

SEGMENT_DESC_SIZE

Size of one segment descriptor in bytes.

Traits

FixedLayout

Trait for types with a compile-time known wire size.

Pod

Marker for types that can be safely overlaid on raw account bytes.

Functions

cast_unchecked^⚠

Raw unchecked cast from bytes to an immutable reference.

cast_unchecked_mut^⚠

Raw unchecked cast from bytes to a mutable reference.

check_header

Validate the header against expected values.

overlay

Overlay immutable reference to a Pod type at the start of a byte slice.

overlay_mut

Overlay mutable reference to a Pod type at the start of a byte slice.

pod_from_bytes

Zero-copy cast from bytes to an immutable reference.

pod_from_bytes_mut

Zero-copy cast from bytes to a mutable reference.

pod_read

Copy a Pod value from bytes (alignment-safe).

pod_write

Write a Pod value to bytes (alignment-safe).

read_discriminator

Read the discriminator byte from raw account data.

read_dynamic_u8

Read a u8-prefixed dynamic field: returns (data_slice, next_offset).

read_dynamic_u16

Read a u16-prefixed dynamic field.

read_dynamic_u32

Read a u32-prefixed dynamic field.

read_header_flags

Read the flags field as u16.

read_layout_id

Read the 8-byte layout_id.

read_version

Read the version byte.

safe_close

Safely close an account by draining all lamports to destination.

safe_close_with_sentinel

Close with sentinel – writes CLOSE_SENTINEL to byte 0 after zeroing.

safe_realloc

Reallocate an account to a new size.

write_dynamic_u8

Write a u8-prefixed dynamic field. Returns next offset after written data.

write_dynamic_u16

Write a u16-prefixed dynamic field.

write_dynamic_u32

Write a u32-prefixed dynamic field.

write_header

Write a complete header to the beginning of data.

zero_init

Zero-initialize a byte slice. Must be called before write_header.