Crate jam_types 

JAM types used within the PVM instances (service code and authorizer code).

Macros

chain_params

Structs

AnyBytes

Non usage-specific data.

AuthConfig

Authorization parameter.

AuthQueueLen

Number of authorizations in a queue allocated to a core.

AuthTrace

Output data of Is Authorized operation, passed into both Refinement and Accumulation.

AuthWindow

Number of items in the authorization window.

Authorization

Data constituting the Authorization Token in a Work Package.

Authorizer

The authorizer tuple which together identifies a means of determining whether a Work Package is acceptable to execute on a core.

AuthorizerHash

Hash of an encoded Authorizer value.

CodeHash

Hash of PVM program code.

CoreCount

Number of cores in the JAM.

EpochPeriod

The epoch period, defined in number of slots.

ExtrinsicHash

Hash of a piece of extrinsic data.

ExtrinsicSpec

Specification of a single piece of extrinsic data.

FixedVec

Vector type with a fixed length.

HeaderHash

Hash of an encoded block header.

ImportSpec

Import segments specification, which identifies a single exported segment.

InvokeArgs

Args for invoking an inner PVM.

MaxDependencies

Maximum number of dependencies (total of prerequisites and SR lookup entries).

MaxExportSegments

Maximum number of DA segments that a Work Package can produce.

MaxImportSegments

Maximum number of DA segments that a Work Package can require as imports. This is twice the maximum number of imports because each import may require a proof segment.

MaxImports

Maximum number of imports in a Work Package.

MaxTicketsPerBlock

Max tickets allowed to be embedded in each block extrinsic.

MaxWorkItems

Maximum number of Work Items in a Work Package.

Memo

Transfer memo data, included with balance transfers between services.

NoWrap

No-op Wrap.

OpaqueBandersnatchPublic

Plain-old-data struct of the same length as an encoded Bandersnatch public key.

OpaqueBlsPublic

Plain-old-data struct of the same length as an encoded BLS public key.

OpaqueEd25519Public

Plain-old-data struct of the same length as an encoded Ed25519 public key.

OpaqueValKeyset

Plain-old-data struct of the same length and layout to ValKeyset struct. This does not bring in any cryptography.

OpaqueValidatorMetadata

Additional information on a validator, opaque to the actual usage.

PayloadHash

Hash of a Work Item’s WorkPayload.

ProtocolParameters

Baseline parameters for the JAM protocol.

RecentBlockCount

The number of blocks which are kept in the recent block cache. We use a u8 to index into this and therefore it may be no larger than 255.

RefineContext

Various pieces of information helpful to contextualize the Refinement process.

SegmentHash

Hash of a Segment value.

SegmentLen

Number of bytes in a segment. This is fixed.

SegmentSliceLen

Returns the number of bytes in a segment slice.

SegmentTreeRoot

Hash of a segment tree root node.

ServiceInfo

Information concerning a particular service’s state.

TicketsAttemptsNumber

Maximum number of tickets which each validator may create.

TransferRecord

A single deferred transfer of balance and/or data, passed in to the Accumulation logic.

ValCount

Total number of validators in the JAM.

VecMap

An mapping of key/value pairs stored as pairs ordered by their key in a Vec.

VecSet

An set of items stored in order in a Vec.

WorkItem

A definition of work to be done by the Refinement logic of a service and transformed into a WorkOutput for its Accumulation logic.

WorkItemRecord

The result and surrounding context of a single Refinement operation passed in to the Accumulation logic.

WorkItemSummary

Work item summary information used by fetch host call.

WorkOutput

Output data of Refinement operation, passed into Accumulation.

WorkPackageHash

Hash of an encoded Work Package.

WorkPayload

Payload data defining a Work Item.

WrappedWorkPackage

A work-package, a collection of work-items together with authorization and contextual information. This is processed in-core with Is-Authorized and Refine logic to produce a work-report.

Enums

AccumulateItem

Accumulate item.

FetchKind

Fetch host calls variants identifiers.

PageMode

Page access mode.

PageOperation

Page operation.

RootIdentifier

Reference to a sequence of import segments, which when combined with an index forms a commitment to a specific segment of data.

Constants

GP_VERSION

Version of the Gray Paper implemented by this and dependent crates.

JAM_COMMON_ERA

Beginning of the Jam “Common Era” (1200 UTC on January 1, 2025), as seconds after the Unix epoch, excluding leap seconds.

MEMO_LEN

Length of a transfer memo in bytes.

PAGE_SIZE

PolkaVM page size in bytes.

POINT_LEN

Number of bytes in an erasure-coding point.

PROVEN_PER_SEGMENT

The maximum number of segments whose justification can be included in a single segment-sized proof-page. Basically just the highest power of 2 which when multiplied by 32 (the size of a hash) leaves enough room from 4104 (the size of a segment) to fit a partial Merkle proof of 6 branches (6 * 32 = 192) plus the overhead for storing the actual number of hashes (should be one byte for PROVEN_PER_SEGMENT < 128). It turns out that this is 2^6 = 64.

SEGMENT_LEN

Number of bytes in a segment. This is fixed.

VALS_PER_CORE

The number of validators on each core.

Traits

BoundedMap

Trait for vector types which have a bounded length allowing element-wise transformation.

Get

A trait for querying a single value from a type.

MapLike

A data-structure providing the storage and lookup of key/value pairs with exclusive keys.

SetLike

A data-structure providing the storage of non-duplicated items and the querying of their inclusion.

ToAny

ToAtomic

Wrap

A Wrap implementation provides a type constructor which “wraps” a type.

Functions

auth_queue_len

Number of authorizations in a queue allocated to a core.

availability_timeout

The period in timeslots after which reported but unavailable work may be replaced.

basic_piece_len

Number of bytes in a basic EC piece.

basic_piece_points

Number of points in a piece.

block_gas_limit

The maximum gas which may be used in a single block. At present this is just the product of the maximum gas per work-report and the number of cores. In the future it should probably be more to account for the possibility of always-accumulate services.

core_count

Number of cores in the JAM.

deposit_per_account

deposit_per_byte

deposit_per_item

epoch_period

The epoch period, defined in number of slots.

epoch_tail_start

The length of the contest, defined in number of slots.

max_accumulate_gas

Maximum gas which may be used to Accumulate a single work-report.

max_authorizer_code_size

max_dependencies

Maximum number of dependencies (total of prerequisites and SR lookup entries).

max_export_segments

Maximum number of DA segments that a Work Package can produce.

max_exports

Maximum number of exports in a Work Package.

max_extrinsics

Maximum number of extrinsics in a Work Package.

max_import_segments

Maximum number of DA segments that a Work Package can require as imports. This is twice the maximum number of imports because each import may require a proof segment.

max_imports

Maximum number of imports in a Work Package.

max_input

Maximum size of a Work Package together with all extrinsic data and imported segments.

max_is_authorized_gas

Maximum gas which may be used to Authorize a single work-package.

max_lookup_anchor_age

Maximum age, in blocks, that the lookup anchor may be, taken from the regular anchor.

max_refine_gas

Maximum gas which may be used to Refine a single work-report.

max_report_elective_data

The maximum total size of all unbounded blobs in a work-report. Maximum age, in blocks, that the lookup anchor may be, taken from the regular anchor.

max_service_code_size

max_tickets_per_block

Max tickets allowed to be embedded in each block extrinsic.

max_work_items

Maximum number of Work Items in a Work Package.

min_turnaround_period

Minimum period in blocks between going from becoming Available to Zombie, and then again from Zombie to non-existent.

pieces_per_segment

Returns the number of pieces in a segment.

recent_block_count

The number of blocks which are kept in the recent block cache. We use a u8 to index into this and therefore it may be no larger than 255.

rotation_period

The rotation period, defined in number of slots.

segment_len

Number of bytes in a segment. This is fixed.

segment_slice_len

Returns the number of bytes in a segment slice.

slot_period_sec

Number of seconds in a time slot.

tickets_attempts_number

Maximum number of tickets which each validator may create.

val_count

Total number of validators in the JAM.

Type Aliases

AuthQueue

A queue of AuthorizerHashs, each of which will be rotated into the authorizer pool for a core.

Balance

Type to represent a balance.

CoreIndex

Type to represent the index of a compute core.

Hash

A basic 256-bit data value.

OpaqueValKeysets

The opaque keys for each validator.

Segment

A segment of data.

ServiceId

Type to represent the index of a service.

SignedGas

Type to represent some gas which may be below zero. This is used primarily for the invoke hostcall API which must be able to return a negative gas amount in case of a gas overrun.

Slot

Type that represents a time slot of six seconds.

TicketAttempt

Index for an attempt at producing a ticket for the right to produce a block.

ValIndex

Type to represent the index of a validator.

WorkItemImportsVec

A sequence of import specifications.

WorkPackage

A work-package, a collection of work-items together with authorization and contextual information. This is processed in-core with Is-Authorized and Refine logic to produce a work-report.