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provider.go
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provider.go
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package xchain
import (
"context"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
)
// ProviderCallback is the callback function signature that will be called with every finalized.
type ProviderCallback func(context.Context, Block) error
// ProviderRequest is the request struct for fetching cross-chain blocks.
// When used in streaming context, the Height defines the starting point (inclusive).
type ProviderRequest struct {
ChainID uint64 // Source chain ID to query for xblocks.
Height uint64 // Height to query (from inclusive).
ConfLevel ConfLevel // Confirmation level to ensure
}
func (r ProviderRequest) ChainVersion() ChainVersion {
return ChainVersion{
ID: r.ChainID,
ConfLevel: r.ConfLevel,
}
}
// EventLogsReq is the request to fetch EVM event logs.
type EventLogsReq struct {
ChainID uint64 // Source chain ID to query for xblocks.
Height uint64 // Height to query (from inclusive).
ConfLevel ConfLevel // Confirmation level to ensure
FilterAddress common.Address // Filter logs by optional address
FilterTopics []common.Hash // Filters zero or more topics (in the first position only).
}
func (r EventLogsReq) ChainVersion() ChainVersion {
return ChainVersion{
ID: r.ChainID,
ConfLevel: r.ConfLevel,
}
}
type EventLogsCallback func(ctx context.Context, height uint64, events []types.Log) error
// Provider abstracts fetching cross chain data from any supported chain.
// This is basically a cross-chain data client for all supported chains.
type Provider interface {
// StreamAsync starts a goroutine that streams xblocks forever from the provided source chain and height (inclusive).
//
// It returns immediately. It only returns an error if the chainID in invalid.
// This is the async version of StreamBlocks.
// It retries forever (with backoff) on all fetch and callback errors.
StreamAsync(ctx context.Context, req ProviderRequest, callback ProviderCallback) error
// StreamBlocks is the synchronous fail-fast version of StreamBlocks. It streams
// xblocks as they become available but returns on the first callback error.
// This is useful for workers that need to reset on application errors.
StreamBlocks(ctx context.Context, req ProviderRequest, callback ProviderCallback) error
// StreamEventLogs streams EVM event logs as they become available.
//
// The callback will be called with strictly-sequential heights with logs matching the provided filter (which may be none).
// It returns any error encountered.
StreamEventLogs(ctx context.Context, req EventLogsReq, callback EventLogsCallback) error
// GetBlock returns the block for the given chain and height, or false if not available (not finalized yet),
// or an error. The AttestOffset field is populated with the provided offset (if required).
GetBlock(ctx context.Context, req ProviderRequest) (Block, bool, error)
// GetSubmittedCursor returns the submitted cursor for the provided stream,
// or false if not available, or an error.
// Calls the destination chain portal InXStreamOffset method.
// Note this is only supported for EVM chains, no the consensus chain.
GetSubmittedCursor(ctx context.Context, ref Ref, stream StreamID) (SubmitCursor, bool, error)
// GetEmittedCursor returns the emitted cursor for the provided stream,
// or false if not available, or an error.
// Calls the source chain portal OutXStreamOffset method.
//
// Note that the AttestOffset field is not populated for emit cursors, since it isn't stored on-chain
// but tracked off-chain.
GetEmittedCursor(ctx context.Context, ref Ref, stream StreamID) (EmitCursor, bool, error)
// ChainVersionHeight returns the height for the provided chain version.
ChainVersionHeight(ctx context.Context, chainVer ChainVersion) (uint64, error)
// GetSubmission returns the submission for the provided chain and tx hash, or an error.
GetSubmission(ctx context.Context, chainID uint64, txHash common.Hash) (Submission, error)
}
// Ref specifies which block to query for cursors.
type Ref struct {
// Height specifies an absolute height to query; if non-nil.
Height *uint64
// ConfLevel specifies a relative-to-head block to query; if non-nil.
ConfLevel *ConfLevel
}
func (r Ref) Valid() bool {
return r.Height != nil || r.ConfLevel != nil
}
// ConfRef returns a Ref with the provided confirmation level.
func ConfRef(level ConfLevel) Ref {
return Ref{
ConfLevel: &level,
}
}
// HeightRef returns a Ref with the provided confirmation level.
func HeightRef(height uint64) Ref {
return Ref{
Height: &height,
}
}
var (
// LatestRef references the latest confirmation level.
LatestRef = ConfRef(ConfLatest)
// FinalizedRef references the latest confirmation level.
FinalizedRef = ConfRef(ConfFinalized)
)