eth::EthWatchService

Ties together EventWatcher, ABI decoding, and eth message dispatch. More...

#include <eth_watch_service.hpp>

Public Functions

	Name
	EthWatchService() =default
	~EthWatchService() =default
	EthWatchService(const EthWatchService & ) =delete
EthWatchService &	operator=(const EthWatchService & ) =delete
	EthWatchService(EthWatchService && ) =default
EthWatchService &	operator=(EthWatchService && ) =default
void	set_send_callback(SendCallback cb) Provide a callback used to send outgoing eth messages.
EventWatchId	watch_event(const codec::Address & contract_address, const std::string & event_signature, const std::vector< abi::AbiParam > & params, DecodedEventCallback callback, std::optional< uint64_t > from_block =std::nullopt, std::optional< uint64_t > to_block =std::nullopt) Register a watch for a specific contract event.
uint64_t	tip() const Return the highest block number seen so far (0 if none).
std::optional< Hash256 >	tip_hash() const Return the hash of the highest block seen, if any.
void	unwatch(EventWatchId id) Remove a previously registered subscription.
size_t	subscription_count() const Return the number of active subscriptions.
void	process_message(uint8_t eth_msg_id, rlp::ByteView payload) Process a raw eth wire message payload.
void	process_receipts(const std::vector< codec::Receipt > & receipts, const std::vector< Hash256 > & tx_hashes, uint64_t block_number, const Hash256 & block_hash) Directly process a batch of receipts for a known block.
void	process_new_block(const NewBlockMessage & msg, const Hash256 & block_hash) Directly process a NewBlock message.
void	request_receipts(const Hash256 & block_hash, uint64_t block_number) Request receipts for a block by hash.

Detailed Description

class eth::EthWatchService;

Ties together EventWatcher, ABI decoding, and eth message dispatch.

Usage:

1. Call set_send_callback() so the service can emit GetReceipts requests.
2. Register subscriptions via watch_event().
3. Feed incoming eth wire messages via process_message().
4. Matching logs trigger the registered DecodedEventCallback.

Thread-safety: not thread-safe; all calls must be externally synchronized.

Public Functions Documentation

function EthWatchService

EthWatchService() =default

function ~EthWatchService

~EthWatchService() =default

function EthWatchService

EthWatchService(
    const EthWatchService & 
) =delete

function operator=

EthWatchService & operator=(
    const EthWatchService & 
) =delete

function EthWatchService

EthWatchService(
    EthWatchService && 
) =default

function operator=

EthWatchService & operator=(
    EthWatchService && 
) =default

function set_send_callback

void set_send_callback(
    SendCallback cb
)

Provide a callback used to send outgoing eth messages.

Must be called before process_message() if automatic GetReceipts requests are desired. Safe to omit if the caller handles receipts manually via process_receipts().

function watch_event

EventWatchId watch_event(
    const codec::Address & contract_address,
    const std::string & event_signature,
    const std::vector< abi::AbiParam > & params,
    DecodedEventCallback callback,
    std::optional< uint64_t > from_block =std::nullopt,
    std::optional< uint64_t > to_block =std::nullopt
)

Register a watch for a specific contract event.

Parameters:

• contract_address Contract to watch; empty address = any contract.
• event_signature Canonical Solidity signature, e.g. "Transfer(address,address,uint256)".
• params Full parameter list in declaration order (mark indexed ones with AbiParam::indexed = true).
• callback Called for each matching decoded log.
• from_block Optional lower block bound for the filter.
• to_block Optional upper block bound for the filter.

Return: WatchId that can be passed to unwatch().

function tip

inline uint64_t tip() const

Return the highest block number seen so far (0 if none).

function tip_hash

inline std::optional< Hash256 > tip_hash() const

Return the hash of the highest block seen, if any.

function unwatch

void unwatch(
    EventWatchId id
)

Remove a previously registered subscription.

function subscription_count

inline size_t subscription_count() const

Return the number of active subscriptions.

function process_message

void process_message(
    uint8_t eth_msg_id,
    rlp::ByteView payload
)

Process a raw eth wire message payload.

Parameters:

• eth_msg_id Eth-layer message id (offset already subtracted).
• payload Raw message bytes.

Call this from your generic_handler with the eth-layer message id (i.e. already minus the rlpx offset) and the raw payload bytes.

Handles NewBlockHashes (0x01), NewBlock (0x07), Receipts (0x10). When a send callback is registered, automatically emits GetReceipts for new blocks.

function process_receipts

void process_receipts(
    const std::vector< codec::Receipt > & receipts,
    const std::vector< Hash256 > & tx_hashes,
    uint64_t block_number,
    const Hash256 & block_hash
)

Directly process a batch of receipts for a known block.

Parameters:

• receipts The receipts for all transactions in the block.
• tx_hashes Corresponding transaction hashes (same order).
• block_number Block number.
• block_hash Block hash.

function process_new_block

void process_new_block(
    const NewBlockMessage & msg,
    const Hash256 & block_hash
)

Directly process a NewBlock message.

function request_receipts

void request_receipts(
    const Hash256 & block_hash,
    uint64_t block_number
)

Request receipts for a block by hash.

Parameters:

• block_hash Hash of the block whose receipts are wanted.
• block_number Block number (stored for context in the callback).

Encodes and sends a GetReceipts message via the send callback. Records the pending request so the Receipts response can be correlated.

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Updated on 2026-04-13 at 23:22:46 -0700