emit

Emit a new transaction from the hook

Concepts

• Emitted Transactions

Behaviour

C

• Read a transaction from read_ptr

• Validate the transaction against the emission rules

• Emit the transaction into consensus when valid

• Write canonical transaction hash to write_ptr

Javascript

• This function emits the provided transaction JSON.

• On success, it returns the number of emitted transaction hashes.

• If there is an error, it returns an error code.

Definition

C

int64_t emit (
    uint32_t write_ptr,
    uint32_t write_len,
    uint32_t read_ptr,
    uint32_t read_len
);

Javascript

function emit(
    txJson: Record<string, any> | Transaction
  ): ErrorCode | ByteArray

Example

C

if (emit(tx, tx_len) < 0)
    rollback("Failed to emit!", 15, 1);

Javascript

const emitResult = emit(txJson)
if(typeof emitResult === 'number')
    rollback("Failed to emit!", 1)

Parameters

C

Name	Type	Description
write_ptr	uint32_t	Pointer to a buffer to write the transaction hash to
write_len	uint32_t	The size of the buffer to write the transaction hash to (should be 32.)
read_ptr	uint32_t	Pointer to the transaction to emit
read_len	uint32_t	The length of the transaction

Javascript

Name	Type	Description
txJson	Record<string, any> | Transaction	The TX JSON to emit.

Return Code

C

Type

Description

int64_t

On success, the number of bytes of transaction hash written (32), or: If negative, an error: OUT_OF_BOUNDS - pointers/lengths specified outside of hook memory. PREREQUISITE_NOT_MET - emit_reserve must be called first TOO_MANY_EMITTED_TXN - the number of emitted transactions is now greater than the promise made when emit_reserve was called earlier EMISSION_FAILURE - the transaction was malformed according to the emission rules.

Javascript

Type	Description
ErrorCode | ByteArray	Returns an ErrorCode if there is an error, or an array of emitted transaction hashes on success.