newBlockFilter Improvement Proposal

Contents

• New Proposal

Currently a filter created with eth_newBlockFilter and call eth_getFilterLogs, or get_filterChanges should return [null] or [null, null,...] If multiple blocks came in since the last poll.

Thats fine as you can check for the current block e.g. using:

web3.eth.filter('latest').watch(function(err, res){
   // i can get the current block here
   web3.eth.getBlock('latest');
});

The problem is that when a lot of blocks came in since the last time you polled with a return of [null, null, null, ...], your callback will fire multiple times accordingly, but using eth.getBlock inside will always give me the latest block, which is actually wrong.

New Proposal

After discussing with Gavin we came up with the following improvement:

// eth_newBlockFilter will receive no parameter
{"jsonrpc":"2.0","method":"eth_newBlockFilter","params":[],"id":529}

// poll
{"jsonrpc":"2.0","method":"eth_getFilterChanges","params":["0xb"],"id":530} // we assume the filter ID is "0xb"

// should return one or more blocks,
// depending on how much arrived since the last poll
{
		"id": 530,
		"jsonrpc": "2.0",
		"result": ['0x234234234..','0x342342342..'] // block hashes of the incoming blocks
	}

// eth_newPendingTransactionFilter will receive no parameter
{"jsonrpc":"2.0","method":"eth_newPendingTransactionFilter","params":[],"id":529}

// poll
{"jsonrpc":"2.0","method":"eth_getFilterChanges","params":["0xb"],"id":530} // we assume the filter ID is "0xb"

// should return one or more pending transactions,
// which were added to the pending state since the last poll
{
		"id": 530,
		"jsonrpc": "2.0",
		"result": ['0x234234234..','0x342342342..'] // tx hashes of new pending transactions
	}

Note This requires that eth_getTransactionByHash also return pending transactions!