When the sync loop first runs it suppresses block sync events both in
the initial loop and when the blocks being processed are greater than
1000.
This fix removed the first check, because otherwise the first block
received by the process ends up not getting sent to the tx pool. Which
means it won't produce new block for polygon.
As well as this fix - I have also moved the gas initialization to the
txpool start method rather than prompting it with a 'synthetic block
event'
As the txpool start has access to the core & tx DB's it can find the
current block and chain config internally so that it doesn't need to be
externally activated it can just do this itself on start up. This has
the advantage of making the txpool more self contained.
This PR contains 3 fixes for interaction between the Bor mining loop and
the TX pool which where causing the regular creation of blocks with zero
transactions.
* Mining/Tx pool block synchronization
The synchronization of the tx pool between the sync loop and the mining
loop has been changed so that both are triggered by the same event and
synchronized via a sync.Cond rather than a polling loop with a hard
coded loop limit. This means that mining now waits for the pool to be
updated from the previous block before it starts the mining process.
* Txpool Startup consolidated into its MainLoop
Previously the tx pool start process was dynamically triggered at
various points in the code. This has all now been moved to the start of
the main loop. This is necessary to avoid a timing hole which can leave
the mining loop hanging waiting for a previously block broadcast which
it missed due to its delay start.
* Mining listens for block broadcast to avoid duplicate mining
operations
The mining loop for bor has a recommit timer in case blocks re not
produced on time. However in the case of sprint transitions where the
seal publication is delayed this can lead to duplicate block production.
This is suppressed by introducing a `waiting` state which is exited upon
the block being broadcast from the sealing operation.
As per [EIP-1559](https://eips.ethereum.org/EIPS/eip-1559) , there is
only initial base fee after which it adjusts automatically. There are no
current references to a minimum protocol base fee on Ethereum, Gnosis or
Polygon.
The existing code would put a 7 wei minimum limit on transactions to be
included in the pool. This PR removes this check within txPool. Any
transaction can now be added to the `queued` sub-pool after which it
could get promoted to `pending` or `baseFee` subpools.
The`pricelimit` flag still exists and acts on non-local transactions as
a minimum feeCap for inclusion.
