fix: L1 gas prices subscription

[vbar]

Fixes sync_gas_prices getting stuck on historical data, ignoring subscribed updates.

The sync_gas_prices function often failed to update L1GasPriceProvider, because L1GasPriceProvider expects its samples to be added in sequential block order, and sync_gas_prices tries twice, possibly with a gap in between.

[kkovaacs]

Hmm, I'm not quite sure I understand this.

Isn't ethereum.subscribe_block_headers(_).await? expected to ~never return unless an error occurs?

[vbar]

Hmm, yes - which would mean the code after it is just dead...

[vbar]

bb1f9d6

[kkovaacs]

Maybe we should wait for some input from @t00ts before going on with this one.

As far as I understand the initial idea was something like this:

• Fetch "historical" price data from the starting block in the config.
• Then subscribe to block headers (you don't get historical headers here).

This is meant to ensure that we do have price data starting from a point in history. Removing fetching of historical prices changes this code significantly and I'm not absolutely convinced that we don't need that.

[vbar]

This is meant to ensure that we do have price data starting from a point in history. Removing fetching of historical prices changes this code significantly and I'm not absolutely convinced that we don't need that.

Yes - upon reflection, if the retrieval of historical prices cannot be before the subscription, and it cannot be after it, it could still be inside...

[vbar]

Superseded by #3197 .