move snapshot loading from nodeos to leap-util

[matthewdarwin]

move snapshot loading from nodeos to leap-util... or at least add snapshot loading into leap-util.

The reason for this is to allow snapshots to be downloaded, processed and removed (saving disk space).

With the current logic you need some scripts to download snapshots and then tell nodeos to start with the snapshot. But that script doesn't really know when nodeos is finished loading the snapshot to allow it to delete the snapshot file (could read the journal log to look for specific message, but that's fragile).

Would be much cleaner to just remove the whole snapshot loading logic out of nodeos and force leap-util to deal with creating the correct statedb and then start nodeos normally.

[matthewdarwin]

Also using nodeos --snapshot with mapped_private mode doesn't free the RAM that it would normally without starting from a snapshot.

[spoonincode]

But that script doesn't really know when nodeos is finished loading the snapshot to allow it to delete the snapshot file

fwiw, at least as of AntelopeIO/spring#440 and possibly earlier, you can work around that by something like

#!/bin/bash

exec 3< snapshot-2024-07-31-19-eos-v6-0386459889.bin
rm snapshot-2024-07-31-19-eos-v6-0386459889.bin
exec nodeos --snapshot /proc/self/fd/3