Client: purge history helper

[ScottyPoi]

Task related to #3931
Add utility function purgeHistory exported from client/src/util/purge.ts

This function will delete block bodies, receipts, and optionally headers from client DB.

Parameters:

• dataDir: database directory
• chain: defaults to mainnet
• before: blockNumber cutoff (defaults to MERGE_BLOCK)
• headers: option to delete headers (defaults to false)

purgeHistorydeletes directly from the DB, and operates as an independent process from the client itself. Therefore, it can be run while the client is running or stopped.

Block and Transaction indexing are left untouched. So NumberToHash, etc. will still be possible for deleted blocks.

[codecov]

Codecov Report

Attention: Patch coverage is 14.70588% with 58 lines in your changes missing coverage. Please review.

Project coverage is 79.18%. Comparing base (8017184) to head (eddc0ab).

Additional details and impacted files

Flag	Coverage Δ
block	83.29% <ø> (ø)
blockchain	89.49% <ø> (ø)
client	67.87% <14.70%> (-0.23%)	⬇️
common	98.49% <ø> (ø)
devp2p	?
evm	72.94% <ø> (ø)
genesis	99.98% <ø> (ø)
mpt	89.76% <ø> (ø)
rlp	91.43% <ø> (ø)
statemanager	69.16% <ø> (ø)
tx	90.58% <ø> (ø)
util	81.96% <ø> (ø)
vm	57.20% <ø> (ø)
wallet	88.55% <ø> (ø)

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[jochem-brouwer]

Therefore, it can be run while the client is running or stopped.

Is this true? I thought that opening a DB (we use LevelDB right?) can only be done by one process?

[scorbajio]

Is this testable? Maybe on a synced client.

[ScottyPoi]

Therefore, it can be run while the client is running or stopped.

Is this true? I thought that opening a DB (we use LevelDB right?) can only be done by one process?

Will test and get back on this. If that's true, than we should also revisit the export history as era1 function from era package. That was also written as a script acting on a DB, in the interest of being able to run it independently of the client.

If this turns out impossible (deleting from DB while client is running) than I may prefer to code this function (and the export history function) into the client itself, maybe as RPC methods.

[ScottyPoi]

Is this testable? Maybe on a synced client.

Right. Not sure that "unit test" is possible here. Testing on a live client will also expose other places in our code that need work for 4444

[acolytec3]

I'm going to do some tests on this today now that client sync is working again.