Optional PoV block limits

[ggwpez]

This MR makes it possible to have optional block weight limits for Ref Time and Proof Size.
Additionally to this it will emit a PovLimitExceeded and print a warning if a block consumes more than 5 MiB of proof size.

🚨 breaking changes:

• WeightsPerClass changed the type of max_extrinsic, max_total and reserved from Option<Weight> to WeightLimit.
• The types for the BlockWeights thereby slightly changed from Option<Weight> to WeightLimit.
• Make the CheckWeight signed extension consider optional weight limits.
• Fix arithmetical semantic of PerDispatchClass:: since the naming was off.
  • add renamed to saturating_accrue
  • checked_add renamed to checked_accrue
  • sub renamed to saturating_reduce

Non breaking additions:

• sp_weights::WeightLimit which can be used to express an upper limit for the consumption of some weight.
• frame_system::SOFT_POV_LIMIT_BYTES and Warning + Event for blocks that consume more weight.
• sp_weights::Weight::{from_all, without_ref_time, without_proof_size, saturating_reduce, checked_accrue, checked_reduce}

Integration Guide (For all chains)

Change your MAXIMUM_BLOCK_WEIGHT from type Weight to WeightLimit and use it in the BlockWeights::builder().
The difference is here that before we had to use u64::MAX, whereas now we can make it actually unlimited.

// Old Code using a `Some`
.for_class(DispatchClass::Normal, |weights| {
	weights.max_total = Some(NORMAL_DISPATCH_RATIO * MAXIMUM_BLOCK_WEIGHT);
})

// Cew Code using an `into()`
.for_class(DispatchClass::Normal, |weights| {
	weights.max_total = NORMAL_DISPATCH_RATIO * MAXIMUM_BLOCK_WEIGHT;
})

Before and after example from the kitchensink of this MR:

And the block weight builder:

You can now also specify a soft PoV limit by calling .pov_soft_limit(…) on the builder. Polkadot et al uses 5 MiB for this limit.

Other errors can arise from testing code.

• If you call expect on the optional limits: Use .exact_limits().expect() instead.
• If you call unwrap_or(Something) on on the optional limits: Use .limited_or(Something), .limited_or_max() or .limited_or_min() instead.

TODO:

• Extend MR description
• Add tests for WeightLimit
• Integration guide
• Companions

Polkadot companion: paritytech/polkadot#6580
Cumulus companion: paritytech/cumulus#2117

[ggwpez]

The compromise that i had to make.

[paritytech-cicd-pr]

The CI pipeline was cancelled due to failure one of the required jobs.
Job name: test-linux-stable
Logs: https://gitlab.parity.io/parity/mirrors/substrate/-/jobs/2290397

[ggwpez]

Okay this is not really what we want.
The two things I can still salvage from it:

• The WeightLimit type since it uses unlimited instead of the hacky u64::MAX
• The PoV limit printing on > 5 MiB