core,params: add fork readiness indicator in logs

[lightclient]

closes #31310

This has been requested a few times in the past and I think it is a nice quality-of-life improvement for users. At a predetermined interval, there will now be a "Fork ready" log when a future fork is scheduled, but not yet active.

It can only possibly print after block import, which kinda avoids the scenario where the client isn't progressing or is syncing and the user thinks it's "ready" because it sees a ready log.

New output:

INFO [03-08|21:32:57.472] Imported new potential chain segment     number=7 hash=aa24ee..f09e62 blocks=1 txs=0 mgas=0.000 elapsed="874.916µs" mgasps=0.000 snapdiffs=973.00B triediffs=7.05KiB triedirty=0.00B
INFO [03-08|21:32:57.473] Ready for fork activation                fork=Prague date="18 Mar 25 19:29 CET" remaining=237h57m0s timestamp=1,742,322,597
INFO [03-08|21:32:57.475] Chain head was updated                   number=7 hash=aa24ee..f09e62 root=19b0de..8d32f2 elapsed="129.125µs"

Easiest way to verify this behavior is to apply this patch and run geth --dev --dev.period=12

diff --git a/params/config.go b/params/config.go
index 9c7719d901..030c4f80e7 100644
--- a/params/config.go
+++ b/params/config.go
@@ -174,7 +174,7 @@ var (
                ShanghaiTime:            newUint64(0),
                CancunTime:              newUint64(0),
                TerminalTotalDifficulty: big.NewInt(0),
-               PragueTime:              newUint64(0),
+               PragueTime:              newUint64(uint64(time.Now().Add(time.Hour * 300).Unix())),
                BlobScheduleConfig: &BlobScheduleConfig{
                        Cancun: DefaultCancunBlobConfig,
                        Prague: DefaultPragueBlobConfig,

[MariusVanDerWijden]

Why not check if we should log out before we compute the ready activation?

Suggested change

	// logForkReadiness will write a log when a future fork is scheduled, but not
	// active. This is useful so operators know their client is ready for the fork.
	func (bc *BlockChain) logForkReadiness(block *types.Block) {
	c := bc.Config()
	current, last := c.LatestFork(block.Time()), c.LatestFork(math.MaxUint64)
	t := c.Timestamp(last)
	if t == nil {
	return
	}
	at := time.Unix(int64(*t), 0)
	if current < last && time.Now().After(bc.lastForkReadyAlert.Add(forkReadyInterval)) {
	log.Info("Ready for fork activation", "fork", last, "date", at.Format(time.RFC822),
	"remaining", time.Until(at).Round(time.Second), "timestamp", at.Unix())
	bc.lastForkReadyAlert = time.Now()
	}
	}
	// logForkReadiness will write a log when a future fork is scheduled, but not
	// active. This is useful so operators know their client is ready for the fork.
	func (bc *BlockChain) logForkReadiness(block *types.Block) {
	if time.Since(bc.lastForkReadyAlert) > forkReadyInterval {
	c := bc.Config()
	current, last := c.LatestFork(block.Time()), c.LatestFork(math.MaxUint64)
	t := c.Timestamp(last)
	if t == nil {
	return
	}
	at := time.Unix(int64(*t), 0)
	if current < last {
	log.Info("Ready for fork activation", "fork", last, "date", at.Format(time.RFC822),
	"remaining", time.Until(at).Round(time.Second), "timestamp", at.Unix())
	bc.lastForkReadyAlert = time.Now()
	}
	}
	}

[MariusVanDerWijden]

Ah nvm, we're never updating bc.lastForkReadyAlert this way

[MariusVanDerWijden]

SGTM, I tested this extensively so it works. I don't really like that we do it on every block, but I guess its not too much work that we're adding per block