Remove time ledger tracker as not used

* bulletin tracker is also looks unused but might me useful while refactoring

Author: algorandskiy

ledger/README.md

@@ -97,11 +97,6 @@ locking.
 - `Totals(round)` returns the totals of accounts, using the account
   tracker.
 
-### Time tracker
-
-- `Timestamp(round)` uses the time tracker to return the time as
-  of `round`.
-
 ### Recent transactions tracker
 
 - `Committed(txnid)` returns whether `txid` has been recently committed,

ledger/ledger.go

@@ -74,7 +74,6 @@ type Ledger struct {
 	txTail   txTail
 	bulletin bulletin
 	notifier blockNotifier
-	time     timeTracker
 	metrics  metricsTracker
 
 	trackers  trackerRegistry
@@ -188,7 +187,6 @@ func (l *Ledger) reloadLedger() error {
 	}
 
 	l.trackers.register(&l.accts)    // update the balances
-	l.trackers.register(&l.time)     // tracks the block timestamps
 	l.trackers.register(&l.txTail)   // update the transaction tail, tracking the recent 1000 txn
 	l.trackers.register(&l.bulletin) // provide closed channel signaling support for completed rounds
 	l.trackers.register(&l.notifier) // send OnNewBlocks to subscribers
@@ -577,14 +575,6 @@ func (l *Ledger) Wait(r basics.Round) chan struct{} {
 	return l.bulletin.Wait(r)
 }
 
-// Timestamp uses the timestamp tracker to return the timestamp
-// from block r.
-func (l *Ledger) Timestamp(r basics.Round) (int64, error) {
-	l.trackerMu.RLock()
-	defer l.trackerMu.RUnlock()
-	return l.time.timestamp(r)
-}
-
 // GenesisHash returns the genesis hash for this ledger.
 func (l *Ledger) GenesisHash() crypto.Digest {
 	return l.genesisHash