minor

README.md

@@ -17,4 +17,11 @@ In this project we try to implement `Serializable Snapshot Isolation` from Badge
 - [MatrixOrigin](https://github.com/arjunsk/matrixone/blob/c80e5add3048e656aac805ae6849d724cb0309dd/pkg/txn/client/types.go#L173)
 - [Serializable Snapshot Isolation Paper](https://github.com/db-modules/awesome-dbdev/blob/master/papers/serializable-snapshot-isolation.pdf)
 - [Write Snapshot Isolation Paper](https://github.com/dbminions/awesome-dbdev/blob/master/papers/write-snapshot-isolation.pdf)
-- [SurrealKV](https://github.com/surrealdb/surrealkv/pull/5/files)
+- [SurrealKV](https://github.com/surrealdb/surrealkv/pull/5/files)
+
+
+### Flow
+
+Reference: [Sarthak Makhija's Blog](https://tech-lessons.in/en/blog/serializable_snapshot_isolation/)
+
+![img.png](img.png)

pkg/txn/b_txn.go

@@ -62,15 +62,15 @@ func (txn *Txn) Commit() error {
 	}
 
 	commitTs, err := txn.scheduler.NewCommitTs(txn)
+	if err != nil {
+		return err
+	}
 
 	{
 		// WAL start entry | START
 		// WAL write entry | DATA
 	}
 
-	if err != nil {
-		return err
-	}
 	doneCh := txn.executor.sendToWriteCh(txn.writeSet.ToExecutorReq(commitTs))
 
 	{

pkg/txn/c_scheduler.go

@@ -85,9 +85,10 @@ func (o *Scheduler) DoneCommit(commitTs uint64) {
 }
 
 func (o *Scheduler) hasConflictFor(txn *Txn) bool {
+	currTxnBeginTs := txn.snapshot.ts
+
 	for _, readyToCommitTxn := range o.readyToCommitTxns {
-		txnBeginTs := txn.snapshot.ts
-		if readyToCommitTxn.commitTs <= txnBeginTs {
+		if readyToCommitTxn.commitTs <= currTxnBeginTs {
 			continue
 		}
 
@@ -102,10 +103,10 @@ func (o *Scheduler) hasConflictFor(txn *Txn) bool {
 
 func (o *Scheduler) gcOldReadyToCommitTxns() {
 	updatedReadyToCommitTxns := o.readyToCommitTxns[:0]
-	lastCommittedTxnTs := o.readTsMarker.DoneTill()
+	lastActiveReadTs := o.readTsMarker.DoneTill()
 
 	for _, readyToCommitTxn := range o.readyToCommitTxns {
-		if readyToCommitTxn.commitTs <= lastCommittedTxnTs {
+		if readyToCommitTxn.commitTs <= lastActiveReadTs {
 			continue
 		}
 		updatedReadyToCommitTxns = append(updatedReadyToCommitTxns, readyToCommitTxn)

pkg/txn/d_ts_waiter.go

@@ -91,6 +91,7 @@ func (w *TsWaiter) Run() {
 		}
 	}
 }
+
 func (w *TsWaiter) processWaitEvent(event Event) {
 	doneTill := w.DoneTill()
 	if doneTill >= event.ts {