From 91ec7b2dab529a463e399888c83f1356c1377033 Mon Sep 17 00:00:00 2001
From: Mitja T <mitjat@oasislabs.com>
Date: Mon, 30 Jan 2023 16:56:47 +0100
Subject: [PATCH] genesis-test: Create DB snapshot using full tx isolation

---
 storage/api.go                | 6 ++++++
 storage/postgres/client.go    | 6 +++++-
 tests/genesis/genesis_test.go | 6 +++++-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/storage/api.go b/storage/api.go
index 8565c930e..7760213d0 100644
--- a/storage/api.go
+++ b/storage/api.go
@@ -40,6 +40,9 @@ type QueryResults = pgx.Rows
 // QueryResult represents the result from a read query.
 type QueryResult = pgx.Row
 
+// TxOptions encodes the way DB transactions are executed.
+type TxOptions = pgx.TxOptions
+
 // Queue adds query to a batch.
 func (b *QueryBatch) Queue(cmd string, args ...interface{}) {
 	b.items = append(b.items, &batchItem{
@@ -283,6 +286,9 @@ type TargetStorage interface {
 	// SendBatch sends a batch of queries to be applied to target storage.
 	SendBatch(ctx context.Context, batch *QueryBatch) error
 
+	// SendBatchWithOptions is like SendBatch, with custom DB options (e.g. level of tx isolation).
+	SendBatchWithOptions(ctx context.Context, batch *QueryBatch, opts TxOptions) error
+
 	// Query submits a query to fetch data from target storage.
 	Query(ctx context.Context, sql string, args ...interface{}) (QueryResults, error)
 
diff --git a/storage/postgres/client.go b/storage/postgres/client.go
index afb52d520..07e91e93d 100644
--- a/storage/postgres/client.go
+++ b/storage/postgres/client.go
@@ -89,8 +89,12 @@ func NewClient(connString string, l *log.Logger) (*Client, error) {
 // by any indexer. We only care about atomic success or failure of the batch of queries
 // corresponding to a new block.
 func (c *Client) SendBatch(ctx context.Context, batch *storage.QueryBatch) error {
+	return c.SendBatchWithOptions(ctx, batch, pgx.TxOptions{})
+}
+
+func (c *Client) SendBatchWithOptions(ctx context.Context, batch *storage.QueryBatch, opts pgx.TxOptions) error {
 	pgxBatch := batch.AsPgxBatch()
-	if err := c.pool.BeginTxFunc(ctx, pgx.TxOptions{}, func(tx pgx.Tx) error {
+	if err := c.pool.BeginTxFunc(ctx, opts, func(tx pgx.Tx) error {
 		batchResults := tx.SendBatch(ctx, &pgxBatch)
 		defer common.CloseOrLog(batchResults, c.logger)
 		for i := 0; i < pgxBatch.Len(); i++ {
diff --git a/tests/genesis/genesis_test.go b/tests/genesis/genesis_test.go
index 289a0d11c..1ea01c534 100644
--- a/tests/genesis/genesis_test.go
+++ b/tests/genesis/genesis_test.go
@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"github.com/iancoleman/strcase"
+	"github.com/jackc/pgx/v4"
 	"github.com/oasisprotocol/oasis-core/go/common/entity"
 	"github.com/oasisprotocol/oasis-core/go/common/node"
 	genesisAPI "github.com/oasisprotocol/oasis-core/go/genesis/api"
@@ -147,7 +148,10 @@ func checkpointBackends(t *testing.T, source *oasis.ConsensusClient, target *pos
 				ON CONFLICT DO NOTHING;
 		`, chainID, chainID))
 
-	if err := target.SendBatch(ctx, batch); err != nil {
+	// Create the snapshot using a high level of isolation; we don't want another
+	// tx to be able to modify the tables while this is running, creating a snapshot that
+	// represents indexer state at two (or more) blockchain heights.
+	if err := target.SendBatchWithOptions(ctx, batch, pgx.TxOptions{IsoLevel: pgx.Serializable}); err != nil {
 		return 0, err
 	}