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replication_test.go
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replication_test.go
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package pgx_test
import (
"github.com/jackc/pgx"
"strconv"
"strings"
"testing"
"time"
"reflect"
"fmt"
)
// This function uses a postgresql 9.6 specific column
func getConfirmedFlushLsnFor(t *testing.T, conn *pgx.Conn, slot string) string {
// Fetch the restart LSN of the slot, to establish a starting point
rows, err := conn.Query(fmt.Sprintf("select confirmed_flush_lsn from pg_replication_slots where slot_name='%s'", slot))
if err != nil {
t.Fatalf("conn.Query failed: %v", err)
}
defer rows.Close()
var restartLsn string
for rows.Next() {
rows.Scan(&restartLsn)
}
return restartLsn
}
// This battleship test (at least somewhat by necessity) does
// several things all at once in a single run. It:
// - Establishes a replication connection & slot
// - Does a series of operations to create some known WAL entries
// - Replicates the entries down, and checks that the rows it
// created come down in order
// - Sends a standby status message to update the server with the
// wal position of the slot
// - Checks the wal position of the slot on the server to make sure
// the update succeeded
func TestSimpleReplicationConnection(t *testing.T) {
t.Parallel()
var err error
if replicationConnConfig == nil {
t.Skip("Skipping due to undefined replicationConnConfig")
}
conn := mustConnect(t, *replicationConnConfig)
defer closeConn(t, conn)
replicationConnConfig.RuntimeParams = make(map[string]string)
replicationConnConfig.RuntimeParams["replication"] = "database"
replicationConn := mustConnect(t, *replicationConnConfig)
defer closeConn(t, replicationConn)
_, err = replicationConn.Exec("CREATE_REPLICATION_SLOT pgx_test LOGICAL test_decoding")
if err != nil {
t.Logf("replication slot create failed: %v", err)
}
// Do a simple change so we can get some wal data
_, err = conn.Exec("create table if not exists replication_test (a integer)")
if err != nil {
t.Fatalf("Failed to create table: %v", err)
}
err = replicationConn.StartReplication("pgx_test", 0, -1)
if err != nil {
t.Fatalf("Failed to start replication: %v", err)
}
var i int32
var insertedTimes []int64
for i < 5 {
var ct pgx.CommandTag
currentTime := time.Now().Unix()
insertedTimes = append(insertedTimes, currentTime)
ct, err = conn.Exec("insert into replication_test(a) values($1)", currentTime)
if err != nil {
t.Fatalf("Insert failed: %v", err)
}
t.Logf("Inserted %d rows", ct.RowsAffected())
i++
}
i = 0
var foundTimes []int64
var foundCount int
var maxWal uint64
for {
var message *pgx.ReplicationMessage
message, err = replicationConn.WaitForReplicationMessage(time.Duration(1 * time.Second))
if err != nil {
if err != pgx.ErrNotificationTimeout {
t.Fatalf("Replication failed: %v %s", err, reflect.TypeOf(err))
}
}
if message != nil {
if message.WalMessage != nil {
// The waldata payload with the test_decoding plugin looks like:
// public.replication_test: INSERT: a[integer]:2
// What we wanna do here is check that once we find one of our inserted times,
// that they occur in the wal stream in the order we executed them.
walString := string(message.WalMessage.WalData)
if strings.Contains(walString, "public.replication_test: INSERT") {
stringParts := strings.Split(walString, ":")
offset, err := strconv.ParseInt(stringParts[len(stringParts)-1], 10, 64)
if err != nil {
t.Fatalf("Failed to parse walString %s", walString)
}
if foundCount > 0 || offset == insertedTimes[0] {
foundTimes = append(foundTimes, offset)
foundCount++
}
}
if message.WalMessage.WalStart > maxWal {
maxWal = message.WalMessage.WalStart
}
}
if message.ServerHeartbeat != nil {
t.Logf("Got heartbeat: %s", message.ServerHeartbeat)
}
} else {
t.Log("Timed out waiting for wal message")
i++
}
if i > 3 {
t.Log("Actual timeout")
break
}
}
if foundCount != len(insertedTimes) {
t.Fatalf("Failed to find all inserted time values in WAL stream (found %d expected %d)", foundCount, len(insertedTimes))
}
for i := range insertedTimes {
if foundTimes[i] != insertedTimes[i] {
t.Fatalf("Found %d expected %d", foundTimes[i], insertedTimes[i])
}
}
t.Logf("Found %d times, as expected", len(foundTimes))
// Before closing our connection, let's send a standby status to update our wal
// position, which should then be reflected if we fetch out our current wal position
// for the slot
status, err := pgx.NewStandbyStatus(maxWal)
if err != nil {
t.Errorf("Failed to create standby status %v", err)
}
replicationConn.SendStandbyStatus(status)
replicationConn.StopReplication()
// Let's push the boundary conditions of the standby status and ensure it errors correctly
status, err = pgx.NewStandbyStatus(0,1,2,3,4)
if err == nil {
t.Errorf("Expected error from new standby status, got %v",status)
}
// And if you provide 3 args, ensure the right fields are set
status, err = pgx.NewStandbyStatus(1,2,3)
if err != nil {
t.Errorf("Failed to create test status: %v", err)
}
if status.WalFlushPosition != 1 {
t.Errorf("Unexpected flush position %d", status.WalFlushPosition)
}
if status.WalApplyPosition != 2 {
t.Errorf("Unexpected apply position %d", status.WalApplyPosition)
}
if status.WalWritePosition != 3 {
t.Errorf("Unexpected write position %d", status.WalWritePosition)
}
err = replicationConn.Close()
if err != nil {
t.Fatalf("Replication connection close failed: %v", err)
}
restartLsn := getConfirmedFlushLsnFor(t, conn, "pgx_test")
integerRestartLsn, _ := pgx.ParseLSN(restartLsn)
if integerRestartLsn != maxWal {
t.Fatalf("Wal offset update failed, expected %s found %s", pgx.FormatLSN(maxWal), restartLsn)
}
_, err = conn.Exec("select pg_drop_replication_slot($1)", "pgx_test")
if err != nil {
t.Fatalf("Failed to drop replication slot: %v", err)
}
}