fix: race on createSession

[sfroment]

trafficstars

Creating multiple session in parallel will data race on init if the schema change, for exemple if you create different keyspace in different goroutine you'll get an error

github.com/gocql/gocql.(*tokenAwareHostPolicy).Init() /Users/sacha/go/pkg/mod/github.com/scylladb/[email protected]/policies.go:436 +0xac github.com/gocql/gocql.NewSession() /Users/sacha/go/pkg/mod/github.com/scylladb/[email protected]/session.go:154 +0xf98 github.com/gocql/gocql.(*ClusterConfig).CreateSession() /Users/sacha/go/pkg/mod/github.com/scylladb/[email protected]/cluster.go:205 +0xf7 XXX.com/org/repo/internal/link.Test_mapper_Map() /Users/sacha/go/src/XXX.com/org/repo/internal/link/mapper_test.go:115 +0x56 testing.tRunner() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1193 +0x202

Previous write at 0x00c0000e61d0 by goroutine 105: github.com/gocql/gocql.(*tokenAwareHostPolicy).Init() /Users/sacha/go/pkg/mod/github.com/scylladb/[email protected]/policies.go:436 +0xac github.com/gocql/gocql.NewSession() /Users/sacha/go/pkg/mod/github.com/scylladb/[email protected]/session.go:154 +0xf98 github.com/gocql/gocql.(*ClusterConfig).CreateSession() /Users/sacha/go/pkg/mod/github.com/scylladb/[email protected]/cluster.go:205 +0xf7 XXX.com/org/repo/internal/mypkg.Test_mapper_GetLinkAdID() /Users/sacha/go/src/XXX.com/org/repo/internal/link/mapper_test.go:197 +0x56 testing.tRunner() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1193 +0x202

Goroutine 52 (running) created at: testing.(*T).Run() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1238 +0x5d7 testing.runTests.func1() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1511 +0xa6 testing.tRunner() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1193 +0x202 testing.runTests() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1509 +0x612 testing.(*M).Run() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1417 +0x3b3 XXX.com/org/repo/common/test.MultipleSetUpTearDown() /Users/sacha/go/src/XXX.com/org/repo/common/test/setupteardown.go:50 +0x129 XXX.com/org/repo/internal/mypkg.TestMain() /Users/sacha/go/src/XXX.com/org/repo/internal/link/mapper_test.go:35 +0x119 main.main() _testmain.go:109 +0x371

Goroutine 105 (running) created at: testing.(*T).Run() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1238 +0x5d7 testing.runTests.func1() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1511 +0xa6 testing.tRunner() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1193 +0x202 testing.runTests() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1509 +0x612 testing.(*M).Run() /Users/sacha/.gimme/versions/go1.16.4.darwin.amd64/src/testing/testing.go:1417 +0x3b3 XXX.com/org/repo/common/test.MultipleSetUpTearDown() /Users/sacha/go/src/XXX.com/org/repo/common/test/setupteardown.go:50 +0x129 XXX.com/org/repo/internal/mypkg.TestMain() /Users/sacha/go/src/XXX.com/org/repo/internal/link/mapper_test.go:35 +0x119 main.main() _testmain.go:109 +0x371

[martin-sucha]

I don't think it's safe to reuse the tokenaware policy between sessions even if you fix this race.

[mmatczuk]

Why would you like to open multiple sessions to the same cluster?

[sfroment]

I use different session on the same cluster in my test