fix: mutex calls to sqlitex

[zombiezen/go-sqlite]
(https://github.com/zombiezen/go-sqlite/blob/main/doc.go#L32) is not
thread safe when used through a single connection. The current code is
provably racing (run the server with `-race` and a few workflows being
run) and it will tell you this if you `argo list` via the server a few
times.

This change doesn't attempt to move to a multiple connection model,
it's a minimal change to stop the server crashing all the time, by
mutexing the use of the sql connection.

Fixes #13154 and #13140

Signed-off-by: Alan Clucas <alan@clucas.org>

server/workflow/store/sqlite_store.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"sync"
 
 	log "github.com/sirupsen/logrus"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -73,6 +74,7 @@ type WorkflowStore interface {
 type SQLiteStore struct {
 	conn            *sqlite.Conn
 	instanceService instanceid.Service
+	mtx             sync.Mutex
 }
 
 var _ WorkflowStore = &SQLiteStore{}
@@ -102,6 +104,8 @@ where instanceid = ?
 	}
 
 	var workflows = wfv1.Workflows{}
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
 	err = sqlitex.Execute(s.conn, query, &sqlitex.ExecOptions{
 		Args: args,
 		ResultFunc: func(stmt *sqlite.Stmt) error {
@@ -143,6 +147,8 @@ where instanceid = ?
 	}
 
 	var total int64
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
 	err = sqlitex.Execute(s.conn, query, &sqlitex.ExecOptions{
 		Args: args,
 		ResultFunc: func(stmt *sqlite.Stmt) error {
@@ -161,6 +167,8 @@ func (s *SQLiteStore) Add(obj interface{}) error {
 	if !ok {
 		return fmt.Errorf("unable to convert object to Workflow. object: %v", obj)
 	}
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
 	done := sqlitex.Transaction(s.conn)
 	err := s.upsertWorkflow(wf)
 	defer done(&err)
@@ -172,6 +180,8 @@ func (s *SQLiteStore) Update(obj interface{}) error {
 	if !ok {
 		return fmt.Errorf("unable to convert object to Workflow. object: %v", obj)
 	}
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
 	done := sqlitex.Transaction(s.conn)
 	err := s.upsertWorkflow(wf)
 	defer done(&err)
@@ -183,6 +193,8 @@ func (s *SQLiteStore) Delete(obj interface{}) error {
 	if !ok {
 		return fmt.Errorf("unable to convert object to Workflow. object: %v", obj)
 	}
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
 	return sqlitex.Execute(s.conn, deleteWorkflowQuery, &sqlitex.ExecOptions{Args: []any{string(wf.UID)}})
 }
 
@@ -195,6 +207,8 @@ func (s *SQLiteStore) Replace(list []interface{}, resourceVersion string) error
 		}
 		wfs = append(wfs, wf)
 	}
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
 	done := sqlitex.Transaction(s.conn)
 	err := s.replaceWorkflows(wfs)
 	defer done(&err)
@@ -222,6 +236,7 @@ func (s *SQLiteStore) GetByKey(key string) (item interface{}, exists bool, err e
 }
 
 func (s *SQLiteStore) upsertWorkflow(wf *wfv1.Workflow) error {
+	// Called with the mutex
 	err := sqlitex.Execute(s.conn, deleteWorkflowQuery, &sqlitex.ExecOptions{Args: []any{string(wf.UID)}})
 	if err != nil {
 		return err