Implement in-application mutex to reduce DB_LOCKED errors

scnserver/logic/application.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"errors"
 	"github.com/rs/zerolog/log"
+	golock "github.com/viney-shih/go-lock"
 	"gogs.mikescher.com/BlackForestBytes/goext/ginext"
 	"gogs.mikescher.com/BlackForestBytes/goext/rext"
 	"gogs.mikescher.com/BlackForestBytes/goext/syncext"
@@ -38,14 +39,16 @@ type Application struct {
 	Port             string
 	IsRunning        *syncext.AtomicBool
 	RequestLogQueue  chan models.RequestLog
+	MainDatabaseLock golock.RWMutex
 }
 
 func NewApp(db *DBPool) *Application {
 	return &Application{
-		Database:        db,
-		stopChan:        make(chan bool),
-		IsRunning:       syncext.NewAtomicBool(false),
-		RequestLogQueue: make(chan models.RequestLog, 1024),
+		Database:         db,
+		stopChan:         make(chan bool),
+		IsRunning:        syncext.NewAtomicBool(false),
+		RequestLogQueue:  make(chan models.RequestLog, 1024),
+		MainDatabaseLock: golock.NewCASMutex(),
 	}
 }
 

scnserver/logic/request.go

@@ -23,7 +23,7 @@ type RequestOptions struct {
 	IgnoreWrongContentType bool
 }
 
-func (app *Application) DoRequest(gectx *ginext.AppContext, g *gin.Context, fn func(ctx *AppContext, finishSuccess func(r ginext.HTTPResponse) ginext.HTTPResponse) ginext.HTTPResponse) ginext.HTTPResponse {
+func (app *Application) DoRequest(gectx *ginext.AppContext, g *gin.Context, lockmode models.TransactionLockMode, fn func(ctx *AppContext, finishSuccess func(r ginext.HTTPResponse) ginext.HTTPResponse) ginext.HTTPResponse) ginext.HTTPResponse {
 
 	maxRetry := scn.Conf.RequestMaxRetry
 	retrySleep := scn.Conf.RequestRetrySleep
@@ -40,6 +40,29 @@ func (app *Application) DoRequest(gectx *ginext.AppContext, g *gin.Context, fn f
 
 		wrap, stackTrace, panicObj := callPanicSafe(func(ctx *AppContext, finishSuccess func(r ginext.HTTPResponse) ginext.HTTPResponse) ginext.HTTPResponse {
 
+			dl, ok := ctx.Deadline()
+			if !ok {
+				dl = time.Now().Add(time.Second * 5)
+			}
+
+			if lockmode == models.TLockRead {
+
+				islock := app.MainDatabaseLock.RTryLockWithTimeout(dl.Sub(time.Now()))
+				if !islock {
+					return ginresp.APIError(g, 500, apierr.INTERNAL_EXCEPTION, "Failed to lock {MainDatabaseLock} [ro]", nil)
+				}
+				defer app.MainDatabaseLock.RUnlock()
+
+			} else if lockmode == models.TLockReadWrite {
+
+				islock := app.MainDatabaseLock.TryLockWithTimeout(dl.Sub(time.Now()))
+				if !islock {
+					return ginresp.APIError(g, 500, apierr.INTERNAL_EXCEPTION, "Failed to lock {MainDatabaseLock} [rw]", nil)
+				}
+				defer app.MainDatabaseLock.Unlock()
+
+			}
+
 			authheader := g.GetHeader("Authorization")
 
 			perm, err := app.getPermissions(actx, authheader)