moved checkout time logic to waitQueueMember

Author: aditi-khare-mongoDB

src/cmap/connection_pool.ts

@@ -104,6 +104,7 @@ export interface WaitQueueMember {
   reject: (err: AnyError) => void;
   timeout: Timeout;
   [kCancelled]?: boolean;
+  checkoutTime: number;
 }
 
 /** @internal */
@@ -162,7 +163,6 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
   [kWaitQueue]: List<WaitQueueMember>;
   [kMetrics]: ConnectionPoolMetrics;
   [kProcessingWaitQueue]: boolean;
-  checkOutTime: undefined | number;
 
   /**
    * Emitted when the connection pool is created.
@@ -356,7 +356,7 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
    * explicitly destroyed by the new owner.
    */
   async checkOut(): Promise<Connection> {
-    this.checkOutTime = Date.now();
+    const checkoutTime = Date.now();
     this.emitAndLog(
       ConnectionPool.CONNECTION_CHECK_OUT_STARTED,
       new ConnectionCheckOutStartedEvent(this)
@@ -371,7 +371,8 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
     const waitQueueMember: WaitQueueMember = {
       resolve,
       reject,
-      timeout
+      timeout,
+      checkoutTime
     };
 
     this[kWaitQueue].push(waitQueueMember);
@@ -387,7 +388,7 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
 
         this.emitAndLog(
           ConnectionPool.CONNECTION_CHECK_OUT_FAILED,
-          new ConnectionCheckOutFailedEvent(this, 'timeout')
+          new ConnectionCheckOutFailedEvent(this, 'timeout', waitQueueMember.checkoutTime)
         );
         const timeoutError = new WaitQueueTimeoutError(
           this.loadBalanced
@@ -762,7 +763,7 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
         const error = this.closed ? new PoolClosedError(this) : new PoolClearedError(this);
         this.emitAndLog(
           ConnectionPool.CONNECTION_CHECK_OUT_FAILED,
-          new ConnectionCheckOutFailedEvent(this, reason, error)
+          new ConnectionCheckOutFailedEvent(this, reason, waitQueueMember.checkoutTime, error)
         );
         waitQueueMember.timeout.clear();
         this[kWaitQueue].shift();
@@ -783,7 +784,7 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
         this[kCheckedOut].add(connection);
         this.emitAndLog(
           ConnectionPool.CONNECTION_CHECKED_OUT,
-          new ConnectionCheckedOutEvent(this, connection)
+          new ConnectionCheckedOutEvent(this, connection, waitQueueMember.checkoutTime)
         );
         waitQueueMember.timeout.clear();
 
@@ -812,14 +813,19 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
             this.emitAndLog(
               ConnectionPool.CONNECTION_CHECK_OUT_FAILED,
               // TODO(NODE-5192): Remove this cast
-              new ConnectionCheckOutFailedEvent(this, 'connectionError', err as MongoError)
+              new ConnectionCheckOutFailedEvent(
+                this,
+                'connectionError',
+                waitQueueMember.checkoutTime,
+                err as MongoError
+              )
             );
             waitQueueMember.reject(err);
           } else if (connection) {
             this[kCheckedOut].add(connection);
             this.emitAndLog(
               ConnectionPool.CONNECTION_CHECKED_OUT,
-              new ConnectionCheckedOutEvent(this, connection)
+              new ConnectionCheckedOutEvent(this, connection, waitQueueMember.checkoutTime)
             );
             waitQueueMember.resolve(connection);
           }

src/cmap/connection_pool_events.ts

@@ -220,10 +220,11 @@ export class ConnectionCheckOutFailedEvent extends ConnectionPoolMonitoringEvent
   constructor(
     pool: ConnectionPool,
     reason: 'poolClosed' | 'timeout' | 'connectionError',
+    checkoutTime: number,
     error?: MongoError
   ) {
     super(pool);
-    this.durationMS = Date.now() - (pool.checkOutTime ?? 0);
+    this.durationMS = Date.now() - checkoutTime;
     this.reason = reason;
     this.error = error;
   }
@@ -249,9 +250,9 @@ export class ConnectionCheckedOutEvent extends ConnectionPoolMonitoringEvent {
   durationMS: number;
 
   /** @internal */
-  constructor(pool: ConnectionPool, connection: Connection) {
+  constructor(pool: ConnectionPool, connection: Connection, checkoutTime: number) {
     super(pool);
-    this.durationMS = Date.now() - (pool.checkOutTime ?? 0);
+    this.durationMS = Date.now() - checkoutTime;
     this.connectionId = connection.id;
   }
 }