initial POC

Author: baileympearson

src/error.ts

@@ -100,7 +100,7 @@ export const MongoErrorLabel = Object.freeze({
   PoolRequestedRetry: 'PoolRequestedRetry',
   InterruptInUseConnections: 'InterruptInUseConnections',
   NoWritesPerformed: 'NoWritesPerformed',
-  SystemOverloadError: 'SystemOverloadError',
+  SystemOverloadedError: 'SystemOverloadedError',
   RetryableError: 'RetryableError'
 } as const);
 

src/operations/execute_operation.ts

@@ -59,7 +59,7 @@ type ResultTypeFromOperation<TOperation extends AbstractOperation> = ReturnType<
  * The expectation is that this function:
  * - Connects the MongoClient if it has not already been connected, see {@link autoConnect}
  * - Creates a session if none is provided and cleans up the session it creates
- * - Tries an operation and retries under certain conditions, see {@link tryOperation}
+ * - Tries an operation and retries under certain conditions, see {@link executeOperationWithRetries}
  *
  * @typeParam T - The operation's type
  * @typeParam TResult - The type of the operation's result, calculated from T
@@ -129,7 +129,7 @@ export async function executeOperation<
   });
 
   try {
-    return await tryOperation(operation, {
+    return await executeOperationWithRetries(operation, {
       topology,
       timeoutContext,
       session,
@@ -193,7 +193,10 @@ type RetryOptions = {
  *
  * @param operation - The operation to execute
  * */
-async function tryOperation<T extends AbstractOperation, TResult = ResultTypeFromOperation<T>>(
+async function executeOperationWithRetries<
+  T extends AbstractOperation,
+  TResult = ResultTypeFromOperation<T>
+>(
   operation: T,
   { topology, timeoutContext, session, readPreference }: RetryOptions
 ): Promise<TResult> {
@@ -247,7 +250,7 @@ async function tryOperation<T extends AbstractOperation, TResult = ResultTypeFro
   const maxNonOverloadRetryAttempts = willRetry ? (timeoutContext.csotEnabled() ? Infinity : 2) : 1;
   let previousOperationError: MongoError | undefined;
   const deprioritizedServers = new DeprioritizedServers();
-  const nonOverloadRetryAttempt = 0;
+  let nonOverloadRetryAttempt = 0;
 
   let systemOverloadRetryAttempt = 0;
   const maxSystemOverloadRetryAttempts = 5;
@@ -259,7 +262,7 @@ async function tryOperation<T extends AbstractOperation, TResult = ResultTypeFro
 
   while (true) {
     if (previousOperationError) {
-      if (previousOperationError.hasErrorLabel(MongoErrorLabel.SystemOverloadError)) {
+      if (previousOperationError.hasErrorLabel(MongoErrorLabel.SystemOverloadedError)) {
         systemOverloadRetryAttempt += 1;
 
         if (
@@ -277,7 +280,7 @@ async function tryOperation<T extends AbstractOperation, TResult = ResultTypeFro
         }
 
         // if we have exhausted overload retry attempts, throw.
-        if (systemOverloadRetryAttempt > maxSystemOverloadRetryAttempts) {
+        if (systemOverloadRetryAttempt >= maxSystemOverloadRetryAttempts) {
           throw previousOperationError;
         }
 
@@ -307,6 +310,7 @@ async function tryOperation<T extends AbstractOperation, TResult = ResultTypeFro
           signal: operation.options.signal
         });
       } else {
+        nonOverloadRetryAttempt++;
         // we have no more retry attempts, throw.
         if (nonOverloadRetryAttempt >= maxNonOverloadRetryAttempts) {
           throw previousOperationError;
@@ -378,7 +382,7 @@ async function tryOperation<T extends AbstractOperation, TResult = ResultTypeFro
     } catch (operationError) {
       if (!(operationError instanceof MongoError)) throw operationError;
 
-      if (!operationError.hasErrorLabel(MongoErrorLabel.SystemOverloadError)) {
+      if (!operationError.hasErrorLabel(MongoErrorLabel.SystemOverloadedError)) {
         // if an operation fails with an error that does not contain the SystemOverloadError, deposit 1 token.
         topology.tokenBucket.deposit(RETRY_COST);
       }