DRIVERS-2695 Add a case of CSOT not enabled for the retryable writes (#…

…1466)

source/retryable-writes/retryable-writes.rst

@@ -455,6 +455,7 @@ The above rules are implemented in the following pseudo-code:
  retryableCommand = addTransactionIdToCommand(command, session);
 
  Exception previousError = null;
+ retrying = false;
  while true {
  try {
  return executeCommand(server, retryableCommand);
@@ -468,7 +469,7 @@ The above rules are implemented in the following pseudo-code:
  * numbers" MUST be re-raised with an actionable error message.
  */
  if (!currentError.hasErrorLabel("RetryableWriteError")) {
- if ( currentError.code == 20 && originalError.errmsg.startsWith("Transaction numbers") ) {
+ if ( currentError.code == 20 && previousError.errmsg.startsWith("Transaction numbers") ) {
  currentError.errmsg = "This MongoDB deployment does not support retryable...";
  }
  throw currentError;
@@ -490,7 +491,7 @@ The above rules are implemented in the following pseudo-code:
  * from the connection pool), we should raise the previous error if there
  * was one.
  */
- if (currentError is not DriverException && ! originalError.hasErrorLabel("NoWritesPerformed")) {
+ if (currentError is not DriverException && ! previousError.hasErrorLabel("NoWritesPerformed")) {
  previousError = currentError;
  }
  }
@@ -516,10 +517,18 @@ The above rules are implemented in the following pseudo-code:
  throw previousError;
  }
 
- /* CSOT is enabled and the operation has timed out. */
- if (timeoutMS != null && isExpired(timeoutMS) {
+ if (timeoutMS == null) {
+ /* If CSOT is not enabled, allow any retryable error from the second
+ * attempt to propagate to our caller, as it will be just as relevant
+ * (if not more relevant) than the original error. */
+ if (retrying) {
+ throw previousError;
+ }
+ } else if (isExpired(timeoutMS)) {
+ /* CSOT is enabled and the operation has timed out. */
  throw previousError;
  }
+ retrying = true;
  }
  }
 
@@ -829,6 +838,7 @@ inconsistent with the server and potentially confusing to developers.
 Changelog
 =========
 
+:2023-10-02: When CSOT is not enabled, one retry attempt occurs.
 :2023-08-26: Require that in a sharded cluster the server on which the
  operation failed MUST be provided to the server selection
  mechanism as a deprioritized server.