define constants

Author: tadjik1

src/operations/execute_operation.ts

@@ -28,7 +28,13 @@ import {
 import type { Topology } from '../sdam/topology';
 import type { ClientSession } from '../sessions';
 import { TimeoutContext } from '../timeout';
-import { RETRY_COST, RETRY_TOKEN_RETURN_RATE } from '../token_bucket';
+import {
+  BASE_BACKOFF_MS,
+  MAX_BACKOFF_MS,
+  MAX_RETRIES,
+  RETRY_COST,
+  RETRY_TOKEN_RETURN_RATE
+} from '../token_bucket';
 import { abortable, maxWireVersion, supportsRetryableWrites } from '../utils';
 import { AggregateOperation } from './aggregate';
 import { AbstractOperation, Aspect } from './operation';
@@ -302,7 +308,7 @@ async function executeOperationWithRetries<
       }
 
       if (operationError.hasErrorLabel(MongoErrorLabel.SystemOverloadedError)) {
-        maxAttempts = Math.min(6, operation.maxAttempts ?? 6);
+        maxAttempts = Math.min(MAX_RETRIES + 1, operation.maxAttempts ?? MAX_RETRIES + 1);
       }
 
       if (attempt + 1 >= maxAttempts) {
@@ -314,14 +320,14 @@ async function executeOperationWithRetries<
           throw error;
         }
 
-        const delayMS = Math.random() * Math.min(10_000, 100 * 2 ** attempt);
+        const backoffMS = Math.random() * Math.min(MAX_BACKOFF_MS, BASE_BACKOFF_MS * 2 ** attempt);
 
-        // if the delay would exhaust the CSOT timeout, short-circuit.
-        if (timeoutContext.csotEnabled() && delayMS > timeoutContext.remainingTimeMS) {
+        // if the backoff would exhaust the CSOT timeout, short-circuit.
+        if (timeoutContext.csotEnabled() && backoffMS > timeoutContext.remainingTimeMS) {
           throw error;
         }
 
-        await setTimeout(delayMS);
+        await setTimeout(backoffMS);
       }
 
       if (

src/sdam/topology.ts

@@ -213,6 +213,7 @@ export class Topology extends TypedEventEmitter<TopologyEvents> {
   hello?: Document;
   _type?: string;
 
+  /** @internal */
   tokenBucket = new TokenBucket(INITIAL_TOKEN_BUCKET_SIZE);
 
   client!: MongoClient;

src/sessions.ts

@@ -30,6 +30,7 @@ import { ReadConcernLevel } from './read_concern';
 import { ReadPreference } from './read_preference';
 import { _advanceClusterTime, type ClusterTime, TopologyType } from './sdam/common';
 import { TimeoutContext } from './timeout';
+import { MAX_RETRIES } from './token_bucket';
 import {
   isTransactionCommand,
   Transaction,
@@ -497,7 +498,7 @@ export class ClientSession
       readPreference: ReadPreference.primary,
       bypassPinningCheck: true
     });
-    operation.maxAttempts = 6;
+    operation.maxAttempts = MAX_RETRIES + 1;
 
     const timeoutContext =
       this.timeoutContext ??
@@ -516,7 +517,7 @@ export class ClientSession
     } catch (firstCommitError) {
       this.commitAttempted = true;
 
-      const remainingAttempts = 6 - (operation.attemptsMade ?? 1);
+      const remainingAttempts = MAX_RETRIES + 1 - (operation.attemptsMade ?? 1);
       if (remainingAttempts <= 0) {
         throw firstCommitError;
       }

src/token_bucket.ts

@@ -31,9 +31,24 @@ export const RETRY_TOKEN_RETURN_RATE = 0.1;
  * @internal
  * The initial size of the token bucket, as defined in the backpressure specification.
  */
-export const INITIAL_TOKEN_BUCKET_SIZE = 1000;
+export const INITIAL_TOKEN_BUCKET_SIZE = 1_000;
 /**
  * @internal
  * The cost of a retry, as defined in the backpressure specification.
  */
 export const RETRY_COST = 1;
+/**
+ * @internal
+ * The maximum number of retries for overload errors
+ * */
+export const MAX_RETRIES = 5;
+/**
+ * @internal
+ * The base backoff duration in milliseconds
+ * */
+export const BASE_BACKOFF_MS = 100;
+/**
+ * @internal
+ * The maximum backoff duration in milliseconds
+ * */
+export const MAX_BACKOFF_MS = 10_000;