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ConcurrencyError

@rotorsoft/act-root

@rotorsoft/act-root / act/src / ConcurrencyError

Class: ConcurrencyError

Defined in: libs/act/src/types/errors.ts:245

Thrown when optimistic concurrency control detects a conflict.

This error occurs when trying to commit events to a stream that has been modified by another process since it was last loaded. The version number doesn't match expectations, indicating a concurrent modification.

This is a normal occurrence in distributed systems and should be handled by reloading the current state and retrying the action.

Examples​

import { ConcurrencyError } from "@rotorsoft/act";

async function transferWithRetry(from, to, amount, maxRetries = 3) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    try {
      await app.do("transfer",
        { stream: from, actor: currentUser },
        { to, amount }
      );
      return { success: true };
    } catch (error) {
      if (error instanceof ConcurrencyError) {
        if (attempt < maxRetries - 1) {
          console.log(`Concurrent modification detected, retrying... (${attempt + 1}/${maxRetries})`);
          await sleep(100 * Math.pow(2, attempt)); // Exponential backoff
          continue;
        }
      }
      throw error;
    }
  }
  return { success: false, reason: "Too many concurrent modifications" };
}
try {
  await app.do("updateInventory", target, payload);
} catch (error) {
  if (error instanceof ConcurrencyError) {
    logger.warn({
      stream: error.stream,
      expectedVersion: error.expectedVersion,
      actualVersion: error.lastVersion,
      events: error.events.map(e => e.name)
    }, "Concurrent modification detected");
  }
}
try {
  await app.do("editDocument", target, { content: newContent });
} catch (error) {
  if (error instanceof ConcurrencyError) {
    return {
      error: "This document was modified by another user. Please refresh and try again.",
      code: "CONCURRENT_MODIFICATION"
    };
  }
}

See​

Store.commit for version checking details

Extends​

  • Error

Constructors​

Constructor​

new ConcurrencyError(stream, lastVersion, events, expectedVersion): ConcurrencyError

Defined in: libs/act/src/types/errors.ts:246

Parameters​

stream​

string

The stream that had the concurrent modification

lastVersion​

number

The actual current version in the store

events​

Message<Schemas, string>[]

The events that were being committed

expectedVersion​

number

The version number that was expected

Returns​

ConcurrencyError

Overrides​

Error.constructor

Properties​

cause?​

optional cause?: unknown

Defined in: node_modules/.pnpm/typescript@5.9.3/node_modules/typescript/lib/lib.es2022.error.d.ts:26

Inherited from​

Error.cause

events​

readonly events: Message<Schemas, string>[]

Defined in: libs/act/src/types/errors.ts:252

The events that were being committed

expectedVersion​

readonly expectedVersion: number

Defined in: libs/act/src/types/errors.ts:254

The version number that was expected

lastVersion​

readonly lastVersion: number

Defined in: libs/act/src/types/errors.ts:250

The actual current version in the store

message​

message: string

Defined in: node_modules/.pnpm/typescript@5.9.3/node_modules/typescript/lib/lib.es5.d.ts:1077

Inherited from​

Error.message

name​

name: string

Defined in: node_modules/.pnpm/typescript@5.9.3/node_modules/typescript/lib/lib.es5.d.ts:1076

Inherited from​

Error.name

stack?​

optional stack?: string

Defined in: node_modules/.pnpm/typescript@5.9.3/node_modules/typescript/lib/lib.es5.d.ts:1078

Inherited from​

Error.stack

stream​

readonly stream: string

Defined in: libs/act/src/types/errors.ts:248

The stream that had the concurrent modification

stackTraceLimit​

static stackTraceLimit: number

Defined in: node_modules/.pnpm/@types+node@25.9.1/node_modules/@types/node/globals.d.ts:67

The Error.stackTraceLimit property specifies the number of stack frames collected by a stack trace (whether generated by new Error().stack or Error.captureStackTrace(obj)).

The default value is 10 but may be set to any valid JavaScript number. Changes will affect any stack trace captured after the value has been changed.

If set to a non-number value, or set to a negative number, stack traces will not capture any frames.

Inherited from​

Error.stackTraceLimit

Methods​

captureStackTrace()​

static captureStackTrace(targetObject, constructorOpt?): void

Defined in: node_modules/.pnpm/@types+node@25.9.1/node_modules/@types/node/globals.d.ts:51

Creates a .stack property on targetObject, which when accessed returns a string representing the location in the code at which Error.captureStackTrace() was called.

const myObject = {};
Error.captureStackTrace(myObject);
myObject.stack;  // Similar to `new Error().stack`

The first line of the trace will be prefixed with ${myObject.name}: ${myObject.message}.

The optional constructorOpt argument accepts a function. If given, all frames above constructorOpt, including constructorOpt, will be omitted from the generated stack trace.

The constructorOpt argument is useful for hiding implementation details of error generation from the user. For instance:

function a() {
  b();
}

function b() {
  c();
}

function c() {
  // Create an error without stack trace to avoid calculating the stack trace twice.
  const { stackTraceLimit } = Error;
  Error.stackTraceLimit = 0;
  const error = new Error();
  Error.stackTraceLimit = stackTraceLimit;

  // Capture the stack trace above function b
  Error.captureStackTrace(error, b); // Neither function c, nor b is included in the stack trace
  throw error;
}

a();

Parameters​

targetObject​

object

constructorOpt?​

Function

Returns​

void

Inherited from​

Error.captureStackTrace

prepareStackTrace()​

static prepareStackTrace(err, stackTraces): any

Defined in: node_modules/.pnpm/@types+node@25.9.1/node_modules/@types/node/globals.d.ts:55

Parameters​

err​

Error

stackTraces​

CallSite[]

Returns​

any

See​

https://v8.dev/docs/stack-trace-api#customizing-stack-traces

Inherited from​

Error.prepareStackTrace