CircuitBreaker plugin

The CircuitBreaker prefix plugin intercepts calls to a circuit-breaker adapter and transparently prefixes all circuit keys with a configurable string. This enables logical key namespacing without modifying the adapter implementation.

Use cases

• Multi-tenant systems — Prefix circuit keys with a tenant identifier to isolate circuit state between tenants
• Service versioning — Separate circuit state for different API versions
• Environment isolation — Keep development, staging, and production circuit state separate
• Region scoping — Prefix keys with a region identifier in multi-region deployments

How it works

The withCircuitBreakerPrefix function returns a PluginFn that calls enhance on each adapter method that accepts a circuit key. When an enhanced method is invoked, the plugin intercepts the call, prepends the configured prefix to the key argument, and forwards the modified arguments to the original method.

The plugin prefixes keys for the following methods:

Method	Key argument	Pattern
getState	Second argument (key)	prefix + key
isolate	Second argument (key)	prefix + key
reset	Second argument (key)	prefix + key
trackFailure	Second argument (key)	prefix + key
trackSuccess	Second argument (key)	prefix + key
updateState	Second argument (key)	prefix + key

Every method on the ICircuitBreakerAdapter that operates on a specific circuit key is prefixed.

Usage

import { enhance } from "@daiso-tech/core/middleware";
import { withPlugin } from "@daiso-tech/core/middleware";
import { MemoryCircuitBreakerStorageAdapter } from "@daiso-tech/core/circuit-breaker/memory-circuit-breaker-storage-adapter";
import { DatabaseCircuitBreakerAdapter } from "@daiso-tech/core/circuit-breaker/database-circuit-breaker-adapter";
import { withCircuitBreakerPrefix } from "@daiso-tech/core/circuit-breaker/plugins";

const adapter = new DatabaseCircuitBreakerAdapter({
    adapter: new MemoryCircuitBreakerStorageAdapter(),
});

// Apply the prefix plugin
const prefixedAdapter = withPlugin(
    adapter,
    withCircuitBreakerPrefix("service-a:"),
);

// The key "api:users" is automatically prefixed to "service-a:api:users"
const state = await prefixedAdapter.getState(context, "api:users");

Using with CircuitBreakerFactory

The plugin can be applied directly to the adapter passed to the CircuitBreakerFactory constructor:

import { CircuitBreakerFactory } from "@daiso-tech/core/circuit-breaker";
import { DatabaseCircuitBreakerAdapter } from "@daiso-tech/core/circuit-breaker/database-circuit-breaker-adapter";
import { withPlugin } from "@daiso-tech/core/middleware";
import { withCircuitBreakerPrefix } from "@daiso-tech/core/circuit-breaker/plugins";

const adapter = new DatabaseCircuitBreakerAdapter({ ... });
const prefixedAdapter = withPlugin(adapter, withCircuitBreakerPrefix("v1:"));

const factory = new CircuitBreakerFactory({
    adapter: prefixedAdapter,
});

Before/after behavior

Before — Circuit keys are used as-is:

adapter.getState(context, "api:users")  →  looks up circuit "api:users"

After — Circuit keys are automatically prefixed:

adapter.getState(context, "api:users")  →  looks up circuit "env:api:users"

info

For more information about the withPlugin function and applying plugins to adapters, see the Middleware plugin documentation.