Domain Fetcher Circuit Breaker & Circuit Breaker Manager

packages/sui-domain/src/circuitBreaker/CircuitBreaker.js

@@ -0,0 +1,65 @@
+const CircuitBreakerStates = {
+  OPENED: 'OPENED',
+  CLOSED: 'CLOSED',
+  HALF: 'HALF'
+}
+
+export class CircuitBreaker {
+  request = null
+  state = CircuitBreakerStates.CLOSED
+  failureCount = 0
+  failureThreshold = 5 // number of failures to determine when to open the circuit
+  resetAfter = 50000
+  timeout = 5000 // declare request failure if the function takes more than 5 seconds
+
+  constructor({options}) {
+    this.state = CircuitBreakerStates.CLOSED // allowing requests to go through by default
+    this.failureCount = 0
+    // allow request to go through after the circuit has been opened for resetAfter seconds
+    // open the circuit again if failure is observed, close the circuit otherwise
+    this.resetAfter = Date.now()
+    if (options) {
+      this.failureThreshold = options.failureThreshold
+      this.timeout = options.timeout
+    } else {
+      this.failureThreshold = 5
+      this.timeout = 5000 // in ms
+    }
+  }
+
+  async fire(requester, url, options) {
+    this.request = requester.call(requester, url, options)
+
+    if (this.state === CircuitBreakerStates.OPENED) {
+      if (this.resetAfter <= Date.now()) {
+        this.state = CircuitBreakerStates.HALF
+      } else {
+        throw new Error('Circuit is in open state right now. Please try again later.')
+      }
+    }
+    try {
+      const response = await this.request
+      if (response.status === 200) return this.success(response)
+      return this.failure(response)
+    } catch (err) {
+      return this.failure(err.message)
+    }
+  }
+
+  success(response) {
+    this.failureCount = 0
+    if (this.state === CircuitBreakerStates.HALF) {
+      this.state = CircuitBreakerStates.CLOSED
+    }
+    return response
+  }
+
+  failure(response) {
+    this.failureCount += 1
+    if (this.state === CircuitBreakerStates.HALF || this.failureCount >= this.failureThreshold) {
+      this.state = CircuitBreakerStates.OPENED
+      this.resetAfter = Date.now() + this.timeout
+    }
+    return response
+  }
+}

packages/sui-domain/src/circuitBreaker/CircuitBreakerManager.js

@@ -0,0 +1,16 @@
+import {CircuitBreaker} from './CircuitBreaker.js'
+
+export default class CircuitBreakerManager {
+  activeRequests = {}
+
+  constructor({options}) {
+    this._options = options
+  }
+
+  async fire(requester, url, requestOptions) {
+    const key = `${requestOptions.method}#${url}`
+    if (!this.activeRequests[key]) this.activeRequests[key] = new CircuitBreaker({options: this._options})
+
+    return this.activeRequests[key].fire(requester, url, requestOptions)
+  }
+}

packages/sui-domain/src/fetcher/AxiosFetcher.js

@@ -11,14 +11,24 @@ export default class AxiosFetcher {
     this._axios = axios.create(config)
   }
 
+  get CircuitBreaker() {
+    return this._config.get('circuitBreaker')
+      ? this._config.get('circuitBreaker')
+      : {
+          fire: (requester, url, options, body) => {
+            requester.call(requester, url, body ?? options, options)
+          }
+        }
+  }
+
   /**
    * Get method
    * @param {String} url
    * @param {Object} options
    * @return {Promise<any>}
    */
   get(url, options) {
-    return this._axios.get(url, options)
+    return this.CircuitBreaker.fire(this._axios.get, url, options)
   }
 
   /**
@@ -30,7 +40,7 @@ export default class AxiosFetcher {
    * @return {Promise}
    */
   post(url, body, options) {
-    return this._axios.post(url, body, options)
+    return this.CircuitBreaker.fire(this._axios.post, url, options, body)
   }
 
   /**
@@ -42,7 +52,7 @@ export default class AxiosFetcher {
    * @return {Object}
    */
   put(url, body, options) {
-    return this._axios.put(url, body, options)
+    return this.CircuitBreaker.fire(this._axios.put, url, options, body)
   }
 
   /**
@@ -54,7 +64,7 @@ export default class AxiosFetcher {
    * @return {Object}
    */
   patch(url, body, options) {
-    return this._axios.patch(url, body, options)
+    return this.CircuitBreaker.fire(this._axios.patch, url, options, body)
   }
 
   /**
@@ -65,6 +75,6 @@ export default class AxiosFetcher {
    * @return {Object}
    */
   delete(url, options) {
-    return this._axios.delete(url, options)
+    return this.CircuitBreaker.fire(this._axios.delete, url, options)
   }
 }

packages/sui-domain/src/index.js

@@ -1,5 +1,6 @@
 export {default as Entity} from './Entity.js'
 export {default as EntryPointFactory} from './EntryPointFactory.js'
+export {default as CircuitBreakerManager} from './circuitBreaker/CircuitBreakerManager.js'
 export {default as FetcherFactory} from './fetcher/factory.js'
 export {default as Mapper} from './Mapper.js'
 export {default as Repository} from './Repository.js'