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[FEAT] added optional heartbeat checks to js#fetch() (#327) [FEAT] added optional heartbeat checks to js#subcribe()
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,139 @@ | ||
| /* | ||
| * Copyright 2022 The NATS Authors | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| /** | ||
| * Called with the number of missed heartbeats. | ||
| * If the function returns true, the monitor will cancel monitoring. | ||
| */ | ||
| export type IdleHeartbeatFn = (n: number) => boolean; | ||
|
|
||
| /** | ||
| * IdleHeartbeatOptions | ||
| */ | ||
| export type IdleHeartbeatOptions = { | ||
| /** | ||
| * @field maxOut - optional maximum number of missed heartbeats before notifying (default is 2) | ||
| */ | ||
| maxOut: number; | ||
| /** | ||
| * @field cancelAfter - optional timer to auto cancel monitoring in millis | ||
| */ | ||
| cancelAfter: number; | ||
| }; | ||
|
|
||
| export class IdleHeartbeat { | ||
| interval: number; | ||
| maxOut: number; | ||
| cancelAfter: number; | ||
| timer?: number; | ||
| autoCancelTimer?: number; | ||
| last!: number; | ||
| missed: number; | ||
| count: number; | ||
| callback: IdleHeartbeatFn; | ||
|
|
||
| /** | ||
| * Constructor | ||
| * @param interval in millis to check | ||
| * @param cb a callback to report when heartbeats are missed | ||
| * @param opts monitor options @see IdleHeartbeatOptions | ||
| */ | ||
| constructor( | ||
| interval: number, | ||
| cb: IdleHeartbeatFn, | ||
| opts: Partial<IdleHeartbeatOptions> = { maxOut: 2 }, | ||
| ) { | ||
| this.interval = interval; | ||
| this.maxOut = opts?.maxOut || 2; | ||
| this.cancelAfter = opts?.cancelAfter || 0; | ||
| this.last = Date.now(); | ||
| this.missed = 0; | ||
| this.count = 0; | ||
| this.callback = cb; | ||
|
|
||
| this._schedule(); | ||
| } | ||
|
|
||
| /** | ||
| * cancel monitoring | ||
| */ | ||
| cancel() { | ||
| if (this.autoCancelTimer) { | ||
| clearTimeout(this.autoCancelTimer); | ||
| } | ||
| if (this.timer) { | ||
| clearInterval(this.timer); | ||
| } | ||
| this.timer = 0; | ||
| this.autoCancelTimer = 0; | ||
| } | ||
|
|
||
| /** | ||
| * work signals that there was work performed | ||
| */ | ||
| work() { | ||
| this.last = Date.now(); | ||
| this.missed = 0; | ||
| } | ||
|
|
||
| /** | ||
| * internal api to change the interval, cancelAfter and maxOut | ||
| * @param interval | ||
| * @param cancelAfter | ||
| * @param maxOut | ||
| */ | ||
| _change(interval: number, cancelAfter = 0, maxOut = 2) { | ||
| this.interval = interval; | ||
| this.maxOut = maxOut; | ||
| this.cancelAfter = cancelAfter; | ||
| this.restart(); | ||
| } | ||
|
|
||
| /** | ||
| * cancels and restarts the monitoring | ||
| */ | ||
| restart() { | ||
| this.cancel(); | ||
| this._schedule(); | ||
| } | ||
|
|
||
| /** | ||
| * internal api called to start monitoring | ||
| */ | ||
| _schedule() { | ||
| if (this.cancelAfter > 0) { | ||
| // @ts-ignore: in node is not a number - we treat this opaquely | ||
| this.autoCancelTimer = setTimeout(() => { | ||
| this.cancel(); | ||
| }, this.cancelAfter); | ||
| } | ||
| // @ts-ignore: in node is not a number - we treat this opaquely | ||
| this.timer = setInterval(() => { | ||
| this.count++; | ||
| if (Date.now() - this.interval > this.last) { | ||
| this.missed++; | ||
| } | ||
| if (this.missed >= this.maxOut) { | ||
| try { | ||
| if (this.callback(this.missed) === true) { | ||
| this.cancel(); | ||
| } | ||
| } catch (err) { | ||
| console.log(err); | ||
| } | ||
| } | ||
| }, this.interval); | ||
| } | ||
| } |
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