feat: honour maxTasksPerRound from spark-api

lib/constants.js

@@ -1,3 +1,3 @@
 export const SPARK_VERSION = '1.6.0'
-export const DELAY_BETWEEN_RETRIEVALS = 10_000
 export const MAX_CAR_SIZE = 200 * 1024 * 1024 // 200 MB
+export const APPROX_ROUND_LENGTH_IN_MS = 60 * 60_000 // 1 hour

lib/spark.js

@@ -1,14 +1,15 @@
 /* global Zinnia */
 
 import { ActivityState } from './activity-state.js'
-import { SPARK_VERSION, DELAY_BETWEEN_RETRIEVALS, MAX_CAR_SIZE } from './constants.js'
+import { SPARK_VERSION, MAX_CAR_SIZE, APPROX_ROUND_LENGTH_IN_MS } from './constants.js'
 import { encodeHex } from './deno-encoding-hex.js'
 
 const sleep = dt => new Promise(resolve => setTimeout(resolve, dt))
 
 export default class Spark {
   #fetch
   #activity = new ActivityState()
+  #maxTasksPerNode = 360
 
   constructor ({ fetch = globalThis.fetch } = {}) {
     this.#fetch = fetch
@@ -23,9 +24,11 @@ export default class Spark {
     })
     await assertOkResponse(res, 'Failed to fetch the current SPARK round')
     this.#activity.onHealthy()
-    const { retrievalTasks, ...round } = await res.json()
+    const { retrievalTasks, maxTasksPerNode, ...round } = await res.json()
     console.log('Current SPARK round:', round)
+    console.log('  %s max tasks per node', maxTasksPerNode ?? '<n/a>')
     console.log('  %s retrieval tasks', retrievalTasks.length)
+    if (maxTasksPerNode) this.#maxTasksPerNode = maxTasksPerNode
 
     const retrieval = retrievalTasks[Math.floor(Math.random() * retrievalTasks.length)]
     console.log({ retrieval })
@@ -161,6 +164,7 @@ export default class Spark {
 
   async run () {
     while (true) {
+      const started = Date.now()
       try {
         await this.nextRetrieval()
         this.#activity.onHealthy()
@@ -172,7 +176,13 @@ export default class Spark {
         }
         console.error(err)
       }
-      await sleep(DELAY_BETWEEN_RETRIEVALS)
+      const duration = Date.now() - started
+      const baseDelay = APPROX_ROUND_LENGTH_IN_MS / this.#maxTasksPerNode
+      const delay = baseDelay - duration
+      if (delay > 0) {
+        console.log('Sleeping for %s seconds before starting the next task...', Math.round(delay / 1000))
+        await sleep(delay)
+      }
     }
   }
 }