event promise chaining

services/events.js

@@ -80,7 +80,6 @@ class EventService {
       }
       return a.blockNumber - b.blockNumber
     })
-
     const lastBlock = allEvents[allEvents.length - 1].blockNumber
 
     this.saveEvents({ events: allEvents, lastBlock, type })
@@ -247,65 +246,60 @@ class EventService {
     }
   }
 
-  getPastEvents({ fromBlock, toBlock, type }) {
+  getPastEvents({ fromBlock, toBlock, type }, shouldRetry = false, i = 0) {
     return new Promise((resolve, reject) => {
-      const repsonse = this.contract.getPastEvents(capitalizeFirstLetter(type), {
+      this.contract
+        .getPastEvents(capitalizeFirstLetter(type), {
           fromBlock,
           toBlock
         })
+        .then((events) => resolve(events))
+        .catch((err) => {
+          i = i + 1
+          // maximum 5 second buffer for rate-limiting
+          if (shouldRetry) {
+            const isRetry = i !== 5
 
-      if (repsonse) {
-        resolve(repsonse)
+            sleep(1000 * i).then(() =>
+              this.getPastEvents({ fromBlock, toBlock, type }, isRetry, i)
+                .then((events) => resolve(events))
+                .catch((_) => resolve(undefined))
+            )
           } else {
-        reject(new Error())
+            reject(new Error(err))
           }
         })
+    })
   }
 
-  async getEventsPartFromRpc({ fromBlock, toBlock, type }, shouldRetry = false, i = 0) {
+  async getEventsPartFromRpc(parameters, shouldRetry = false) {
     try {
+      const { fromBlock, type } = parameters
       const { currentBlockNumber } = await this.getBlocksDiff({ fromBlock })
 
-      if (fromBlock > currentBlockNumber) {
+      if (fromBlock < currentBlockNumber) {
+        const eventsPart = await this.getPastEvents(parameters, shouldRetry)
+
+        if (eventsPart) {
+          if (eventsPart.length > 0) {
             return {
-          events: [],
-          lastBlock: fromBlock
+              events: formatEvents(eventsPart, type),
+              lastBlock: eventsPart[eventsPart.length - 1].blockNumber
             }
-      }
-
-      let events = []
-
-      try {
-        events = await this.getPastEvents({ fromBlock, toBlock, type })
-      } catch (e) {
-        if (shouldRetry) {
-          i = i + 1
-          // maximum 5 second buffer for rate-limiting
-          await sleep(1000 * i)
-
-          events = await this.getEventsPartFromRpc(
-            {
-              fromBlock,
-              toBlock,
-              type
-            },
-            i !== 5,
-            i
-          )
           } else {
-          throw new Error(`Failed to fetch block ${toBlock}`)
-        }
-      }
-
-      if (!events?.length) {
             return {
               events: [],
               lastBlock: fromBlock
             }
           }
+        } else {
+          return undefined
+        }
+      } else {
         return {
-        events: formatEvents(events, type),
-        lastBlock: events[events.length - 1].blockNumber
+          events: [],
+          lastBlock: fromBlock
+        }
       }
     } catch (err) {
       return undefined
@@ -315,16 +309,18 @@ class EventService {
   createBatchRequest(batchArray) {
     return batchArray.map(
       (e, i) =>
-        new Promise(async (resolve) => {
-          try {
-            sleep(20 * i)
-            const { events } = await this.getEventsPartFromRpc({ ...e }, true)
-            resolve(events)
-          } catch (e) {
-            resolve({ isFailedBatch: true, ...e })
+        new Promise((resolve) =>
+          sleep(20 * i).then(() =>
+            this.getEventsPartFromRpc({ ...e }, true).then((batch) => {
+              if (!batch) {
+                resolve([{ isFailedBatch: true, ...e }])
+              } else {
+                resolve(batch.events)
               }
             })
           )
+        )
+    )
   }
 
   async getBatchEventsFromRpc({ fromBlock, type }) {
@@ -352,33 +348,35 @@ class EventService {
             return { fromBlock, toBlock, type }
           })
           const batch = await Promise.all(this.createBatchRequest(params))
+          const requests = flattenNArray(batch)
 
+          events = events.concat(requests.filter((e) => !e.isFailedBatch))
+          failed = failed.concat(requests.filter((e) => e.isFailedBatch))
           lastBlock = params[batchSize - 1].toBlock
-          events = events.concat(batch.filter((e) => !e.isFailedBatch))
-          failed = failed.concat(batch.filter((e) => e.isFailedBatch))
 
           const progressIndex = batchIndex - failed.length / batchSize
 
           if (isLastBatch && failed.length !== 0) {
-            const fbatch = await Promise.all(this.createBatchRequest(failed))
-            const isFailedBatch = fbatch.filter((e) => e.isFailedBatch).length !== 0
+            const failedBatch = await Promise.all(this.createBatchRequest(failed))
+            const failedReqs = flattenNArray(failedBatch)
+            const failedRept = failedReqs.filter((e) => e.isFailedBatch)
 
-            if (isFailedBatch) {
-              throw new Error('Failed to batch events')
+            if (failedRept.length === 0) {
+              events = events.concat(failedReqs)
             } else {
-              events = events.concat(fbatch)
+              throw new Error('Failed to batch events')
             }
           }
           await this.updateEventProgress(progressIndex / batchCount, type)
         }
-        events = flattenNArray(events)
 
         return {
           lastBlock: events[events.length - 1].blockNumber,
           events
         }
-      }
+      } else {
         return undefined
+      }
     } catch (err) {
       return undefined
     }

services/registry/index.js

@@ -28,53 +28,83 @@ class RelayerRegister {
   fetchEvents = ({ fromBlock, toBlock }, shouldRetry = false) => {
     return new Promise((resolve, reject) => {
       if (fromBlock <= toBlock) {
-        try {
-          const registeredEventsPart = this.relayerRegistry.getPastEvents('RelayerRegistered', {
-            fromBlock,
-            toBlock
-          })
-
-          resolve(registeredEventsPart)
-        } catch (error) {
+        this.relayerRegistry
+          .getPastEvents('RelayerRegistered', { fromBlock, toBlock })
+          .then((events) => resolve(events))
+          .catch((_) => {
             if (shouldRetry) {
-            sleep(500)
-
-            const events = this.fetchEvents({ fromBlock, toBlock })
-
-            resolve(events)
+              sleep(500).then(() =>
+                this.fetchEvents({ fromBlock, toBlock })
+                  .then((events) => resolve(events))
+                  .catch((_) => resolve(undefined))
+              )
             } else {
-            reject(new Error(error))
-          }
+              resolve(undefined)
             }
+          })
       } else {
-        resolve([])
+        resolve(undefined)
       }
     })
   }
 
   batchFetchEvents = async ({ fromBlock, toBlock }) => {
+    const batchSize = 10
     const blockRange = 10000
     const blockDifference = toBlock - fromBlock
     const chunkCount = Math.ceil(blockDifference / blockRange)
     const blockDenom = Math.ceil(blockDifference / chunkCount)
+    const chunkSize = Math.ceil(chunkCount / batchSize)
 
-    const promises = new Array(chunkCount).fill('').map(
+    let failed = []
+    let events = []
+    let lastBlock = fromBlock
+
+    for (let batchIndex = 0; batchIndex < chunkSize; batchIndex++) {
+      const params = new Array(batchSize).fill('').map((_, i) => {
+        const toBlock = (i + 1) * blockDenom + lastBlock
+        const fromBlock = toBlock - blockDenom
+        return { fromBlock, toBlock }
+      })
+      const promises = new Array(batchSize).fill('').map(
         (_, i) =>
-        new Promise((resolve) => {
-          sleep(20 * i)
-          const batch = this.fetchEvents(
-            {
-              fromBlock: i * blockDenom + fromBlock,
-              toBlock: (i + 1) * blockDenom + fromBlock
-            },
-            true
-          )
+          new Promise((resolve) =>
+            sleep(i * 20).then(() => {
+              this.fetchEvents(params[i], true).then((batch) => {
+                if (!batch) {
+                  resolve([{ isFailedBatch: true, fromBlock, toBlock }])
+                } else {
                   resolve(batch)
+                }
+              })
             })
           )
+      )
+      const requests = flattenNArray(await Promise.all(promises))
+      const failedIndexes = requests
+        .filter((e) => e.isFailedBatch)
+        .map((e) => {
+          const reqIndex = requests.indexOf(e)
+          return params[reqIndex]
+        })
 
-    const batchEvents = flattenNArray(await Promise.all(promises))
-    const events = batchEvents.map((e) => ({ ...e.returnValues }))
+      failed = failed.concat(failedIndexes || [])
+      events = events.concat(requests.filter((e) => !e.isFailedBatch))
+      lastBlock = params[batchSize - 1].toBlock
+    }
+
+    if (failed.length !== 0) {
+      const failedReqs = failed.map((e) => this.fetchEvents(e))
+      const failedBatch = flattenNArray(await Promise.all(failedReqs))
+
+      events = events.concat(failedBatch || [])
+    }
+
+    events = events.map((e) => ({ ...e.returnValues }))
+
+    if (events.length === 0) {
+      throw new Error('Failed to fetch registry events')
+    }
 
     return events
   }
@@ -169,6 +199,7 @@ class RelayerRegister {
       for (let x = 0; x < relayerEvents.length; x++) {
         const { ensName, relayerAddress } = relayerEvents[x]
         let ensAddress
+
         if (!isAddress(relayerAddress)) {
           ensAddress = await this.getENSAddress(ensName)
           ensAddress = toChecksumAddress(ensAddress)