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merged 2 commits into from
Oct 20, 2025
Merged

Handle errors gracefullly in process and lower data size limit #551

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f1decb4
change panics to events (#549)
devbugging Oct 20, 2025
a4e60c4
lowers data size
joshuahannan Oct 20, 2025
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72 changes: 39 additions & 33 deletions contracts/FlowTransactionScheduler.cdc
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,9 @@ access(all) contract FlowTransactionScheduler {
// if they need to
access(all) event ConfigUpdated()

// Emitted when a critical issue is encountered
access(all) event CriticalIssue(message: String)
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I think including the transaction id would be important for anyone wishing to identify a critical issue related to their schedule transaction


/// Entitlements
access(all) entitlement Execute
access(all) entitlement Process
Expand Down Expand Up @@ -583,7 +586,7 @@ access(all) contract FlowTransactionScheduler {
Priority.Low: 0
},
lowPriorityEffortLimit: 2_500,
maxDataSizeMB: 0.1,
maxDataSizeMB: 0.001,
priorityFeeMultipliers: {
Priority.High: 10.0,
Priority.Medium: 5.0,
Expand Down Expand Up @@ -1078,27 +1081,29 @@ access(all) contract FlowTransactionScheduler {
access(self) fun rescheduleLowPriorityTransactions(slot: UFix64, transactions: [UInt64]) {
for id in transactions {
let tx = self.borrowTransaction(id: id)
?? panic("Invalid ID: \(id) transaction not found") // critical bug

assert (
tx.priority == Priority.Low,
message: "Invalid Priority: Cannot reschedule transaction with id \(id) because it is not low priority"
)
if tx == nil {
emit CriticalIssue(message: "Invalid ID: \(id) transaction not found while rescheduling low priority transactions")
continue
}

assert (
tx.scheduledTimestamp == slot,
message: "Invalid Timestamp: Cannot reschedule transaction with id \(id) because it is not scheduled at the same slot as the new transaction"
)
if tx!.priority != Priority.Low {
emit CriticalIssue(message: "Invalid Priority: Cannot reschedule transaction with id \(id) because it is not low priority")
continue
}

if tx!.scheduledTimestamp != slot {
emit CriticalIssue(message: "Invalid Timestamp: Cannot reschedule transaction with id \(id) because it is not scheduled at the same slot as the new transaction")
continue
}

let newTimestamp = self.calculateScheduledTimestamp(
timestamp: slot + 1.0,
priority: Priority.Low,
executionEffort: tx.executionEffort
executionEffort: tx!.executionEffort
)!

let effort = tx.executionEffort

let transactionData = self.removeTransaction(txData: tx)
let effort = tx!.executionEffort
let transactionData = self.removeTransaction(txData: tx!)

// Subtract the execution effort for this transaction from the slot's priority
let slotEfforts = self.slotUsedEffort[slot]!
Expand Down Expand Up @@ -1175,32 +1180,35 @@ access(all) contract FlowTransactionScheduler {
let transactionIDs = transactionPriorities[priority] ?? {}
for id in transactionIDs.keys {
let tx = self.borrowTransaction(id: id)
?? panic("Invalid ID: \(id) transaction not found during initial processing") // critical bug

if tx == nil {
emit CriticalIssue(message: "Invalid ID: \(id) transaction not found while preparing pending queue")
continue
}

// Only add scheduled transactions to the queue
if tx.status != Status.Scheduled {
if tx!.status != Status.Scheduled {
continue
}

// this is safeguard to prevent collection growing too large in case of block production slowdown
if tx.executionEffort >= collectionAvailableEffort || transactionsAvailableCount == 0 {
if tx!.executionEffort >= collectionAvailableEffort || transactionsAvailableCount == 0 {
emit CollectionLimitReached(
collectionEffortLimit: transactionsAvailableCount == 0 ? nil : self.config.collectionEffortLimit,
collectionTransactionsLimit: transactionsAvailableCount == 0 ? self.config.collectionTransactionsLimit : nil
)
break
}

collectionAvailableEffort = collectionAvailableEffort.saturatingSubtract(tx.executionEffort)
collectionAvailableEffort = collectionAvailableEffort.saturatingSubtract(tx!.executionEffort)
transactionsAvailableCount = transactionsAvailableCount - 1

switch tx.priority {
switch tx!.priority {
case Priority.High:
high.append(tx)
high.append(tx!)
case Priority.Medium:
medium.append(tx)
medium.append(tx!)
case Priority.Low:
low.append(tx)
low.append(tx!)
}
}
}
Expand Down Expand Up @@ -1235,18 +1243,20 @@ access(all) contract FlowTransactionScheduler {
}

let tx = self.borrowTransaction(id: id)
?? panic("Invalid ID: \(id) transaction not found during removal") // critical bug
if tx == nil {
emit CriticalIssue(message: "Invalid ID: \(id) transaction not found while removing executed transactions")
continue
}

// Only remove executed transactions
if tx.status != Status.Executed {
if tx!.status != Status.Executed {
continue
}

// charge the full fee for transaction execution
destroy tx.payAndRefundFees(refundMultiplier: 0.0)
destroy tx!.payAndRefundFees(refundMultiplier: 0.0)

// remove all associated transaction data
self.removeTransaction(txData: tx)
self.removeTransaction(txData: tx!)
}
}
}
Expand All @@ -1269,10 +1279,6 @@ access(all) contract FlowTransactionScheduler {
self.removeExecutedTransactions(currentTimestamp)

let pendingTransactions = self.pendingQueue()

if pendingTransactions.length == 0 {
return
}

for tx in pendingTransactions {
// Only emit the pending execution event if the transaction handler capability is borrowable
Expand Down
6 changes: 3 additions & 3 deletions lib/go/contracts/internal/assets/assets.go
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19 changes: 3 additions & 16 deletions tests/transactionScheduler_test.cdc
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Original file line number Diff line number Diff line change
Expand Up @@ -86,25 +86,12 @@ access(all) fun testGetSizeOfData() {
Test.assertEqual(0.00000000 as UFix64, size)

let largeArray: [Int] = []
while largeArray.length < 10000 {
while largeArray.length < 199 {
largeArray.append(1)
}

size = getSizeOfData(data: largeArray)
Test.assertEqual(0.05337100 as UFix64, size)

// let currentTime = getCurrentBlock().timestamp
// let futureTime = currentTime + 100.0

// let estimate = FlowTransactionScheduler.estimate(
// data: testData,
// timestamp: futureTime,
// priority: FlowTransactionScheduler.Priority.Medium,
// executionEffort: 1000
// )

// size = getSizeOfData(data: estimate)
// Test.assertEqual(0.00021000 as UFix64, size)
Test.assertEqual(0.00107500 as UFix64, size)
}

/** ---------------------------------------------------------------------------------
Expand Down Expand Up @@ -481,7 +468,7 @@ access(all) fun testConfigDetails() {
Test.assertEqual(highPriorityMaxEffort as UInt64,oldConfig.priorityEffortLimit[FlowTransactionScheduler.Priority.High]!)
Test.assertEqual(mediumPriorityMaxEffort as UInt64,oldConfig.priorityEffortLimit[FlowTransactionScheduler.Priority.Medium]!)
Test.assertEqual(lowPriorityMaxEffort as UInt64,oldConfig.priorityEffortLimit[FlowTransactionScheduler.Priority.Low]!)
Test.assertEqual(0.1,oldConfig.maxDataSizeMB)
Test.assertEqual(0.001,oldConfig.maxDataSizeMB)
Test.assertEqual(10.0,oldConfig.priorityFeeMultipliers[FlowTransactionScheduler.Priority.High]!)
Test.assertEqual(5.0,oldConfig.priorityFeeMultipliers[FlowTransactionScheduler.Priority.Medium]!)
Test.assertEqual(2.0,oldConfig.priorityFeeMultipliers[FlowTransactionScheduler.Priority.Low]!)
Expand Down
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