feat: subscriptions get passed result questionable (#91)

Co-authored-by: Eric <[email protected]>

Author: AuHau

.github/workflows/ci.yml

@@ -1,6 +1,11 @@
 name: CI
 
-on: [push, pull_request, workflow_dispatch]
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
 
 jobs:
   test:
@@ -12,6 +17,8 @@ jobs:
     steps:
     - name: Checkout
       uses: actions/checkout@v4
+      with:
+        ref: ${{ github.event.pull_request.head.sha }}
 
     - name: Install Nim
       uses: iffy/install-nim@v4

Readme.md

@@ -131,14 +131,22 @@ You can now subscribe to Transfer events by calling `subscribe` on the contract
 instance.
 
 ```nim
-proc handleTransfer(transfer: Transfer) =
-  echo "received transfer: ", transfer
+proc handleTransfer(transferResult: ?!Transfer) =
+  if transferResult.isOk:
+    echo "received transfer: ", transferResult.value
+  else:
+    echo "error during transfer: ", transferResult.error.msg
 
 let subscription = await token.subscribe(Transfer, handleTransfer)
 ```
 
 When a Transfer event is emitted, the `handleTransfer` proc that you just
-defined will be called.
+defined will be called with a [Result](https://github.com/arnetheduck/nim-results) type
+which contains the event value.
+
+In case there is some underlying error in the event subscription, the handler will
+be called as well, but the Result will contain error instead, so do proper error
+management in your handlers.
 
 When you're no longer interested in these events, you can unsubscribe:
 

ethers/contract.nim

@@ -3,6 +3,7 @@ import std/macros
 import std/sequtils
 import pkg/chronicles
 import pkg/chronos
+import pkg/questionable
 import pkg/contractabi
 import ./basics
 import ./provider
@@ -35,11 +36,10 @@ type
     gasLimit*: ?UInt256
   CallOverrides* = ref object of TransactionOverrides
     blockTag*: ?BlockTag
-  ContractError* = object of EthersError
   Confirmable* = object
     response*: ?TransactionResponse
     convert*: ConvertCustomErrors
-  EventHandler*[E: Event] = proc(event: E) {.gcsafe, raises:[].}
+  EventHandler*[E: Event] = proc(event: ?!E) {.gcsafe, raises:[].}
 
 func new*(ContractType: type Contract,
           address: Address,
@@ -292,9 +292,13 @@ proc subscribe*[E: Event](contract: Contract,
   let topic = topic($E, E.fieldTypes).toArray
   let filter = EventFilter(address: contract.address, topics: @[topic])
 
-  proc logHandler(log: Log) {.raises: [].} =
+  proc logHandler(logResult: ?!Log) {.raises: [].} =
+    without log =? logResult, error:
+      handler(failure(E, error))
+      return
+
     if event =? E.decode(log.data, log.topics):
-      handler(event)
+      handler(success(event))
 
   contract.provider.subscribe(filter, logHandler)
 

ethers/errors.nim

@@ -1,7 +1,20 @@
 import ./basics
 
-type SolidityError* = object of EthersError
+type
+  SolidityError* = object of EthersError
+  ContractError* = object of EthersError
+  SignerError* = object of EthersError
+  SubscriptionError* = object of EthersError
+  ProviderError* = object of EthersError
+    data*: ?seq[byte]
 
 {.push raises:[].}
 
+proc toErr*[E1: ref CatchableError, E2: EthersError](
+  e1: E1,
+  _: type E2,
+  msg: string = e1.msg): ref E2 =
+
+  return newException(E2, msg, e1)
+
 template errors*(types) {.pragma.}

ethers/provider.nim

@@ -1,5 +1,6 @@
 import pkg/chronicles
 import pkg/serde
+import pkg/questionable
 import ./basics
 import ./transaction
 import ./blocktag
@@ -8,13 +9,12 @@ import ./errors
 export basics
 export transaction
 export blocktag
+export errors
 
 {.push raises: [].}
 
 type
   Provider* = ref object of RootObj
-  ProviderError* = object of EthersError
-    data*: ?seq[byte]
   EstimateGasError* = object of ProviderError
     transaction*: Transaction
   Subscription* = ref object of RootObj
@@ -56,8 +56,8 @@ type
     effectiveGasPrice*: ?UInt256
     status*: TransactionStatus
     transactionType* {.serialize("type"), deserialize("type").}: TransactionType
-  LogHandler* = proc(log: Log) {.gcsafe, raises:[].}
-  BlockHandler* = proc(blck: Block) {.gcsafe, raises:[].}
+  LogHandler* = proc(log: ?!Log) {.gcsafe, raises:[].}
+  BlockHandler* = proc(blck: ?!Block) {.gcsafe, raises:[].}
   Topic* = array[32, byte]
   Block* {.serialize.} = object
     number*: ?UInt256
@@ -227,7 +227,7 @@ proc confirm*(
   tx: TransactionResponse,
   confirmations = EthersDefaultConfirmations,
   timeout = EthersReceiptTimeoutBlks): Future[TransactionReceipt]
-  {.async: (raises: [CancelledError, ProviderError, EthersError]).} =
+  {.async: (raises: [CancelledError, ProviderError, SubscriptionError, EthersError]).} =
 
   ## Waits for a transaction to be mined and for the specified number of blocks
   ## to pass since it was mined (confirmations). The number of confirmations
@@ -238,6 +238,12 @@ proc confirm*(
   assert confirmations > 0
 
   var blockNumber: UInt256
+
+  ## We need initialized succesfull Result, because the first iteration of the `while` loop
+  ## bellow is triggered "manually" by calling `await updateBlockNumber` and not by block
+  ## subscription. If left uninitialized then the Result is in error state and error is raised.
+  ## This result is not used for block value, but for block subscription errors.
+  var blockSubscriptionResult: ?!Block = success(Block(number: UInt256.none, timestamp: 0.u256, hash: BlockHash.none))
   let blockEvent = newAsyncEvent()
 
   proc updateBlockNumber {.async: (raises: []).} =
@@ -250,7 +256,13 @@ proc confirm*(
       # there's nothing we can do here
       discard
 
-  proc onBlock(_: Block) =
+  proc onBlock(blckResult: ?!Block) =
+    blockSubscriptionResult = blckResult
+
+    if blckResult.isErr:
+      blockEvent.fire()
+      return
+
     # ignore block parameter; hardhat may call this with pending blocks
     asyncSpawn updateBlockNumber()
 
@@ -264,6 +276,16 @@ proc confirm*(
     await blockEvent.wait()
     blockEvent.clear()
 
+    if blockSubscriptionResult.isErr:
+      let error = blockSubscriptionResult.error()
+
+      if error of SubscriptionError:
+        raise (ref SubscriptionError)(error)
+      elif error of CancelledError:
+        raise (ref CancelledError)(error)
+      else:
+        raise error.toErr(ProviderError)
+
     if blockNumber >= finish:
       await subscription.unsubscribe()
       raise newException(EthersError, "tx not mined before timeout")

ethers/providers/jsonrpc/errors.nim

@@ -1,9 +1,12 @@
 import std/strutils
 import pkg/stew/byteutils
 import ../../basics
+import ../../errors
 import ../../provider
 import ./conversions
 
+export errors
+
 {.push raises:[].}
 
 type JsonRpcProviderError* = object of ProviderError