fix gas price setting for transaction attempt to fix some race condition on sending a transaction

Author: Alex Vlasov

web3swift.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
 s.name             = "web3swift"
-s.version          = "1.1.0"
+s.version          = "1.1.1"
 s.summary          = "Web3 implementation in vanilla Swift for iOS ans macOS"
 
 s.description      = <<-DESC

web3swift/Promises/Classes/Promise+Batching.swift

@@ -22,7 +22,8 @@ public class JSONRPCrequestDispatcher {
         self.provider = provider
         self.queue = queue
         self.policy = policy
-        self.lockQueue = DispatchQueue(label: "batchingQueue", qos: .userInitiated)
+        self.lockQueue = DispatchQueue.init(label: "batchingQueue") // serial simplest queue
+//        DispatchQueue(label: "batchingQueue", qos: .userInitiated)
         self.batches.append(Batch(provider: self.provider, capacity: 32, queue: self.queue, lockQueue: self.lockQueue))
     }
 
@@ -41,7 +42,7 @@ public class JSONRPCrequestDispatcher {
             }
             let requestID = request.id
             let promiseToReturn = Promise<JSONRPCresponse>.pending()
-            self.queue.async {
+            self.lockQueue.async {
                 if self.promisesDict[requestID] != nil {
                     promiseToReturn.resolver.reject(Web3Error.processingError("Request ID collision"))
                 }

web3swift/Web3/Classes/Web3+Options.swift

@@ -132,4 +132,15 @@ public struct Web3Options {
             }
         }
     }
+    
+    public static func smartMergeGasPrice(originalOptions: Web3Options?, extraOptions: Web3Options?, priceEstimate: BigUInt) -> BigUInt? {
+        guard let mergedOptions = Web3Options.merge(originalOptions, with: extraOptions) else {return nil} //just require any non-nils
+        if mergedOptions.gasPrice == nil {
+            return priceEstimate
+        } else if mergedOptions.gasPrice == 0 {
+            return priceEstimate
+        } else {
+            return mergedOptions.gasPrice!
+        }
+    }
 }

web3swift/Web3/Classes/Web3+TransactionIntermediate.swift

@@ -178,13 +178,17 @@ extension web3.web3contract.TransactionIntermediate {
                 }
                 assembledTransaction.nonce = nonce
                 assembledTransaction.gasLimit = estimate
-                if assembledTransaction.gasPrice == 0 {
-                    if mergedOptions.gasPrice != nil {
-                        assembledTransaction.gasPrice = mergedOptions.gasPrice!
-                    } else {
-                        assembledTransaction.gasPrice = gasPrice
-                    }
+                guard let finalGasPrice = Web3Options.smartMergeGasPrice(originalOptions: options, extraOptions: mergedOptions, priceEstimate: gasPrice) else {
+                    throw Web3Error.processingError("Missing parameter of gas price for transaction")
                 }
+                assembledTransaction.gasPrice = finalGasPrice
+//                if assembledTransaction.gasPrice == 0 {
+//                    if mergedOptions.gasPrice != nil {
+//                        assembledTransaction.gasPrice = mergedOptions.gasPrice!
+//                    } else {
+//                        assembledTransaction.gasPrice = gasPrice
+//                    }
+//                }
                 return assembledTransaction
             }).done(on: queue) {tx in
                     seal.fulfill(tx)