feat: support for new node feature next-nonce of release 6.2.0 (#1299)

* feat: select nonce using next-nonce api from node v6.2.0 release

* refactor: fix nonce strategy to continuity

* feat: allow nonce strategy selection

* docs(nonce): add nonce strategy selection to tx options

* refactor(nonce): get rid of getAccount request

* fix: missing nonce field

* refactor: determine nonce only when not supplied

.env

@@ -1,2 +1,2 @@
-NODE_TAG=v6.1.0
+NODE_TAG=v6.2.0
 COMPILER_TAG=v6.0.0

docs/transaction-options.md

@@ -22,9 +22,14 @@ These options are common and can be provided to every tx-type:
     - You can specify the account that should be used to sign a transaction.
     - Note:
         - The account needs to be provided to the SDK instance in order to be used for signing.
-- `nonce` (default: current nonce of the account obtained via node API + 1)
+- `nonce` (default: obtain nonce of the account via node API)
     - The default behavior might cause problems if you perform many transactions in a short period of time.
     - You might want to implement your own nonce management and provide the nonce "manually".
+    - 2 different strategies to use in order to determine the next nonce, See option `strategy` to learn more.
+- `strategy` (default: `max`)
+    - The strategy to obtain next nonce for an account via node API
+    - If set to `max`, then the greatest nonce seen in the account or currently in the transaction pool is incremented with 1 and returned. 
+    If the strategy is set to `continuity`, then transactions in the mempool are checked if there are gaps - missing nonces that prevent transactions with greater nonces to get included
 - `ttl` (default: `0`)
     - Should be set if you want the transaction to be only valid until a certain block height is reached.
 - `fee` (default: calculated for each tx-type)

src/node.js

@@ -113,7 +113,7 @@ const Node = AsyncInit.compose({
   }
 })
 
-const NODE_GE_VERSION = '6.0.0'
+const NODE_GE_VERSION = '6.2.0'
 const NODE_LT_VERSION = '7.0.0'
 
 export default Node

src/tx/tx.js

@@ -481,14 +481,8 @@ async function getAccountNonce (accountId, nonce) {
  * @param {Object} params Object which contains all tx data
  * @return {Object} { ttl, nonce, fee } Object with account nonce, absolute ttl and transaction fee
  */
-async function prepareTxParams (txType, { senderId, nonce: n, ttl: t, fee: f, gas, absoluteTtl, vsn }) {
-  const account = await this.getAccount(senderId).catch(e => ({ nonce: 0 }))
-  // Is GA account
-  if (account.contractId) {
-    n = 0
-  } else {
-    n = n || (account.nonce + 1)
-  }
+async function prepareTxParams (txType, { senderId, nonce: n, ttl: t, fee: f, gas, absoluteTtl, vsn, strategy }) {
+  n = n || (await this.api.getAccountNextNonce(senderId, { strategy }).catch(e => ({ nextNonce: 1 }))).nextNonce
   const ttl = await calculateTtl.call(this, t, !absoluteTtl)
   const fee = calculateFee(f, txType, { showWarning: this.showWarning, gas, params: R.merge(R.last(arguments), { nonce: n, ttl }), vsn })
   return { fee, ttl, nonce: n }