[predictoor] Infinite token approval and cache allowance

pdr_backend/predictoor/main.py

@@ -15,6 +15,7 @@
 
 last_block_time = 0
 topics: Dict[str, dict] = {}
+contract_map: Dict[str, PredictoorContract] = {}
 
 rpc_url = env.get_rpc_url_or_exit()
 subgraph_url = env.get_subgraph_or_exit()
@@ -42,7 +43,9 @@ def process_block(block):
     print(f"Got new block: {block['number']} with {len(topics)} topics")
     for address in topics:
         topic = topics[address]
-        predictoor_contract = PredictoorContract(web3_config, address)
+        if contract_map.get(address) is None:
+            contract_map[address] = PredictoorContract(web3_config, address)
+        predictoor_contract = contract_map[address]
         epoch = predictoor_contract.get_current_epoch()
         seconds_per_epoch = predictoor_contract.get_secondsPerEpoch()
         seconds_till_epoch_end = (

pdr_backend/utils/constants.py

@@ -1,4 +1,6 @@
 ZERO_ADDRESS = "0x0000000000000000000000000000000000000000"
+MAX_UINT = 2**256 - 1
+
 SAPPHIRE_TESTNET_RPC = "https://testnet.sapphire.oasis.dev"
 SAPPHIRE_TESTNET_CHAINID = 23295
 SAPPHIRE_MAINNET_RPC = "https://sapphire.oasis.io"

pdr_backend/utils/contract.py

@@ -18,11 +18,11 @@
 from web3.middleware import construct_sign_and_send_raw_middleware
 from web3.logs import DISCARD
 
-
 from pdr_backend.utils.constants import (
     ZERO_ADDRESS,
     SAPPHIRE_TESTNET_CHAINID,
     SAPPHIRE_MAINNET_CHAINID,
+    MAX_UINT,
 )
 
 keys = KeyAPI(NativeECCBackend)
@@ -127,6 +127,7 @@ def __init__(self, config: Web3Config, address: str):
         )
         stake_token = self.get_stake_token()
         self.token = Token(config, stake_token)
+        self.last_allowance = 0
 
     def is_valid_subscription(self):
         return self.contract_instance.functions.isValidSubscription(
@@ -364,17 +365,18 @@ def submit_prediction(
         amount_wei = self.config.w3.to_wei(str(stake_amount), "ether")
 
         # Check allowance first, only approve if needed
-        current_allowance = self.token.allowance(
-            self.config.owner, self.contract_address
-        )
-        if current_allowance < amount_wei:
+        if self.last_allowance <= 0:
+            self.last_allowance = self.token.allowance(
+                self.config.owner, self.contract_address
+            )
+        if self.last_allowance < amount_wei:
             try:
-                self.token.approve(self.contract_address, amount_wei)
+                self.token.approve(self.contract_address, MAX_UINT)
+                self.last_allowance = MAX_UINT
             except Exception as e:
                 print("Error while approving the contract to spend tokens:", e)
                 return None
 
-        self.token.approve(self.contract_address, amount_wei)
         gasPrice = self.config.w3.eth.gas_price
         try:
             txhash = None
@@ -405,7 +407,7 @@ def submit_prediction(
                     predicted_value, amount_wei, prediction_ts
                 ).transact({"from": self.config.owner, "gasPrice": gasPrice})
                 txhash = tx.hex()
-
+            self.last_allowance -= amount_wei
             print(f"Submitted prediction, txhash: {txhash}")
             if not wait_for_receipt:
                 return txhash