Reduce shard staking requirement for PoSW

quarkchain/cluster/posw.py

@@ -64,6 +64,7 @@ def get_posw_info(
     header: Header,
     stake_func: Callable[[], int],
     block_cnt: Dict[bytes, int],
+    stake_per_block: Optional[int] = None,
     signer: Optional[bytes] = None,
 ) -> Optional[PoSWInfo]:
     if (
@@ -75,7 +76,9 @@ def get_posw_info(
     # evaluate stakes before the to-be-added block
     stakes = stake_func()
     coinbase_recipient = header.coinbase_address.recipient
-    block_threshold = min(config.WINDOW_SIZE, stakes // config.TOTAL_STAKE_PER_BLOCK)
+
+    required_stakes_per_block = stake_per_block or config.TOTAL_STAKE_PER_BLOCK
+    block_threshold = min(config.WINDOW_SIZE, stakes // required_stakes_per_block)
     cnt = block_cnt.get(coinbase_recipient, 0)
 
     diff = header.difficulty

quarkchain/cluster/root_state.py

@@ -665,4 +665,6 @@ def get_posw_info(
             block.header.hash_prev_block,
             self.db.get_root_block_header_by_hash,
         )
-        return get_posw_info(config, block.header, lambda: stakes, block_cnt, signer)
+        return get_posw_info(
+            config, block.header, lambda: stakes, block_cnt, signer=signer
+        )

quarkchain/cluster/shard_state.py

@@ -1024,22 +1024,13 @@ def add_block(
         return evm_state.xshard_list, coinbase_amount_map
 
     def get_coinbase_amount_map(self, height) -> TokenBalanceMap:
-        epoch = (
-            height
-            // self.env.quark_chain_config.shards[self.full_shard_id].EPOCH_INTERVAL
-        )
-        decay_numerator = (
-            self.env.quark_chain_config.block_reward_decay_factor.numerator ** epoch
-        )
-        decay_denominator = (
-            self.env.quark_chain_config.block_reward_decay_factor.denominator ** epoch
-        )
         coinbase_amount = (
-            self.env.quark_chain_config.shards[self.full_shard_id].COINBASE_AMOUNT
+            self.__decay_by_epoch(
+                self.env.quark_chain_config.shards[self.full_shard_id].COINBASE_AMOUNT,
+                height,
+            )
             * self.local_fee_rate.numerator
-            * decay_numerator
             // self.local_fee_rate.denominator
-            // decay_denominator
         )
         # shard coinbase only in genesis_token
         return TokenBalanceMap(
@@ -1838,6 +1829,10 @@ def _posw_info(self, block: MinorBlock) -> Optional[PoSWInfo]:
         if header.height == 0:  # genesis
             return None
         block_cnt = self._get_posw_coinbase_blockcnt(header.hash_prev_minor_block)
+        # require stakes will decay as our mining rewards
+        stake_per_block = self.__decay_by_epoch(
+            self.shard_config.POSW_CONFIG.TOTAL_STAKE_PER_BLOCK, header.height
+        )
         return get_posw_info(
             self.shard_config.POSW_CONFIG,
             header,
@@ -1848,6 +1843,7 @@ def _posw_info(self, block: MinorBlock) -> Optional[PoSWInfo]:
                 self.env.quark_chain_config.genesis_token,
             ),
             block_cnt,
+            stake_per_block=stake_per_block,
         )
 
     def _get_evm_state_from_height(self, height: Optional[int]) -> Optional[EvmState]:
@@ -1970,3 +1966,16 @@ def _qkchashx_enabled(self, header):
             config.ENABLE_QKCHASHX_HEIGHT is not None
             and header.height >= config.ENABLE_QKCHASHX_HEIGHT
         )
+
+    def __decay_by_epoch(self, value: int, block_height: int):
+        epoch = (
+            block_height
+            // self.env.quark_chain_config.shards[self.full_shard_id].EPOCH_INTERVAL
+        )
+        decay_numerator = (
+            self.env.quark_chain_config.block_reward_decay_factor.numerator ** epoch
+        )
+        decay_denominator = (
+            self.env.quark_chain_config.block_reward_decay_factor.denominator ** epoch
+        )
+        return value * decay_numerator // decay_denominator

quarkchain/cluster/tests/test_shard_state.py

@@ -1532,9 +1532,6 @@ def test_xshard_gas_limit_from_multiple_shards(self):
         env1 = get_test_env(
             genesis_account=acc1, genesis_minor_quarkash=10000000, shard_size=64
         )
-        env2 = get_test_env(
-            genesis_account=acc1, genesis_minor_quarkash=10000000, shard_size=64
-        )
         state0 = create_default_shard_state(env=env0, shard_id=0)
         state1 = create_default_shard_state(env=env1, shard_id=16)
         state2 = create_default_shard_state(env=env1, shard_id=8)
@@ -1679,10 +1676,9 @@ def test_xshard_gas_limit_from_multiple_shards(self):
             10000000 + 1000000 + 12345 + 888888 + 111111,
         )
 
-    def test_xshard_rootblock_coinbase(self):
+    def test_xshard_root_block_coinbase(self):
         id1 = Identity.create_random_identity()
         acc1 = Address.create_from_identity(id1, full_shard_key=0)
-        acc2 = Address.create_from_identity(id1, full_shard_key=16)
 
         env0 = get_test_env(
             genesis_account=acc1, genesis_minor_quarkash=10000000, shard_size=64
@@ -1738,7 +1734,6 @@ def test_xshard_sender_gas_limit(self):
         id1 = Identity.create_random_identity()
         acc1 = Address.create_from_identity(id1, full_shard_key=0)
         acc2 = Address.create_from_identity(id1, full_shard_key=16)
-        acc3 = Address.create_random_account(full_shard_key=0)
 
         env0 = get_test_env(
             genesis_account=acc1, genesis_minor_quarkash=10000000, shard_size=64
@@ -2775,7 +2770,6 @@ def test_enable_tx_timestamp(self):
     def test_enable_evm_timestamp_with_contract_create(self):
         id1 = Identity.create_random_identity()
         acc1 = Address.create_from_identity(id1, full_shard_key=0)
-        acc2 = Address.create_random_account(full_shard_key=0)
 
         env = get_test_env(genesis_account=acc1, genesis_minor_quarkash=10000000)
         state = create_default_shard_state(env=env)
@@ -3727,3 +3721,22 @@ def tx_gen(to):
             state_to.get_token_balance(miner.recipient, token_id=self.genesis_token),
             self.get_after_tax_reward(self.shard_coinbase + (3 * gas_price) * 9000),
         )
+
+    def test_posw_stake_by_block_decay_by_epoch(self):
+        acc = Address(b"\x01" * 20, full_shard_key=0)
+        env = get_test_env(genesis_account=acc, genesis_minor_quarkash=200)
+        state = create_default_shard_state(env=env, shard_id=0, posw_override=True)
+
+        state.shard_config.CONSENSUS_TYPE = ConsensusType.POW_DOUBLESHA256
+        state.shard_config.POSW_CONFIG.TOTAL_STAKE_PER_BLOCK = 100
+        state.shard_config.POSW_CONFIG.WINDOW_SIZE = 256
+
+        b1 = state.get_tip().create_block_to_append(address=acc)
+        posw_info = state._posw_info(b1)
+        # 200 qkc with 100 required per block, should equal 2 mineable blocks
+        self.assertEqual(posw_info.posw_mineable_blocks, 200 / 100)
+
+        # decay (factor = 0.5) should kick in and double mineable blocks
+        b1.header.height = state.shard_config.EPOCH_INTERVAL
+        posw_info = state._posw_info(b1)
+        self.assertEqual(posw_info.posw_mineable_blocks, 200 / (100 / 2))