Merge pull request #269 from input-output-hk/compute_slots_offset

refactor: remove slots_offset and add dynamic calculation

Author: mkoura

README.md

@@ -29,21 +29,6 @@ The library needs working `cardano-cli` (the command is available on `PATH`, `ca
 cluster = clusterlib.ClusterLib(state_dir="path/to/cluster/state_dir")
 ```
 
-On custom testnets that were started in Byron era, you might need to specify a slots offset between Byron epochs and Shelley epochs.
-The "slots_offset" is a difference between number of slots in Byron epochs and in the same number of Shelley epochs.
-
-E.g. for a testnet with parameters
-
-* 100 slots per epoch in Byron era
-* 1000 slots per epoch in Shelley era
-* two epochs in Byron era before forking to Shelley
-
-The offset will be `2 * (1000 - 100) = 1800`.
-
-```python
-cluster = clusterlib.ClusterLib(state_dir="path/to/cluster/state_dir", slots_offset=1800)
-```
-
 ### Transfer funds
 
 ```python

cardano_clusterlib/clusterlib.py

@@ -12,7 +12,6 @@
 from cardano_clusterlib.consts import MAINNET_MAGIC
 from cardano_clusterlib.consts import MultiSigTypeArgs
 from cardano_clusterlib.consts import MultiSlotTypeArgs
-from cardano_clusterlib.consts import SLOTS_OFFSETS
 from cardano_clusterlib.consts import ScriptTypes
 from cardano_clusterlib.consts import Votes
 from cardano_clusterlib.coverage import record_cli_coverage

cardano_clusterlib/clusterlib_helpers.py

@@ -333,3 +333,17 @@ def wait_for_epoch(
 
     LOGGER.debug(f"Expected epoch started; epoch number: {this_epoch}")
     return this_epoch
+
+
+def get_slots_offset(clusterlib_obj: "itp.ClusterLib") -> int:
+    """Get offset of slots from Byron era vs current configuration."""
+    tip = clusterlib_obj.g_query.get_tip()
+    slot = int(tip["slot"])
+    slots_ep_end = int(tip["slotsToEpochEnd"])
+    epoch = int(tip["epoch"])
+
+    slots_total = slot + slots_ep_end
+    slots_shelley = int(clusterlib_obj.epoch_length) * (epoch + 1)
+
+    offset = slots_shelley - slots_total
+    return offset

cardano_clusterlib/clusterlib_klass.py

@@ -36,8 +36,8 @@ class ClusterLib:
     Attributes:
         state_dir: A directory with cluster state files (keys, config files, logs, ...).
         protocol: A cluster protocol - full cardano mode by default.
-        slots_offset: Difference in slots between cluster's start era and current era
-            (e.g. Byron->Mary)
+        slots_offset: Difference in slots between cluster's start era and Shelley era
+            (Byron vs Shelley)
         socket_path: A path to socket file for communication with the node. This overrides the
             `CARDANO_NODE_SOCKET_PATH` environment variable.
         command_era: An era used for CLI commands, by default same as the latest network Era.
@@ -48,7 +48,7 @@ class ClusterLib:
     def __init__(
         self,
         state_dir: itp.FileType,
-        slots_offset: int = 0,
+        slots_offset: tp.Optional[int] = None,
         socket_path: itp.FileType = "",
         command_era: str = consts.CommandEras.LATEST,
     ):
@@ -95,7 +95,8 @@ def __init__(
         else:
             self.magic_args = ["--testnet-magic", str(self.network_magic)]
 
-        self.slots_offset = slots_offset or consts.SLOTS_OFFSETS.get(self.network_magic) or 0
+        self._slots_offset = slots_offset if slots_offset is not None else None
+
         self.ttl_length = 1000
         # TODO: proper calculation based on `utxoCostPerWord` needed
         self._min_change_value = 1800_000
@@ -153,6 +154,13 @@ def cli_version(self) -> version.Version:
             self._cli_version = version.parse(version_str)
         return self._cli_version
 
+    @property
+    def slots_offset(self) -> int:
+        """Get offset of slots from Byron era vs current configuration."""
+        if self._slots_offset is None:
+            self._slots_offset = clusterlib_helpers.get_slots_offset(clusterlib_obj=self)
+        return self._slots_offset
+
     @property
     def g_transaction(self) -> transaction_group.TransactionGroup:
         """Transaction group."""

cardano_clusterlib/consts.py

@@ -4,14 +4,6 @@
 DEFAULT_COIN: tp.Final[str] = "lovelace"
 MAINNET_MAGIC: tp.Final[int] = 764824073
 
-# offset of slots from Byron configuration vs current era configuration
-SLOTS_OFFSETS: tp.Final[tp.Dict[int, int]] = {
-    764824073: 85363200,  # mainnet
-    1097911063: 30369600,  # testnet
-    1: 1641600,  # preprod
-}
-
-
 # The SUBCOMMAND_MARK is used to mark the beginning of a subcommand. It is used to differentiate
 # between options and subcommands. That is needed for CLI coverage recording.
 # For example, the command `cardano-cli query tx-mempool --cardano-mode info`