Top Down Checkpoint - Parent View

fendermint/vm/topdown/Cargo.toml

@@ -17,3 +17,5 @@ serde_json = { workspace = true }
 cid = { workspace = true }
 fvm_ipld_encoding = { workspace = true }
 num-traits = { workspace = true }
+async-stm = { workspace = true }
+thiserror = { workspace = true }

fendermint/vm/topdown/src/error.rs

@@ -0,0 +1,47 @@
+// Copyright 2022-2023 Protocol Labs
+// SPDX-License-Identifier: Apache-2.0, MIT
+
+use crate::{BlockHeight, Bytes, Nonce};
+use thiserror::Error;
+
+/// The errors for top down checkpointing
+#[derive(Error, Debug, Eq, PartialEq, Clone)]
+pub enum Error {
+    #[error("The latest height of the parent view is not ready")]
+    HeightNotReady,
+    #[error("The latest height has yet to reach the configured threshold")]
+    HeightThresholdNotReached,
+    #[error("The data specified in this height is not found in cache")]
+    HeightNotFoundInCache(BlockHeight),
+    #[error("Exceeding current parent view's latest block height.")]
+    ExceedingLatestHeight {
+        proposal: BlockHeight,
+        parent: BlockHeight,
+    },
+    #[error("The block height in the proposal is already committed")]
+    HeightAlreadyCommitted(BlockHeight),
+    #[error("Proposal's block hash and parent's block hash not match")]
+    BlockHashNotMatch {
+        proposal: Bytes,
+        parent: Bytes,
+        height: BlockHeight,
+    },
+    #[error("Proposal's block hash at height not found in parent view")]
+    BlockHashNotFound(BlockHeight),
+    #[error("Proposal's validator set and that of the parent view not match")]
+    ValidatorSetNotMatch(BlockHeight),
+    #[error("Proposal's validator set at height not found in parent view")]
+    ValidatorSetNotFound(BlockHeight),
+    #[error("Proposal's min top down msg nonce is smaller than the last committed nonce")]
+    InvalidNonce {
+        proposal: Nonce,
+        parent: Nonce,
+        block: BlockHeight,
+    },
+    #[error("Parent block chain reorg detected")]
+    ParentReorgDetected(BlockHeight),
+    #[error("Incoming top down messages are not order by nonce sequentially")]
+    NonceNotSequential,
+    #[error("First ever top down message does not have starting nonce")]
+    NotStartingNonce(Nonce),
+}