feat: add finality checking module

contracts/gw-utils/src/error.rs

@@ -52,6 +52,8 @@ pub enum Error {
     DuplicatedScriptHash = 42,
     RegistryAddressNotFound = 43,
     DuplicatedRegistryAddress = 44,
+    NotFinalized = 45,
+    HeaderDepsNotFound = 46,
 }
 
 impl From<SysError> for Error {

contracts/gw-utils/src/finality.rs

@@ -0,0 +1,80 @@
+//! # Finality machenism
+//!
+//! https://talk.nervos.org/t/optimize-godwoken-finality-and-on-chain-cost/6739
+//!
+//! ## Check finality
+//!
+//! - post_version < 2, entity is number-based
+//!   Assert `post_global_state.block.count - 1 + FINALITY_CONFIGURATION >= entity.number`
+//!
+//! - post_version < 2, entity is time-based
+//!   Impossible
+//!
+//! - post_version >= 2, entity is number-based
+//!   Assert `post_global_state.block.count - 1 + FINALITY_CONFIGURATION >= entity.number`
+//!
+//! - post_version >= 2, entity is time-based
+//!   post_global_state.last_finalized_block_number must be time-based.
+//!   Assert `post_global_state.last_finalized_block_number + FINALITY_CONFIGURATION >= entity.time`
+
+use crate::error::Error;
+use ckb_std::{
+    ckb_constants::Source,
+    high_level::{load_header, QueryIter},
+};
+use gw_types::core::Timepoint;
+use gw_types::packed::{GlobalState, RollupConfig};
+use gw_types::prelude::{Entity, Unpack};
+
+// 7 * 24 * 60 * 60 / 16800 * 1000 = 36000
+const BLOCK_INTERVAL_IN_MILLISECONDS: u64 = 36000;
+
+pub fn is_timestamp_finalized(
+    rollup_config: &RollupConfig,
+    global_state: &GlobalState,
+    timestamp: u64,
+) -> Result<bool, Error> {
+    let finality = finality_as_duration(rollup_config);
+    match Timepoint::from_full_value(global_state.last_finalized_block_number().unpack()) {
+        Timepoint::BlockNumber(_) => Err(Error::InvalidPostGlobalState),
+        Timepoint::Timestamp(finalized) => Ok(timestamp <= finalized.saturating_add(finality)),
+    }
+}
+
+pub fn is_block_number_finalized(
+    rollup_config: &RollupConfig,
+    global_state: &GlobalState,
+    block_number: u64,
+) -> bool {
+    let finality = finality_as_blocks(rollup_config);
+    let tip_number: u64 = global_state.block().count().unpack().saturating_sub(1);
+    block_number.saturating_add(finality) <= tip_number
+}
+
+pub fn finality_as_duration(rollup_config: &RollupConfig) -> u64 {
+    match Timepoint::from_full_value(rollup_config.finality_blocks().unpack()) {
+        Timepoint::BlockNumber(block_number) => {
+            block_number.saturating_mul(BLOCK_INTERVAL_IN_MILLISECONDS)
+        }
+        Timepoint::Timestamp(timestamp) => timestamp,
+    }
+}
+
+pub fn finality_as_blocks(rollup_config: &RollupConfig) -> u64 {
+    match Timepoint::from_full_value(rollup_config.finality_blocks().unpack()) {
+        Timepoint::BlockNumber(block_number) => block_number,
+        Timepoint::Timestamp(timestamp) => timestamp / BLOCK_INTERVAL_IN_MILLISECONDS,
+    }
+}
+
+/// Obtain the max timestamp of the header-deps
+pub fn obtain_max_timestamp_of_header_deps() -> Option<u64> {
+    let mut buf = [0u8; 8];
+    QueryIter::new(load_header, Source::HeaderDep)
+        .map(|header| {
+            buf.copy_from_slice(header.raw().timestamp().as_slice());
+            let timestamp: u64 = u64::from_le_bytes(buf);
+            timestamp
+        })
+        .max()
+}

contracts/gw-utils/src/lib.rs

@@ -11,6 +11,7 @@ pub use gw_types;
 
 pub mod cells;
 pub mod error;
+pub mod finality;
 pub mod signature;
 pub mod type_id;
 pub mod withdrawal;