[WIP] Implementation of EIP-1153: Transient Storage using Disk Persistence and Lifecycle Management

actors/evm/src/interpreter/execution.rs

@@ -163,6 +163,8 @@ pub mod opcodes {
         0x59: MSIZE,
         0x5a: GAS,
         0x5b: JUMPDEST,
+        0x5c: TLOAD,
+        0x5d: TSTORE,
         0x5e: MCOPY,
         0x5F: PUSH0,
         0x60: PUSH1,
@@ -400,6 +402,8 @@ mod tests {
             MSTORE8,
             SLOAD,
             SSTORE,
+            TLOAD,
+            TSTORE,
             LOG0,
             LOG1,
             LOG2,

actors/evm/src/interpreter/instructions/mod.rs

@@ -338,6 +338,8 @@ def_stdproc! { MSTORE(a, b) => memory::mstore }
 def_stdproc! { MSTORE8(a, b) => memory::mstore8 }
 def_stdfun! { SLOAD(a) => storage::sload }
 def_stdproc! { SSTORE(a, b) => storage::sstore }
+def_stdfun! { TLOAD(a) => storage::tload }
+def_stdproc! { TSTORE(a, b) => storage::tstore }
 def_stdfun! { MSIZE() => memory::msize }
 def_stdfun! { GAS() => context::gas }
 def_stdlog! { LOG0(0, ()) }

actors/evm/src/interpreter/instructions/storage.rs

@@ -30,6 +30,30 @@ pub fn sstore(
     system.set_storage(key, value)
 }
 
+#[inline]
+pub fn tload(
+    _state: &mut ExecutionState,
+    system: &mut System<impl Runtime>,
+    location: U256,
+) -> Result<U256, ActorError> {
+    // get from storage and place on stack
+    system.get_transient_storage(location)
+}
+
+#[inline]
+pub fn tstore(
+    _state: &mut ExecutionState,
+    system: &mut System<impl Runtime>,
+    key: U256,
+    value: U256,
+) -> Result<(), ActorError> {
+    if system.readonly {
+        return Err(ActorError::read_only("store called while read-only".into()));
+    }
+
+    system.set_transient_storage(key, value)
+}
+
 #[cfg(test)]
 mod tests {
     use fil_actors_evm_shared::uints::U256;
@@ -82,4 +106,53 @@ mod tests {
             assert_eq!(m.system.get_storage(U256::from(0)).unwrap(), U256::from(0x42));
         };
     }
+
+    // TODO test transient storage lifecycle
+
+    #[test]
+    fn test_tload() {
+        // happy path
+        evm_unit_test! {
+            (m) {
+                TLOAD;
+            }
+            m.system.set_transient_storage(U256::from(0), U256::from(0x42)).unwrap();
+            m.state.stack.push(U256::from(0)).unwrap();
+            let result = m.step();
+            assert!(result.is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 1);
+            assert_eq!(m.state.stack.pop().unwrap(), U256::from(0x42));
+        };
+    }
+
+    #[test]
+    fn test_tload_oob() {
+        // oob access -- it is a zero
+        evm_unit_test! {
+            (m) {
+                TLOAD;
+            }
+            m.state.stack.push(U256::from(1234)).unwrap();
+            let result = m.step();
+            assert!(result.is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 1);
+            assert_eq!(m.state.stack.pop().unwrap(), U256::from(0));
+        };
+    }
+
+    #[test]
+    fn test_tstore() {
+        evm_unit_test! {
+            (m) {
+                TSTORE;
+            }
+
+            m.state.stack.push(U256::from(0x42)).unwrap();
+            m.state.stack.push(U256::from(0)).unwrap();
+            let result = m.step();
+            assert!(result.is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+            assert_eq!(m.system.get_transient_storage(U256::from(0)).unwrap(), U256::from(0x42));
+        };
+    }
 }

actors/evm/src/interpreter/system.rs

@@ -16,7 +16,7 @@ use fvm_shared::error::{ErrorNumber, ExitCode};
 use fvm_shared::sys::SendFlags;
 use fvm_shared::{MethodNum, Response, IPLD_RAW, METHOD_SEND};
 
-use crate::state::{State, Tombstone};
+use crate::state::{State, Tombstone, TransientDataLifespan};
 use crate::BytecodeHash;
 
 use cid::Cid;
@@ -91,6 +91,11 @@ pub struct System<'r, RT: Runtime> {
     bytecode: Option<EvmBytecode>,
     /// The contract's EVM storage slots.
     slots: StateKamt<RT::Blockstore>,
+
+    /// The contract's EVM transient storage slots.
+    transient_slots: StateKamt<RT::Blockstore>,
+    pub(crate) transient_data_lifespan: Option<TransientDataLifespan>,
+
     /// The contracts "nonce" (incremented when creating new actors).
     pub(crate) nonce: u64,
     /// The last saved state root. None if the current state hasn't been saved yet.
@@ -111,9 +116,12 @@ impl<'r, RT: Runtime> System<'r, RT> {
         RT::Blockstore: Clone,
     {
         let store = rt.store().clone();
+        let transient_store = rt.store().clone();
         Self {
             rt,
             slots: StateKamt::new_with_config(store, KAMT_CONFIG.clone()),
+            transient_slots: StateKamt::new_with_config(transient_store, KAMT_CONFIG.clone()),
+            transient_data_lifespan: None,
             nonce: 1,
             saved_state_root: None,
             bytecode: None,
@@ -164,6 +172,7 @@ impl<'r, RT: Runtime> System<'r, RT> {
         RT::Blockstore: Clone,
     {
         let store = rt.store().clone();
+        let transient_store = rt.store().clone();
         let state_root = rt.get_state_root()?;
         let state: State = store
             .get_cbor(&state_root)
@@ -182,6 +191,13 @@ impl<'r, RT: Runtime> System<'r, RT> {
             rt,
             slots: StateKamt::load_with_config(&state.contract_state, store, KAMT_CONFIG.clone())
                 .context_code(ExitCode::USR_ILLEGAL_STATE, "state not in blockstore")?,
+            transient_slots: StateKamt::load_with_config(
+                &state.transient_state,
+                transient_store,
+                KAMT_CONFIG.clone(),
+            )
+            .context_code(ExitCode::USR_ILLEGAL_STATE, "state not in blockstore")?,
+            transient_data_lifespan: state.transient_data_lifespan,
             nonce: state.nonce,
             saved_state_root: Some(state_root),
             bytecode: Some(EvmBytecode::new(state.bytecode, state.bytecode_hash)),
@@ -255,7 +271,7 @@ impl<'r, RT: Runtime> System<'r, RT> {
         Ok(result.map_err(|e| e.0))
     }
 
-    /// Flush the actor state (bytecode, nonce, and slots).
+    /// Flush the actor state (bytecode, nonce, transient data and slots).
     pub fn flush(&mut self) -> Result<(), ActorError> {
         if self.saved_state_root.is_some() {
             return Ok(());
@@ -281,6 +297,11 @@ impl<'r, RT: Runtime> System<'r, RT> {
                         ExitCode::USR_ILLEGAL_STATE,
                         "failed to flush contract state",
                     )?,
+                    transient_state: self.transient_slots.flush().context_code(
+                        ExitCode::USR_ILLEGAL_STATE,
+                        "failed to flush contract state",
+                    )?,
+                    transient_data_lifespan: self.transient_data_lifespan,
                     nonce: self.nonce,
                     tombstone: self.tombstone,
                 },
@@ -314,6 +335,10 @@ impl<'r, RT: Runtime> System<'r, RT> {
         self.slots
             .set_root(&state.contract_state)
             .context_code(ExitCode::USR_ILLEGAL_STATE, "state not in blockstore")?;
+        self.transient_slots
+            .set_root(&state.transient_state)
+            .context_code(ExitCode::USR_ILLEGAL_STATE, "transient_state not in blockstore")?;
+        self.transient_data_lifespan = state.transient_data_lifespan;
         self.nonce = state.nonce;
         self.saved_state_root = Some(root);
         self.bytecode = Some(EvmBytecode::new(state.bytecode, state.bytecode_hash));
@@ -384,6 +409,38 @@ impl<'r, RT: Runtime> System<'r, RT> {
         };
         Ok(())
     }
+    ///
+    /// Get value of a storage key.
+    pub fn get_transient_storage(&mut self, key: U256) -> Result<U256, ActorError> {
+        //TODO check tombstone for liveliness of data
+        Ok(self
+            .transient_slots
+            .get(&key)
+            .context_code(ExitCode::USR_ILLEGAL_STATE, "failed to clear storage slot")?
+            .cloned()
+            .unwrap_or_default())
+    }
+
+    /// Set value of a storage key.
+    pub fn set_transient_storage(&mut self, key: U256, value: U256) -> Result<(), ActorError> {
+        //TODO check tombstone for liveliness of data
+        let changed = if value.is_zero() {
+            self.transient_slots
+                .delete(&key)
+                .map(|v| v.is_some())
+                .context_code(ExitCode::USR_ILLEGAL_STATE, "failed to clear storage slot")?
+        } else {
+            self.transient_slots
+                .set(key, value)
+                .map(|v| v != Some(value))
+                .context_code(ExitCode::USR_ILLEGAL_STATE, "failed to update storage slot")?
+        };
+
+        if changed {
+            self.saved_state_root = None; // dirty.
+        };
+        Ok(())
+    }
 
     /// Resolve the address to the ethereum equivalent, if possible.
     ///

actors/evm/src/state.rs

@@ -17,6 +17,15 @@ pub struct Tombstone {
     pub nonce: u64,
 }
 
+/// A structure representing the transient data lifespan.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Serialize_tuple, Deserialize_tuple)]
+pub struct TransientDataLifespan {
+    /// The origin actor ID associated with the transient data.
+    pub origin: ActorID,
+    /// A unique nonce identifying the transaction.
+    pub nonce: u64,
+}
+
 /// A Keccak256 digest of EVM bytecode.
 #[derive(Deserialize, Serialize, Clone, Copy, Eq, PartialEq)]
 #[serde(transparent)]
@@ -106,6 +115,11 @@ pub struct State {
     /// KAMT<U256, U256>
     pub contract_state: Cid,
 
+    /// The EVM contract state diciontary that represents the transient storage
+    pub transient_state: Cid,
+    /// The nonce and actor id that represents the lifespan of the transient storage data
+    pub transient_data_lifespan: Option<TransientDataLifespan>,
+
     /// The EVM nonce used to track how many times CREATE or CREATE2 have been called.
     pub nonce: u64,