refactor storage prefix iter

.changelog/unreleased/improvements/1093-unify-native-and-wasm-vp.md

@@ -0,0 +1,3 @@
+- Added WASM transaction and validity predicate `Ctx` with methods for host
+  environment functions to unify the interface of native VPs and WASM VPs under
+  `trait VpEnv` ([#1093](https://github.com/anoma/anoma/pull/1093))

.changelog/unreleased/improvements/331-common-write-storage-trait.md

@@ -0,0 +1,2 @@
+- Added a StorageWrite trait for a common interface for transactions and direct
+  storage access for protocol ([#331](https://github.com/anoma/namada/pull/331))

.changelog/unreleased/improvements/335-refactor-storage-prefix-iter.md

@@ -0,0 +1,3 @@
+- Added a simpler prefix iterator API that returns `std::iter::Iterator` with
+  the storage keys parsed and a variant that also decodes stored values with
+  Borsh ([#335](https://github.com/anoma/namada/pull/335))

apps/src/lib/node/ledger/protocol/mod.rs

@@ -249,10 +249,13 @@ where
                 }
                 Address::Internal(internal_addr) => {
                     let ctx = native_vp::Ctx::new(
+                        addr,
                         storage,
                         write_log,
                         tx,
                         gas_meter,
+                        &keys_changed,
+                        &verifiers,
                         vp_wasm_cache.clone(),
                     );
                     let tx_data = match tx.data.as_ref() {

macros/src/lib.rs

@@ -15,7 +15,10 @@ use syn::{parse_macro_input, DeriveInput, ItemFn};
 /// This macro expects a function with signature:
 ///
 /// ```compiler_fail
-/// fn apply_tx(tx_data: Vec<u8>)
+/// fn apply_tx(
+///     ctx: &mut Ctx,
+///     tx_data: Vec<u8>
+/// ) -> TxResult
 /// ```
 #[proc_macro_attribute]
 pub fn transaction(_attr: TokenStream, input: TokenStream) -> TokenStream {
@@ -38,7 +41,19 @@ pub fn transaction(_attr: TokenStream, input: TokenStream) -> TokenStream {
                 )
             };
             let tx_data = slice.to_vec();
-            #ident(tx_data);
+
+            // The context on WASM side is only provided by the VM once its
+            // being executed (in here it's implicit). But because we want to
+            // have interface consistent with the VP interface, in which the
+            // context is explicit, in here we're just using an empty `Ctx`
+            // to "fake" it.
+            let mut ctx = unsafe { namada_tx_prelude::Ctx::new() };
+
+            if let Err(err) = #ident(&mut ctx, tx_data) {
+                namada_tx_prelude::debug_log!("Transaction error: {}", err);
+                // crash the transaction to abort
+                panic!();
+            }
         }
     };
     TokenStream::from(gen)
@@ -50,11 +65,12 @@ pub fn transaction(_attr: TokenStream, input: TokenStream) -> TokenStream {
 ///
 /// ```compiler_fail
 /// fn validate_tx(
+///     ctx: &Ctx,
 ///     tx_data: Vec<u8>,
 ///     addr: Address,
 ///     keys_changed: BTreeSet<storage::Key>,
 ///     verifiers: BTreeSet<Address>
-/// ) -> bool
+/// ) -> VpResult
 /// ```
 #[proc_macro_attribute]
 pub fn validity_predicate(
@@ -74,7 +90,6 @@ pub fn validity_predicate(
         #[no_mangle]
         extern "C" fn _validate_tx(
             // VP's account's address
-            // TODO Should the address be on demand (a call to host function?)
             addr_ptr: u64,
             addr_len: u64,
             tx_data_ptr: u64,
@@ -113,11 +128,22 @@ pub fn validity_predicate(
             };
             let verifiers: BTreeSet<Address> = BTreeSet::try_from_slice(slice).unwrap();
 
+            // The context on WASM side is only provided by the VM once its
+            // being executed (in here it's implicit). But because we want to
+            // have interface identical with the native VPs, in which the
+            // context is explicit, in here we're just using an empty `Ctx`
+            // to "fake" it.
+            let ctx = unsafe { namada_vp_prelude::Ctx::new() };
+
             // run validation with the concrete type(s)
-            if #ident(tx_data, addr, keys_changed, verifiers) {
-                1
-            } else {
-                0
+            match #ident(&ctx, tx_data, addr, keys_changed, verifiers)
+            {
+                Ok(true) => 1,
+                Ok(false) => 0,
+                Err(err) => {
+                    namada_vp_prelude::debug_log!("Validity predicate error: {}", err);
+                    0
+                },
             }
         }
     };