chore: Hint the light account space in LightAccountMeta

examples/name-service/programs/name-service-without-macros/tests/test.rs

@@ -1,6 +1,9 @@
 #![cfg(feature = "test-sbf")]
 
-use std::net::{Ipv4Addr, Ipv6Addr};
+use std::{
+    mem,
+    net::{Ipv4Addr, Ipv6Addr},
+};
 
 use anchor_lang::{AnchorDeserialize, InstructionData, ToAccountMetas};
 use light_client::indexer::test_indexer::TestIndexer;
@@ -297,12 +300,13 @@ where
         address_queue_pubkey: env.address_merkle_tree_queue_pubkey,
     };
     let account = LightAccountMeta::new_init(
-        None,
         &env.merkle_tree_pubkey,
         Some(&address_merkle_context),
         Some(rpc_result.address_root_indices[0]),
+        Some(mem::size_of::<NameRecord>() + name.len()),
         remaining_accounts,
-    );
+    )
+    .unwrap();
 
     let inputs = LightInstructionData {
         proof: Some(rpc_result),

sdk/src/account_info.rs

@@ -79,35 +79,20 @@ impl<'a> LightAccountInfo<'a> {
                 .ok_or(LightSdkError::ExpectedAddressRootIndex)?,
         };
 
+        let data = match meta.space {
+            Some(space) => Vec::with_capacity(space.into()),
+            None => Vec::new(),
+        };
+        let data = Some(Rc::new(RefCell::new(data)));
+
         let account_info = LightAccountInfo {
             input: None,
             owner: Some(*program_id),
             // Needs to be assigned by the program.
             lamports: None,
             // Needs to be assigned by the program.
             discriminator: Some(discriminator),
-            // NOTE(vadorovsky): A `clone()` here is unavoidable.
-            // What we have here is an immutable reference to `LightAccountMeta`,
-            // from which we can take an immutable reference to `data`.
-            //
-            // - That immutable reference can be used in the input account,
-            //   since we don't make modifications there.
-            // - In the most cases, we intend to make modifications for the
-            //   output account. We make a copy, which then we try not to
-            //   copy again until the moment of creating a CPI call.
-            //
-            // The reason why `solana_account_info::AccountInfo` stores data as
-            // `Rc<RefCell<&'a mut [u8]>>` is that the reference points to
-            // runtime's memory region which provides the accout and is mutable
-            // by design.
-            //
-            // In our case, compressed accounts are part of instruction data.
-            // Instruction data is immutable (`&[u8]`). There is no way to
-            // mutate instruction data without copy.
-            data: meta
-                .data
-                .as_ref()
-                .map(|data| Rc::new(RefCell::new(data.clone()))),
+            data,
             // Needs to be assigned by the program.
             data_hash: None,
             address: Some(new_address),

sdk/src/account_meta.rs

@@ -5,6 +5,7 @@ use solana_program::pubkey::Pubkey;
 
 use crate::{
     compressed_account::CompressedAccountWithMerkleContext,
+    error::LightSdkError,
     merkle_context::{
         pack_address_merkle_context, pack_merkle_context, AddressMerkleContext,
         PackedAddressMerkleContext, PackedMerkleContext, RemainingAccounts,
@@ -19,6 +20,14 @@ pub struct LightAccountMeta {
     pub address: Option<[u8; 32]>,
     /// Data of the account.
     pub data: Option<Vec<u8>>,
+    /// Size of the account.
+    ///
+    /// Relevant only for `init` accounts.
+    ///
+    /// This option is not mandatory, but it's recommended and used for
+    /// memory allocation of the new account data in the program. Not
+    /// setting it might result in wasteful re-allocations.
+    pub space: Option<u16>,
     /// Merkle tree.
     pub merkle_context: Option<PackedMerkleContext>,
     /// Merkle tree root index.
@@ -38,26 +47,31 @@ pub struct LightAccountMeta {
 impl LightAccountMeta {
     #[allow(clippy::too_many_arguments)]
     pub fn new_init(
-        data: Option<Vec<u8>>,
         output_merkle_tree: &Pubkey,
         address_merkle_context: Option<&AddressMerkleContext>,
         address_merkle_tree_root_index: Option<u16>,
+        space: Option<usize>,
         remaining_accounts: &mut RemainingAccounts,
-    ) -> Self {
+    ) -> Result<Self, LightSdkError> {
         let output_merkle_tree_index = remaining_accounts.insert_or_get(*output_merkle_tree);
         let address_merkle_context =
             address_merkle_context.map(|ctx| pack_address_merkle_context(ctx, remaining_accounts));
-        Self {
+        let space = match space {
+            Some(space) => Some(space.try_into().map_err(|_| LightSdkError::SpaceTooLarge)?),
+            None => None,
+        };
+        Ok(Self {
             lamports: None,
             address: None,
-            data,
+            data: None,
+            space,
             merkle_context: None,
             merkle_tree_root_index: None,
             output_merkle_tree_index: Some(output_merkle_tree_index),
             address_merkle_context,
             address_merkle_tree_root_index,
             read_only: false,
-        }
+        })
     }
 
     #[allow(clippy::too_many_arguments)]
@@ -82,6 +96,7 @@ impl LightAccountMeta {
                 .data
                 .as_ref()
                 .map(|data| data.data.clone()),
+            space: None,
             merkle_context: Some(merkle_context),
             merkle_tree_root_index: Some(merkle_tree_root_index),
             output_merkle_tree_index: Some(output_merkle_tree_index),
@@ -106,6 +121,7 @@ impl LightAccountMeta {
                 .data
                 .as_ref()
                 .map(|data| data.data.clone()),
+            space: None,
             merkle_context: Some(merkle_context),
             merkle_tree_root_index: Some(merkle_tree_root_index),
             output_merkle_tree_index: None,

sdk/src/error.rs

@@ -22,6 +22,8 @@ pub enum LightSdkError {
     ExpectedMerkleContext,
     #[msg("Expected root index to be provided")]
     ExpectedRootIndex,
+    #[msg("Provided account space is too large")]
+    SpaceTooLarge,
     #[msg("Cannot transfer lamports from an account without input")]
     TransferFromNoInput,
     #[msg("Cannot transfer from an account without lamports")]

test-programs/sdk-test-program/programs/sdk-test/tests/test.rs

@@ -161,7 +161,6 @@ where
         address_queue_pubkey: env.address_merkle_tree_queue_pubkey,
     };
     let account = LightAccountMeta::new_init(
-        None,
         &env.merkle_tree_pubkey,
         Some(&address_merkle_context),
         Some(rpc_result.address_root_indices[0]),