Add support of anchor deserialzation (#93)

* Add support of anchor deserialization

* cleanup

* cleanup

* Remove the redundant automatically_derived

* Use PriceAccount for anchor recommended deserialization

* It seems to work!

* It works

* Use PriceFeed and implement Deref

Author: yhzhang0128

examples/sol-anchor-contract/.gitignore

@@ -6,3 +6,4 @@ target
 **/*.rs.bk
 node_modules
 test-ledger
+program_address.json

examples/sol-anchor-contract/Anchor.toml

@@ -1,5 +1,5 @@
 [programs.devnet]
-example_sol_anchor_contract = "9azQ2ePzPvMPQgHric53kdSNmwjVM5KijDE4ANFCE9D4"
+example_sol_anchor_contract = "BZh3CP454Ca1C9yBp2tpGAkXoKFti9x8ShJLSxNDpoxa"
 
 [provider]
 cluster = "devnet"

examples/sol-anchor-contract/programs/example-sol-anchor-contract/Cargo.toml

@@ -17,5 +17,6 @@ default = []
 
 [dependencies]
 anchor-lang = "0.25.0"
+pyth-sdk = { path = "../../../../pyth-sdk", version = "0.7.0" }
 pyth-sdk-solana = { path = "../../../../pyth-sdk-solana", version = "0.7.0" }
 solana-program = ">= 1.10, < 1.15"

examples/sol-anchor-contract/programs/example-sol-anchor-contract/src/error.rs

@@ -0,0 +1,23 @@
+use anchor_lang::prelude::*;
+
+#[error_code]
+pub enum ErrorCode {
+    #[msg("You are not authorized to perform this action.")]
+    Unauthorized,
+    #[msg("The config has already been initialized.")]
+    ReInitialize,
+    #[msg("The config has not been initialized.")]
+    UnInitialize,
+    #[msg("Argument is invalid.")]
+    InvalidArgument,
+    #[msg("An overflow occurs.")]
+    Overflow,
+    #[msg("Pyth has an internal error.")]
+    PythError,
+    #[msg("Pyth price oracle is offline.")]
+    PythOffline,
+    #[msg("The loan value is higher than the collateral value.")]
+    LoanValueTooHigh,
+    #[msg("Program should not try to serialize a price account.")]
+    TryToSerializePriceAccount,
+}

examples/sol-anchor-contract/programs/example-sol-anchor-contract/src/lib.rs

@@ -1,15 +1,15 @@
 use std::mem::size_of;
 use anchor_lang::prelude::*;
 use solana_program::account_info::AccountInfo;
-use pyth_sdk_solana::load_price_feed_from_account_info;
 
-declare_id!("9azQ2ePzPvMPQgHric53kdSNmwjVM5KijDE4ANFCE9D4");
+pub mod state;
+use state::PriceFeed;
+use state::AdminConfig;
 
-#[account]
-pub struct AdminConfig {
-    pub loan_price_feed_id:       Pubkey,
-    pub collateral_price_feed_id: Pubkey,
-}
+mod error;
+use error::ErrorCode;
+
+declare_id!("BZh3CP454Ca1C9yBp2tpGAkXoKFti9x8ShJLSxNDpoxa");
 
 #[derive(Accounts)]
 pub struct InitRequest<'info> {
@@ -25,12 +25,10 @@ pub struct InitRequest<'info> {
 #[derive(Accounts)]
 pub struct QueryRequest<'info> {
     pub config: Account<'info, AdminConfig>,
-    /// CHECK: Pyth structs don't seem to support Anchor deserialization
     #[account(address = config.loan_price_feed_id @ ErrorCode::InvalidArgument)]
-    pub pyth_loan_account: AccountInfo<'info>,
-    /// CHECK: Pyth structs don't seem to support Anchor deserialization
+    pub pyth_loan_account: Account<'info, PriceFeed>,
     #[account(address = config.collateral_price_feed_id @ ErrorCode::InvalidArgument)]
-    pub pyth_collateral_account: AccountInfo<'info>,
+    pub pyth_collateral_account: Account<'info, PriceFeed>,
 }
 
 #[program]
@@ -46,66 +44,63 @@ pub mod example_sol_anchor_contract {
         msg!("Loan quantity is {}.", loan_qty);
         msg!("Collateral quantity is {}.", collateral_qty);
 
-        let pyth_loan_account = &ctx.accounts.pyth_loan_account;
-        let pyth_collateral_account = &ctx.accounts.pyth_collateral_account;
+
+        let loan_feed = &ctx.accounts.pyth_loan_account;
+        let collateral_feed = &ctx.accounts.pyth_collateral_account;
         // With high confidence, the maximum value of the loan is
         // (price + conf) * loan_qty * 10 ^ (expo).
         // Here is more explanation on confidence interval in Pyth:
         // https://docs.pyth.network/consume-data/best-practices
-        let feed1 = load_price_feed_from_account_info(pyth_loan_account)
-            .map_err(|_x| error!(ErrorCode::PythError))?;
         let current_timestamp1 = Clock::get()?.unix_timestamp;
-        let result1 = feed1
+        let loan_price = loan_feed
             .get_price_no_older_than(current_timestamp1, 60)
             .ok_or(ErrorCode::PythOffline)?;
-        let loan_max_price = result1
+        let loan_max_price = loan_price
             .price
-            .checked_add(result1.conf as i64)
+            .checked_add(loan_price.conf as i64)
             .ok_or(ErrorCode::Overflow)?;
         let mut loan_max_value = loan_max_price
             .checked_mul(loan_qty)
             .ok_or(ErrorCode::Overflow)?;
         msg!(
             "The maximum loan value is {} * 10^({}).",
             loan_max_value,
-            result1.expo
+            loan_price.expo
         );
 
         // With high confidence, the minimum value of the collateral is
         // (price - conf) * collateral_qty * 10 ^ (expo).
         // Here is more explanation on confidence interval in Pyth:
         // https://docs.pyth.network/consume-data/best-practices
-        let feed2 = load_price_feed_from_account_info(pyth_collateral_account)
-                        .map_err(|_x| error!(ErrorCode::PythError))?;
         let current_timestamp2 = Clock::get()?.unix_timestamp;
-        let result2 = feed2
+        let collateral_price = collateral_feed
             .get_price_no_older_than(current_timestamp2, 60)
             .ok_or(ErrorCode::PythOffline)?;
-        let collateral_min_price = result2
+        let collateral_min_price = collateral_price
             .price
-            .checked_sub(result2.conf as i64)
+            .checked_sub(collateral_price.conf as i64)
             .ok_or(ErrorCode::Overflow)?;
         let mut collateral_min_value = collateral_min_price
             .checked_mul(collateral_qty)
             .ok_or(ErrorCode::Overflow)?;
         msg!(
             "The minimum collateral value is {} * 10^({}).",
             collateral_min_value,
-            result2.expo
+            collateral_price.expo
         );
 
         // If the loan and collateral prices use different exponent,
         // normalize the value.
-        if result1.expo > result2.expo {
+        if loan_price.expo > collateral_price.expo {
             let normalize = (10 as i64)
-                .checked_pow((result1.expo - result2.expo) as u32)
+                .checked_pow((loan_price.expo - collateral_price.expo) as u32)
                 .ok_or(ErrorCode::Overflow)?;
             collateral_min_value = collateral_min_value
                 .checked_mul(normalize)
                 .ok_or(ErrorCode::Overflow)?;
-        } else if result1.expo < result2.expo {
+        } else if loan_price.expo < collateral_price.expo {
             let normalize = (10 as i64)
-                .checked_pow((result2.expo - result1.expo) as u32)
+                .checked_pow((collateral_price.expo - loan_price.expo) as u32)
                 .ok_or(ErrorCode::Overflow)?;
             loan_max_value = loan_max_value
                 .checked_mul(normalize)
@@ -121,23 +116,3 @@ pub mod example_sol_anchor_contract {
         }
     }
 }
-
-#[error_code]
-pub enum ErrorCode {
-    #[msg("You are not authorized to perform this action.")]
-    Unauthorized,
-    #[msg("The config has already been initialized.")]
-    ReInitialize,
-    #[msg("The config has not been initialized.")]
-    UnInitialize,
-    #[msg("Argument is invalid.")]
-    InvalidArgument,
-    #[msg("An overflow occurs.")]
-    Overflow,
-    #[msg("Pyth has an internal error.")]
-    PythError,
-    #[msg("Pyth price oracle is offline.")]
-    PythOffline,
-    #[msg("The loan value is higher than the collateral value.")]
-    LoanValueTooHigh,
-}

examples/sol-anchor-contract/programs/example-sol-anchor-contract/src/state.rs

@@ -0,0 +1,50 @@
+use std::ops::Deref;
+use std::str::FromStr;
+use anchor_lang::prelude::*;
+use pyth_sdk_solana::state::load_price_account;
+
+use crate::ErrorCode;
+
+#[account]
+pub struct AdminConfig {
+    pub loan_price_feed_id:       Pubkey,
+    pub collateral_price_feed_id: Pubkey,
+}
+
+#[derive(Clone)]
+pub struct PriceFeed (pyth_sdk::PriceFeed);
+
+impl anchor_lang::Owner for PriceFeed {
+    fn owner() -> Pubkey {
+        // Make sure the owner is the pyth oracle account on solana devnet
+        let oracle_addr = "gSbePebfvPy7tRqimPoVecS2UsBvYv46ynrzWocc92s";
+        return  Pubkey::from_str(&oracle_addr).unwrap();
+    }
+}
+
+impl anchor_lang::AccountDeserialize for PriceFeed {
+    fn try_deserialize_unchecked(data: &mut &[u8]) -> Result<Self>{
+        let account = load_price_account(data)
+            .map_err(|_x| error!(ErrorCode::PythError))?;
+
+        // Use a dummy key since the key field will be removed from the SDK
+        let zeros: [u8; 32] = [0; 32];
+        let dummy_key = Pubkey::new(&zeros);
+        let feed = account.to_price_feed(&dummy_key);
+        return Ok(PriceFeed(feed));
+    }
+}
+
+impl anchor_lang::AccountSerialize for PriceFeed {
+    fn try_serialize<W: std::io::Write>(&self, _writer: &mut W,) -> std::result::Result<(), Error> {
+        Err(error!(ErrorCode::TryToSerializePriceAccount))
+    }
+}
+
+impl Deref for PriceFeed {
+    type Target = pyth_sdk::PriceFeed;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}