From e608580040a6bcc9ab600c94510fce6234113e7e Mon Sep 17 00:00:00 2001
From: Brooks Prumo <brooks@solana.com>
Date: Tue, 17 May 2022 11:46:34 -0500
Subject: [PATCH] Add get_stake_minimum_delegation() to rpc_client (#25200)

---
 client/src/nonblocking/rpc_client.rs | 40 +++++++++++++++++++++++++-
 client/src/rpc_client.rs             | 43 +++++++++++++++++++++++++++-
 2 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/client/src/nonblocking/rpc_client.rs b/client/src/nonblocking/rpc_client.rs
index c03dfec1be4b28..f899f723112d43 100644
--- a/client/src/nonblocking/rpc_client.rs
+++ b/client/src/nonblocking/rpc_client.rs
@@ -39,10 +39,11 @@ use {
         epoch_schedule::EpochSchedule,
         fee_calculator::{FeeCalculator, FeeRateGovernor},
         hash::Hash,
+        instruction::InstructionError,
         message::Message,
         pubkey::Pubkey,
         signature::Signature,
-        transaction::{self, uses_durable_nonce, Transaction},
+        transaction::{self, uses_durable_nonce, Transaction, TransactionError},
     },
     solana_transaction_status::{
         EncodedConfirmedBlock, EncodedConfirmedTransactionWithStatusMeta, TransactionStatus,
@@ -4513,6 +4514,43 @@ impl RpcClient {
         parse_keyed_accounts(accounts, RpcRequest::GetProgramAccounts)
     }
 
+    /// Returns the stake minimum delegation, in lamports.
+    pub async fn get_stake_minimum_delegation(&self) -> ClientResult<u64> {
+        let instruction = solana_sdk::stake::instruction::get_minimum_delegation();
+        let transaction = Transaction::new_with_payer(&[instruction], None);
+        let response = self.simulate_transaction(&transaction).await?;
+        let RpcTransactionReturnData {
+            program_id,
+            data: (data, encoding),
+        } = response
+            .value
+            .return_data
+            .ok_or_else(|| ClientErrorKind::Custom("return data was empty".to_string()))?;
+        if Pubkey::from_str(&program_id) != Ok(solana_sdk::stake::program::id()) {
+            return Err(TransactionError::InstructionError(
+                0,
+                InstructionError::IncorrectProgramId,
+            )
+            .into());
+        }
+        if encoding != ReturnDataEncoding::Base64 {
+            return Err(
+                ClientErrorKind::Custom("return data encoding is invalid".to_string()).into(),
+            );
+        }
+        let data = base64::decode(data).map_err(|err| {
+            ClientErrorKind::Custom(format!("failed to decode return data: {}", err))
+        })?;
+        let minimum_delegation = u64::from_le_bytes(data.try_into().map_err(|data: Vec<u8>| {
+            ClientErrorKind::Custom(format!(
+                "return data cannot be represented as a u64: expected size: {}, actual size: {}",
+                std::mem::size_of::<u64>(),
+                data.len()
+            ))
+        })?);
+        Ok(minimum_delegation)
+    }
+
     /// Request the transaction count.
     pub async fn get_transaction_count(&self) -> ClientResult<u64> {
         self.get_transaction_count_with_commitment(self.commitment())
diff --git a/client/src/rpc_client.rs b/client/src/rpc_client.rs
index 89959de20e56fa..67d71a39cc287e 100644
--- a/client/src/rpc_client.rs
+++ b/client/src/rpc_client.rs
@@ -3712,6 +3712,11 @@ impl RpcClient {
         )
     }
 
+    /// Returns the stake minimum delegation, in lamports.
+    pub fn get_stake_minimum_delegation(&self) -> ClientResult<u64> {
+        self.invoke(self.rpc_client.get_stake_minimum_delegation())
+    }
+
     /// Request the transaction count.
     pub fn get_transaction_count(&self) -> ClientResult<u64> {
         self.invoke(self.rpc_client.get_transaction_count())
@@ -4101,7 +4106,7 @@ mod tests {
             system_transaction,
             transaction::TransactionError,
         },
-        std::{io, thread},
+        std::{collections::HashMap, io, thread},
     };
 
     #[test]
@@ -4317,4 +4322,40 @@ mod tests {
         let is_err = rpc_client.get_latest_blockhash().is_err();
         assert!(is_err);
     }
+
+    #[test]
+    fn test_get_stake_minimum_delegation() {
+        let expected_minimum_delegation: u64 = 123_456_789;
+        let rpc_client = {
+            let mocks = {
+                let rpc_response = {
+                    let program_id = solana_sdk::stake::program::id().to_string();
+                    let data = (
+                        base64::encode(expected_minimum_delegation.to_le_bytes()),
+                        ReturnDataEncoding::Base64,
+                    );
+                    serde_json::to_value(Response {
+                        context: RpcResponseContext { slot: 1 },
+                        value: RpcSimulateTransactionResult {
+                            err: None,
+                            logs: None,
+                            accounts: None,
+                            units_consumed: None,
+                            return_data: Some(RpcTransactionReturnData { program_id, data }),
+                        },
+                    })
+                    .unwrap()
+                };
+                let mut mocks = HashMap::new();
+                mocks.insert(RpcRequest::SimulateTransaction, rpc_response);
+                mocks
+            };
+            RpcClient::new_mock_with_mocks("succeeds".to_string(), mocks)
+        };
+
+        let client_result = rpc_client.get_stake_minimum_delegation();
+        assert!(client_result.is_ok());
+        let actual_minimum_delegation = client_result.unwrap();
+        assert_eq!(actual_minimum_delegation, expected_minimum_delegation);
+    }
 }