From 4c4b7d39b8e64b336085e3620e52bc8797d78aad Mon Sep 17 00:00:00 2001
From: Jack May <jack@solana.com>
Date: Fri, 6 Sep 2019 14:44:41 -0700
Subject: [PATCH] Cleanup program's ProcessInstruction (#5828)

---
 programs/bpf/rust/external_spend/src/lib.rs |  3 ++-
 programs/bpf/rust/noop/src/lib.rs           |  5 ++--
 programs/bpf/rust/tick_height/src/lib.rs    |  3 ++-
 sdk/src/entrypoint.rs                       | 28 ++++++++++-----------
 4 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/programs/bpf/rust/external_spend/src/lib.rs b/programs/bpf/rust/external_spend/src/lib.rs
index 705f4c696..a50ecca43 100644
--- a/programs/bpf/rust/external_spend/src/lib.rs
+++ b/programs/bpf/rust/external_spend/src/lib.rs
@@ -3,9 +3,10 @@
 extern crate solana_sdk;
 use solana_sdk::entrypoint;
 use solana_sdk::entrypoint::*;
+use solana_sdk::pubkey::Pubkey;
 
 entrypoint!(process_instruction);
-fn process_instruction(ka: &mut [SolKeyedAccount], _info: &SolClusterInfo, _data: &[u8]) -> bool {
+fn process_instruction(_program_id: &Pubkey, ka: &mut [SolKeyedAccount], _data: &[u8]) -> bool {
     // account 0 is the mint and not owned by this program, any debit of its lamports
     // should result in a failed program execution.  Test to ensure that this debit
     // is seen by the runtime and fails as expected
diff --git a/programs/bpf/rust/noop/src/lib.rs b/programs/bpf/rust/noop/src/lib.rs
index a09ed3bc3..1b31b415b 100644
--- a/programs/bpf/rust/noop/src/lib.rs
+++ b/programs/bpf/rust/noop/src/lib.rs
@@ -5,6 +5,7 @@
 extern crate solana_sdk;
 use solana_sdk::entrypoint::*;
 use solana_sdk::log::*;
+use solana_sdk::pubkey::Pubkey;
 use solana_sdk::{entrypoint, info};
 
 #[derive(Debug, PartialEq)]
@@ -20,9 +21,9 @@ fn return_sstruct() -> SStruct {
 }
 
 entrypoint!(process_instruction);
-fn process_instruction(ka: &mut [SolKeyedAccount], info: &SolClusterInfo, data: &[u8]) -> bool {
+fn process_instruction(program_id: &Pubkey, ka: &mut [SolKeyedAccount], data: &[u8]) -> bool {
     info!("Program identifier:");
-    info.program_id.log();
+    program_id.log();
 
     // Log the provided account keys and instruction input data.  In the case of
     // the no-op program, no account keys or input data are expected but real
diff --git a/programs/bpf/rust/tick_height/src/lib.rs b/programs/bpf/rust/tick_height/src/lib.rs
index 78d5908ff..888f67f7e 100644
--- a/programs/bpf/rust/tick_height/src/lib.rs
+++ b/programs/bpf/rust/tick_height/src/lib.rs
@@ -3,10 +3,11 @@
 extern crate solana_sdk;
 use byteorder::{ByteOrder, LittleEndian};
 use solana_sdk::entrypoint::*;
+use solana_sdk::pubkey::Pubkey;
 use solana_sdk::{entrypoint, info};
 
 entrypoint!(process_instruction);
-fn process_instruction(ka: &mut [SolKeyedAccount], _info: &SolClusterInfo, _data: &[u8]) -> bool {
+fn process_instruction(_program_id: &Pubkey, ka: &mut [SolKeyedAccount], _data: &[u8]) -> bool {
     let tick_height = LittleEndian::read_u64(ka[2].data);
     assert_eq!(10u64, tick_height);
 
diff --git a/sdk/src/entrypoint.rs b/sdk/src/entrypoint.rs
index 2e7388968..2deb04927 100644
--- a/sdk/src/entrypoint.rs
+++ b/sdk/src/entrypoint.rs
@@ -1,10 +1,10 @@
 //! @brief Solana Rust-based BPF program entrypoint and its parameter types
 extern crate alloc;
 
+use crate::pubkey::Pubkey;
 use alloc::vec::Vec;
 use core::mem::size_of;
 use core::slice::{from_raw_parts, from_raw_parts_mut};
-use crate::pubkey::Pubkey;
 
 /// Keyed Account
 pub struct SolKeyedAccount<'a> {
@@ -20,17 +20,18 @@ pub struct SolKeyedAccount<'a> {
     pub owner: &'a Pubkey,
 }
 
-/// Information about the state of the cluster immediately before the program
-/// started executing the current instruction
-pub struct SolClusterInfo<'a> {
-    /// program_id of the currently executing program
-    pub program_id: &'a Pubkey,
-}
+/// User implemented program entrypoint
+///
+/// program_id: Program ID of the currently executing program
+/// accounts: Accounts passed as part of the instruction
+/// data: Instruction data
+pub type ProcessInstruction =
+    fn(program_id: &Pubkey, accounts: &mut [SolKeyedAccount], data: &[u8]) -> bool;
 
 /// Declare entrypoint of the program.
 ///
 /// Deserialize the program input parameters and call
-/// a user defined entrypoint.  Users must call
+/// the user defined `ProcessInstruction`.  Users must call
 /// this function otherwise an entrypoint for
 /// their program will not be created.
 #[macro_export]
@@ -38,9 +39,9 @@ macro_rules! entrypoint {
     ($process_instruction:ident) => {
         #[no_mangle]
         pub unsafe extern "C" fn entrypoint(input: *mut u8) -> bool {
-            unsafe {
-                if let Ok((mut kas, info, data)) = $crate::entrypoint::deserialize(input) {
-                    $process_instruction(&mut kas, &info, &data)
+               unsafe {
+                if let Ok((program_id, mut kas, data)) = $crate::entrypoint::deserialize(input) {
+                    $process_instruction(&program_id, &mut kas, &data)
                 } else {
                     false
                 }
@@ -53,7 +54,7 @@ macro_rules! entrypoint {
 #[allow(clippy::type_complexity)]
 pub unsafe fn deserialize<'a>(
     input: *mut u8,
-) -> Result<(Vec<SolKeyedAccount<'a>>, SolClusterInfo<'a>, &'a [u8]), ()> {
+) -> Result<(&'a Pubkey, Vec<SolKeyedAccount<'a>>, &'a [u8]), ()> {
     let mut offset: usize = 0;
 
     // Number of KeyedAccounts present
@@ -111,7 +112,6 @@ pub unsafe fn deserialize<'a>(
     // Program Id
 
     let program_id: &Pubkey = &*(input.add(offset) as *const Pubkey);
-    let info = SolClusterInfo { program_id };
 
-    Ok((kas, info, data))
+    Ok((program_id, kas, data))
 }