pubkey: Add a simple program comparing two pubkeys

#### Problem

It can be expensive to compare two pubkeys in an on-chain program, but
it hasn't been quantified.

#### Summary of changes

Add a Rust and Zig program to do that

.github/workflows/main.yml

@@ -19,7 +19,7 @@ jobs:
     name: Run tests against Zig implementations
     strategy:
       matrix:
-        program: [helloworld, transfer-lamports, cpi, token]
+        program: [helloworld, transfer-lamports, cpi, pubkey, token]
       fail-fast: false
     runs-on: ubuntu-latest
     steps:
@@ -53,7 +53,7 @@ jobs:
     name: Run tests against Rust implementations
     strategy:
       matrix:
-        program: [helloworld, transfer-lamports, cpi, token]
+        program: [helloworld, transfer-lamports, cpi, pubkey, token]
       fail-fast: false
     runs-on: ubuntu-latest
     steps:

Cargo.toml

@@ -3,6 +3,7 @@ members = [
   "cpi",
   "cpi/pinocchio",
   "helloworld",
+  "pubkey",
   "token",
   "transfer-lamports",
   "transfer-lamports/pinocchio"

README.md

@@ -194,6 +194,16 @@ Note: `create_program_address` consumes 1500 CUs, and `invoke` consumes 1000, so
 we can subtract 2500 CUs from each program to see the actual cost of the program
 logic.
 
+### Pubkey
+
+A program to compare two `Pubkey` instances. This operation is very common in
+on-chain programs, but it can be expensive.
+
+| Language | CU Usage |
+| --- | --- |
+| Rust | 14 |
+| Zig | 15 |
+
 ### Token
 
 A reduced instruction set from SPL-Token. Includes an entrypoint, instruction

pubkey/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "solana-program-rosetta-pubkey"
+version = "1.0.0"
+edition = "2021"
+
+[features]
+test-sbf = []
+
+[dependencies]
+solana-program-entrypoint = "2.1.0"
+solana-pubkey = "2.1.0"
+
+[dev-dependencies]
+solana-instruction = "2.1.0"
+solana-program-test = "2.1.0"
+solana-sdk = "2.1.0"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+
+[lints]
+workspace = true

pubkey/src/lib.rs

@@ -0,0 +1,24 @@
+//! A program demonstrating a comparison of pubkeys
+#![deny(missing_docs)]
+#![allow(clippy::arithmetic_side_effects)]
+
+use solana_pubkey::Pubkey;
+
+/// Entrypoint for the program
+#[no_mangle]
+pub extern "C" fn entrypoint(input: *mut u8) -> u64 {
+    unsafe {
+        let key: &Pubkey = &*(input.add(16) as *const Pubkey);
+        let owner: &Pubkey = &*(input.add(16 + 32) as *const Pubkey);
+
+        if *key == *owner {
+            0
+        } else {
+            1
+        }
+    }
+}
+#[cfg(target_os = "solana")]
+#[no_mangle]
+fn custom_panic(_info: &core::panic::PanicInfo<'_>) {}
+solana_program_entrypoint::custom_heap_default!();

pubkey/tests/functional.rs

@@ -0,0 +1,39 @@
+use {
+    solana_instruction::{AccountMeta, Instruction},
+    solana_program_test::*,
+    solana_pubkey::Pubkey,
+    solana_sdk::{account::Account, signature::Signer, transaction::Transaction},
+};
+
+const PROGRAM_ID: Pubkey = Pubkey::from_str_const("PubkeyComp111111111111111111111111111111111");
+const TEST_KEY: Pubkey = Pubkey::from_str_const("PubkeyComp111111111111111111111111111111112");
+
+#[tokio::test]
+async fn correct_key() {
+    let mut program_test = ProgramTest::new(
+        option_env!("PROGRAM_NAME").unwrap_or("solana_program_rosetta_pubkey"),
+        PROGRAM_ID,
+        None,
+    );
+    program_test.add_account(
+        TEST_KEY,
+        Account {
+            lamports: 100_000,
+            data: vec![0],
+            owner: TEST_KEY,
+            ..Account::default()
+        },
+    );
+    let (banks_client, payer, recent_blockhash) = program_test.start().await;
+
+    let mut transaction = Transaction::new_with_payer(
+        &[Instruction::new_with_bincode(
+            PROGRAM_ID,
+            &(),
+            vec![AccountMeta::new_readonly(TEST_KEY, false)],
+        )],
+        Some(&payer.pubkey()),
+    );
+    transaction.sign(&[&payer], recent_blockhash);
+    banks_client.process_transaction(transaction).await.unwrap();
+}

pubkey/zig/build.zig

@@ -0,0 +1,15 @@
+const std = @import("std");
+const solana = @import("solana-program-sdk");
+
+pub fn build(b: *std.Build) !void {
+    const target = b.resolveTargetQuery(solana.sbf_target);
+    const optimize = .ReleaseFast;
+    const program = b.addSharedLibrary(.{
+        .name = "solana_program_rosetta_pubkey",
+        .root_source_file = b.path("main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    _ = solana.buildProgram(b, program, target, optimize);
+    b.installArtifact(program);
+}

pubkey/zig/build.zig.zon

@@ -0,0 +1,30 @@
+.{
+    .name = "solana-program-rosetta-pubkey-zig",
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.13.0",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    .minimum_zig_version = "0.13.0",
+
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        .@"solana-program-sdk" = .{
+            .url = "https://github.com/joncinque/solana-program-sdk-zig/archive/refs/tags/v0.14.0.tar.gz",
+            .hash = "1220bdfa4ea1ab6330959ce4bc40feb5b39a7f98923a266a94b69e27fd20c3526786",
+        },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "main.zig",
+        "../../LICENSE",
+        "../../README.md",
+    },
+}

pubkey/zig/main.zig

@@ -0,0 +1,12 @@
+const std = @import("std");
+const PublicKey = @import("solana-program-sdk").PublicKey;
+
+export fn entrypoint(input: [*]u8) u64 {
+    const id: *align(1) PublicKey = @ptrCast(input + 16);
+    const owner_id: *align(1) PublicKey = @ptrCast(input + 16 + 32);
+    if (id.equals(owner_id.*)) {
+        return 0;
+    } else {
+        return 1;
+    }
+}