Skip to content

Commit

Permalink
piecrust: allow for a HostQuery to take &mut Session
Browse files Browse the repository at this point in the history
This will allow for downstream to make use of a `Session` while defining
host functions, enabling contracts to be called during their execution.

Resolves: #327
  • Loading branch information
Eduardo Leegwater Simões committed Feb 12, 2024
1 parent b4d3a0c commit 6f27bc1
Show file tree
Hide file tree
Showing 4 changed files with 80 additions and 8 deletions.
2 changes: 2 additions & 0 deletions piecrust/CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

### Changed

- Allow for a `HostQuery` to take a `&mut Session` [#327]
- Change to have one instance per contract function call [#325]
- Upgrade `dusk-wasmtime` to version `17`

Expand Down Expand Up @@ -359,6 +360,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
[#234]: https://github.com/dusk-network/piecrust/pull/234

<!-- ISSUES -->
[#327]: https://github.com/dusk-network/piecrust/issues/327
[#325]: https://github.com/dusk-network/piecrust/issues/325
[#301]: https://github.com/dusk-network/piecrust/issues/313
[#301]: https://github.com/dusk-network/piecrust/issues/301
Expand Down
5 changes: 4 additions & 1 deletion piecrust/src/session.rs
Original file line number Diff line number Diff line change
Expand Up @@ -552,7 +552,10 @@ impl Session {
buf: &mut [u8],
arg_len: u32,
) -> Option<u32> {
self.inner.host_queries.call(name, buf, arg_len)
let mut session = self.clone();
self.inner
.host_queries
.call(&mut session, name, buf, arg_len)
}

pub(crate) fn nth_from_top(&self, n: usize) -> Option<CallTreeElem> {
Expand Down
29 changes: 25 additions & 4 deletions piecrust/src/vm.rs
Original file line number Diff line number Diff line change
Expand Up @@ -236,8 +236,16 @@ impl HostQueries {
self.map.insert(name.into(), Arc::new(query));
}

pub fn call(&self, name: &str, buf: &mut [u8], len: u32) -> Option<u32> {
self.map.get(name).map(|host_query| host_query(buf, len))
pub fn call(
&self,
session: &mut Session,
name: &str,
buf: &mut [u8],
len: u32,
) -> Option<u32> {
self.map
.get(name)
.map(|host_query| host_query(session, buf, len))
}
}

Expand All @@ -248,5 +256,18 @@ impl HostQueries {
/// function, and should be processed first. Once this is done, the implementor
/// should emplace the return of the query in the same buffer, and return the
/// length written.
pub trait HostQuery: Send + Sync + Fn(&mut [u8], u32) -> u32 {}
impl<F> HostQuery for F where F: Send + Sync + Fn(&mut [u8], u32) -> u32 {}
///
/// The host query will have access to the underlying session, and can use it to
/// perform calls to other contracts.
///
/// # Panics
/// The implementor should panic if any error occurs during the execution of a
/// host function.
pub trait HostQuery:
Send + Sync + Fn(&mut Session, &mut [u8], u32) -> u32
{
}
impl<F> HostQuery for F where
F: Send + Sync + Fn(&mut Session, &mut [u8], u32) -> u32
{
}
52 changes: 49 additions & 3 deletions piecrust/tests/host.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,10 @@

use dusk_plonk::prelude::*;
use once_cell::sync::Lazy;
use piecrust::{contract_bytecode, ContractData, Error, SessionData, VM};
use piecrust::{
contract_bytecode, ContractData, Error, Session, SessionData, VM,
};
use piecrust_uplink::ContractId;
use rand::rngs::OsRng;
use rkyv::Deserialize;

Expand All @@ -30,7 +33,7 @@ fn get_prover_verifier() -> &'static (Prover, Verifier) {
&PROVER_VERIFIER
}

fn hash(buf: &mut [u8], len: u32) -> u32 {
fn hash(_: &mut Session, buf: &mut [u8], len: u32) -> u32 {
let a = unsafe { rkyv::archived_root::<Vec<u8>>(&buf[..len as usize]) };
let v: Vec<u8> = a.deserialize(&mut rkyv::Infallible).unwrap();

Expand All @@ -40,7 +43,7 @@ fn hash(buf: &mut [u8], len: u32) -> u32 {
32
}

fn verify_proof(buf: &mut [u8], len: u32) -> u32 {
fn verify_proof(_: &mut Session, buf: &mut [u8], len: u32) -> u32 {
let a = unsafe {
rkyv::archived_root::<(Proof, Vec<BlsScalar>)>(&buf[..len as usize])
};
Expand All @@ -58,10 +61,24 @@ fn verify_proof(buf: &mut [u8], len: u32) -> u32 {
valid_bytes.len() as u32
}

pub const COUNTER_ID: ContractId = ContractId::from_bytes([1; 32]);

fn get_counter(session: &mut Session, buf: &mut [u8], _: u32) -> u32 {
let receipt = session
.call_raw(COUNTER_ID, "read_value", &*buf, u64::MAX)
.expect("calling the counter contract should succeed");

let data = receipt.data;
buf[..data.len()].copy_from_slice(&data);

data.len() as u32
}

fn new_ephemeral_vm() -> Result<VM, Error> {
let mut vm = VM::ephemeral()?;
vm.register_host_query("hash", hash);
vm.register_host_query("verify_proof", verify_proof);
vm.register_host_query("get_counter", get_counter);
Ok(vm)
}

Expand All @@ -87,6 +104,35 @@ pub fn host_hash() -> Result<(), Error> {
Ok(())
}

/// Queries a contract for the value held in the counter contract through the
/// host, using a host query.
#[test]
fn host_counter() -> Result<(), Error> {
let vm = new_ephemeral_vm()?;

let mut session = vm.session(SessionData::builder())?;

session.deploy(
contract_bytecode!("counter"),
ContractData::builder(OWNER).contract_id(COUNTER_ID),
LIMIT,
)?;

let id = session.deploy(
contract_bytecode!("host"),
ContractData::builder(OWNER),
LIMIT,
)?;

let counter = session
.call::<_, i64>(id, "host_get_counter", &(), LIMIT)?
.data;

assert_eq!(counter, 0xfc);

Ok(())
}

/// Proves that we know a number `c` such that `a + b = c`.
#[derive(Default)]
struct TestCircuit {
Expand Down

0 comments on commit 6f27bc1

Please sign in to comment.