jsmpi 0.1.0

A browser-oriented MPI compatibility layer for Rust/WASM using Web Workers
Documentation 
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use serde::de::DeserializeOwned;
use serde::{Deserialize, Serialize};

use crate::error::{Error, Result};
use crate::datatype::{Rank, Tag};

pub const PROTOCOL_VERSION: u16 = 1;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum EnvelopeKind {
    PointToPoint,
}

fn default_protocol_version() -> u16 {
    PROTOCOL_VERSION
}

fn default_envelope_kind() -> EnvelopeKind {
    EnvelopeKind::PointToPoint
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Envelope {
    #[serde(default = "default_protocol_version")]
    pub protocol_version: u16,
    #[serde(default = "default_envelope_kind")]
    pub kind: EnvelopeKind,
    pub src: Rank,
    pub dst: Rank,
    pub tag: Tag,
    pub payload: Vec<u8>,
}

impl Envelope {
    pub fn new(src: Rank, dst: Rank, tag: Tag, payload: Vec<u8>) -> Self {
        Self {
            protocol_version: PROTOCOL_VERSION,
            kind: EnvelopeKind::PointToPoint,
            src,
            dst,
            tag,
            payload,
        }
    }

    pub fn validate(&self, size: Rank) -> Result<()> {
        if self.protocol_version != PROTOCOL_VERSION {
            return Err(Error::Protocol(format!(
                "PROTO_UNSUPPORTED_VERSION: expected={}, got={}",
                PROTOCOL_VERSION, self.protocol_version
            )));
        }

        if size <= 0 {
            return Err(Error::Protocol(
                "PROTO_INVALID_ENVELOPE: communicator size must be > 0".to_string(),
            ));
        }

        if self.src < 0 || self.src >= size {
            return Err(Error::Protocol(format!(
                "PROTO_INVALID_ENVELOPE: invalid source rank {}, size={}",
                self.src, size
            )));
        }

        if self.dst < 0 || self.dst >= size {
            return Err(Error::Protocol(format!(
                "PROTO_INVALID_ENVELOPE: invalid destination rank {}, size={}",
                self.dst, size
            )));
        }

        Ok(())
    }
}

pub fn encode<T>(value: &T) -> Result<Vec<u8>>
where
    T: Serialize,
{
    serde_json::to_vec(value).map_err(|err| Error::Serialization(err.to_string()))
}

pub fn decode<T>(payload: &[u8]) -> Result<T>
where
    T: DeserializeOwned,
{
    serde_json::from_slice(payload).map_err(|err| Error::Serialization(err.to_string()))
}

#[cfg(test)]
mod tests {
    use super::{Envelope, EnvelopeKind, PROTOCOL_VERSION};

    #[test]
    fn envelope_new_sets_protocol_defaults() {
        let env = Envelope::new(0, 1, 7, vec![1, 2, 3]);
        assert_eq!(env.protocol_version, PROTOCOL_VERSION);
        assert_eq!(env.kind, EnvelopeKind::PointToPoint);
    }

    #[test]
    fn envelope_validate_rejects_bad_version() {
        let mut env = Envelope::new(0, 1, 0, vec![]);
        env.protocol_version = PROTOCOL_VERSION + 1;
        let err = env.validate(2).expect_err("version mismatch must fail");
        assert!(err.to_string().contains("PROTO_UNSUPPORTED_VERSION"));
    }

    #[test]
    fn envelope_validate_rejects_bad_ranks() {
        let env = Envelope::new(5, 1, 0, vec![]);
        let err = env
            .validate(2)
            .expect_err("source rank out of range must fail");
        assert!(err.to_string().contains("PROTO_INVALID_ENVELOPE"));
    }
}