use std::str::FromStr; use std::sync::atomic::{AtomicU64, Ordering}; use lazy_static::lazy_static; use rand::prelude::*; use serde::{de::Error, Deserialize, Deserializer, Serialize, Serializer}; use crate::timestamp::now_msec; /// An internal Mail Identifier is composed of two components: /// - a process identifier, 128 bits, itself composed of: /// - the timestamp of when the process started, 64 bits /// - a 64-bit random number /// - a sequence number, 64 bits /// They are not part of the protocol but an internal representation /// required by Aerogramme. /// Their main property is to be unique without having to rely /// on synchronization between IMAP processes. #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash)] pub struct UniqueIdent(pub [u8; 24]); struct IdentGenerator { pid: u128, sn: AtomicU64, } impl IdentGenerator { fn new() -> Self { let time = now_msec() as u128; let rand = thread_rng().gen::() as u128; Self { pid: (time << 64) | rand, sn: AtomicU64::new(0), } } fn gen(&self) -> UniqueIdent { let sn = self.sn.fetch_add(1, Ordering::Relaxed); let mut res = [0u8; 24]; res[0..16].copy_from_slice(&u128::to_be_bytes(self.pid)); res[16..24].copy_from_slice(&u64::to_be_bytes(sn)); UniqueIdent(res) } } lazy_static! { static ref GENERATOR: IdentGenerator = IdentGenerator::new(); } pub fn gen_ident() -> UniqueIdent { GENERATOR.gen() } // -- serde -- impl<'de> Deserialize<'de> for UniqueIdent { fn deserialize(d: D) -> Result where D: Deserializer<'de>, { let v = String::deserialize(d)?; UniqueIdent::from_str(&v).map_err(D::Error::custom) } } impl Serialize for UniqueIdent { fn serialize(&self, serializer: S) -> Result where S: Serializer, { serializer.serialize_str(&self.to_string()) } } impl std::fmt::Display for UniqueIdent { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{}", hex::encode(self.0)) } } impl std::fmt::Debug for UniqueIdent { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{}", hex::encode(self.0)) } } impl FromStr for UniqueIdent { type Err = &'static str; fn from_str(s: &str) -> Result { let bytes = hex::decode(s).map_err(|_| "invalid hex")?; if bytes.len() != 24 { return Err("bad length"); } let mut tmp = [0u8; 24]; tmp[..].copy_from_slice(&bytes); Ok(UniqueIdent(tmp)) } }