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