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use std::cell::RefCell;
use std::fmt::{self, Write};
use std::str;
use time::{self, Duration};
pub const DATE_VALUE_LENGTH: usize = 29;
pub(crate) fn extend(dst: &mut Vec<u8>) {
CACHED.with(|cache| {
let mut cache = cache.borrow_mut();
if !cache.interval {
cache.update_without_interval();
}
dst.extend_from_slice(cache.bytes());
})
}
pub(crate) fn update_interval() {
CACHED.with(|cache| {
let mut cache = cache.borrow_mut();
cache.interval = true;
cache.render(time::get_time());
})
}
pub(crate) fn interval_off() {
CACHED.with(|cache| {
let mut cache = cache.borrow_mut();
cache.interval = false;
})
}
struct CachedDate {
bytes: [u8; DATE_VALUE_LENGTH],
pos: usize,
next_update: time::Timespec,
interval: bool,
}
thread_local!(static CACHED: RefCell<CachedDate> = RefCell::new(CachedDate {
bytes: [0; DATE_VALUE_LENGTH],
pos: 0,
next_update: time::Timespec::new(0, 0),
interval: false,
}));
impl CachedDate {
fn bytes(&self) -> &[u8] {
&self.bytes[..]
}
fn render(&mut self, now: time::Timespec) {
self.pos = 0;
write!(self, "{}", time::at_utc(now).rfc822()).unwrap();
debug_assert!(self.pos == DATE_VALUE_LENGTH);
}
fn update_without_interval(&mut self) {
let now = time::get_time();
if now > self.next_update {
self.render(now);
self.next_update = now + Duration::seconds(1);
self.next_update.nsec = 0;
}
}
}
impl fmt::Write for CachedDate {
fn write_str(&mut self, s: &str) -> fmt::Result {
let len = s.len();
self.bytes[self.pos..self.pos + len].copy_from_slice(s.as_bytes());
self.pos += len;
Ok(())
}
}
#[test]
fn test_date_len() {
assert_eq!(DATE_VALUE_LENGTH, "Sun, 06 Nov 1994 08:49:37 GMT".len());
}