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use std::ops::Sub;
use std::sync::Arc;
use std::sync::Mutex;
use std::sync::Condvar;
use std::sync::atomic::Ordering;
use std::sync::atomic::AtomicBool;
use std::time::Duration;
use std::time::Instant;
use crate::Error;
use crate::net::Packet;
use crate::net::BinaryReader;
pub const BLOCK_COUNT : usize = 255;
pub const BLOCK_OFFSET : usize = 1;
pub const WAIT_TIME_MILLIS : Duration = Duration::from_secs(3);
pub struct BlockManager {
blocks: Vec<Arc<BlockInner>>
}
impl Default for BlockManager {
fn default() -> Self {
BlockManager {
blocks: {
let mut vec = Vec::with_capacity(BLOCK_COUNT);
for id in 0..BLOCK_COUNT as u8 {
vec.push(Arc::new({
let mut inner = BlockInner::default();
inner.id = id + BLOCK_OFFSET as u8;
inner
}));
}
vec
}
}
}
}
impl BlockManager {
pub fn block(&self) -> Result<Block, Error> {
let inner = self.blocks
.iter()
.find_map(|inner|
if inner.try_activate() {
Some(inner.clone())
} else {
None
}
)
.ok_or(Error::NoFreeSlots)?;
Ok(Block {
inner,
timestamp: Instant::now(),
})
}
pub fn answer(&self, response: Packet) {
let id = response.session() as usize;
self.blocks[id - BLOCK_OFFSET].answer(response);
}
}
pub struct Block {
inner: Arc<BlockInner>,
timestamp: Instant,
}
impl Block {
pub fn id(&self) -> u8 {
self.inner.id
}
pub fn wait(&mut self) -> Result<Packet, Error> {
let packet : Packet = match self.inner.r#await(self.timestamp, WAIT_TIME_MILLIS) {
Some(packet) => packet,
None => return Err(Error::Timeout)
};
if packet.command() == 0xFF { if packet.path_sub() == 0xFF { let reader : &mut BinaryReader = &mut packet.read();
return Err(Error::ServerError {
exception_type: reader.read_string()?,
message: reader.read_string()?,
stack_trace: reader.read_string()?
});
} else {
return Err(Error::error_code(packet.path_sub()))
}
}
Ok(packet)
}
}
impl Drop for Block {
fn drop(&mut self) {
self.inner.deactivate();
}
}
#[derive(Default)]
struct BlockInner {
id: u8,
active: AtomicBool,
data: Mutex<Option<Packet>>,
cond: Condvar,
}
impl BlockInner {
fn try_activate(&self) -> bool {
!self.active.swap(true, Ordering::Relaxed)
}
fn deactivate(&self) {
{
let mut lock = self.data.lock().expect("Failed to acquire lock for BlockInner::data");
*lock = None;
}
self.active.store(false, Ordering::Relaxed);
}
fn answer(&self, packet: Packet) {
{
let mut lock = self.data.lock().expect("Failed to acquire lock for BlockInner::data");
*lock = Some(packet);
}
self.cond.notify_all();
}
fn r#await(&self, time: Instant, timeout: Duration) -> Option<Packet> {
let mut lock = self.data.lock().expect("Failed to acquire lock for BlockInner::data");
let mut elapsed = time.elapsed();
while elapsed < timeout {
let (returned_lock, _timeout_result) = self.cond.wait_timeout(lock, timeout.sub(elapsed)).expect("wait_timeout failed");
lock = returned_lock;
if let Some(response) = lock.take() {
return Some(response);
}
elapsed = time.elapsed();
}
None
}
}