liner_broker 1.2.1

Redis based message serverless broker.
Documentation
use crate::{bytestream, print_error};
use crate::mempool::Mempool;
use crate::settings;
use std::io::{Write, Read};
use std::sync::{Arc, Mutex};

const COMPRESS: u8 = 0x01;
const AT_LEAST_ONCE_DELIVERY: u8 = 0x02;

pub struct Message{
    pub number_mess: u64,
    pub listener_topic_key: i32,
    flags: u8,
    mem_alloc_pos: usize,
    mem_alloc_length: usize,
}

impl Message{ 
    pub fn new(mempool: &Arc<Mutex<Mempool>>, connection_key: i32, listener_topic_key: i32,
               number_mess: u64, data: &[u8], at_least_once_delivery: bool) -> Message {
        let mut flags = 0;
        if at_least_once_delivery{
            flags |= AT_LEAST_ONCE_DELIVERY;
        }
        let number_mess_len = std::mem::size_of::<u64>();
        let connection_key_len = std::mem::size_of::<i32>();
        let listener_topic_key_len = std::mem::size_of::<i32>();
        let flags_len = std::mem::size_of::<u8>();
        let mut cdata: Option<Vec<u8>> = None;
        if data.len() > settings::MIN_SIZE_DATA_FOR_COMPRESS_BYTE{
            cdata = Some(compress(data)); 
        }
        let mut data_len = data.len() + std::mem::size_of::<u32>();
        if let Some(cdata) = &cdata{
            data_len = cdata.len() + std::mem::size_of::<u32>();
            flags |= COMPRESS;
        }
        let mess_size = number_mess_len +   
                               connection_key_len + 
                               listener_topic_key_len +              
                               flags_len +
                               data_len;
        let mut mem_alloc_pos = 0;
        let mut mem_alloc_length = 0;
        if let Ok(mut mempool) = mempool.lock(){
            (mem_alloc_pos, mem_alloc_length) = mempool.alloc(mess_size);
            let number_mess_pos = mem_alloc_pos; 
            let connection_key_pos = number_mess_pos + number_mess_len;
            let listener_topic_key_pos = connection_key_pos + connection_key_len;        
            let flags_pos = listener_topic_key_pos + listener_topic_key_len;
            let data_pos = flags_pos + flags_len;
                        
            mempool.write_num(number_mess_pos, number_mess);
            mempool.write_num(connection_key_pos, connection_key);
            mempool.write_num(listener_topic_key_pos, listener_topic_key);
            mempool.write_num(flags_pos, flags);
            match cdata{
                Some(cdata)=>{
                    mempool.write_array(data_pos, &cdata);
                },
                None=>{
                    mempool.write_array(data_pos, data);
                }
            }
        }
        Message{number_mess, listener_topic_key, flags, mem_alloc_pos, mem_alloc_length}
    }   

    pub fn free(&self, mempool: &Arc<Mutex<Mempool>>){
        if let Ok(mut mempool) = mempool.lock(){
            mempool.free(self.mem_alloc_pos, self.mem_alloc_length);
        }
    }
    
    pub fn from_stream<T>(mempool: &Arc<Mutex<Mempool>>, stream: &mut T, is_shutdown: &mut bool) -> Option<Message>
        where T: Read{
        let (mem_alloc_pos, mem_alloc_length, is_shutdown_) = bytestream::read_stream(stream, mempool);
        if mem_alloc_length == 0{
            *is_shutdown = is_shutdown_;
            return None;
        }
        if let Ok(mempool) = mempool.lock(){
            let number_mess_pos = mem_alloc_pos; 
            let number_mess_len = std::mem::size_of::<u64>();
            let number_mess = mempool.read_u64(number_mess_pos);
            
            let connection_key_pos = number_mess_pos + number_mess_len;
            let connection_key_len = std::mem::size_of::<i32>();

            let listener_topic_key_pos = connection_key_pos + connection_key_len;
            let listener_topic_key_len = std::mem::size_of::<i32>();
            let listener_topic_key = mempool.read_u32(listener_topic_key_pos) as i32;

            let flags_pos = listener_topic_key_pos + listener_topic_key_len;        
            let flags = mempool.read_u8(flags_pos);
            return Some(Message{number_mess, listener_topic_key, flags, mem_alloc_pos, mem_alloc_length});
        }
        None        
    }
    pub fn to_stream<T>(&self, mempool: &Arc<Mutex<Mempool>>, stream: &mut T)->bool 
        where T: Write{        
        bytestream::write_stream(stream, self.mem_alloc_pos, self.mem_alloc_length, mempool)       
    }

    pub fn get_data(&self, mempool: &Arc<Mutex<Mempool>>, out: &mut Vec<u8>)->usize{ 
        let mut data_len = 0;
        if let Ok(mempool) = mempool.lock(){
            let data_pos =  data_pos();
            let size_u32 = std::mem::size_of::<u32>() as usize;
            data_len = mempool.read_u32(self.mem_alloc_pos + data_pos) as usize;
            if out.len() < data_len{
                out.resize(data_len, 0);
            }
            mempool.read_data(self.mem_alloc_pos + data_pos + size_u32, &mut out[..data_len]);
        }
        if self.is_compressed(){            
            let decomp_data = decompress(&out[..data_len]);
            if out.len() < decomp_data.len(){
                out.resize(decomp_data.len(), 0);
            } 
            out[..decomp_data.len()].copy_from_slice(&decomp_data);
            return decomp_data.len()
        }
        data_len
    }
        
    pub fn at_least_once_delivery(&self)->bool{
        self.flags & AT_LEAST_ONCE_DELIVERY > 0
    }
    fn is_compressed(&self)->bool{
        self.flags & COMPRESS > 0
    }
    pub fn connection_key(&self, mempool: &Arc<Mutex<Mempool>>)->i32{
        let number_mess_len = std::mem::size_of::<u64>(); 
        let key_pos = self.mem_alloc_pos + number_mess_len;
        mempool.lock().unwrap().read_u32(key_pos) as i32
    }   
}

fn data_pos()->usize{ 
    let number_mess_pos = 0; 
    let number_mess_len = std::mem::size_of::<u64>();        
    let connection_key_pos = number_mess_pos + number_mess_len;
    let connection_key_len = std::mem::size_of::<u32>();
    let listener_topic_key_pos = connection_key_pos + connection_key_len;
    let listener_topic_key_len = std::mem::size_of::<u32>();
    let flags_pos = listener_topic_key_pos + listener_topic_key_len; 
    let flags_len = std::mem::size_of::<u8>(); 
    let data_pos = flags_pos + flags_len;
    data_pos
}

fn compress(data: &[u8])->Vec<u8>{
    let mut cdata: Vec<u8> = Vec::new(); 
    match zstd::stream::encode_all(data, settings::DATA_COMPRESS_LEVEL){
        Ok(data)=>{
            cdata = data;
        },
        Err(err)=>{
            print_error!(format!("compress error, dsz {}, err {}", data.len(), err));
        }
    }
    cdata
}
fn decompress(cdata: &[u8])->Vec<u8>{
    let mut data: Vec<u8> = Vec::new(); 
    match zstd::stream::decode_all(cdata){
        Ok(data_)=>{
            data = data_;
        },
        Err(err)=>{
            print_error!(format!("decompress error, dsz {}, err {}", cdata.len(), err));
        }
    }
    data
}