rustdesk/libs/hbb_common/src/compress.rs

use std::{cell::RefCell, io};
use zstd::bulk::{Compressor, Decompressor};

// The library supports regular compression levels from 1 up to ZSTD_maxCLevel(),
// which is currently 22. Levels >= 20
// Default level is ZSTD_CLEVEL_DEFAULT==3.
// value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT
thread_local! {
    static COMPRESSOR: RefCell<io::Result<Compressor<'static>>> = RefCell::new(Compressor::new(crate::config::COMPRESS_LEVEL));
    static DECOMPRESSOR: RefCell<io::Result<Decompressor<'static>>> = RefCell::new(Decompressor::new());
}

pub fn compress(data: &[u8]) -> Vec<u8> {
    let mut out = Vec::new();
    COMPRESSOR.with(|c| {
        if let Ok(mut c) = c.try_borrow_mut() {
            match &mut *c {
                Ok(c) => match c.compress(data) {
                    Ok(res) => out = res,
                    Err(err) => {
                        crate::log::debug!("Failed to compress: {}", err);
                    }
                },
                Err(err) => {
                    crate::log::debug!("Failed to get compressor: {}", err);
                }
            }
        }
    });
    out
}

pub fn decompress(data: &[u8]) -> Vec<u8> {
    let mut out = Vec::new();
    DECOMPRESSOR.with(|d| {
        if let Ok(mut d) = d.try_borrow_mut() {
            match &mut *d {
                Ok(d) => {
                    const MAX: usize = 1024 * 1024 * 64;
                    const MIN: usize = 1024 * 1024;
                    let mut n = 30 * data.len();
                    n = n.clamp(MIN, MAX);
                    match d.decompress(data, n) {
                        Ok(res) => out = res,
                        Err(err) => {
                            crate::log::debug!("Failed to decompress: {}", err);
                        }
                    }
                }
                Err(err) => {
                    crate::log::debug!("Failed to get decompressor: {}", err);
                }
            }
        }
    });
    out
}