path: root/examples/demo1.rs

use std::os::unix::io::RawFd;
use nix::unistd::{close, mkdir, unlinkat, UnlinkatFlags, ftruncate};
use nix::fcntl::{open, openat, OFlag, fallocate, FallocateFlags};
use nix::sys::{stat::Mode, uio::{pwrite, pread}};
use rand::{Rng, seq::SliceRandom};
use libc::off_t;

use growthring::{WALFile, WALStore, WALPos, WALBytes, WALLoader, WALWriter, WALRingId};

struct WALFileTest {
    filename: String,
    fd: RawFd,
}

impl WALFileTest {
    fn new(rootfd: RawFd, filename: &str) -> Self {
        let fd = openat(rootfd, filename,
            OFlag::O_CREAT | OFlag::O_RDWR,
            Mode::S_IRUSR | Mode::S_IWUSR).unwrap();
        let filename = filename.to_string();
        WALFileTest {
            filename,
            fd,
        }
    }
}

impl Drop for WALFileTest {
    fn drop(&mut self) {
        close(self.fd).unwrap();
    }
}

impl WALFile for WALFileTest {
    fn allocate(&self, offset: WALPos, length: usize) -> Result<(), ()> {
        println!("{}.allocate(offset=0x{:x}, end=0x{:x})", self.filename, offset, offset + length as u64);
        fallocate(self.fd,
                FallocateFlags::FALLOC_FL_ZERO_RANGE,
                offset as off_t, length as off_t).and_then(|_| Ok(())).or_else(|_| Err(()))
    }

    fn truncate(&self, length: usize) -> Result<(), ()> {
        println!("{}.truncate(length={})", self.filename, length);
        ftruncate(self.fd, length as off_t).or_else(|_| Err(()))
    }

    fn write(&self, offset: WALPos, data: WALBytes) {
        println!("{}.write(offset=0x{:x}, end=0x{:x}, data=0x{})",
                self.filename, offset, offset + data.len() as u64, hex::encode(&data));
        pwrite(self.fd, &*data, offset as off_t).unwrap();
    }
    fn read(&self, offset: WALPos, length: usize) -> WALBytes {
        let mut buff = Vec::new();
        buff.resize(length, 0);
        pread(self.fd, &mut buff[..], offset as off_t).unwrap();
        buff.into_boxed_slice()
    }
}

struct WALStoreTest {
    rootfd: RawFd,
    rootpath: String
}

impl WALStoreTest {
    fn new(wal_dir: &str, truncate: bool) -> Self {
        let rootpath = wal_dir.to_string();
        if truncate {
            let _ = std::fs::remove_dir_all(wal_dir);
        }
        match mkdir(wal_dir, Mode::S_IRUSR | Mode::S_IWUSR | Mode::S_IXUSR) {
            Err(e) => if truncate { panic!("error while creating directory: {}", e) },
            Ok(_) => ()
        }
        let rootfd = match open(wal_dir, OFlag::O_DIRECTORY | OFlag::O_PATH, Mode::empty()) {
            Ok(fd) => fd,
            Err(_) => panic!("error while opening the DB")
        };
        WALStoreTest { rootfd, rootpath }
    }
}

impl Drop for WALStoreTest {
    fn drop(&mut self) {
        close(self.rootfd).unwrap();
    }
}

impl WALStore for WALStoreTest {
    fn open_file(&self, filename: &str, touch: bool) -> Option<Box<dyn WALFile>> {
        println!("open_file(filename={}, touch={})", filename, touch);
        let filename = filename.to_string();
        Some(Box::new(WALFileTest::new(self.rootfd, &filename)))
    }

    fn remove_file(&self, filename: &str) -> Result<(), ()> {
        println!("remove_file(filename={})", filename);
        unlinkat(Some(self.rootfd), filename, UnlinkatFlags::NoRemoveDir).or_else(|_| Err(()))
    }

    fn enumerate_files(&self) -> Box