proxmox-backup/src/backup/chunk_store.rs

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Rust
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use failure::*;
use std::path::{Path, PathBuf};
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use std::io::Write;
use crypto::digest::Digest;
use crypto::sha2::Sha512Trunc256;
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use std::sync::Mutex;
use std::fs::{File, OpenOptions};
use nix::fcntl::{flock, FlockArg};
use std::os::unix::io::AsRawFd;
pub struct ChunkStore {
base: PathBuf,
chunk_dir: PathBuf,
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hasher: Sha512Trunc256,
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mutex: Mutex<bool>,
lockfile: File,
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}
const HEX_CHARS: &'static [u8; 16] = b"0123456789abcdef";
fn u256_to_hex(digest: &[u8; 32]) -> String {
let mut buf = Vec::<u8>::with_capacity(64);
for i in 0..32 {
buf.push(HEX_CHARS[(digest[i] >> 4) as usize]);
buf.push(HEX_CHARS[(digest[i] & 0xf) as usize]);
}
unsafe { String::from_utf8_unchecked(buf) }
}
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fn u256_to_prefix(digest: &[u8; 32]) -> PathBuf {
let mut buf = Vec::<u8>::with_capacity(3+1+2+1);
buf.push(HEX_CHARS[(digest[0] as usize) >> 4]);
buf.push(HEX_CHARS[(digest[0] as usize) &0xf]);
buf.push(HEX_CHARS[(digest[1] as usize) >> 4]);
buf.push('/' as u8);
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buf.push(HEX_CHARS[(digest[1] as usize) & 0xf]);
buf.push(HEX_CHARS[(digest[2] as usize) >> 4]);
buf.push('/' as u8);
let path = unsafe { String::from_utf8_unchecked(buf)};
path.into()
}
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fn lock_file<P: AsRef<Path>>(filename: P, timeout: usize) -> Result<File, Error> {
let path = filename.as_ref();
let lockfile = match OpenOptions::new()
.create(true)
.append(true)
.open(path) {
Ok(file) => file,
Err(err) => bail!("Unable to open lock {:?} - {}",
path, err),
};
let fd = lockfile.as_raw_fd();
let now = std::time::SystemTime::now();
let mut print_msg = true;
loop {
match flock(fd, FlockArg::LockExclusiveNonblock) {
Ok(_) => break,
Err(_) => {
if print_msg {
print_msg = false;
eprintln!("trying to aquire lock...");
}
}
}
match now.elapsed() {
Ok(elapsed) => {
if elapsed.as_secs() >= (timeout as u64) {
bail!("unable to aquire lock {:?} - got timeout", path);
}
}
Err(err) => {
bail!("unable to aquire lock {:?} - clock problems - {}", path, err);
}
}
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std::thread::sleep(std::time::Duration::from_millis(100));
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}
Ok(lockfile)
}
impl ChunkStore {
fn chunk_dir<P: AsRef<Path>>(path: P) -> PathBuf {
let mut chunk_dir: PathBuf = PathBuf::from(path.as_ref());
chunk_dir.push(".chunks");
chunk_dir
}
pub fn create<P: Into<PathBuf>>(path: P) -> Result<Self, Error> {
let base: PathBuf = path.into();
let chunk_dir = Self::chunk_dir(&base);
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if let Err(err) = std::fs::create_dir(&base) {
bail!("unable to create chunk store {:?} - {}", base, err);
}
if let Err(err) = std::fs::create_dir(&chunk_dir) {
bail!("unable to create chunk store subdir {:?} - {}", chunk_dir, err);
}
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// create 4096 subdir
for i in 0..4096 {
let mut l1path = base.clone();
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l1path.push(format!("{:03x}",i));
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if let Err(err) = std::fs::create_dir(&l1path) {
bail!("unable to create chunk subdir {:?} - {}", l1path, err);
}
}
Self::open(base)
}
pub fn open<P: Into<PathBuf>>(path: P) -> Result<Self, Error> {
let base: PathBuf = path.into();
let chunk_dir = Self::chunk_dir(&base);
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if let Err(err) = std::fs::metadata(&chunk_dir) {
bail!("unable to open chunk store {:?} - {}", chunk_dir, err);
}
let mut lockfile_path = base.clone();
lockfile_path.push(".lock");
// make sure only one process/thread/task can use it
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let lockfile = lock_file(lockfile_path, 10)?;
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Ok(ChunkStore {
base,
chunk_dir,
hasher: Sha512Trunc256::new(),
lockfile,
mutex: Mutex::new(false)
})
}
pub fn insert_chunk(&mut self, chunk: &[u8]) -> Result<(bool, [u8; 32]), Error> {
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self.hasher.reset();
self.hasher.input(chunk);
let mut digest = [0u8; 32];
self.hasher.result(&mut digest);
println!("DIGEST {}", u256_to_hex(&digest));
let mut chunk_path = self.base.clone();
let prefix = u256_to_prefix(&digest);
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chunk_path.push(&prefix);
let digest_str = u256_to_hex(&digest);
chunk_path.push(&digest_str);
let lock = self.mutex.lock();
if let Ok(metadata) = std::fs::metadata(&chunk_path) {
if metadata.is_file() {
return Ok((true, digest));
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} else {
bail!("Got unexpected file type for chunk {}", digest_str);
}
}
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let mut chunk_dir = self.base.clone();
chunk_dir.push(&prefix);
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if let Err(_) = std::fs::create_dir(&chunk_dir) { /* ignore */ }
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let mut tmp_path = chunk_path.clone();
tmp_path.set_extension("tmp");
let mut f = std::fs::File::create(&tmp_path)?;
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f.write_all(chunk)?;
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if let Err(err) = std::fs::rename(&tmp_path, &chunk_path) {
if let Err(_) = std::fs::remove_file(&tmp_path) { /* ignore */ }
bail!("Atomic rename failed for chunk {} - {}", digest_str, err);
}
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println!("PATH {:?}", chunk_path);
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drop(lock);
Ok((false, digest))
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}
}
#[test]
fn test_chunk_store1() {
if let Err(_e) = std::fs::remove_dir_all(".testdir") { /* ignore */ }
let chunk_store = ChunkStore::open(".testdir");
assert!(chunk_store.is_err());
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let mut chunk_store = ChunkStore::create(".testdir").unwrap();
let (exists, _) = chunk_store.insert_chunk(&[0u8, 1u8]).unwrap();
assert!(!exists);
let (exists, _) = chunk_store.insert_chunk(&[0u8, 1u8]).unwrap();
assert!(exists);
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let chunk_store = ChunkStore::create(".testdir");
assert!(chunk_store.is_err());
}