src/backup/chunk_store.rs

   1 use failure::*;
   2 use std::path::{Path, PathBuf};
   3 use std::io::Write;
   4 use std::time::Duration;
   5
   6 use openssl::sha;
   7 use std::sync::Mutex;
   8
   9 use std::fs::File;
  10 use std::os::unix::io::AsRawFd;
  11
  12 use crate::tools;
  13
  14 pub struct GarbageCollectionStatus {
  15     pub used_bytes: usize,
  16     pub used_chunks: usize,
  17     pub disk_bytes: usize,
  18     pub disk_chunks: usize,
  19 }
  20
  21 impl Default for GarbageCollectionStatus {
  22     fn default() -> Self {
  23         GarbageCollectionStatus {
  24             used_bytes: 0,
  25             used_chunks: 0,
  26             disk_bytes: 0,
  27             disk_chunks: 0,
  28         }
  29     }
  30 }
  31
  32 pub struct ChunkStore {
  33     name: String, // used for error reporting
  34     pub (crate) base: PathBuf,
  35     chunk_dir: PathBuf,
  36     mutex: Mutex<bool>,
  37     _lockfile: File,
  38 }
  39
  40 const HEX_CHARS: &'static [u8; 16] = b"0123456789abcdef";
  41
  42 // TODO: what about sysctl setting vm.vfs_cache_pressure (0 - 100) ?
  43
  44 pub fn digest_to_hex(digest: &[u8]) -> String {
  45
  46     let mut buf = Vec::<u8>::with_capacity(digest.len()*2);
  47
  48     for i in 0..digest.len() {
  49         buf.push(HEX_CHARS[(digest[i] >> 4) as usize]);
  50         buf.push(HEX_CHARS[(digest[i] & 0xf) as usize]);
  51     }
  52
  53     unsafe { String::from_utf8_unchecked(buf) }
  54 }
  55
  56 fn digest_to_prefix(digest: &[u8]) -> PathBuf {
  57
  58     let mut buf = Vec::<u8>::with_capacity(2+1+2+1);
  59
  60     buf.push(HEX_CHARS[(digest[0] as usize) >> 4]);
  61     buf.push(HEX_CHARS[(digest[0] as usize) &0xf]);
  62     buf.push(HEX_CHARS[(digest[1] as usize) >> 4]);
  63     buf.push(HEX_CHARS[(digest[1] as usize) & 0xf]);
  64     buf.push('/' as u8);
  65
  66     let path = unsafe { String::from_utf8_unchecked(buf)};
  67
  68     path.into()
  69 }
  70
  71
  72 impl ChunkStore {
  73
  74     fn chunk_dir<P: AsRef<Path>>(path: P) -> PathBuf {
  75
  76         let mut chunk_dir: PathBuf = PathBuf::from(path.as_ref());
  77         chunk_dir.push(".chunks");
  78
  79         chunk_dir
  80     }
  81
  82     pub fn create<P: Into<PathBuf>>(name: &str, path: P) -> Result<Self, Error> {
  83
  84         let base: PathBuf = path.into();
  85
  86         if !base.is_absolute() {
  87             bail!("expected absolute path - got {:?}", base);
  88         }
  89
  90         let chunk_dir = Self::chunk_dir(&base);
  91
  92         if let Err(err) = std::fs::create_dir(&base) {
  93             bail!("unable to create chunk store '{}' at {:?} - {}", name, base, err);
  94         }
  95
  96         if let Err(err) = std::fs::create_dir(&chunk_dir) {
  97             bail!("unable to create chunk store '{}' subdir {:?} - {}", name, chunk_dir, err);
  98         }
  99
 100         // create 64*1024 subdirs
 101         let mut last_percentage = 0;
 102
 103         for i in 0..64*1024 {
 104             let mut l1path = chunk_dir.clone();
 105             l1path.push(format!("{:04x}", i));
 106             if let Err(err) = std::fs::create_dir(&l1path) {
 107                 bail!("unable to create chunk store '{}' subdir {:?} - {}", name, l1path, err);
 108             }
 109             let percentage = (i*100)/(64*1024);
 110             if percentage != last_percentage {
 111                 eprintln!("Percentage done: {}", percentage);
 112                 last_percentage = percentage;
 113             }
 114         }
 115
 116         Self::open(name, base)
 117     }
 118
 119     pub fn open<P: Into<PathBuf>>(name: &str, path: P) -> Result<Self, Error> {
 120
 121         let base: PathBuf = path.into();
 122
 123         if !base.is_absolute() {
 124             bail!("expected absolute path - got {:?}", base);
 125         }
 126
 127         let chunk_dir = Self::chunk_dir(&base);
 128
 129         if let Err(err) = std::fs::metadata(&chunk_dir) {
 130             bail!("unable to open chunk store '{}' at {:?} - {}", name, chunk_dir, err);
 131         }
 132
 133         let mut lockfile_path = base.clone();
 134         lockfile_path.push(".lock");
 135
 136         // make sure only one process/thread/task can use it
 137         let lockfile = tools::open_file_locked(
 138             lockfile_path, Duration::from_secs(10))?;
 139
 140         Ok(ChunkStore {
 141             name: name.to_owned(),
 142             base,
 143             chunk_dir,
 144             _lockfile: lockfile,
 145             mutex: Mutex::new(false)
 146         })
 147     }
 148
 149     pub fn touch_chunk(&self, digest:&[u8]) -> Result<(), Error> {
 150
 151         let mut chunk_path = self.chunk_dir.clone();
 152         let prefix = digest_to_prefix(&digest);
 153         chunk_path.push(&prefix);
 154         let digest_str = digest_to_hex(&digest);
 155         chunk_path.push(&digest_str);
 156
 157         const UTIME_NOW: i64 = ((1 << 30) - 1);
 158         const UTIME_OMIT: i64 = ((1 << 30) - 2);
 159
 160         let times: [libc::timespec; 2] = [
 161             libc::timespec { tv_sec: 0, tv_nsec: UTIME_NOW },
 162             libc::timespec { tv_sec: 0, tv_nsec: UTIME_OMIT }
 163         ];
 164
 165         use nix::NixPath;
 166
 167         let res = chunk_path.with_nix_path(|cstr| unsafe {
 168             libc::utimensat(-1, cstr.as_ptr(), &times[0], libc::AT_SYMLINK_NOFOLLOW)
 169         })?;
 170
 171         if let Err(err) = nix::errno::Errno::result(res) {
 172             bail!("updata atime failed for chunk {:?} - {}", chunk_path, err);
 173         }
 174
 175         Ok(())
 176     }
 177
 178     pub fn read_chunk(&self, digest:&[u8], buffer: &mut Vec<u8>) -> Result<(), Error> {
 179
 180         let mut chunk_path = self.chunk_dir.clone();
 181         let prefix = digest_to_prefix(&digest);
 182         chunk_path.push(&prefix);
 183         let digest_str = digest_to_hex(&digest);
 184         chunk_path.push(&digest_str);
 185
 186         let mut f = std::fs::File::open(&chunk_path)?;
 187
 188         let stat = nix::sys::stat::fstat(f.as_raw_fd())?;
 189         let size = stat.st_size as usize;
 190
 191         if buffer.capacity() < size {
 192             let mut newsize =  buffer.capacity();
 193             while newsize < size { newsize = newsize << 1; }
 194             let additional = newsize - buffer.len();
 195             buffer.reserve_exact(additional);
 196         }
 197         unsafe { buffer.set_len(size); }
 198
 199         use std::io::Read;
 200
 201         f.read_exact(buffer.as_mut_slice())?;
 202
 203         Ok(())
 204     }
 205
 206     fn sweep_old_files(&self, handle: &mut nix::dir::Dir, status: &mut GarbageCollectionStatus) -> Result<(), Error> {
 207
 208         let rawfd = handle.as_raw_fd();
 209
 210         let now = unsafe { libc::time(std::ptr::null_mut()) };
 211
 212         for entry in handle.iter() {
 213             let entry = match entry {
 214                 Ok(entry) => entry,
 215                 Err(_) => continue /* ignore */,
 216             };
 217             let file_type = match entry.file_type() {
 218                 Some(file_type) => file_type,
 219                 None => bail!("unsupported file system type on chunk store '{}'", self.name),
 220             };
 221             if file_type != nix::dir::Type::File { continue; }
 222
 223             let filename = entry.file_name();
 224             if let Ok(stat) = nix::sys::stat::fstatat(rawfd, filename, nix::fcntl::AtFlags::AT_SYMLINK_NOFOLLOW) {
 225                 let age = now - stat.st_atime;
 226                 //println!("FOUND {}  {:?}", age/(3600*24), filename);
 227                 if age/(3600*24) >= 2 {
 228                     println!("UNLINK {}  {:?}", age/(3600*24), filename);
 229                     let res = unsafe { libc::unlinkat(rawfd, filename.as_ptr(), 0) };
 230                     if res != 0 {
 231                         let err = nix::Error::last();
 232                         bail!("unlink chunk {:?} failed on store '{}' - {}", filename, self.name, err);
 233                     }
 234                 } else {
 235                     status.disk_chunks += 1;
 236                     status.disk_bytes += stat.st_size as usize;
 237
 238                 }
 239             }
 240         }
 241         Ok(())
 242     }
 243
 244     pub fn sweep_unused_chunks(&self, status: &mut GarbageCollectionStatus) -> Result<(), Error> {
 245
 246         use nix::fcntl::OFlag;
 247         use nix::sys::stat::Mode;
 248         use nix::dir::Dir;
 249
 250         let base_handle = match Dir::open(
 251             &self.chunk_dir, OFlag::O_RDONLY, Mode::empty()) {
 252             Ok(h) => h,
 253             Err(err) => bail!("unable to open store '{}' chunk dir {:?} - {}",
 254                               self.name, self.chunk_dir, err),
 255         };
 256
 257         let base_fd = base_handle.as_raw_fd();
 258
 259         let mut last_percentage = 0;
 260
 261         for i in 0..64*1024 {
 262
 263             let percentage = (i*100)/(64*1024);
 264             if percentage != last_percentage {
 265                 eprintln!("Percentage done: {}", percentage);
 266                 last_percentage = percentage;
 267             }
 268
 269             let l1name = PathBuf::from(format!("{:04x}", i));
 270             match nix::dir::Dir::openat(base_fd, &l1name, OFlag::O_RDONLY, Mode::empty()) {
 271                 Ok(mut h) => {
 272                     //println!("SCAN {:?} {:?}", l1name);
 273                    self.sweep_old_files(&mut h, status)?;
 274                 }
 275                 Err(err) => bail!("unable to open store '{}' dir {:?}/{:?} - {}",
 276                                   self.name, self.chunk_dir, l1name, err),
 277             };
 278         }
 279         Ok(())
 280     }
 281
 282     pub fn insert_chunk(&self, chunk: &[u8]) -> Result<(bool, [u8; 32]), Error> {
 283
 284         // fixme: use Sha512/256 when available
 285         let mut hasher = sha::Sha256::new();
 286         hasher.update(chunk);
 287
 288         let digest = hasher.finish();
 289
 290         //println!("DIGEST {}", digest_to_hex(&digest));
 291
 292         let mut chunk_path = self.chunk_dir.clone();
 293         let prefix = digest_to_prefix(&digest);
 294         chunk_path.push(&prefix);
 295         let digest_str = digest_to_hex(&digest);
 296         chunk_path.push(&digest_str);
 297
 298         let lock = self.mutex.lock();
 299
 300         if let Ok(metadata) = std::fs::metadata(&chunk_path) {
 301             if metadata.is_file() {
 302                  return Ok((true, digest));
 303             } else {
 304                 bail!("Got unexpected file type on store '{}' for chunk {}", self.name, digest_str);
 305             }
 306         }
 307
 308         let mut tmp_path = chunk_path.clone();
 309         tmp_path.set_extension("tmp");
 310         let mut f = std::fs::File::create(&tmp_path)?;
 311         f.write_all(chunk)?;
 312
 313         if let Err(err) = std::fs::rename(&tmp_path, &chunk_path) {
 314             if let Err(_) = std::fs::remove_file(&tmp_path)  { /* ignore */ }
 315             bail!("Atomic rename on store '{}' failed for chunk {} - {}", self.name, digest_str, err);
 316         }
 317
 318         //println!("PATH {:?}", chunk_path);
 319
 320         drop(lock);
 321
 322         Ok((false, digest))
 323     }
 324
 325     pub fn relative_path(&self, path: &Path) -> PathBuf {
 326
 327         let mut full_path = self.base.clone();
 328         full_path.push(path);
 329         full_path
 330     }
 331
 332     pub fn base_path(&self) -> PathBuf {
 333         self.base.clone()
 334     }
 335 }
 336
 337
 338 #[test]
 339 fn test_chunk_store1() {
 340
 341     let mut path = std::fs::canonicalize(".").unwrap(); // we need absulute path
 342     path.push(".testdir");
 343
 344     if let Err(_e) = std::fs::remove_dir_all(".testdir") { /* ignore */ }
 345
 346     let chunk_store = ChunkStore::open("test", &path);
 347     assert!(chunk_store.is_err());
 348
 349     let chunk_store = ChunkStore::create("test", &path).unwrap();
 350     let (exists, _) = chunk_store.insert_chunk(&[0u8, 1u8]).unwrap();
 351     assert!(!exists);
 352
 353     let (exists, _) = chunk_store.insert_chunk(&[0u8, 1u8]).unwrap();
 354     assert!(exists);
 355
 356
 357     let chunk_store = ChunkStore::create("test", &path);
 358     assert!(chunk_store.is_err());
 359
 360
 361 }