multi-hdd support (fix #218) #625

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lx merged 26 commits from multihdd into next 2023-09-11 10:52:02 +00:00
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@ -11,25 +11,28 @@ type Idx = u16;
const DRIVE_NPART: usize = 1024;
const DPART_BYTES: (usize, usize) = (2, 3);
const HASH_DRIVE_BYTES: (usize, usize) = (2, 3);
#[derive(Serialize, Deserialize, Debug, Clone)]
pub(crate) struct DataLayout {
pub(crate) data_dirs: Vec<DataDir>,
/// Primary storage location (index in data_dirs) for each partition
/// = the location where the data is supposed to be, blocks are always
/// written there (copies in other dirs may be deleted if they exist)
pub(crate) part_prim: Vec<Idx>,
/// Secondary storage locations for each partition
/// Secondary storage locations for each partition = locations
/// where data blocks might be, we check from these dirs when reading
pub(crate) part_sec: Vec<Vec<Idx>>,
}
#[derive(Serialize, Deserialize, Debug, Clone)]
#[derive(Serialize, Deserialize, Debug, Clone, Eq, PartialEq)]
pub(crate) struct DataDir {
pub(crate) path: PathBuf,
pub(crate) state: DataDirState,
}
#[derive(Serialize, Deserialize, Debug, Clone, Copy)]
#[derive(Serialize, Deserialize, Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) enum DataDirState {
Active { capacity: u64 },
ReadOnly,
@ -55,8 +58,9 @@ impl DataLayout {
assert_eq!(cum_cap, total_cap);
assert_eq!(part_prim.len(), DRIVE_NPART);
// If any of the storage locations is non-empty, add it as a secondary
// storage location for all partitions
// If any of the storage locations is non-empty, it probably existed before
// this algorithm was added, so add it as a secondary storage location for all partitions
// to make sure existing files are not lost
let mut part_sec = vec![vec![]; DRIVE_NPART];
for (i, dd) in data_dirs.iter().enumerate() {
if dir_not_empty(&dd.path)? {
@ -75,10 +79,14 @@ impl DataLayout {
})
}
pub(crate) fn update(&mut self, dirs: &DataDirEnum) -> Result<Self, Error> {
// Compute list of new data directories and mapping of old indices
// to new indices
pub(crate) fn update(&mut self, dirs: &DataDirEnum) -> Result<(), Error> {
// Make list of new data directories, exit if nothing changed
let data_dirs = make_data_dirs(dirs)?;
if data_dirs == self.data_dirs {
return Ok(());
}
// Compute mapping of old indices to new indices
let old2new = self
.data_dirs
.iter()
@ -114,15 +122,13 @@ impl DataLayout {
// Compute the target number of partitions per data directory
let total_cap = data_dirs.iter().filter_map(|x| x.capacity()).sum::<u64>();
let mut cum_cap = 0;
let mut npart_per_dir = vec![];
for dd in data_dirs.iter() {
let mut npart_per_dir = vec![0; data_dirs.len()];
for (idir, dd) in data_dirs.iter().enumerate() {
if let DataDirState::Active { capacity } = dd.state {
let begin = (cum_cap * DRIVE_NPART as u64) / total_cap;
cum_cap += capacity;
let end = (cum_cap * DRIVE_NPART as u64) / total_cap;
npart_per_dir.push((end - begin) as usize);
} else {
npart_per_dir.push(0);
npart_per_dir[idir] = (end - begin) as usize;
}
}
assert_eq!(cum_cap, total_cap);
@ -161,13 +167,16 @@ impl DataLayout {
// add partitions from unassigned
for (idir, (parts, tgt_npart)) in dir_prim.iter_mut().zip(npart_per_dir.iter()).enumerate()
{
assert!(unassigned.len() >= *tgt_npart - parts.len());
for _ in parts.len()..*tgt_npart {
if parts.len() < *tgt_npart {
let required = *tgt_npart - parts.len();
assert!(unassigned.len() >= required);
for _ in 0..required {
let new_part = unassigned.pop().unwrap();
part_prim[new_part] = Some(idir as Idx);
part_sec[new_part].retain(|x| *x != idir as Idx);
}
}
}
// Sanity checks
assert!(part_prim.iter().all(|x| x.is_some()));
@ -183,11 +192,12 @@ impl DataLayout {
.unwrap_or(0)
> 0));
Ok(Self {
*self = Self {
data_dirs,
part_prim,
part_sec,
})
};
Ok(())
}
pub(crate) fn primary_block_dir(&self, hash: &Hash) -> PathBuf {
@ -208,8 +218,8 @@ impl DataLayout {
fn partition_from(&self, hash: &Hash) -> usize {
u16::from_be_bytes([
hash.as_slice()[DPART_BYTES.0],
hash.as_slice()[DPART_BYTES.1],
hash.as_slice()[HASH_DRIVE_BYTES.0],
hash.as_slice()[HASH_DRIVE_BYTES.1],
]) as usize % DRIVE_NPART
}