diff options
Diffstat (limited to 'src/lib.rs')
| -rw-r--r-- | src/lib.rs | 355 |
1 files changed, 1 insertions, 354 deletions
@@ -1,355 +1,2 @@ #[macro_use] extern crate scan_fmt; -use std::collections::BinaryHeap; - -#[repr(u8)] -enum WALRingType { - #[allow(dead_code)] - Null = 0x0, - Full, - First, - Middle, - Last -} - -#[repr(packed)] -struct WALRingBlob { - crc32: u32, - rsize: u32, - rtype: WALRingType, - // payload follows -} - -pub type WALBytes = Box<[u8]>; -pub type WALFileId = u64; -pub type WALPos = u64; - -#[derive(Eq, PartialEq, Copy, Clone, Debug)] -pub struct WALRingId { - start: WALPos, - end: WALPos -} - -impl Ord for WALRingId { - fn cmp(&self, other: &WALRingId) -> std::cmp::Ordering { - other.start.cmp(&self.start).then_with(|| other.end.cmp(&self.end)) - } -} - -impl PartialOrd for WALRingId { - fn partial_cmp(&self, other: &WALRingId) -> Option<std::cmp::Ordering> { - Some(self.cmp(other)) - } -} - -/// the state for a WAL writer -struct WALState { - /// the first file id of WAL - first_fid: WALFileId, - /// the next position for a record, addressed in the entire WAL space - next: WALPos, - /// number of bits for a file - file_nbit: u64, -} - -pub trait WALFile { - /// Initialize the file space in [offset, offset + length) to zero. - fn allocate(&self, offset: WALPos, length: usize) -> Result<(), ()>; - /// Truncate a file to a specified length. - fn truncate(&self, length: usize) -> Result<(), ()>; - /// Write data with offset. - fn write(&self, offset: WALPos, data: WALBytes); - /// Read data with offset. - fn read(&self, offset: WALPos, length: usize) -> WALBytes; -} - -pub trait WALStore { - /// Open a file given the filename, create the file if not exists when `touch` is `true`. - fn open_file(&self, filename: &str, touch: bool) -> Option<Box<dyn WALFile>>; - /// Unlink a file given the filename. - fn remove_file(&self, filename: &str) -> Result<(), ()>; - /// Enumerate all WAL files. - fn enumerate_files(&self) -> Box<[String]>; - /// Apply (redo) the payload during recovery. - fn apply_payload(&self, payload: WALBytes); -} - -/// The middle layer that manages WAL file handles and invokes public trait functions to actually -/// manipulate files and their contents. -struct WALFilePool<F: WALStore> { - store: F, - handles: lru::LruCache<WALFileId, Box<dyn WALFile>>, - file_nbit: u64, - file_size: u64, - block_nbit: u64, -} - -impl<F: WALStore> WALFilePool<F> { - fn new(store: F, file_nbit: u8, block_nbit: u8, cache_size: usize) -> Self { - let file_nbit = file_nbit as u64; - let block_nbit = block_nbit as u64; - WALFilePool { - store, - handles: lru::LruCache::new(cache_size), - file_nbit, - file_size: 1 << (file_nbit as u64), - block_nbit, - } - } - - fn get_fname(fid: WALFileId) -> String { - format!("{:08x}.log", fid) - } - - fn get_file(&mut self, fid: u64, touch: bool) -> &'static dyn WALFile { - let h = match self.handles.get(&fid) { - Some(h) => &**h, - None => { - self.handles.put(fid, self.store.open_file(&Self::get_fname(fid), touch).unwrap()); - &**self.handles.get(&fid).unwrap() - } - }; - unsafe {&*(h as *const dyn WALFile)} - } - - fn get_fid(&mut self, fname: &str) -> WALFileId { - scan_fmt!(fname, "{x}.log", [hex WALFileId]).unwrap() - } - - // TODO: evict stale handles - fn write(&mut self, writes: Vec<(WALPos, WALBytes)>) { - // pre-allocate the file space - let mut fid = writes[0].0 >> self.file_nbit; - let mut alloc_start = writes[0].0 & (self.file_size - 1); - let mut alloc_end = alloc_start + writes[0].1.len() as u64; - let mut h = self.get_file(fid, true); - for (off, w) in &writes[1..] { - let next_fid = off >> self.file_nbit; - if next_fid != fid { - h.allocate(alloc_start, (alloc_end - alloc_start) as usize).unwrap(); - h = self.get_file(next_fid, true); - alloc_start = 0; - alloc_end = alloc_start + w.len() as u64; - fid = next_fid; - } else { - alloc_end += w.len() as u64; - } - } - h.allocate(alloc_start, (alloc_end - alloc_start) as usize).unwrap(); - for (off, w) in writes.into_iter() { - self.get_file(off >> self.file_nbit, true).write(off & (self.file_size - 1), w); - } - } - - fn remove_file(&self, fid: u64) -> Result<(), ()> { - self.store.remove_file(&Self::get_fname(fid)) - } - - fn reset(&mut self) { self.handles.clear() } -} - -pub struct WALWriter<F: WALStore> { - state: WALState, - file_pool: WALFilePool<F>, - block_buffer: WALBytes, - block_size: u32, - next_complete: WALPos, - io_complete: BinaryHeap<WALRingId> -} - -impl<F: WALStore> WALWriter<F> { - fn new(state: WALState, file_pool: WALFilePool<F>) -> Self { - let mut b = Vec::new(); - let block_size = 1 << file_pool.block_nbit as u32; - //let block_nbit = state.block_nbit; - //let block_size = 1 << (block_nbit as u32); - //let file_nbit = state.file_nbit; - //let file_size = 1 << (file_nbit as u64); - b.resize(block_size as usize, 0); - WALWriter{ - state, - file_pool, - block_buffer: b.into_boxed_slice(), - block_size, - next_complete: 0, - io_complete: BinaryHeap::new(), - } - } - - /// Submit a sequence of records to WAL; WALStore/WALFile callbacks are invoked before the - /// function returns. The caller then has the knowledge of WAL writes so it should defer - /// actual data writes after WAL writes. - pub fn grow<T: AsRef<[WALBytes]>>(&mut self, records: T) -> Box<[WALRingId]> { - let mut res = Vec::new(); - let mut writes = Vec::new(); - let msize = std::mem::size_of::<WALRingBlob>() as u32; - // the global offest of the begining of the block - // the start of the unwritten data - let mut bbuff_start = self.state.next as u32 & (self.block_size - 1); - // the end of the unwritten data - let mut bbuff_cur = bbuff_start; - - for _rec in records.as_ref() { - let mut rec = &_rec[..]; - let mut rsize = rec.len() as u32; - let mut started = false; - while rsize > 0 { - let remain = self.block_size - bbuff_cur; - if remain > msize { - let d = remain - msize; - let ring_start = self.state.next + (bbuff_cur - bbuff_start) as u64; - let blob = unsafe {std::mem::transmute::<*mut u8, &mut WALRingBlob>( - (&mut self.block_buffer[bbuff_cur as usize..]).as_mut_ptr())}; - bbuff_cur += msize; - if d >= rsize { - // the remaining rec fits in the block - let payload = rec; - blob.crc32 = crc::crc32::checksum_ieee(payload); - blob.rsize = rsize; - blob.rtype = if started {WALRingType::Last} else {WALRingType::Full}; - &mut self.block_buffer[ - bbuff_cur as usize.. - bbuff_cur as usize + payload.len()].copy_from_slice(payload); - bbuff_cur += rsize; - rsize = 0; - } else { - // the remaining block can only accommodate partial rec - let payload = &rec[..d as usize]; - blob.crc32 = crc::crc32::checksum_ieee(payload); - blob.rsize = d; - blob.rtype = if started {WALRingType::Middle} else { - started = true; - WALRingType::First - }; - &mut self.block_buffer[ - bbuff_cur as usize.. - bbuff_cur as usize + payload.len()].copy_from_slice(payload); - bbuff_cur += d; - rsize -= d; - rec = &rec[d as usize..]; - } - let ring_end = self.state.next + (bbuff_cur - bbuff_start) as u64; - res.push(WALRingId{start: ring_start, end: ring_end}); - } else { - // add padding space by moving the point to the end of the block - bbuff_cur = self.block_size; - } - if bbuff_cur == self.block_size { - writes.push((self.state.next, - self.block_buffer[bbuff_start as usize..] - .to_vec().into_boxed_slice())); - self.state.next += (self.block_size - bbuff_start) as u64; - bbuff_start = 0; - bbuff_cur = 0; - } - } - } - if bbuff_cur > bbuff_start { - writes.push((self.state.next, - self.block_buffer[bbuff_start as usize..bbuff_cur as usize] - .to_vec().into_boxed_slice())); - self.state.next += (bbuff_cur - bbuff_start) as u64; - } - self.file_pool.write(writes); - res.into_boxed_slice() - } - - /// Inform the WALWriter that data writes (specified by a slice of (offset, length) tuples) are - /// complete so that it could automatically remove obsolete WAL files. - pub fn peel<T: AsRef<[WALRingId]>>(&mut self, records: T) { - let msize = std::mem::size_of::<WALRingBlob>() as u64; - let block_size = self.block_size as u64; - for rec in records.as_ref() { - self.io_complete.push(*rec) - } - let orig_fid = self.state.first_fid; - while let Some(s) = self.io_complete.peek().and_then(|&e| Some(e.start)) { - if s != self.next_complete { - break - } - let mut m = self.io_complete.pop().unwrap(); - let block_remain = block_size - (m.end & (block_size - 1)); - if block_remain <= msize as u64 { - m.end += block_remain - } - self.next_complete = m.end - } - let next_fid = self.next_complete >> self.state.file_nbit; - for fid in orig_fid..next_fid { - self.file_pool.remove_file(fid).unwrap(); - } - self.state.first_fid = next_fid; - } -} - -pub struct WALLoader<F: WALStore> { - file_pool: WALFilePool<F>, -} - -impl<F: WALStore> WALLoader<F> { - pub fn new(store: F, file_nbit: u8, block_nbit: u8, cache_size: usize) -> Self { - let file_pool = WALFilePool::new(store, file_nbit, block_nbit, cache_size); - WALLoader{ file_pool } - } - - pub fn recover(mut self) -> WALWriter<F> { - let block_size = 1 << self.file_pool.block_nbit; - let msize = std::mem::size_of::<WALRingBlob>() as u32; - let mut logfiles = self.file_pool.store.enumerate_files(); - // TODO: use regex to filter out invalid files - // TODO: check for missing logfiles - logfiles.sort(); - let mut chunks = None; - for fname in logfiles.iter() { - let fid = self.file_pool.get_fid(fname); - let f = self.file_pool.get_file(fid, false); - let mut off = 0; - while block_size - (off & (block_size - 1)) > msize as u64 { - let header_raw = f.read(off, msize as usize); - off += msize as u64; - let header = unsafe { - std::mem::transmute::<*const u8, &WALRingBlob>(header_raw.as_ptr())}; - let rsize = header.rsize; - match header.rtype { - WALRingType::Full => { - assert!(chunks.is_none()); - let payload = f.read(off, rsize as usize); - off += rsize as u64; - self.file_pool.store.apply_payload(payload); - }, - WALRingType::First => { - assert!(chunks.is_none()); - chunks = Some(vec![f.read(off, rsize as usize)]); - off += rsize as u64; - }, - WALRingType::Middle => { - chunks.as_mut().unwrap().push(f.read(off, rsize as usize)); - off += rsize as u64; - }, - WALRingType::Last => { - chunks.as_mut().unwrap().push(f.read(off, rsize as usize)); - off += rsize as u64; - - let _chunks = chunks.take().unwrap(); - let mut payload = Vec::new(); - payload.resize(_chunks.iter().fold(0, |acc, v| acc + v.len()), 0); - let mut ps = &mut payload[..]; - for c in _chunks { - ps[..c.len()].copy_from_slice(&*c); - ps = &mut ps[c.len()..]; - } - self.file_pool.store.apply_payload(payload.into_boxed_slice()); - }, - WALRingType::Null => break, - } - } - f.truncate(0).unwrap(); - self.file_pool.remove_file(fid).unwrap(); - } - self.file_pool.reset(); - WALWriter::new(WALState { - first_fid: 0, - next: 0, - file_nbit: self.file_pool.file_nbit, - }, self.file_pool) - } -} +pub mod wal; |