Call madvise for existing index files (#211)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "parity-db"
-version = "0.4.8"
+version = "0.4.9"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"

src/index.rs

@@ -142,6 +142,20 @@ fn file_size(index_bits: u8) -> u64 {
  total_entries(index_bits) * 8 + META_SIZE as u64
 }
 
+#[cfg(unix)]
+fn madvise_random(id: TableId, map: &mut memmap2::MmapMut) {
+ unsafe {
+ libc::madvise(
+ map.as_mut_ptr() as _,
+ file_size(id.index_bits()) as usize,
+ libc::MADV_RANDOM,
+ );
+ }
+}
+
+#[cfg(not(unix))]
+fn madvise_random(_id: TableId, _map: &mut memmap2::MmapMut) {}
+
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub struct TableId(u16);
 
@@ -201,7 +215,8 @@ impl IndexTable {
  };
 
  try_io!(file.set_len(file_size(id.index_bits())));
- let map = try_io!(unsafe { memmap2::MmapMut::map_mut(&file) });
+ let mut map = try_io!(unsafe { memmap2::MmapMut::map_mut(&file) });
+ madvise_random(id, &mut map);
  log::debug!(target: "parity-db", "Opened existing index {}", id);
  Ok(Some(IndexTable { id, path, map: RwLock::new(Some(map)) }))
  }
@@ -547,10 +562,9 @@ impl IndexTable {
  .create_new(true)
  .open(self.path.as_path()));
  log::debug!(target: "parity-db", "Created new index {}", self.id);
- //TODO: check for potential overflows on 32-bit platforms
  try_io!(file.set_len(file_size(self.id.index_bits())));
  let mut mmap = try_io!(unsafe { memmap2::MmapMut::map_mut(&file) });
- self.madvise_random(&mut mmap);
+ madvise_random(self.id, &mut mmap);
  *wmap = Some(mmap);
  map = RwLockWriteGuard::downgrade_to_upgradable(wmap);
  }
@@ -620,20 +634,6 @@ impl IndexTable {
  }
  Ok(())
  }
-
- #[cfg(unix)]
- fn madvise_random(&self, map: &mut memmap2::MmapMut) {
- unsafe {
- libc::madvise(
- map.as_mut_ptr() as _,
- file_size(self.id.index_bits()) as usize,
- libc::MADV_RANDOM,
- );
- }
- }
-
- #[cfg(not(unix))]
- fn madvise_random(&self, _map: &mut memmap2::MmapMut) {}
 }
 
 #[cfg(test)]