Line data    Source code

       1              : use std::collections::HashMap;
       2              : 
       3              : const BLOCK_SIZE: usize = 8192;
       4              : 
       5              : /// A simple in-memory implementation of a block storage. Can be used to implement external
       6              : /// storage in tests.
       7              : pub struct BlockStorage {
       8              :     blocks: HashMap<u64, [u8; BLOCK_SIZE]>,
       9              : }
      10              : 
      11              : impl Default for BlockStorage {
      12            0 :     fn default() -> Self {
      13            0 :         Self::new()
      14            0 :     }
      15              : }
      16              : 
      17              : impl BlockStorage {
      18        10736 :     pub fn new() -> Self {
      19        10736 :         BlockStorage {
      20        10736 :             blocks: HashMap::new(),
      21        10736 :         }
      22        10736 :     }
      23              : 
      24         1523 :     pub fn read(&self, pos: u64, buf: &mut [u8]) {
      25         1523 :         let mut buf_offset = 0;
      26         1523 :         let mut storage_pos = pos;
      27         3662 :         while buf_offset < buf.len() {
      28         2139 :             let block_id = storage_pos / BLOCK_SIZE as u64;
      29         2139 :             let block = self.blocks.get(&block_id).unwrap_or(&[0; BLOCK_SIZE]);
      30         2139 :             let block_offset = storage_pos % BLOCK_SIZE as u64;
      31         2139 :             let block_len = BLOCK_SIZE as u64 - block_offset;
      32         2139 :             let buf_len = buf.len() - buf_offset;
      33         2139 :             let copy_len = std::cmp::min(block_len as usize, buf_len);
      34         2139 :             buf[buf_offset..buf_offset + copy_len]
      35         2139 :                 .copy_from_slice(&block[block_offset as usize..block_offset as usize + copy_len]);
      36         2139 :             buf_offset += copy_len;
      37         2139 :             storage_pos += copy_len as u64;
      38         2139 :         }
      39         1523 :     }
      40              : 
      41        12158 :     pub fn write(&mut self, pos: u64, buf: &[u8]) {
      42        12158 :         let mut buf_offset = 0;
      43        12158 :         let mut storage_pos = pos;
      44        24555 :         while buf_offset < buf.len() {
      45        12397 :             let block_id = storage_pos / BLOCK_SIZE as u64;
      46        12397 :             let block = self.blocks.entry(block_id).or_insert([0; BLOCK_SIZE]);
      47        12397 :             let block_offset = storage_pos % BLOCK_SIZE as u64;
      48        12397 :             let block_len = BLOCK_SIZE as u64 - block_offset;
      49        12397 :             let buf_len = buf.len() - buf_offset;
      50        12397 :             let copy_len = std::cmp::min(block_len as usize, buf_len);
      51        12397 :             block[block_offset as usize..block_offset as usize + copy_len]
      52        12397 :                 .copy_from_slice(&buf[buf_offset..buf_offset + copy_len]);
      53        12397 :             buf_offset += copy_len;
      54        12397 :             storage_pos += copy_len as u64
      55              :         }
      56        12158 :     }
      57              : }