src/client/remote_chunk_reader.rs

   1 use std::collections::HashMap;
   2 use std::sync::Arc;
   3
   4 use failure::*;
   5
   6 use super::BackupReader;
   7 use crate::backup::{ReadChunk, DataBlob, CryptConfig};
   8
   9 /// Read chunks from remote host using ``BackupReader``
  10 pub struct RemoteChunkReader {
  11     client: Arc<BackupReader>,
  12     crypt_config: Option<Arc<CryptConfig>>,
  13     cache_hint: HashMap<[u8; 32], usize>,
  14     cache:  HashMap<[u8; 32], Vec<u8>>,
  15 }
  16
  17 impl RemoteChunkReader {
  18
  19     /// Create a new instance.
  20     ///
  21     /// Chunks listed in ``cache_hint`` are cached and kept in RAM.
  22     pub fn new(
  23         client: Arc<BackupReader>,
  24         crypt_config: Option<Arc<CryptConfig>>,
  25         cache_hint: HashMap<[u8; 32], usize>,
  26     ) -> Self {
  27
  28         Self { client, crypt_config, cache_hint, cache: HashMap::new() }
  29     }
  30 }
  31
  32 impl ReadChunk for RemoteChunkReader {
  33
  34     fn read_raw_chunk(&mut self, digest:&[u8; 32]) -> Result<DataBlob, Error> {
  35
  36         let mut chunk_data = Vec::with_capacity(4*1024*1024);
  37
  38         tokio::task::block_in_place(|| futures::executor::block_on(self.client.download_chunk(&digest, &mut chunk_data)))?;
  39
  40         let chunk = DataBlob::from_raw(chunk_data)?;
  41         chunk.verify_crc()?;
  42
  43         Ok(chunk)
  44     }
  45
  46     fn read_chunk(&mut self, digest:&[u8; 32]) -> Result<Vec<u8>, Error> {
  47
  48         if let Some(raw_data) = self.cache.get(digest) {
  49             return Ok(raw_data.to_vec());
  50         }
  51
  52         let chunk = self.read_raw_chunk(digest)?;
  53
  54         let raw_data =  chunk.decode(self.crypt_config.as_ref().map(Arc::as_ref))?;
  55
  56         // fixme: verify digest?
  57
  58         let use_cache = self.cache_hint.contains_key(digest);
  59         if use_cache {
  60             self.cache.insert(*digest, raw_data.to_vec());
  61         }
  62
  63         Ok(raw_data)
  64     }
  65
  66 }