Re: [pbs-devel] [PATCH proxmox-backup-qemu] adapt to chunk reader changes

[Stefan Reiter <s.reiter@proxmox.com>]

On 8/11/20 9:53 AM, Fabian Grünbichler wrote:
> On August 10, 2020 5:13 pm, Stefan Reiter wrote:
>> makes sense in general, one comment inline
>>
>> On 8/10/20 1:25 PM, Fabian Grünbichler wrote:
>>> for verification of chunk crypt mode <=> index crypt mode match
>>>
>>> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
>>> ---
>>> follows patch #4 in proxmox-backup
>>>
>>>    src/restore.rs | 30 +++++++++++++-----------------
>>>    1 file changed, 13 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/src/restore.rs b/src/restore.rs
>>> index e43d040..9d8c4a2 100644
>>> --- a/src/restore.rs
>>> +++ b/src/restore.rs
>>> @@ -1,5 +1,4 @@
>>>    use std::sync::{Arc, Mutex};
>>> -use std::collections::HashMap;
>>>    use std::io::SeekFrom;
>>>    use std::convert::TryInto;
>>>    
>>> @@ -27,7 +26,6 @@ pub(crate) struct RestoreTask {
>>>        runtime: Arc<Runtime>,
>>>        crypt_config: Option<Arc<CryptConfig>>,
>>>        client: OnceCell<Arc<BackupReader>>,
>>> -    chunk_reader: OnceCell<RemoteChunkReader>,
>>>        manifest: OnceCell<Arc<BackupManifest>>,
>>>        image_registry: Arc<Mutex<Registry<ImageAccessInfo>>>,
>>>    }
>>> @@ -59,7 +57,6 @@ impl RestoreTask {
>>>                crypt_config,
>>>                client: OnceCell::new(),
>>>                manifest: OnceCell::new(),
>>> -            chunk_reader: OnceCell::new(),
>>>                image_registry: Arc::new(Mutex::new(Registry::<ImageAccessInfo>::new())),
>>>            })
>>>        }
>>> @@ -94,15 +91,6 @@ impl RestoreTask {
>>>                true
>>>            ).await?;
>>>    
>>> -        let chunk_reader = RemoteChunkReader::new(
>>> -            client.clone(),
>>> -            self.crypt_config.clone(),
>>> -            HashMap::with_capacity(0),
>>> -        );
>>> -
>>> -        self.chunk_reader.set(chunk_reader)
>>> -            .map_err(|_| format_err!("already connected!"))?;
>>> -
>>>            let (manifest, _) = client.download_manifest().await?;
>>>    
>>>            self.manifest.set(Arc::new(manifest))
>>> @@ -150,9 +138,12 @@ impl RestoreTask {
>>>    
>>>            let most_used = index.find_most_used_chunks(8);
>>>    
>>> +        let file_info = manifest.lookup_file_info(&archive_name)?;
>>> +
>>>            let mut chunk_reader = RemoteChunkReader::new(
>>>                client.clone(),
>>>                self.crypt_config.clone(),
>>> +            file_info.chunk_crypt_mode(),
>>>                most_used,
>>>            );
>>>    
>>> @@ -219,11 +210,6 @@ impl RestoreTask {
>>>                None => bail!("not connected"),
>>>            };
>>>    
>>> -        let chunk_reader = match self.chunk_reader.get() {
>>> -            Some(chunk_reader) => chunk_reader.clone(),
>>> -            None => bail!("not connected"),
>>> -        };
>>> -
>>>            let manifest = match self.manifest.get() {
>>>                Some(manifest) => manifest.clone(),
>>>                None => bail!("no manifest"),
>>> @@ -231,6 +217,16 @@ impl RestoreTask {
>>>    
>>>            let index = client.download_fixed_index(&manifest, &archive_name).await?;
>>>            let archive_size = index.index_bytes();
>>> +        let most_used = index.find_most_used_chunks(8);
>>
>> You change the cache hint from previously an empty HashMap to the 8
>> most-used chunks, is that intentional?
>>
>> I don't believe that really does anything for a fixed index, and the
>> AsyncIndexReader already caches the currently accessed chunk.
> 
> I made it do that same thing that the other RemoteChunkReader in
> restore.rs does ;)
> 
>> If anything, maybe add the zero digest here to keep that in cache, or
>> even better maybe add that to the RemoteChunkReader?
> 
> yeah, could do that. the restore itself already skips it to write zeroes
> directly without even asking the chunk reader, so not sure how much we
> gain by teaching the chunk reader to skip them as well..
> 

Well then other usages of the readers would gain that functionality too, 
like mapping backup images (both in VMs and soon on the host). But we 
can change this later anyway, not too important atm.

>>
>>> +
>>> +        let file_info = manifest.lookup_file_info(&archive_name)?;
>>> +
>>> +        let chunk_reader = RemoteChunkReader::new(
>>> +            client.clone(),
>>> +            self.crypt_config.clone(),
>>> +            file_info.chunk_crypt_mode(),
>>> +            most_used,
>>> +        );
>>>    
>>>            let reader = AsyncIndexReader::new(index, chunk_reader);
>>>    
>>>
>>