[Kimchi-devel] [PATCH 3/4] Upload storage volume

[Crístian Deives]

On 12-05-2015 13:59, Aline Manera wrote:
>> Is there a specific reason to why "chunk_size" is not a number? It 
>> should be a number.
>>
>
> It is because the data is sent in the request body. So all data is 
> encoded as unicode.
> As you can see in the tests, we chunk_size is actually an integer, but 
> it will be encoded as unicode for the request.

Still, this doesn't look good to me :-(

>> "4M"? Why? I'd say the volume capacity there is the size of 
>> COPYING.LGPL, which is about ~7 KiB, not 4 MiB. I understand that the 
>> test below will fail anyway, but the comment doesn't seem right.
>
> The max body size is a server configuration. It represents how much 
> data the request body can have.
>
> The test below is not related to the COPYING.LGPL file. It creates a 
> new file '/tmp/5m-file' which has 5M of size. (it is an empty file).
> And then tries to upload all its content using the upload API.
> The test will fail as the max body size is 4M and the content has 5M.

OK, thanks for the explanation! I thought this test was trying to write 
more than what the storage volume can hold (KCHVOL0028E), but this 
doesn't seem to have nothing to do with the upload operation itself, 
this is a generic limitation for all REST commands.

>
>>
>>
>>> +            newfile = '/tmp/5m-file'
>>> +            with open(newfile, 'wb') as fd:
>>> +                fd.seek(5*1024*1024-1)
>>> +                fd.write("\0")
>>> +            rollback.prependDefer(os.remove, newfile)
>>> +
>>> +            with open(newfile, 'rb') as fd:
>>> +                with open(newfile + '.tmp', 'wb') as tmp_fd:
>>> +                    data = fd.read()
>>> +                    tmp_fd.write(data)
>>> +
>>> +                with open(newfile + '.tmp', 'rb') as tmp_fd:
>>> +                    r = requests.put(url, data={'chunk_size': 
>>> len(data)},
>>> +                                     files={'chunk': tmp_fd},
>>> +                                     verify=False,
>>> + headers=fake_auth_header())
>>> +                    self.assertEquals(r.status_code, 413)
>>
>> Why going all the trouble of creating one file with \0s, then copying 
>> it to another file? Why not using only one?
>
> It is a requirement on how to build the request. The file descriptor 
> used for the request must have the data write otherwise, it will 
> assume it is empty.
>
>>
>>> +            # Do upload
>>> +            index = 0
>>> +            chunk_size = 2 * 1024
>>> +
>>> +            with open(filepath, 'rb') as fd:
>>> +                while True:
>>> +                    with open(filepath + '.tmp', 'wb') as tmp_fd:
>>> +                        fd.seek(index*chunk_size)
>>> +                        data = fd.read(chunk_size)
>>> +                        tmp_fd.write(data)
>>
>> Again, why do you need to create a new file here with a copy of the 
>> original data?
>>
>
> Same as I said before. And also, the first file descriptor will point 
> to the entire file and the second one will point to a piece of content 
> to be uploaded.

So you mean the browser will also need to create one file for each data 
chunk and copy its contents locally before sending it to the server? 
I.e. will uploading a 4 GiB ISO file copy 4 GiB of local data + send 4 
GiB of remote data?

Isn't it possible to pass the original file handler seek'd to the 
desired offset, and the server only reads "chunk_size" bytes?