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From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	qemu-block@nongnu.org
Cc: kwolf@redhat.com, den@openvz.org, qemu-devel@nongnu.org,
	mreitz@redhat.com
Subject: Re: [PATCH v12 09/11] qcow2_format.py: collect fields to dump in JSON format
Date: Thu, 6 Aug 2020 12:08:40 +0300	[thread overview]
Message-ID: <9a56462e-fc51-5438-13c7-ab1c687a86e1@virtuozzo.com> (raw)
In-Reply-To: <4aff9a66-89e2-2a66-e9d5-46a7e9d650fc@virtuozzo.com>

On 05.08.2020 19:58, Vladimir Sementsov-Ogievskiy wrote:
> 30.07.2020 17:15, Andrey Shinkevich wrote:
>> As __dict__ is being extended with class members we do not want to
>> print, add the to_dict() method to classes that returns a dictionary
>> with desired fields and their values. Extend it in subclass when
>> necessary to print the final dictionary in the JSON output which
>> follows.
>>
>> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
>> ---
>>   tests/qemu-iotests/qcow2_format.py | 34 
>> ++++++++++++++++++++++++++++++++++
>>   1 file changed, 34 insertions(+)
>>
>> diff --git a/tests/qemu-iotests/qcow2_format.py 
>> b/tests/qemu-iotests/qcow2_format.py
>> index 2000de3..a4114cb 100644
>> --- a/tests/qemu-iotests/qcow2_format.py
>> +++ b/tests/qemu-iotests/qcow2_format.py
>> @@ -119,6 +119,9 @@ class Qcow2Struct(metaclass=Qcow2StructMeta):
>>                 print('{:<25} {}'.format(f[2], value_str))
>>   +    def to_dict(self):
>> +        return dict((f[2], self.__dict__[f[2]]) for f in self.fields)
>> +
>>     class Qcow2BitmapExt(Qcow2Struct):
>>   @@ -151,6 +154,11 @@ class Qcow2BitmapExt(Qcow2Struct):
>>               print()
>>               entry.dump()
>>   +    def to_dict(self):
>> +        fields_dict = super().to_dict()
>> +        fields_dict['bitmap_directory'] = self.bitmap_directory
>> +        return fields_dict
>> +
>>     class Qcow2BitmapDirEntry(Qcow2Struct):
>>   @@ -189,6 +197,14 @@ class Qcow2BitmapDirEntry(Qcow2Struct):
>>           super(Qcow2BitmapDirEntry, self).dump()
>>           self.bitmap_table.dump()
>>   +    def to_dict(self):
>> +        fields_dict = super().to_dict()
>> +        fields_dict['bitmap_table'] = self.bitmap_table.entries
>
> the fact that we have to access internals of bitmap_table is not nice, 
> but let's refactor it later.
>
>> +        bmp_name = dict(name=self.name)
>> +        # Put the name ahead of the dict
>
> Aha. I don't think that ordering is necessary for json, but why not to 
> order it a bit.
>
>> +        bme_dict = {**bmp_name, **fields_dict}
>
>
> strange to create bmp_name dict just to unpack it. You may as well do
>
> bme_dict = {'name': self.name, **fields_dict}
>
>> +        return bme_dict
>
> bme_dict is extra variable: it's created just to return it, so, how 
> about just
>
> return {'name': self.name, **fields_dict}
>
>
> or, maybe
>
> return {
>            'name': self.name,
>            **super().to_dict(),
>            'bitmap_table': self.bitmap_table.entries
>        }
>
>> +
>>     class Qcow2BitmapTableEntry(Qcow2Struct):
>>   @@ -214,6 +230,9 @@ class Qcow2BitmapTableEntry(Qcow2Struct):
>>           else:
>>               self.type = 'all-zeroes'
>>   +    def to_dict(self):
>> +        return dict(type=self.type, offset=self.offset, 
>> reserved=self.reserved)
>> +
>
> Python has a special syntax for creating dicts :), let's use:
>
> return {'type': self.type, 'offset': self.offset, 'reserved': 
> self.reserved}
>
>
>>     class Qcow2BitmapTable:
>>   @@ -246,6 +265,9 @@ class QcowHeaderExtension(Qcow2Struct):
>>               0x44415441: 'Data file'
>>           }
>>   +        def to_dict(self):
>> +            return self.mapping.get(self.value, "<unknown>")
>
> aha, so, actually, to_dict() returns not dict, but string. So it 
> should better be named to_json() (and return any json-dumpable object, 
> like string or dict)
>
> and then, we can add to_json() method to Qcow2BitmapTable as well, to 
> return list.


So, should I refactor it now?

Andrey


>
>
>> +
>>       fields = (
>>           ('u32', Magic, 'magic'),
>>           ('u32', '{}', 'length')
>> @@ -308,6 +330,18 @@ class QcowHeaderExtension(Qcow2Struct):
>>           else:
>>               self.obj.dump()
>>   +    def to_dict(self):
>> +        fields_dict = super().to_dict()
>> +        ext_name = dict(name=self.Magic(self.magic))
>
> strange that we have to create Magic object here... Ok, let's refactor 
> it later
>
>> +        # Put the name ahead of the dict
>> +        he_dict = {**ext_name, **fields_dict}
>> +        if self.obj is not None:
>> +            he_dict['data'] = self.obj
>> +        else:
>> +            he_dict['data_str'] = self.data_str
>> +
>> +        return he_dict
>
> again, let's avoid extra dict variables:
>
> res = {'name': self.Magic(self.magic), **super().to_dict()}
> if ...
>
>
>> +
>>       @classmethod
>>       def create(cls, magic, data):
>>           return QcowHeaderExtension(magic, len(data), data)
>>
>
>


  reply	other threads:[~2020-08-06 12:09 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30 14:15 [PATCH v12 00/11] iotests: Dump QCOW2 dirty bitmaps metadata Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 01/11] iotests: add test for QCOW2 header dump Andrey Shinkevich
2020-07-30 19:05   ` Eric Blake
2020-07-31  7:28     ` Andrey Shinkevich
2020-08-05 11:23   ` Vladimir Sementsov-Ogievskiy
2020-08-05 12:10     ` Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 02/11] qcow2_format.py: make printable data an extension class member Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 03/11] qcow2_format.py: change Qcow2BitmapExt initialization method Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 04/11] qcow2_format.py: dump bitmap flags in human readable way Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 05/11] qcow2_format.py: Dump bitmap directory information Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 06/11] qcow2_format.py: pass cluster size to substructures Andrey Shinkevich
2020-07-30 14:15 ` [PATCH v12 07/11] qcow2_format.py: Dump bitmap table serialized entries Andrey Shinkevich
2020-08-05 15:57   ` Vladimir Sementsov-Ogievskiy
2020-07-30 14:15 ` [PATCH v12 08/11] qcow2.py: Introduce '-j' key to dump in JSON format Andrey Shinkevich
2020-08-05 16:12   ` Vladimir Sementsov-Ogievskiy
2020-07-30 14:15 ` [PATCH v12 09/11] qcow2_format.py: collect fields " Andrey Shinkevich
2020-08-05 16:58   ` Vladimir Sementsov-Ogievskiy
2020-08-06  9:08     ` Andrey Shinkevich [this message]
2020-08-06  9:18       ` Vladimir Sementsov-Ogievskiy
2020-07-30 14:15 ` [PATCH v12 10/11] qcow2_format.py: support dumping metadata " Andrey Shinkevich
2020-08-05 17:04   ` Vladimir Sementsov-Ogievskiy
2020-07-30 14:15 ` [PATCH v12 11/11] iotests: dump QCOW2 header in JSON in #303 Andrey Shinkevich
2020-08-05 17:08   ` Vladimir Sementsov-Ogievskiy

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