From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 06 Oct 2016 22:53:35 GMT
Subject: Re: [PATCH v2 05/25] sequencer: allow the sequencer to take custody of malloc()ed data
Message-ID: <xmqq8tu1hyxc.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <28935e27-5ba8-c261-ba44-424f7b91cdda@gmail.com>

Jakub Narębski <jnareb@gmail.com> writes:

>> We manage lifetime of a field in a structure in one of three ways in
>> our codebase [*1*].
>> 
>>  ...
>>  * A field can sometimes own and sometimes borrow the memory, and it
>>    is accompanied by another field to tell which case it is, so that
>>    cleaning-up can tell when it needs to be free(3)d.  This is a
>>    minority case, and we generally avoid it especially in modern
>>    code for small allocation, as it makes the lifetime rule more
>>    complex than it is worth.
> ...
> On the other hand the _entrust() mechanism might be a good solution
> if the amount of memory was large, for example order of magnitude more
> than what would be needed to keep ownership info *and* borrowing would
> not be possible for some reason.

We have approach #3 exactly for that usage pattern.