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From: Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Mergen Imeev <imeevma@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH v4 06/16] sql: introduce mem_append()
Date: Mon, 11 Oct 2021 23:50:08 +0200
Message-ID: <797b7cc5-800a-69a2-0d4d-51727d0a5607@tarantool.org> (raw)
In-Reply-To: <20211005093250.GC55311@tarantool.org>

Hi! Thanks for the fixes!

>>> diff --git a/src/box/sql/mem.c b/src/box/sql/mem.c
>>> index 079083fa1..b8ead8f41 100644
>>> --- a/src/box/sql/mem.c
>>> +++ b/src/box/sql/mem.c
>>> @@ -1925,6 +1925,27 @@ mem_move(struct Mem *to, struct Mem *from)
>>>  	from->zMalloc = NULL;
>>>  }
>>>  
>>> +int
>>> +mem_append(struct Mem *mem, const char *value, uint32_t len)
>>> +{
>>> +	assert((mem->type & (MEM_TYPE_BIN | MEM_TYPE_STR)) != 0);
>>> +	if (len == 0)
>>> +		return 0;
>>> +	int new_size = mem->n + len;
>>> +	if (((mem->flags & (MEM_Static | MEM_Dyn | MEM_Ephem)) != 0) ||
>>> +	    mem->szMalloc < new_size) {
>>> +		/*
>>> +		 * Force exponential buffer size growth to avoid having to call
>>> +		 * this routine too often.
>>> +		 */
>>> +		if (sqlVdbeMemGrow(mem, new_size + mem->n, 1) != 0)
>>
>> Looks like you could call sqlVdbeMemGrow() without all these checks
>> above. The grow function does them already.
>>
> True, fixed. There is a case where the behavior will be different - I
> mean the case where new_size < szMalloc and new_size + n > szMalloc,
> but that doesn't seem to be a very common case.

Wait, this does not look correct either. I thought sqlVdbeMemGrow()
does the exponential grow. But if it does not, we need to either patch
it, or keep some checks above. The 'standard' way is to grow only when
necessary, but at least x2. How this new way works I can't tell. It
might be worse. You will always have unused free space. Lets either
stick to the old way or patch the grow function.

  reply	other threads:[~2021-10-11 21:50 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-01 12:48 [Tarantool-patches] [PATCH v4 00/16] sql: refactor aggregate functions Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 01/16] sql: remove MEM_Zero flag from struct MEM Mergen Imeev via Tarantool-patches
2021-10-04 21:51   ` Vladislav Shpilevoy via Tarantool-patches
2021-10-05  8:46     ` Mergen Imeev via Tarantool-patches
2021-10-05  9:42       ` Mergen Imeev via Tarantool-patches
2021-10-05 12:28         ` Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 02/16] sql: fix possible undefined behavior during cast Mergen Imeev via Tarantool-patches
2021-10-04 21:52   ` Vladislav Shpilevoy via Tarantool-patches
2021-10-05  9:00     ` Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 03/16] sql: use register P1 for number of arguments Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 04/16] sql: remove AggStep0 and OP_BuiltinFunction0 Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 05/16] sql: move collation to struct sql_context Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 06/16] sql: introduce mem_append() Mergen Imeev via Tarantool-patches
2021-10-04 21:52   ` Vladislav Shpilevoy via Tarantool-patches
2021-10-05  9:32     ` Mergen Imeev via Tarantool-patches
2021-10-11 21:50       ` Vladislav Shpilevoy via Tarantool-patches [this message]
2021-10-19 10:49         ` Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 07/16] sql: remove sql_vdbemem_finalize() Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 08/16] sql: refactor SUM() function Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 09/16] sql: refactor TOTAL() function Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 10/16] sql: refactor AVG() function Mergen Imeev via Tarantool-patches
2021-10-04 21:53   ` Vladislav Shpilevoy via Tarantool-patches
2021-10-05  9:48     ` Mergen Imeev via Tarantool-patches
2021-10-11 21:50       ` Vladislav Shpilevoy via Tarantool-patches
2021-10-19 11:14         ` Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 11/16] sql: refactor COUNT() function Mergen Imeev via Tarantool-patches
2021-10-04 21:53   ` Vladislav Shpilevoy via Tarantool-patches
2021-10-05  9:55     ` Mergen Imeev via Tarantool-patches
2021-10-11 21:51       ` Vladislav Shpilevoy via Tarantool-patches
2021-10-19 11:17         ` Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 12/16] sql: refactor MIN() and MAX() functions Mergen Imeev via Tarantool-patches
2021-10-04 21:54   ` Vladislav Shpilevoy via Tarantool-patches
2021-10-05 10:07     ` Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 13/16] sql: refactor GROUP_CONCAT() function Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 14/16] sql: remove copying of result in finalizers Mergen Imeev via Tarantool-patches
2021-10-01 12:48 ` [Tarantool-patches] [PATCH v4 15/16] sql: remove MEM_TYPE_AGG Mergen Imeev via Tarantool-patches
2021-10-01 12:49 ` [Tarantool-patches] [PATCH v4 16/16] sql: remove field argv from struct sql_context Mergen Imeev via Tarantool-patches
2021-10-25 20:58 ` [Tarantool-patches] [PATCH v4 00/16] sql: refactor aggregate functions Vladislav Shpilevoy via Tarantool-patches
2021-10-26 10:34 Mergen Imeev via Tarantool-patches
2021-10-26 10:34 ` [Tarantool-patches] [PATCH v4 06/16] sql: introduce mem_append() Mergen Imeev via Tarantool-patches

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