[Tarantool-patches] [PATCH v4 4/5] sql: use parser's region of "index" array

[Roman Khabibov]

Hi! Thanks for the review.

> On Nov 6, 2020, at 01:26, Nikita Pettik <korablev at tarantool.org> wrote:
> 
> On 09 Oct 16:45, Roman Khabibov wrote:
>> Allocate memory for the "index" array of ephemeral space on the
>> parser's region instead of a heap as it was before. Fixed a memory
>> leak that realloc() generated.
> 
> Would be nice pointing out where leak occured. Also realloc usage looks
> better to me (27 lines vs 8 with straight execution flaw). 
Vlad said that main point of the region - speed, and it is also harder
to leave a memory leak, because the region is destroyed in the end of
parsing entirely.

>> Needed for #2349
>> ---
>> src/box/sql/build.c | 48 +++++++++++++++++++++++++++++++++------------
>> 1 file changed, 35 insertions(+), 13 deletions(-)
>> 
>> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
>> index 3b3c8099a..fd8e7ed1e 100644
>> --- a/src/box/sql/build.c
>> +++ b/src/box/sql/build.c
>> @@ -2228,29 +2228,52 @@ vdbe_emit_new_sec_index_id(struct Parse *parse, uint32_t space_id,
>> }
>> 
>> /**
>> - * Add new index to table's indexes list.
>> + * Add new index to ephemeral @a space's "index" array. Reallocate
>> + * memory on @a parse's region if needed.
>> + *
>>  * We follow convention that PK comes first in list.
>>  *
>> + * @param parse Parsing structure.
>>  * @param space Space to which belongs given index.
>>  * @param index Index to be added to list.
>>  */
>> -static void
>> -table_add_index(struct space *space, struct index *index)
>> +static int
>> +sql_space_add_index(struct Parse *parse, struct space *space,
>> +		    struct index *index)
>> {
>> 	uint32_t idx_count = space->index_count;
>> -	size_t indexes_sz = sizeof(struct index *) * (idx_count + 1);
>> -	struct index **idx = (struct index **) realloc(space->index,
>> -						       indexes_sz);
>> -	if (idx == NULL) {
>> -		diag_set(OutOfMemory, indexes_sz, "realloc", "idx");
>> -		return;
>> -	}
>> -	space->index = idx;
>> +	size_t size = 0;
>> +	struct index **idx = NULL;
>> +	struct region *region = &parse->region;
>> +	if (idx_count == 0) {
>> +		idx = region_alloc_array(region, typeof(struct index *), 1,
>> +					 &size);
>> +		if (idx == NULL)
>> +			goto alloc_error;
>> +	/*
>> +	 * Reallocate each time the idx_count becomes equal to the
>> +	 * power of two.
>> +	 */
>> +	} else if ((idx_count & (idx_count - 1)) == 0) {
>> +		idx = region_alloc_array(region, typeof(struct index *),
>> +					 idx_count * 2, &size);
>> +		if (idx == NULL)
>> +			goto alloc_error;
>> +		memcpy(idx, space->index, idx_count * sizeof(struct index *));
>> +	}
>> +	if (idx != NULL)
>> +		space->index = idx;
>> 	/* Make sure that PK always comes as first member. */
>> 	if (index->def->iid == 0 && idx_count != 0)
>> 		SWAP(space->index[0], index);
>> 	space->index[space->index_count++] = index;
>> 	space->index_id_max =  MAX(space->index_id_max, index->def->iid);;
>> +	return 0;
>> +
>> +alloc_error:
>> +	diag_set(OutOfMemory, size, "region_alloc_array", "idx");
>> +	parse->is_aborted = true;
>> +	return -1;
>> }
>> 
>> int
>> @@ -2717,9 +2740,8 @@ sql_create_index(struct Parse *parse) {
>> 		sqlVdbeAddOp0(vdbe, OP_Expire);
>> 	}
>> 
>> -	if (tbl_name != NULL)
>> +	if (tbl_name != NULL || sql_space_add_index(parse, space, index) != 0)
>> 		goto exit_create_index;
>> -	table_add_index(space, index);
>> 	index = NULL;
>> 
>> 	/* Clean up before exiting. */
>> -- 
>> 2.24.3 (Apple Git-128)
>> 

commit 459410f559a1c2f36a2da8925565a32a4caf4ae3 (HEAD)
Author: Roman Khabibov <roman.habibov at tarantool.org>
Date:   Thu Sep 3 14:26:47 2020 +0300

    sql: use parser's region of "index" array
    
    Allocate memory for the "index" array of ephemeral space on the
    parser's region instead of a heap as it was before. Fixed a memory
    leak that realloc() generated for the index array of ephemeral
    space. The memory was never released.
    
    Needed for #2349

diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index 3b3c8099a..fd8e7ed1e 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -2228,29 +2228,52 @@ vdbe_emit_new_sec_index_id(struct Parse *parse, uint32_t space_id,
 }
 
 /**
- * Add new index to table's indexes list.
+ * Add new index to ephemeral @a space's "index" array. Reallocate
+ * memory on @a parse's region if needed.
+ *
  * We follow convention that PK comes first in list.
  *
+ * @param parse Parsing structure.
  * @param space Space to which belongs given index.
  * @param index Index to be added to list.
  */
-static void
-table_add_index(struct space *space, struct index *index)
+static int
+sql_space_add_index(struct Parse *parse, struct space *space,
+		    struct index *index)
 {
 	uint32_t idx_count = space->index_count;
-	size_t indexes_sz = sizeof(struct index *) * (idx_count + 1);
-	struct index **idx = (struct index **) realloc(space->index,
-						       indexes_sz);
-	if (idx == NULL) {
-		diag_set(OutOfMemory, indexes_sz, "realloc", "idx");
-		return;
-	}
-	space->index = idx;
+	size_t size = 0;
+	struct index **idx = NULL;
+	struct region *region = &parse->region;
+	if (idx_count == 0) {
+		idx = region_alloc_array(region, typeof(struct index *), 1,
+					 &size);
+		if (idx == NULL)
+			goto alloc_error;
+	/*
+	 * Reallocate each time the idx_count becomes equal to the
+	 * power of two.
+	 */
+	} else if ((idx_count & (idx_count - 1)) == 0) {
+		idx = region_alloc_array(region, typeof(struct index *),
+					 idx_count * 2, &size);
+		if (idx == NULL)
+			goto alloc_error;
+		memcpy(idx, space->index, idx_count * sizeof(struct index *));
+	}
+	if (idx != NULL)
+		space->index = idx;
 	/* Make sure that PK always comes as first member. */
 	if (index->def->iid == 0 && idx_count != 0)
 		SWAP(space->index[0], index);
 	space->index[space->index_count++] = index;
 	space->index_id_max =  MAX(space->index_id_max, index->def->iid);;
+	return 0;
+
+alloc_error:
+	diag_set(OutOfMemory, size, "region_alloc_array", "idx");
+	parse->is_aborted = true;
+	return -1;
 }
 
 int
@@ -2717,9 +2740,8 @@ sql_create_index(struct Parse *parse) {
 		sqlVdbeAddOp0(vdbe, OP_Expire);
 	}
 
-	if (tbl_name != NULL)
+	if (tbl_name != NULL || sql_space_add_index(parse, space, index) != 0)
 		goto exit_create_index;
-	table_add_index(space, index);
 	index = NULL;
 
 	/* Clean up before exiting. */