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Better comments, move Lifo_buffer to separate file.

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This commit is contained in:
Sergey Petrunya
2010-09-28 12:19:50 +04:00
parent 3066c37718
commit 4f56acb676
5 changed files with 77 additions and 464 deletions
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135
sql/multi_range_read.cc
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@ -332,7 +332,7 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
is_mrr_assoc= !test(mode & HA_MRR_NO_ASSOCIATION);
/*
Figure out what steps we'll need to do
Determine whether we'll need to do key sorting and/or rnd_pos() scan
*/
do_sort_keys= FALSE;
if ((mode & HA_MRR_SINGLE_POINT) &&
@ -362,8 +362,9 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
status_var_increment(table->in_use->status_var.ha_multi_range_read_init_count);
/*
At start, alloc all of the buffer for rowids. Key sorting code will grab a
piece if necessary.
At start, alloc all of the buffer for rowids. When/if key sorting code
figures how much buffer space it needs, it will call setup_buffer_sizes()
to re-distribute the buffer space.
*/
full_buf= buf->buffer;
full_buf_end= buf->buffer_end;
@ -530,22 +531,19 @@ static int rowid_cmp_reverse(void *h, uchar *a, uchar *b)
/**
DS-MRR: Fill and sort the rowid buffer
{This is an internal function of DiskSweep MRR implementation}
Scan the MRR ranges and collect ROWIDs (or {ROWID, range_id} pairs) into
buffer. When the buffer is full or scan is completed, sort the buffer by
rowid and return.
When this function returns, either rowid buffer is not empty, or the source
of lookup keys (i.e. ranges) is exhaused.
dsmrr_eof is set to indicate whether we've exhausted the list of ranges we're
scanning. This function never returns HA_ERR_END_OF_FILE.
post-condition:
rowid buffer is not empty, or key source is exhausted.
@retval 0 OK, the next portion of rowids is in the buffer,
properly ordered
@retval other Error
*/
int DsMrr_impl::dsmrr_fill_rowid_buffer()
@ -556,15 +554,13 @@ int DsMrr_impl::dsmrr_fill_rowid_buffer()
DBUG_ENTER("DsMrr_impl::dsmrr_fill_rowid_buffer");
DBUG_ASSERT(rowid_buffer.is_empty());
rowid_buffer.reset_for_writing();
rowid_buffer.reset();
rowid_buffer.setup_writing(&h2->ref, h2->ref_length,
is_mrr_assoc? (uchar**)&range_info_ptr: NULL, sizeof(void*));
is_mrr_assoc? (uchar**)&range_info_ptr: NULL,
sizeof(void*));
last_identical_rowid= NULL;
//if (do_sort_keys && key_buffer.is_reverse())
// key_buffer.flip();
while (rowid_buffer.can_write())
{
if (do_sort_keys)
@ -652,18 +648,21 @@ equals:
return 0;
}
int DsMrr_impl::key_tuple_cmp_reverse(void* arg, uchar* key1, uchar* key2)
{
return -key_tuple_cmp(arg, key1, key2);
}
/*
Setup key/rowid buffer sizes based on sample_key
DESCRIPTION
Setup key/rowid buffer sizes based on sample_key and its length.
This function must be called when all buffer space is empty.
/**
Setup key/rowid buffer sizes based on sample_key and its length.
@param
sample_key A lookup key to use as a sample. It is assumed that
all other keys will have the same length/etc.
@note
This function must be called when all buffers are empty
*/
void DsMrr_impl::setup_buffer_sizes(key_range *sample_key)
@ -737,22 +736,19 @@ void DsMrr_impl::setup_buffer_sizes(key_range *sample_key)
}
/*
/**
DS-MRR/CPK: Fill the buffer with (lookup_tuple, range_id) pairs and sort
SYNOPSIS
DsMrr_impl::dsmrr_fill_key_buffer()
DESCRIPTION
DS-MRR/CPK: Enumerate the input range (=key) sequence, fill the key buffer
(lookup_key, range_id) pairs and sort.
Enumerate the input range (=key) sequence, fill the key buffer with
(lookup_key, range_id) pairs and sort it.
When this function returns, either
- key buffer is non-empty, or
- key buffer is empty and source range sequence is exhausted
@note
dsmrr_eof is set to indicate whether we've exhausted the list of ranges
we're scanning.
post-condition:
- key buffer is non-empty
- key buffer is empty and source range sequence is exhausted
*/
void DsMrr_impl::dsmrr_fill_key_buffer()
@ -778,7 +774,7 @@ void DsMrr_impl::dsmrr_fill_key_buffer()
identical_key_it= &backward_key_it;
key_buffer->set_buffer_space(rowid_buffer_end, full_buf_end);
}
key_buffer->reset_for_writing();
key_buffer->reset();
key_buffer->setup_writing(&key_ptr, key_size_in_keybuf,
is_mrr_assoc? (uchar**)&range_info_ptr : NULL,
sizeof(uchar*));
@ -825,8 +821,8 @@ void DsMrr_impl::dsmrr_fill_key_buffer()
}
/*
Take unused space from key buffer and give it to rowid buffer.
/**
Take unused space from the key buffer and give it to the rowid buffer
*/
void DsMrr_impl::reallocate_buffer_space()
@ -837,30 +833,25 @@ void DsMrr_impl::reallocate_buffer_space()
}
/*
/**
DS-MRR/CPK: multi_range_read_next() function
DESCRIPTION
DsMrr_impl::dsmrr_next_from_index()
range_info OUT identifier of range that the returned record belongs to
DESCRIPTION
This function walks over key buffer and does index reads, i.e. it produces
{current_record, range_id} pairs.
The function has the same call contract like multi_range_read_next()'s.
We actually iterate nested sequences:
@param range_info OUT identifier of range that the returned record belongs to
- a disjoint sequence of index ranges
- each range has multiple records
- each record goes into multiple identical ranges.
@note
This function walks over key buffer and does index reads, i.e. it produces
{current_record, range_id} pairs.
RETURN
0 OK, next record was successfully read
HA_ERR_END_OF_FILE End of records
Other Some other error
The function has the same call contract like multi_range_read_next()'s.
We actually iterate over nested sequences:
- a disjoint sequence of index ranges
- each range has multiple records
- each record goes into multiple identical ranges.
@retval 0 OK, next record was successfully read
@retval HA_ERR_END_OF_FILE End of records
@retval Other Some other error
*/
int DsMrr_impl::dsmrr_next_from_index(char **range_info_arg)
@ -1007,7 +998,9 @@ end:
/**
DS-MRR implementation: multi_range_read_next() function
DS-MRR implementation: multi_range_read_next() function.
Calling convention is like multi_range_read_next() has.
*/
int DsMrr_impl::dsmrr_next(char **range_info)
@ -1237,17 +1230,12 @@ bool key_uses_partial_cols(TABLE *table, uint keyno)
/*
Check if key/flags allow DS-MRR/CPK strategy to be used
SYNOPSIS
DsMrr_impl::check_cpk_scan()
keyno Index that will be used
mrr_flags
@param thd
@param keyno Index that will be used
@param mrr_flags
DESCRIPTION
Check if key/flags allow DS-MRR/CPK strategy to be used.
RETURN
TRUE DS-MRR/CPK should be used
FALSE Otherwise
@retval TRUE DS-MRR/CPK should be used
@retval FALSE Otherwise
*/
bool DsMrr_impl::check_cpk_scan(THD *thd, uint keyno, uint mrr_flags)
@ -1413,17 +1401,14 @@ bool DsMrr_impl::get_disk_sweep_mrr_cost(uint keynr, ha_rows rows, uint flags,
/*
Get cost of one sort-and-sweep step
It consists of two parts:
- sort an array of #nrows ROWIDs using qsort
- read #nrows records from table in a sweep.
SYNOPSIS
get_sort_and_sweep_cost()
table Table being accessed
nrows Number of rows to be sorted and retrieved
cost OUT The cost
DESCRIPTION
Get cost of these operations:
- sort an array of #nrows ROWIDs using qsort
- read #nrows records from table in a sweep.
@param table Table being accessed
@param nrows Number of rows to be sorted and retrieved
@param cost OUT The cost of scan
*/
static