MySQL 8.0.30
Source Code Documentation
merge_many_buff.h
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22
23#ifndef MERGE_MANY_BUFF_INCLUDED
24#define MERGE_MANY_BUFF_INCLUDED
25
26#include <algorithm>
27
28#include "my_dbug.h"
29#include "my_sys.h" // open_cached_file
30#include "sql/mysqld.h" // mysql_tmpdir
31#include "sql/sql_base.h" // TEMP_PREFIX
32#include "sql/sql_sort.h" // Sort_buffer
33
34class THD;
35
36/**
37 Merges buffers to make < MERGEBUFF2 buffers.
38
39 @param thd thread context
40 @param param Sort parameters.
41 @param sort_buffer The main memory buffer.
42 @param chunk_array Array of chunk descriptors to merge.
43 @param [out] p_num_chunks The number of chunks left in the output file.
44 @param [out] t_file Where to store the result.
45
46 @returns false if success, true if error
47*/
48
49template <typename Merge_param>
50bool merge_many_buff(THD *thd, Merge_param *param, Sort_buffer sort_buffer,
51 Merge_chunk_array chunk_array, size_t *p_num_chunks,
52 IO_CACHE *t_file) {
53 IO_CACHE t_file2;
55
56 size_t num_chunks = chunk_array.size();
57 *p_num_chunks = num_chunks;
58
59 if (num_chunks <= MERGEBUFF2) return false; /* purecov: inspected */
60
61 if (flush_io_cache(t_file) ||
63 MYF(MY_WME)))
64 return true; /* purecov: inspected */
65
66 IO_CACHE *from_file = t_file;
67 IO_CACHE *to_file = &t_file2;
68
69 while (num_chunks > MERGEBUFF2) {
70 if (reinit_io_cache(from_file, READ_CACHE, 0L, false, false)) goto cleanup;
71 if (reinit_io_cache(to_file, WRITE_CACHE, 0L, false, false)) goto cleanup;
72 Merge_chunk *last_chunk = chunk_array.begin();
73 uint i;
74 for (i = 0; i < num_chunks - MERGEBUFF * 3U / 2U; i += MERGEBUFF) {
75 if (merge_buffers(thd, param, from_file, to_file, sort_buffer,
76 last_chunk++,
77 Merge_chunk_array(&chunk_array[i], MERGEBUFF),
78 /*include_keys=*/true))
79 goto cleanup;
80 }
81 if (merge_buffers(thd, param, from_file, to_file, sort_buffer, last_chunk++,
82 Merge_chunk_array(&chunk_array[i], num_chunks - i),
83 /*include_keys=*/true))
84 break; /* purecov: inspected */
85 if (flush_io_cache(to_file)) break; /* purecov: inspected */
86
87 std::swap(from_file, to_file);
88 setup_io_cache(from_file);
89 setup_io_cache(to_file);
90 num_chunks = last_chunk - chunk_array.begin();
91 }
93 close_cached_file(to_file); // This holds old result
94 if (to_file == t_file) {
95 *t_file = t_file2; // Copy result file
96 setup_io_cache(t_file);
97 }
98
99 *p_num_chunks = num_chunks;
100 return num_chunks > MERGEBUFF2; /* Return true if interrupted */
101} /* merge_many_buff */
102
103#endif // MERGE_MANY_BUFF_INCLUDED
A wrapper class which provides array bounds checking.
Definition: sql_array.h:46
iterator begin()
begin : Returns a pointer to the first element in the array.
Definition: sql_array.h:116
size_t size() const
Definition: sql_array.h:131
For each client connection we create a separate thread with THD serving as a thread/connection descri...
Definition: sql_class.h:922
void cleanup(void)
Definition: sql_class.cc:1219
#define L
Definition: ctype-tis620.cc:75
DBUG_TRACE
Definition: do_ctype.cc:46
static int merge_buffers(THD *thd, Sort_param *param, IO_CACHE *from_file, IO_CACHE *to_file, Sort_buffer sort_buffer, Merge_chunk *last_chunk, Merge_chunk_array chunk_array, bool include_keys)
Merge buffers to one buffer.
Definition: filesort.cc:1900
void close_cached_file(IO_CACHE *cache)
Definition: mf_cache.cc:86
#define MY_WME
Definition: my_sys.h:122
void setup_io_cache(IO_CACHE *info)
Definition: mf_iocache.cc:117
#define flush_io_cache(info)
Definition: my_sys.h:757
bool reinit_io_cache(IO_CACHE *info, enum cache_type type, my_off_t seek_offset, bool use_async_io, bool clear_cache)
Definition: mf_iocache.cc:328
bool open_cached_file(IO_CACHE *cache, const char *dir, const char *prefix, size_t cache_size, myf cache_myflags)
Definition: mf_cache.cc:52
@ WRITE_CACHE
Definition: my_sys.h:284
@ READ_CACHE
Definition: my_sys.h:283
bool merge_many_buff(THD *thd, Merge_param *param, Sort_buffer sort_buffer, Merge_chunk_array chunk_array, size_t *p_num_chunks, IO_CACHE *t_file)
Merges buffers to make < MERGEBUFF2 buffers.
Definition: merge_many_buff.h:50
#define MYF(v)
Definition: my_inttypes.h:96
constexpr const unsigned int DISK_BUFFER_SIZE
Definition: my_io.h:163
Common header for many mysys elements.
#define mysql_tmpdir
Definition: mysqld.h:694
#define TEMP_PREFIX
Definition: sql_base.h:77
constexpr size_t MERGEBUFF2
Definition: sql_sort.h:40
Bounds_checked_array< Merge_chunk > Merge_chunk_array
Definition: sql_sort.h:142
constexpr size_t MERGEBUFF
Definition: sql_sort.h:39
static void swap(String &a, String &b) noexcept
Definition: sql_string.h:611
Definition: my_sys.h:340
Descriptor for a merge chunk to be sort-merged.
Definition: sql_sort.h:56
unsigned int uint
Definition: uca-dump.cc:29