[RP003] Revives my_hash_*() functions and changes to use HASH instead of std::unordered_[map/set]

std::unordered_[map/set] are estimated to waste CPU data cache more than the legacy mysys HASH implementation. So, reverts to use the legacy functions for frequent paths. - The filename "hash.[cc/h]" changed to "my_hash.[cc/h]" to avoid name confliction - table_def_cache, Table_cache, Tablespace_hash_set, schema_set have been changed This change is almost consist of the following commits partial reverting. > commit a8a7961 > Author: Steinar H. Gunderson <steinar.gunderson@oracle.com> > Date: Fri Jul 7 12:04:18 2017 +0200 > > Bug #25997748: MIGRATE FROM HASH TO STD::UNORDERED_MAP [patch 15] > commit b77037d > Author: Steinar H. Gunderson <steinar.gunderson@oracle.com> > Date: Fri May 26 13:05:59 2017 +0200 > > Bug #25997748: MIGRATE FROM HASH TO STD::UNORDERED_MAP [patch 8, noclose] > commit 532421a > Author: Steinar H. Gunderson <steinar.gunderson@oracle.com> > Date: Tue May 2 10:41:39 2017 +0200 > > Bug #25997748: MIGRATE FROM HASH TO STD::UNORDERED_MAP * Just picked up reset_dynamic() and pop_dynamic() from > commit 781d234 > Author: Jon Olav Hauglid <jon.hauglid@oracle.com> > Date: Tue Jul 30 10:28:15 2019 +0200 > > Bug#30112842: REMOVE DEAD CODE IDENTIFIED BY FASTCOV [noclose]

Author: buildup-db

MYSQL_VERSION

@@ -3,4 +3,4 @@ MYSQL_VERSION_MINOR=0
 MYSQL_VERSION_PATCH=42
 MYSQL_VERSION_EXTRA=
 MYSQL_VERSION_STABILITY="LTS"
-MYSQL_RP_REVISION="-RP002"
+MYSQL_RP_REVISION="-RP003"

include/my_hash.h

@@ -0,0 +1,117 @@
+/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
+
+#ifndef HASH_INCLUDED
+#define HASH_INCLUDED
+
+/**
+ @file include/hash.h
+ Dynamic hashing of record with different key-length.
+*/
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <new>
+
+#include "m_ctype.h"
+#include "my_inttypes.h"
+#include "my_sys.h" /* DYNAMIC_ARRAY */
+#include "mysql/psi/psi_memory.h"
+
+struct CHARSET_INFO;
+
+/*
+ Overhead to store an element in hash
+ Can be used to approximate memory consumption for a hash
+ */
+#define HASH_OVERHEAD (sizeof(char *) * 2)
+
+/* flags for hash_init */
+#define HASH_UNIQUE 1 /* hash_insert fails on duplicate key */
+
+typedef uint my_hash_value_type;
+
+/**
+ Callback for extracting key and key length from user data in a HASH.
+ @param arg Pointer to user data.
+ @param[out] length Store key length here.
+ @return Pointer to key to be hashed.
+
+ @note Was my_hash_get_key, with lots of C-style casting when calling
+ my_hash_init. Renamed to force build error (since signature changed)
+ in case someone keeps following that coding style.
+ */
+typedef const uchar *(*hash_get_key_function)(const uchar *arg, size_t *length);
+
+typedef void (*hash_free_element_function)(void *);
+
+typedef struct st_hash {
+ st_hash()
+ : key_length(0),
+ blength(0),
+ records(0),
+ flags(0),
+ get_key(nullptr),
+ free_element(nullptr),
+ charset(nullptr),
+ m_psi_key(PSI_NOT_INSTRUMENTED) {
+ array = DYNAMIC_ARRAY();
+ }
+ size_t key_length; /* Length of key if const length */
+ size_t blength;
+ ulong records;
+ uint flags;
+ DYNAMIC_ARRAY array; /* Place for hash_keys */
+ hash_get_key_function get_key;
+ hash_free_element_function free_element;
+ const CHARSET_INFO *charset;
+ PSI_memory_key m_psi_key;
+} HASH;
+
+/* A search iterator state */
+typedef uint HASH_SEARCH_STATE;
+
+bool my_hash_init(HASH *hash, const CHARSET_INFO *charset, ulong reserve_size,
+ size_t key_length, hash_get_key_function get_key,
+ hash_free_element_function free_element, uint flags,
+ PSI_memory_key psi_key);
+void my_hash_free(HASH *tree);
+void my_hash_reset(HASH *hash);
+uchar *my_hash_element(HASH *hash, ulong idx);
+uchar *my_hash_search(const HASH *info, const uchar *key, size_t length);
+uchar *my_hash_search_using_hash_value(const HASH *info,
+ my_hash_value_type hash_value,
+ const uchar *key, size_t length);
+my_hash_value_type my_calc_hash(const HASH *info, const uchar *key,
+ size_t length);
+uchar *my_hash_first(const HASH *info, const uchar *key, size_t length,
+ HASH_SEARCH_STATE *state);
+uchar *my_hash_first_from_hash_value(const HASH *info,
+ my_hash_value_type hash_value,
+ const uchar *key, size_t length,
+ HASH_SEARCH_STATE *state);
+uchar *my_hash_next(const HASH *info, const uchar *key, size_t length,
+ HASH_SEARCH_STATE *state);
+bool my_hash_insert(HASH *info, const uchar *data);
+bool my_hash_delete(HASH *hash, uchar *record);
+bool my_hash_update(HASH *hash, uchar *record, uchar *old_key,
+ size_t old_key_length);
+void my_hash_replace(HASH *hash, HASH_SEARCH_STATE *state, uchar *new_row);
+bool my_hash_check(HASH *hash); /* Only in debug library */
+
+inline void my_hash_clear(HASH *h) { new (h) st_hash(); }
+inline bool my_hash_inited(const HASH *h) { return h->blength != 0; }
+
+#endif // HASH_INCLUDED

include/my_sys.h

@@ -793,7 +793,9 @@ extern bool my_init_dynamic_array(DYNAMIC_ARRAY *array, PSI_memory_key key,
 /* Some functions are still in use in C++, because HASH uses DYNAMIC_ARRAY */
 extern bool insert_dynamic(DYNAMIC_ARRAY *array, const void *element);
 extern void *alloc_dynamic(DYNAMIC_ARRAY *array);
+extern void *pop_dynamic(DYNAMIC_ARRAY *);
 extern void delete_dynamic(DYNAMIC_ARRAY *array);
+static inline void reset_dynamic(DYNAMIC_ARRAY *array) { array->elements = 0; }
 
 extern bool init_dynamic_string(DYNAMIC_STRING *str, const char *init_str,
  size_t init_alloc);

mysys/CMakeLists.txt

@@ -74,6 +74,7 @@ SET(MYSYS_SOURCES
  my_fstream.cc
  my_gethwaddr.cc
  my_getwd.cc
+ my_hash.cc
  my_init.cc
  my_lib.cc
  my_malloc.cc

mysys/array.cc

@@ -165,6 +165,24 @@ void *alloc_dynamic(DYNAMIC_ARRAY *array) {
  return array->buffer + (array->elements++ * array->size_of_element);
 }
 
+/*
+ Pop last element from array.
+
+ SYNOPSIS
+ pop_dynamic()
+ array
+
+ RETURN VALUE
+ pointer Ok
+ 0 Array is empty
+*/
+
+void *pop_dynamic(DYNAMIC_ARRAY *array) {
+ if (array->elements)
+ return array->buffer + (--array->elements * array->size_of_element);
+ return 0;
+}
+
 /*
  Empty array by freeing all memory