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/* Copyright (c) 2002, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
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, version 2.0, 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 */
#include "sql/sp_cache.h"
#include <stddef.h>
#include <atomic>
#include <memory>
#include <string>
#include "lex_string.h"
#include "m_ctype.h"
#include "map_helpers.h"
#include "my_dbug.h"
#include "sql/psi_memory_key.h"
#include "sql/sp_head.h"
/*
Cache of stored routines.
*/
class sp_cache {
public:
sp_cache() : m_hashtable(system_charset_info, key_memory_sp_cache) {}
~sp_cache() = default;
/**
Inserts a sp_head object into a hash table.
@returns Success status
@return true Failure
@return false Success
*/
bool insert(sp_head *sp) {
m_hashtable.emplace(to_string(sp->m_qname),
std::unique_ptr<sp_head, sp_head_deleter>(sp));
return false;
}
sp_head *lookup(char *name, size_t namelen) {
return find_or_nullptr(m_hashtable, std::string(name, namelen));
}
void remove(sp_head *sp) { m_hashtable.erase(to_string(sp->m_qname)); }
/**
Remove all elements from a stored routine cache if the current
number of elements exceeds the argument value.
@param[in] upper_limit_for_elements Soft upper limit of elements that
can be stored in the cache.
*/
void enforce_limit(ulong upper_limit_for_elements) {
if (m_hashtable.size() > upper_limit_for_elements) m_hashtable.clear();
}
private:
struct sp_head_deleter {
void operator()(sp_head *sp) const { sp_head::destroy(sp); }
};
/* All routines in this cache */
collation_unordered_map<std::string,
std::unique_ptr<sp_head, sp_head_deleter>>
m_hashtable;
}; // class sp_cache
static std::atomic<int64> atomic_Cversion{0};
/*
Clear the cache *cp and set *cp to NULL.
SYNOPSIS
sp_cache_clear()
cp Pointer to cache to clear
NOTE
This function doesn't invalidate other caches.
*/
void sp_cache_clear(sp_cache **cp) {
sp_cache *c = *cp;
if (c) {
delete c;
*cp = nullptr;
}
}
/*
Insert a routine into the cache.
SYNOPSIS
sp_cache_insert()
cp The cache to put routine into
sp Routine to insert.
TODO: Perhaps it will be more straightforward if in case we returned an
error from this function when we couldn't allocate sp_cache. (right
now failure to put routine into cache will cause a 'SP not found'
error to be reported at some later time)
*/
void sp_cache_insert(sp_cache **cp, sp_head *sp) {
sp_cache *c;
if (!(c = *cp)) {
if (!(c = new sp_cache())) return; // End of memory error
}
sp->set_sp_cache_version(sp_cache_version());
DBUG_PRINT("info", ("sp_cache: inserting: %.*s", (int)sp->m_qname.length,
sp->m_qname.str));
c->insert(sp);
*cp = c; // Update *cp if it was NULL
}
/*
Look up a routine in the cache.
SYNOPSIS
sp_cache_lookup()
cp Cache to look into
name Name of rutine to find
NOTE
An obsolete (but not more obsolete then since last
sp_cache_flush_obsolete call) routine may be returned.
RETURN
The routine or
NULL if the routine not found.
*/
sp_head *sp_cache_lookup(sp_cache **cp, const sp_name *name) {
sp_cache *c = *cp;
if (!c) return nullptr;
return c->lookup(name->m_qname.str, name->m_qname.length);
}
/*
Invalidate all routines in all caches.
SYNOPSIS
sp_cache_invalidate()
NOTE
This is called when a VIEW definition is created or modified (and in some
other contexts). We can't destroy sp_head objects here as one may modify
VIEW definitions from prelocking-free SPs.
*/
void sp_cache_invalidate() {
DBUG_PRINT("info", ("sp_cache: invalidating"));
atomic_Cversion++;
}
/**
Remove an out-of-date SP from the cache.
@param[in] cp Cache to flush
@param[in] sp SP to remove.
@note This invalidates pointers to sp_head objects this thread
uses. In practice that means 'dont call this function when
inside SP'.
*/
void sp_cache_flush_obsolete(sp_cache **cp, sp_head **sp) {
if ((*sp)->sp_cache_version() < sp_cache_version() && !(*sp)->is_invoked()) {
(*cp)->remove(*sp);
*sp = nullptr;
}
}
/**
Return the current global version of the cache.
*/
int64 sp_cache_version() { return atomic_Cversion; }
/**
Enforce that the current number of elements in the cache don't exceed
the argument value by flushing the cache if necessary.
@param[in] c Cache to check
@param[in] upper_limit_for_elements Soft upper limit for number of sp_head
objects that can be stored in the cache.
*/
void sp_cache_enforce_limit(sp_cache *c, ulong upper_limit_for_elements) {
if (c) c->enforce_limit(upper_limit_for_elements);
}
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