/* Copyright (c) 2020, 2024, 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 <include/mysql/components/services/mysql_mutex.h>

#include <cassert>

#include <cstring>

#include "cache.h"

#include "channel.h"

#include "component.h"

namespace reference_caching {

cache_imp *cache_imp::create(channel_imp *channel,

SERVICE_TYPE(registry) * registry) {

assert(channel != nullptr);

mysql_rwlock_rdlock(&LOCK_channels);

cache_imp *retval = new cache_imp(channel, registry);

mysql_rwlock_unlock(&LOCK_channels);

return retval;

}

bool cache_imp::destroy(cache_imp *cache) {

delete cache;

return false;

}

bool cache_imp::get(unsigned service_name_index, const my_h_service **out_ref) {

const bool channel_is_valid = (m_cache_version == m_channel->version());

if (unlikely(service_name_index >= m_service_names.size())) {

*out_ref = nullptr;

return true;

}

*out_ref = nullptr;

if (m_populated && channel_is_valid) {

if (m_cache) {

// cache hit

*out_ref = m_cache[service_name_index];

}

return *out_ref ? false : true;

}

// cache miss

flush();

/*

Channel's ignore list may have been updated.

So we have to update the local copy.

Note that it is always safe to refer to m_channel

without taking LOCK_channels because reference count

for the channel was increased at the time of creating

the cache. A channel cannot be destroyed when its

reference count is > 1.

ignore_list_copy() will take read lock on the channel.

*/

m_channel->ignore_list_copy(m_ignore_list);

m_service_names = m_channel->get_service_names();

m_cache_version = m_channel->version();

bool no_op = true;

for (auto service_name : m_service_names) {

no_op &= (service_name.count_.load() == 0);

}

if (!no_op) {

m_cache = (my_h_service **)my_malloc(

KEY_mem_reference_cache,

m_service_names.size() * sizeof(my_h_service *), MY_ZEROFILL);

unsigned offset = 0;

for (auto service_name : m_service_names) {

if (service_name.count_.load() == 0) continue;

std::set<my_h_service> cache_set;

my_h_service_iterator iter;

if (!current_registry_query->create(service_name.name_.c_str(), &iter)) {

while (!current_registry_query->is_valid(iter)) {

const char *implementation_name;

my_h_service svc;

// can't get the name

if (current_registry_query->get(iter, &implementation_name)) break;

const char *dot = strchr(implementation_name, '.');

size_t service_name_length = (dot - implementation_name);

// not the same service

if ((service_name_length != service_name.name_.length()) ||

strncmp(implementation_name, service_name.name_.c_str(),

service_name.name_.length()))

break;

// not in the ignore list

if (dot != nullptr && ++dot != nullptr) {

if (m_ignore_list.find(dot) != m_ignore_list.end()) {

if (current_registry_query->next(iter)) break;

continue;

}

}

// add the reference to the list

if (!m_registry->acquire(implementation_name, &svc)) {

auto res = cache_set.insert(svc);

/*

release the unused reference if it's a duplicate of a reference

already added

*/

if (!res.second) m_registry->release(svc);

}

if (current_registry_query->next(iter)) break;

}

current_registry_query->release(iter);

} else {

// The service is not present in the registry.

continue;

}

my_h_service *cache_row = (my_h_service *)my_malloc(

KEY_mem_reference_cache,

(cache_set.size() + 1) * sizeof(my_h_service), MY_ZEROFILL);

my_h_service *cache_ptr = cache_row;

for (my_h_service ref : cache_set) *cache_ptr++ = ref;

if (offset == service_name_index) *out_ref = cache_row;

m_cache[offset++] = cache_row;

}

}

m_populated = true;

return *out_ref ? false : true;

}

bool cache_imp::flush() {

if (m_cache) {

unsigned offset = 0;

for (auto service_name : m_service_names) {

my_h_service *cache_row = m_cache[offset];

if (cache_row) {

for (my_h_service *iter = cache_row; *iter; iter++)

m_registry->release(*iter);

my_free(cache_row);

m_cache[offset] = nullptr;

}

offset++;

}

my_free(m_cache);

m_cache = nullptr;

}

m_populated = false;

return false;

}

cache_imp::cache_imp(channel_imp *channel, SERVICE_TYPE(registry) * registry)

: m_channel{channel->ref()},

m_cache{nullptr},

m_registry{registry},

m_cache_version{channel->version()},

m_populated{false} {

m_service_names = channel->get_service_names();

}

cache_imp::~cache_imp() {

flush();

m_channel->unref();

}

} // namespace reference_caching