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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2009 - 2010 Toru Maesaka
*
* 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
*/
#include "config.h"
#include "ha_blitz.h"
using namespace drizzled;
BlitzLock::BlitzLock() : scanner_count(0), updater_count(0) {
pthread_cond_init(&condition, NULL);
pthread_mutex_init(&mutex, NULL);
for (int i = 0; i < BLITZ_LOCK_SLOTS; i++)
pthread_mutex_init(&slots[i], NULL);
}
BlitzLock::~BlitzLock() {
pthread_cond_destroy(&condition);
pthread_mutex_destroy(&mutex);
for (int i = 0; i < BLITZ_LOCK_SLOTS; i++)
pthread_mutex_destroy(&slots[i]);
}
uint32_t BlitzLock::slot_id(const void *data, size_t len) {
uint64_t hash = 14695981039346656037ULL;
const unsigned char *rp = (unsigned char *)data;
const unsigned char *ep = rp + len;
while (rp < ep)
hash = (hash ^ *(rp++)) * 109951162811ULL;
return (uint32_t)(hash % BLITZ_LOCK_SLOTS);
}
int BlitzLock::slotted_lock(const uint32_t id) {
return pthread_mutex_lock(&slots[id]);
}
int BlitzLock::slotted_unlock(const uint32_t id) {
return pthread_mutex_unlock(&slots[id]);
}
void BlitzLock::update_begin() {
pthread_mutex_lock(&mutex);
while (true) {
if (scanner_count < 1) {
updater_count++;
pthread_mutex_unlock(&mutex);
return;
}
pthread_cond_wait(&condition, &mutex);
}
pthread_mutex_unlock(&mutex);
}
void BlitzLock::update_end() {
pthread_mutex_lock(&mutex);
updater_count--;
assert(updater_count >= 0);
if (updater_count == 0)
pthread_cond_broadcast(&condition);
pthread_mutex_unlock(&mutex);
}
void BlitzLock::scan_begin() {
pthread_mutex_lock(&mutex);
while (true) {
if (updater_count == 0) {
scanner_count++;
pthread_mutex_unlock(&mutex);
return;
}
pthread_cond_wait(&condition, &mutex);
}
pthread_mutex_unlock(&mutex);
}
void BlitzLock::scan_end() {
pthread_mutex_lock(&mutex);
scanner_count--;
assert(scanner_count >= 0);
if (scanner_count == 0)
pthread_cond_broadcast(&condition);
pthread_mutex_unlock(&mutex);
}
void BlitzLock::scan_update_begin() {
pthread_mutex_lock(&mutex);
while (true) {
if (scanner_count == 0 && updater_count == 0) {
scanner_count++;
updater_count++;
pthread_mutex_unlock(&mutex);
return;
}
pthread_cond_wait(&condition, &mutex);
}
pthread_mutex_unlock(&mutex);
}
void BlitzLock::scan_update_end() {
pthread_mutex_lock(&mutex);
scanner_count--;
updater_count--;
assert(scanner_count >= 0 && updater_count >= 0);
/* All other threads are guaranteed to be
waiting so broadcast regardless. */
pthread_cond_broadcast(&condition);
pthread_mutex_unlock(&mutex);
}
int ha_blitz::blitz_optimal_lock() {
if (sql_command_type == SQLCOM_ALTER_TABLE ||
sql_command_type == SQLCOM_UPDATE ||
sql_command_type == SQLCOM_DELETE ||
sql_command_type == SQLCOM_REPLACE ||
sql_command_type == SQLCOM_REPLACE_SELECT) {
share->blitz_lock.scan_update_begin();
} else {
share->blitz_lock.scan_begin();
}
thread_locked = true;
return 0;
}
int ha_blitz::blitz_optimal_unlock() {
if (sql_command_type == SQLCOM_ALTER_TABLE ||
sql_command_type == SQLCOM_UPDATE ||
sql_command_type == SQLCOM_DELETE ||
sql_command_type == SQLCOM_REPLACE ||
sql_command_type == SQLCOM_REPLACE_SELECT) {
share->blitz_lock.scan_update_end();
} else {
share->blitz_lock.scan_end();
}
thread_locked = false;
return 0;
}
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