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eb58939395
The problem from a user point of view was that on Solaris the time related functions (e.g. NOW(), SYSDATE(), etc) would always return a fixed time. This bug was happening due to a logic in the time retrieving wrapper function which would only call the time() function every half second. This interval between calls would be calculated using the gethrtime() and the logic relied on the fact that time returned by it is monotonic. Unfortunately, due to bugs in the gethrtime() implementation, there are some cases where the time returned by it can drift (See Solaris bug id 6600939), potentially causing the interval calculation logic to fail. Since newer versions of Solaris (10+) have alleviated the performance degradation associated with time(2), the solution is to simply directly rely on time() at each invocation. This simplification has an upside that it allows us to eliminate a lock which was used to control access to the variables used to track the half second interval, thus improving the overall scalability of timekeeping related functions (e.g. NOW()). Benchmarks runs have shown no significant degradation associated with this change. With this, there are actually improvements in performance for cases involving many connections. In summary, the changes introduced by this patch are: a) my_time() and my_micro_time_and_time() no longer use gethrtime(). Instead, time() and gettimeofdate() are used correspondingly. b) my_micro_time() is changed to not use gethrtime() so as to have the same time source as my_micro_time_and_time(). There shouldn't be any performance impact from this change since this function is used only a few times during statement execution and, on Solaris, gettimeofday() shows acceptable performance. mysys/my_getsystime.c: Use time() even if gethrtime() is available. Remove logic which relied on gethrtime() to only call time() every half second. Since gethrtime() is not used anymore, also remove it from my_micro_time() to keep a common time source. Also, function comments are cleaned up (fixed typos and wrong information) and converted to doxygen. mysys/my_thr_init.c: Remove mutex which is no longer used. mysys/mysys_priv.h: Remove mutex which is no longer used.
107 lines
3.9 KiB
C
107 lines
3.9 KiB
C
/* Copyright (C) 2000 MySQL AB, 2008-2009 Sun Microsystems, Inc
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include <my_global.h>
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#include <my_sys.h>
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#ifdef USE_SYSTEM_WRAPPERS
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#include "system_wrappers.h"
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#endif
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#ifdef HAVE_GETRUSAGE
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#include <sys/resource.h>
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#endif
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#include <my_pthread.h>
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#ifdef HAVE_PSI_INTERFACE
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#if !defined(HAVE_PREAD) && !defined(_WIN32)
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extern PSI_mutex_key key_my_file_info_mutex;
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#endif /* !defined(HAVE_PREAD) && !defined(_WIN32) */
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#if !defined(HAVE_LOCALTIME_R) || !defined(HAVE_GMTIME_R)
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extern PSI_mutex_key key_LOCK_localtime_r;
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#endif /* !defined(HAVE_LOCALTIME_R) || !defined(HAVE_GMTIME_R) */
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#ifndef HAVE_GETHOSTBYNAME_R
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extern PSI_mutex_key key_LOCK_gethostbyname_r;
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#endif /* HAVE_GETHOSTBYNAME_R */
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extern PSI_mutex_key key_BITMAP_mutex, key_IO_CACHE_append_buffer_lock,
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key_IO_CACHE_SHARE_mutex, key_KEY_CACHE_cache_lock, key_LOCK_alarm,
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key_my_thread_var_mutex, key_THR_LOCK_charset, key_THR_LOCK_heap,
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key_THR_LOCK_isam, key_THR_LOCK_lock, key_THR_LOCK_malloc,
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key_THR_LOCK_mutex, key_THR_LOCK_myisam, key_THR_LOCK_net,
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key_THR_LOCK_open, key_THR_LOCK_threads,
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key_TMPDIR_mutex, key_THR_LOCK_myisam_mmap;
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extern PSI_cond_key key_COND_alarm, key_IO_CACHE_SHARE_cond,
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key_IO_CACHE_SHARE_cond_writer, key_my_thread_var_suspend,
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key_THR_COND_threads;
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#ifdef USE_ALARM_THREAD
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extern PSI_thread_key key_thread_alarm;
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#endif /* USE_ALARM_THREAD */
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#endif /* HAVE_PSI_INTERFACE */
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extern mysql_mutex_t THR_LOCK_malloc, THR_LOCK_open, THR_LOCK_keycache;
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extern mysql_mutex_t THR_LOCK_lock, THR_LOCK_isam, THR_LOCK_net;
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extern mysql_mutex_t THR_LOCK_charset;
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#include <mysql/psi/mysql_file.h>
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#ifdef HAVE_PSI_INTERFACE
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#ifdef HUGETLB_USE_PROC_MEMINFO
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extern PSI_file_key key_file_proc_meminfo;
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#endif /* HUGETLB_USE_PROC_MEMINFO */
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extern PSI_file_key key_file_charset, key_file_cnf;
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#endif /* HAVE_PSI_INTERFACE */
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/*
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EDQUOT is used only in 3 C files only in mysys/. If it does not exist on
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system, we set it to some value which can never happen.
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*/
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#ifndef EDQUOT
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#define EDQUOT (-1)
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#endif
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void my_error_unregister_all(void);
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#ifdef _WIN32
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#include <sys/stat.h>
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/* my_winfile.c exports, should not be used outside mysys */
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extern File my_win_open(const char *path, int oflag);
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extern int my_win_close(File fd);
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extern size_t my_win_read(File fd, uchar *buffer, size_t count);
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extern size_t my_win_write(File fd, const uchar *buffer, size_t count);
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extern size_t my_win_pread(File fd, uchar *buffer, size_t count,
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my_off_t offset);
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extern size_t my_win_pwrite(File fd, const uchar *buffer, size_t count,
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my_off_t offset);
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extern my_off_t my_win_lseek(File fd, my_off_t pos, int whence);
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extern int my_win_chsize(File fd, my_off_t newlength);
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extern FILE* my_win_fopen(const char *filename, const char *type);
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extern File my_win_fclose(FILE *file);
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extern File my_win_fileno(FILE *file);
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extern FILE* my_win_fdopen(File Filedes, const char *type);
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extern int my_win_stat(const char *path, struct _stati64 *buf);
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extern int my_win_fstat(File fd, struct _stati64 *buf);
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extern int my_win_fsync(File fd);
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extern File my_win_dup(File fd);
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extern File my_win_sopen(const char *path, int oflag, int shflag, int perm);
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extern File my_open_osfhandle(HANDLE handle, int oflag);
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#endif
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