1/*****************************************************************************
2
3Copyright (c) 2013, 2021, Oracle and/or its affiliates.
4
5Portions of this file contain modifications contributed and copyrighted by
6Google, Inc. Those modifications are gratefully acknowledged and are described
7briefly in the InnoDB documentation. The contributions by Google are
8incorporated with their permission, and subject to the conditions contained in
9the file COPYING.Google.
10
11This program is free software; you can redistribute it and/or modify
12it under the terms of the GNU General Public License, version 2.0,
13as published by the Free Software Foundation.
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15This program is also distributed with certain software (including
16but not limited to OpenSSL) that is licensed under separate terms,
17as designated in a particular file or component or in included license
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19permission to link the program and your derivative works with the
20separately licensed software that they have included with MySQL.
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22This program is distributed in the hope that it will be useful,
23but WITHOUT ANY WARRANTY; without even the implied warranty of
24MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
25GNU General Public License, version 2.0, for more details.
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27You should have received a copy of the GNU General Public License along with
28this program; if not, write to the Free Software Foundation, Inc.,
2951 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
30
31*****************************************************************************/
32
33/**************************************************//**
34@file include/ut0mutex.ic
35Mutex implementation include file
36
37Created 2012/08/21 Sunny Bains
38*******************************************************/
39
40#include "sync0arr.h"
41#include "sync0debug.h"
42
43/**
44Wait in the sync array.
45@return true if the mutex acquisition was successful. */
46
47template <template <typename> class Policy>
48bool
49TTASEventMutex<Policy>::wait(
50	const char*	filename,
51	uint32_t	line,
52	uint32_t	spin)
53	UNIV_NOTHROW
54{
55	sync_cell_t*	cell;
56	sync_array_t*	sync_arr;
57	latch_id_t	latch_id = m_policy.get_id();
58	ulint		type = SYNC_MUTEX;
59
60	if (latch_id == LATCH_ID_BUF_BLOCK_MUTEX
61	    || latch_id == LATCH_ID_BUF_POOL_ZIP) {
62	    type = SYNC_BUF_BLOCK;
63	} else if (latch_id == LATCH_ID_AUTOINC) {
64	    type = SYNC_DICT_AUTOINC_MUTEX;
65	}
66
67	sync_arr = sync_array_get_and_reserve_cell(
68		this,
69		type,
70		filename, line, &cell);
71
72	/* The memory order of the array reservation and
73	the change in the waiters field is important: when
74	we suspend a thread, we first reserve the cell and
75	then set waiters field to 1. When threads are released
76	in mutex_exit, the waiters field is first set to zero
77	and then the event is set to the signaled state. */
78
79	set_waiters();
80
81	DBUG_EXECUTE_IF("catch_autoinc_mutex_os_lock",
82		if (m_policy.get_id() == LATCH_ID_AUTOINC) {
83			DEBUG_SYNC_C("autoinc_mutex_wait");
84		}
85	);
86
87	/* Try to reserve still a few times. */
88
89	for (uint32_t i = 0; i < spin; ++i) {
90
91		if (try_lock()) {
92
93			sync_array_free_cell(sync_arr, cell);
94
95			/* Note that in this case we leave
96			the waiters field set to 1. We cannot
97			reset it to zero, as we do not know if
98			there are other waiters. */
99
100			return(true);
101		}
102	}
103
104	/* Now we know that there has been some thread
105	holding the mutex after the change in the wait
106	array and the waiters field was made.  Now there
107	is no risk of infinite wait on the event. */
108
109	sync_array_wait_event(sync_arr, cell);
110
111	return(false);
112}
113
114
115/** Wakeup any waiting thread(s). */
116
117template <template <typename> class Policy>
118void
119TTASEventMutex<Policy>::signal() UNIV_NOTHROW
120{
121	clear_waiters();
122
123	/* The memory order of resetting the waiters field and
124	signaling the object is important. See LEMMA 1 above. */
125	os_event_set(&m_event);
126
127	sync_array_object_signalled();
128}
129