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alarm.h
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1 /*
2 *
3 * Copyright 2015, Google Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met:
9 *
10 * * Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * * Redistributions in binary form must reproduce the above
13 * copyright notice, this list of conditions and the following disclaimer
14 * in the documentation and/or other materials provided with the
15 * distribution.
16 * * Neither the name of Google Inc. nor the names of its
17 * contributors may be used to endorse or promote products derived from
18 * this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 *
32 */
33
34 #ifndef GRPC_INTERNAL_CORE_IOMGR_ALARM_H
35 #define GRPC_INTERNAL_CORE_IOMGR_ALARM_H
36
37 #include "src/core/iomgr/iomgr.h"
38 #include <grpc/support/port_platform.h>
39 #include <grpc/support/time.h>
40
41 typedef struct grpc_alarm {
42 gpr_timespec deadline;
43 gpr_uint32 heap_index; /* INVALID_HEAP_INDEX if not in heap */
44 int triggered;
45 struct grpc_alarm *next;
46 struct grpc_alarm *prev;
47 grpc_iomgr_cb_func cb;
48 void *cb_arg;
49 } grpc_alarm;
50
51 /* Initialize *alarm. When expired or canceled, alarm_cb will be called with
52 *alarm_cb_arg and status to indicate if it expired (SUCCESS) or was
53 canceled (CANCELLED). alarm_cb is guaranteed to be called exactly once,
54 and application code should check the status to determine how it was
55 invoked. The application callback is also responsible for maintaining
56 information about when to free up any user-level state. */
57 void grpc_alarm_init(grpc_alarm *alarm, gpr_timespec deadline,
58 grpc_iomgr_cb_func alarm_cb, void *alarm_cb_arg,
59 gpr_timespec now);
60
61 /* Note that there is no alarm destroy function. This is because the
62 alarm is a one-time occurrence with a guarantee that the callback will
63 be called exactly once, either at expiration or cancellation. Thus, all
64 the internal alarm event management state is destroyed just before
65 that callback is invoked. If the user has additional state associated with
66 the alarm, the user is responsible for determining when it is safe to
67 destroy that state. */
68
69 /* Cancel an *alarm.
70 There are three cases:
71 1. We normally cancel the alarm
72 2. The alarm has already run
73 3. We can't cancel the alarm because it is "in flight".
74
75 In all of these cases, the cancellation is still considered successful.
76 They are essentially distinguished in that the alarm_cb will be run
77 exactly once from either the cancellation (with status CANCELLED)
78 or from the activation (with status SUCCESS)
79
80 Note carefully that the callback function MAY occur in the same callstack
81 as grpc_alarm_cancel. It's expected that most alarms will be cancelled (their
82 primary use is to implement deadlines), and so this code is optimized such
83 that cancellation costs as little as possible. Making callbacks run inline
84 matches this aim.
85
86 Requires: cancel() must happen after add() on a given alarm */
87 void grpc_alarm_cancel(grpc_alarm *alarm);
88
89 #endif /* GRPC_INTERNAL_CORE_IOMGR_ALARM_H */
grpc_alarm
Definition: alarm.h:41
port_platform.h
grpc_alarm_cancel
void grpc_alarm_cancel(grpc_alarm *alarm)
Definition: alarm.c:227
grpc_alarm::cb
grpc_iomgr_cb_func cb
Definition: alarm.h:47
time.h
grpc_alarm::next
struct grpc_alarm * next
Definition: alarm.h:45
gpr_uint32
uint32_t gpr_uint32
Definition: port_platform.h:309
grpc_alarm::cb_arg
void * cb_arg
Definition: alarm.h:48
grpc_alarm_init
void grpc_alarm_init(grpc_alarm *alarm, gpr_timespec deadline, grpc_iomgr_cb_func alarm_cb, void *alarm_cb_arg, gpr_timespec now)
Definition: alarm.c:176
grpc_alarm::heap_index
gpr_uint32 heap_index
Definition: alarm.h:43
grpc_alarm::deadline
gpr_timespec deadline
Definition: alarm.h:42
grpc_iomgr_cb_func
void(* grpc_iomgr_cb_func)(void *arg, int success)
gRPC Callback definition.
Definition: iomgr.h:42
grpc_alarm
struct grpc_alarm grpc_alarm
grpc_alarm::triggered
int triggered
Definition: alarm.h:44
grpc_alarm::prev
struct grpc_alarm * prev
Definition: alarm.h:46
gpr_timespec
Definition: time.h:60
iomgr.h