1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/*
*
* Copyright 2015, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "src/core/lib/iomgr/timer_heap.h"
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/useful.h>
/* Adjusts a heap so as to move a hole at position i closer to the root,
until a suitable position is found for element t. Then, copies t into that
position. This functor is called each time immediately after modifying a
value in the underlying container, with the offset of the modified element as
its argument. */
static void adjust_upwards(grpc_timer **first, uint32_t i, grpc_timer *t) {
while (i > 0) {
uint32_t parent = (uint32_t)(((int)i - 1) / 2);
if (gpr_time_cmp(first[parent]->deadline, t->deadline) <= 0) break;
first[i] = first[parent];
first[i]->heap_index = i;
i = parent;
}
first[i] = t;
t->heap_index = i;
}
/* Adjusts a heap so as to move a hole at position i farther away from the root,
until a suitable position is found for element t. Then, copies t into that
position. */
static void adjust_downwards(grpc_timer **first, uint32_t i, uint32_t length,
grpc_timer *t) {
for (;;) {
uint32_t left_child = 1u + 2u * i;
if (left_child >= length) break;
uint32_t right_child = left_child + 1;
uint32_t next_i = right_child < length &&
gpr_time_cmp(first[left_child]->deadline,
first[right_child]->deadline) > 0
? right_child
: left_child;
if (gpr_time_cmp(t->deadline, first[next_i]->deadline) <= 0) break;
first[i] = first[next_i];
first[i]->heap_index = i;
i = next_i;
}
first[i] = t;
t->heap_index = i;
}
#define SHRINK_MIN_ELEMS 8
#define SHRINK_FULLNESS_FACTOR 2
static void maybe_shrink(grpc_timer_heap *heap) {
if (heap->timer_count >= 8 &&
heap->timer_count <= heap->timer_capacity / SHRINK_FULLNESS_FACTOR / 2) {
heap->timer_capacity = heap->timer_count * SHRINK_FULLNESS_FACTOR;
heap->timers =
gpr_realloc(heap->timers, heap->timer_capacity * sizeof(grpc_timer *));
}
}
static void note_changed_priority(grpc_timer_heap *heap, grpc_timer *timer) {
uint32_t i = timer->heap_index;
uint32_t parent = (uint32_t)(((int)i - 1) / 2);
if (gpr_time_cmp(heap->timers[parent]->deadline, timer->deadline) > 0) {
adjust_upwards(heap->timers, i, timer);
} else {
adjust_downwards(heap->timers, i, heap->timer_count, timer);
}
}
void grpc_timer_heap_init(grpc_timer_heap *heap) {
memset(heap, 0, sizeof(*heap));
}
void grpc_timer_heap_destroy(grpc_timer_heap *heap) { gpr_free(heap->timers); }
int grpc_timer_heap_add(grpc_timer_heap *heap, grpc_timer *timer) {
if (heap->timer_count == heap->timer_capacity) {
heap->timer_capacity =
GPR_MAX(heap->timer_capacity + 1, heap->timer_capacity * 3 / 2);
heap->timers =
gpr_realloc(heap->timers, heap->timer_capacity * sizeof(grpc_timer *));
}
timer->heap_index = heap->timer_count;
adjust_upwards(heap->timers, heap->timer_count, timer);
heap->timer_count++;
return timer->heap_index == 0;
}
void grpc_timer_heap_remove(grpc_timer_heap *heap, grpc_timer *timer) {
uint32_t i = timer->heap_index;
if (i == heap->timer_count - 1) {
heap->timer_count--;
maybe_shrink(heap);
return;
}
heap->timers[i] = heap->timers[heap->timer_count - 1];
heap->timers[i]->heap_index = i;
heap->timer_count--;
maybe_shrink(heap);
note_changed_priority(heap, heap->timers[i]);
}
int grpc_timer_heap_is_empty(grpc_timer_heap *heap) {
return heap->timer_count == 0;
}
grpc_timer *grpc_timer_heap_top(grpc_timer_heap *heap) {
return heap->timers[0];
}
void grpc_timer_heap_pop(grpc_timer_heap *heap) {
grpc_timer_heap_remove(heap, grpc_timer_heap_top(heap));
}
|
