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
|
//
// Copyright 2016, 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/transport/hashtable.h"
#include <stdbool.h>
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include "src/core/lib/transport/metadata.h"
struct grpc_hash_table {
gpr_refcount refs;
size_t num_entries;
grpc_hash_table_entry* entries;
};
// Helper function for insert and get operations that performs quadratic
// probing (https://en.wikipedia.org/wiki/Quadratic_probing).
static size_t grpc_hash_table_find_index(
grpc_hash_table* table, grpc_mdstr* key, bool find_empty) {
for (size_t i = 0; i < table->num_entries; ++i) {
const size_t idx = (key->hash + i * i) % table->num_entries;
if (table->entries[idx].key == NULL)
return find_empty ? idx : table->num_entries;
if (table->entries[idx].key == key) return idx;
}
return table->num_entries; // Not found.
}
static void grpc_hash_table_add(grpc_hash_table* table, grpc_mdstr* key,
void* value,
const grpc_hash_table_vtable* vtable) {
GPR_ASSERT(value != NULL);
const size_t idx =
grpc_hash_table_find_index(table, key, true /* find_empty */);
// This can happen if the table is full.
GPR_ASSERT(idx != table->num_entries);
grpc_hash_table_entry* entry = &table->entries[idx];
entry->key = GRPC_MDSTR_REF(key);
entry->value = vtable->copy_value(value);
entry->vtable = vtable;
}
grpc_hash_table* grpc_hash_table_create(size_t num_entries,
grpc_hash_table_entry* entries) {
grpc_hash_table* table = gpr_malloc(sizeof(*table));
memset(table, 0, sizeof(*table));
gpr_ref_init(&table->refs, 1);
// Quadratic probing gets best performance when the table is no more
// than half full.
table->num_entries = num_entries * 2;
const size_t entry_size = sizeof(grpc_hash_table_entry) * table->num_entries;
table->entries = gpr_malloc(entry_size);
memset(table->entries, 0, entry_size);
for (size_t i = 0; i < num_entries; ++i) {
grpc_hash_table_entry* entry = &entries[i];
grpc_hash_table_add(table, entry->key, entry->value, entry->vtable);
}
return table;
}
grpc_hash_table* grpc_hash_table_ref(grpc_hash_table* table) {
if (table != NULL) gpr_ref(&table->refs);
return table;
}
int grpc_hash_table_unref(grpc_hash_table* table) {
if (table != NULL && gpr_unref(&table->refs)) {
for (size_t i = 0; i < table->num_entries; ++i) {
grpc_hash_table_entry* entry = &table->entries[i];
if (entry->key != NULL) {
GRPC_MDSTR_UNREF(entry->key);
entry->vtable->destroy_value(entry->value);
}
}
gpr_free(table->entries);
gpr_free(table);
return 1;
}
return 0;
}
void* grpc_hash_table_get(grpc_hash_table* table, grpc_mdstr* key) {
const size_t idx =
grpc_hash_table_find_index(table, key, false /* find_empty */);
if (idx == table->num_entries) return NULL; // Not found.
return table->entries[idx].value;
}
int grpc_hash_table_cmp(grpc_hash_table* table1, grpc_hash_table* table2) {
// Compare by num_entries.
if (table1->num_entries < table2->num_entries) return -1;
if (table1->num_entries > table2->num_entries) return 1;
for (size_t i = 0; i < table1->num_entries; ++i) {
grpc_hash_table_entry* e1 = &table1->entries[i];
grpc_hash_table_entry* e2 = &table2->entries[i];
// Compare keys by hash value.
if (e1->key->hash < e2->key->hash) return -1;
if (e1->key->hash > e2->key->hash) return 1;
// Compare by vtable (pointer equality).
if (e1->vtable < e2->vtable) return -1;
if (e1->vtable > e2->vtable) return 1;
// Compare values via vtable.
const int value_result = e1->vtable->compare_value(e1->value, e2->value);
if (value_result != 0) return value_result;
}
return 0;
}
|
