epan/wmem_scopes.c

   1 /* wmem_scopes.c
   2  * Wireshark Memory Manager Scopes
   3  * Copyright 2012, Evan Huus <eapache@gmail.com>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 #include <glib.h>
  13
  14 #include "wmem_scopes.h"
  15
  16 #include <wsutil/ws_assert.h>
  17
  18 /* One of the supposed benefits of wmem over the old emem was going to be that
  19  * the scoping of the various memory pools would be obvious, since they would
  20  * no longer be global. Instead, the pools would be managed as variables scoped
  21  * by the compiler, so functions outside of that scope wouldn't have access to
  22  * the pools and wouldn't be able to allocate memory in a scope to which they
  23  * didn't belong.
  24  *
  25  * That idea fell apart rather quickly :P
  26  *
  27  * The principle still stands, and most pools should be managed in that way.
  28  * The three in this file are *exceptions*. They are the three scopes that emem
  29  * provided as globals. Converting all of the code that used them to pass an
  30  * extra parameter (or three) around would have been a nightmare of epic
  31  * proportions, so we provide these three as globals still.
  32  *
  33  * We do, however, use some extra booleans and a mountain of assertions to try
  34  * and catch anybody accessing the pools out of the correct scope. It's not
  35  * perfect, but it should stop most of the bad behaviour that emem permitted.
  36  */
  37
  38 /* TODO: Make these thread-local */
  39 static wmem_allocator_t *packet_scope;
  40 static wmem_allocator_t *file_scope;
  41 static wmem_allocator_t *epan_scope;
  42
  43 /* Packet Scope */
  44
  45 wmem_allocator_t *
  46 wmem_packet_scope(void)
  47 {
  48     ws_assert(packet_scope);
  49
  50     return packet_scope;
  51 }
  52
  53 void
  54 wmem_enter_packet_scope(void)
  55 {
  56     ws_assert(packet_scope);
  57     ws_assert(wmem_in_scope(file_scope));
  58     ws_assert(!wmem_in_scope(packet_scope));
  59
  60     wmem_enter_scope(packet_scope);
  61 }
  62
  63 void
  64 wmem_leave_packet_scope(void)
  65 {
  66     ws_assert(packet_scope);
  67     ws_assert(wmem_in_scope(packet_scope));
  68
  69     wmem_leave_scope(packet_scope);
  70 }
  71
  72 /* File Scope */
  73
  74 wmem_allocator_t *
  75 wmem_file_scope(void)
  76 {
  77     ws_assert(file_scope);
  78
  79     return file_scope;
  80 }
  81
  82 void
  83 wmem_enter_file_scope(void)
  84 {
  85     ws_assert(file_scope);
  86     ws_assert(!wmem_in_scope(file_scope));
  87
  88     wmem_enter_scope(file_scope);
  89 }
  90
  91 void
  92 wmem_leave_file_scope(void)
  93 {
  94     ws_assert(file_scope);
  95     ws_assert(wmem_in_scope(file_scope));
  96     ws_assert(!wmem_in_scope(packet_scope));
  97
  98     wmem_leave_scope(file_scope);
  99
 100     /* this seems like a good time to do garbage collection */
 101     wmem_gc(file_scope);
 102     wmem_gc(packet_scope);
 103 }
 104
 105 /* Epan Scope */
 106
 107 wmem_allocator_t *
 108 wmem_epan_scope(void)
 109 {
 110     ws_assert(epan_scope);
 111
 112     return epan_scope;
 113 }
 114
 115 /* Scope Management */
 116
 117 void
 118 wmem_init_scopes(void)
 119 {
 120     ws_assert(packet_scope == NULL);
 121     ws_assert(file_scope   == NULL);
 122     ws_assert(epan_scope   == NULL);
 123
 124     wmem_init();
 125
 126     packet_scope = wmem_allocator_new(WMEM_ALLOCATOR_BLOCK_FAST);
 127     file_scope   = wmem_allocator_new(WMEM_ALLOCATOR_BLOCK);
 128     epan_scope   = wmem_allocator_new(WMEM_ALLOCATOR_BLOCK);
 129
 130     /* Scopes are initialized to true by default on creation */
 131     wmem_leave_scope(packet_scope);
 132     wmem_leave_scope(file_scope);
 133 }
 134
 135 void
 136 wmem_cleanup_scopes(void)
 137 {
 138     ws_assert(packet_scope);
 139     ws_assert(file_scope);
 140     ws_assert(epan_scope);
 141
 142     ws_assert(!wmem_in_scope(packet_scope));
 143     ws_assert(!wmem_in_scope(file_scope));
 144
 145     wmem_destroy_allocator(packet_scope);
 146     wmem_destroy_allocator(file_scope);
 147     wmem_destroy_allocator(epan_scope);
 148
 149     wmem_cleanup();
 150
 151     packet_scope = NULL;
 152     file_scope   = NULL;
 153     epan_scope   = NULL;
 154 }
 155
 156 /*
 157  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 158  *
 159  * Local variables:
 160  * c-basic-offset: 4
 161  * tab-width: 8
 162  * indent-tabs-mode: nil
 163  * End:
 164  *
 165  * vi: set shiftwidth=4 tabstop=8 expandtab:
 166  * :indentSize=4:tabSize=8:noTabs=true:
 167  */