1/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2/* dbus-resources.c Resource tracking/limits
3 *
4 * Copyright (C) 2003  Red Hat Inc.
5 *
6 * Licensed under the Academic Free License version 2.1
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
21 *
22 */
23
24#include <config.h>
25#include <dbus/dbus-resources.h>
26#include <dbus/dbus-internals.h>
27
28/**
29 * @defgroup DBusResources Resource limits related code
30 * @ingroup  DBusInternals
31 * @brief DBusCounter and other stuff related to resource limits
32 *
33 * Types and functions related to tracking resource limits,
34 * such as the maximum amount of memory/unix fds a connection can use
35 * for messages, etc.
36 */
37
38/**
39 * @defgroup DBusResourcesInternals Resource limits implementation details
40 * @ingroup  DBusInternals
41 * @brief Resource limits implementation details
42 *
43 * Implementation details of resource limits code.
44 *
45 * @{
46 */
47
48/**
49 * @brief Internals of DBusCounter.
50 *
51 * DBusCounter internals. DBusCounter is an opaque object, it must be
52 * used via accessor functions.
53 */
54struct DBusCounter
55{
56  int refcount;  /**< reference count */
57
58  long size_value;       /**< current size counter value */
59  long unix_fd_value;    /**< current unix fd counter value */
60
61#ifdef DBUS_ENABLE_STATS
62  long peak_size_value;     /**< largest ever size counter value */
63  long peak_unix_fd_value;  /**< largest ever unix fd counter value */
64#endif
65
66  long notify_size_guard_value;    /**< call notify function when crossing this size value */
67  long notify_unix_fd_guard_value; /**< call notify function when crossing this unix fd value */
68
69  DBusCounterNotifyFunction notify_function; /**< notify function */
70  void *notify_data; /**< data for notify function */
71  dbus_bool_t notify_pending : 1; /**< TRUE if the guard value has been crossed */
72};
73
74/** @} */  /* end of resource limits internals docs */
75
76/**
77 * @addtogroup DBusResources
78 * @{
79 */
80
81/**
82 * Creates a new DBusCounter. DBusCounter is used
83 * to count usage of some resource such as memory.
84 *
85 * @returns new counter or #NULL on failure
86 */
87DBusCounter*
88_dbus_counter_new (void)
89{
90  DBusCounter *counter;
91
92  counter = dbus_new0 (DBusCounter, 1);
93  if (counter == NULL)
94    return NULL;
95
96  counter->refcount = 1;
97
98  return counter;
99}
100
101/**
102 * Increments refcount of the counter
103 *
104 * @param counter the counter
105 * @returns the counter
106 */
107DBusCounter *
108_dbus_counter_ref (DBusCounter *counter)
109{
110  _dbus_assert (counter->refcount > 0);
111
112  counter->refcount += 1;
113
114  return counter;
115}
116
117/**
118 * Decrements refcount of the counter and possibly
119 * finalizes the counter.
120 *
121 * @param counter the counter
122 */
123void
124_dbus_counter_unref (DBusCounter *counter)
125{
126  _dbus_assert (counter->refcount > 0);
127
128  counter->refcount -= 1;
129
130  if (counter->refcount == 0)
131    {
132
133      dbus_free (counter);
134    }
135}
136
137/**
138 * Adjusts the value of the size counter by the given
139 * delta which may be positive or negative.
140 *
141 * This function may be called with locks held. After calling it, when
142 * any relevant locks are no longer held you must call _dbus_counter_notify().
143 *
144 * @param counter the counter
145 * @param delta value to add to the size counter's current value
146 */
147void
148_dbus_counter_adjust_size (DBusCounter *counter,
149                           long         delta)
150{
151  long old = counter->size_value;
152
153  counter->size_value += delta;
154
155#ifdef DBUS_ENABLE_STATS
156  if (counter->peak_size_value < counter->size_value)
157    counter->peak_size_value = counter->size_value;
158#endif
159
160#if 0
161  _dbus_verbose ("Adjusting counter %ld by %ld = %ld\n",
162                 old, delta, counter->size_value);
163#endif
164
165  if (counter->notify_function != NULL &&
166      ((old < counter->notify_size_guard_value &&
167        counter->size_value >= counter->notify_size_guard_value) ||
168       (old >= counter->notify_size_guard_value &&
169        counter->size_value < counter->notify_size_guard_value)))
170    counter->notify_pending = TRUE;
171}
172
173/**
174 * Calls the notify function from _dbus_counter_set_notify(),
175 * if that function has been specified and the counter has crossed the
176 * guard value (in either direction) since the last call to this function.
177 *
178 * This function must not be called with locks held, since it can call out
179 * to user code.
180 */
181void
182_dbus_counter_notify (DBusCounter *counter)
183{
184  if (counter->notify_pending)
185    {
186      counter->notify_pending = FALSE;
187      (* counter->notify_function) (counter, counter->notify_data);
188    }
189}
190
191/**
192 * Adjusts the value of the unix fd counter by the given
193 * delta which may be positive or negative.
194 *
195 * This function may be called with locks held. After calling it, when
196 * any relevant locks are no longer held you must call _dbus_counter_notify().
197 *
198 * @param counter the counter
199 * @param delta value to add to the unix fds counter's current value
200 */
201void
202_dbus_counter_adjust_unix_fd (DBusCounter *counter,
203                              long         delta)
204{
205  long old = counter->unix_fd_value;
206
207  counter->unix_fd_value += delta;
208
209#ifdef DBUS_ENABLE_STATS
210  if (counter->peak_unix_fd_value < counter->unix_fd_value)
211    counter->peak_unix_fd_value = counter->unix_fd_value;
212#endif
213
214#if 0
215  _dbus_verbose ("Adjusting counter %ld by %ld = %ld\n",
216                 old, delta, counter->unix_fd_value);
217#endif
218
219  if (counter->notify_function != NULL &&
220      ((old < counter->notify_unix_fd_guard_value &&
221        counter->unix_fd_value >= counter->notify_unix_fd_guard_value) ||
222       (old >= counter->notify_unix_fd_guard_value &&
223        counter->unix_fd_value < counter->notify_unix_fd_guard_value)))
224    counter->notify_pending = TRUE;
225}
226
227/**
228 * Gets the current value of the size counter.
229 *
230 * @param counter the counter
231 * @returns its current size value
232 */
233long
234_dbus_counter_get_size_value (DBusCounter *counter)
235{
236  return counter->size_value;
237}
238
239/**
240 * Gets the current value of the unix fd counter.
241 *
242 * @param counter the counter
243 * @returns its current unix fd value
244 */
245long
246_dbus_counter_get_unix_fd_value (DBusCounter *counter)
247{
248  return counter->unix_fd_value;
249}
250
251/**
252 * Sets the notify function for this counter; the notify function is
253 * called whenever the counter's values cross the guard values in
254 * either direction (moving up, or moving down).
255 *
256 * @param counter the counter
257 * @param size_guard_value the value we're notified if the size counter crosses
258 * @param unix_fd_guard_value the value we're notified if the unix fd counter crosses
259 * @param function function to call in order to notify
260 * @param user_data data to pass to the function
261 */
262void
263_dbus_counter_set_notify (DBusCounter               *counter,
264                          long                       size_guard_value,
265                          long                       unix_fd_guard_value,
266                          DBusCounterNotifyFunction  function,
267                          void                      *user_data)
268{
269  counter->notify_size_guard_value = size_guard_value;
270  counter->notify_unix_fd_guard_value = unix_fd_guard_value;
271  counter->notify_function = function;
272  counter->notify_data = user_data;
273  counter->notify_pending = FALSE;
274}
275
276#ifdef DBUS_ENABLE_STATS
277long
278_dbus_counter_get_peak_size_value (DBusCounter *counter)
279{
280  return counter->peak_size_value;
281}
282
283long
284_dbus_counter_get_peak_unix_fd_value (DBusCounter *counter)
285{
286  return counter->peak_unix_fd_value;
287}
288#endif
289
290/** @} */  /* end of resource limits exported API */
291