OpenMPI  0.1.1
bufferevent-internal.h
1 /*
2  * Copyright (c) 2008-2010 Niels Provos and Nick Mathewson
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  * notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  * notice, this list of conditions and the following disclaimer in the
11  * documentation and/or other materials provided with the distribution.
12  * 3. The name of the author may not be used to endorse or promote products
13  * derived from this software without specific prior written permission.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 #ifndef _BUFFEREVENT_INTERNAL_H_
27 #define _BUFFEREVENT_INTERNAL_H_
28 
29 #ifdef __cplusplus
30 extern "C" {
31 #endif
32 
33 #include "event2/event-config.h"
34 #include "event2/util.h"
35 #include "defer-internal.h"
36 #include "evthread-internal.h"
37 #include "event2/thread.h"
38 #include "ratelim-internal.h"
40 
41 /* These flags are reasons that we might be declining to actually enable
42  reading or writing on a bufferevent.
43  */
44 
45 /* On a all bufferevents, for reading: used when we have read up to the
46  watermark value.
47 
48  On a filtering bufferevent, for writing: used when the underlying
49  bufferevent's write buffer has been filled up to its watermark
50  value.
51 */
52 #define BEV_SUSPEND_WM 0x01
53 /* On a base bufferevent: when we have emptied a bandwidth buckets */
54 #define BEV_SUSPEND_BW 0x02
55 /* On a base bufferevent: when we have emptied the group's bandwidth bucket. */
56 #define BEV_SUSPEND_BW_GROUP 0x04
57 /* On a socket bufferevent: can't do any operations while we're waiting for
58  * name lookup to finish. */
59 #define BEV_SUSPEND_LOOKUP 0x08
60 /* On a base bufferevent, for reading: used when a filter has choked this
61  * (underlying) bufferevent because it has stopped reading from it. */
62 #define BEV_SUSPEND_FILT_READ 0x10
63 
64 typedef ev_uint16_t bufferevent_suspend_flags;
65 
67  /** List of all members in the group */
68  TAILQ_HEAD(rlim_group_member_list, bufferevent_private) members;
69  /** Current limits for the group. */
71  struct ev_token_bucket_cfg rate_limit_cfg;
72 
73  /** True iff we don't want to read from any member of the group.until
74  * the token bucket refills. */
75  unsigned read_suspended : 1;
76  /** True iff we don't want to write from any member of the group.until
77  * the token bucket refills. */
78  unsigned write_suspended : 1;
79  /** True iff we were unable to suspend one of the bufferevents in the
80  * group for reading the last time we tried, and we should try
81  * again. */
82  unsigned pending_unsuspend_read : 1;
83  /** True iff we were unable to suspend one of the bufferevents in the
84  * group for writing the last time we tried, and we should try
85  * again. */
87 
88  /*@{*/
89  /** Total number of bytes read or written in this group since last
90  * reset. */
91  ev_uint64_t total_read;
92  ev_uint64_t total_written;
93  /*@}*/
94 
95  /** The number of bufferevents in the group. */
96  int n_members;
97 
98  /** The smallest number of bytes that any member of the group should
99  * be limited to read or write at a time. */
100  ev_ssize_t min_share;
101  /** Timeout event that goes off once a tick, when the bucket is ready
102  * to refill. */
104  /** Lock to protect the members of this group. This lock should nest
105  * within every bufferevent lock: if you are holding this lock, do
106  * not assume you can lock another bufferevent. */
107  void *lock;
108 };
109 
110 /** Fields for rate-limiting a single bufferevent. */
112  /* Linked-list elements for storing this bufferevent_private in a
113  * group.
114  *
115  * Note that this field is supposed to be protected by the group
116  * lock */
117  TAILQ_ENTRY(bufferevent_private) next_in_group;
118  /** The rate-limiting group for this bufferevent, or NULL if it is
119  * only rate-limited on its own. */
121 
122  /* This bufferevent's current limits. */
123  struct ev_token_bucket limit;
124  /* Pointer to the rate-limit configuration for this bufferevent.
125  * Can be shared. XXX reference-count this? */
126  struct ev_token_bucket_cfg *cfg;
127 
128  /* Timeout event used when one this bufferevent's buckets are
129  * empty. */
130  struct event refill_bucket_event;
131 };
132 
133 /** Parts of the bufferevent structure that are shared among all bufferevent
134  * types, but not exposed in bufferevent_struct.h. */
136  /** The underlying bufferevent structure. */
137  struct bufferevent bev;
138 
139  /** Evbuffer callback to enforce watermarks on input. */
141 
142  /** If set, we should free the lock when we free the bufferevent. */
143  unsigned own_lock : 1;
144 
145  /** Flag: set if we have deferred callbacks and a read callback is
146  * pending. */
147  unsigned readcb_pending : 1;
148  /** Flag: set if we have deferred callbacks and a write callback is
149  * pending. */
150  unsigned writecb_pending : 1;
151  /** Flag: set if we are currently busy connecting. */
152  unsigned connecting : 1;
153  /** Flag: set if a connect failed prematurely; this is a hack for
154  * getting around the bufferevent abstraction. */
155  unsigned connection_refused : 1;
156  /** Set to the events pending if we have deferred callbacks and
157  * an events callback is pending. */
159 
160  /** If set, read is suspended until one or more conditions are over.
161  * The actual value here is a bitfield of those conditions; see the
162  * BEV_SUSPEND_* flags above. */
163  bufferevent_suspend_flags read_suspended;
164 
165  /** If set, writing is suspended until one or more conditions are over.
166  * The actual value here is a bitfield of those conditions; see the
167  * BEV_SUSPEND_* flags above. */
168  bufferevent_suspend_flags write_suspended;
169 
170  /** Set to the current socket errno if we have deferred callbacks and
171  * an events callback is pending. */
173 
174  /** The DNS error code for bufferevent_socket_connect_hostname */
176 
177  /** Used to implement deferred callbacks */
179 
180  /** The options this bufferevent was constructed with */
182 
183  /** Current reference count for this bufferevent. */
184  int refcnt;
185 
186  /** Lock for this bufferevent. Shared by the inbuf and the outbuf.
187  * If NULL, locking is disabled. */
188  void *lock;
189 
190  /** Rate-limiting information for this bufferevent */
192 };
193 
194 /** Possible operations for a control callback. */
195 enum bufferevent_ctrl_op {
196  BEV_CTRL_SET_FD,
197  BEV_CTRL_GET_FD,
198  BEV_CTRL_GET_UNDERLYING
199 };
200 
201 /** Possible data types for a control callback */
203  void *ptr;
204  evutil_socket_t fd;
205 };
206 
207 /**
208  Implementation table for a bufferevent: holds function pointers and other
209  information to make the various bufferevent types work.
210 */
212  /** The name of the bufferevent's type. */
213  const char *type;
214  /** At what offset into the implementation type will we find a
215  bufferevent structure?
216 
217  Example: if the type is implemented as
218  struct bufferevent_x {
219  int extra_data;
220  struct bufferevent bev;
221  }
222  then mem_offset should be offsetof(struct bufferevent_x, bev)
223  */
224  off_t mem_offset;
225 
226  /** Enables one or more of EV_READ|EV_WRITE on a bufferevent. Does
227  not need to adjust the 'enabled' field. Returns 0 on success, -1
228  on failure.
229  */
230  int (*enable)(struct bufferevent *, short);
231 
232  /** Disables one or more of EV_READ|EV_WRITE on a bufferevent. Does
233  not need to adjust the 'enabled' field. Returns 0 on success, -1
234  on failure.
235  */
236  int (*disable)(struct bufferevent *, short);
237 
238  /** Free any storage and deallocate any extra data or structures used
239  in this implementation.
240  */
241  void (*destruct)(struct bufferevent *);
242 
243  /** Called when the timeouts on the bufferevent have changed.*/
244  int (*adj_timeouts)(struct bufferevent *);
245 
246  /** Called to flush data. */
247  int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode);
248 
249  /** Called to access miscellaneous fields. */
250  int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
251 
252 };
253 
254 extern const struct bufferevent_ops bufferevent_ops_socket;
255 extern const struct bufferevent_ops bufferevent_ops_filter;
256 extern const struct bufferevent_ops bufferevent_ops_pair;
257 
258 #define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket)
259 #define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter)
260 #define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair)
261 
262 #ifdef WIN32
263 extern const struct bufferevent_ops bufferevent_ops_async;
264 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)
265 #else
266 #define BEV_IS_ASYNC(bevp) 0
267 #endif
268 
269 /** Initialize the shared parts of a bufferevent. */
270 int bufferevent_init_common(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options);
271 
272 /** For internal use: temporarily stop all reads on bufev, until the conditions
273  * in 'what' are over. */
274 void bufferevent_suspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
275 /** For internal use: clear the conditions 'what' on bufev, and re-enable
276  * reading if there are no conditions left. */
277 void bufferevent_unsuspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
278 
279 /** For internal use: temporarily stop all writes on bufev, until the conditions
280  * in 'what' are over. */
281 void bufferevent_suspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
282 /** For internal use: clear the conditions 'what' on bufev, and re-enable
283  * writing if there are no conditions left. */
284 void bufferevent_unsuspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
285 
286 #define bufferevent_wm_suspend_read(b) \
287  bufferevent_suspend_read((b), BEV_SUSPEND_WM)
288 #define bufferevent_wm_unsuspend_read(b) \
289  bufferevent_unsuspend_read((b), BEV_SUSPEND_WM)
290 
291 /*
292  Disable a bufferevent. Equivalent to bufferevent_disable(), but
293  first resets 'connecting' flag to force EV_WRITE down for sure.
294 
295  XXXX this method will go away in the future; try not to add new users.
296  See comment in evhttp_connection_reset() for discussion.
297 
298  @param bufev the bufferevent to be disabled
299  @param event any combination of EV_READ | EV_WRITE.
300  @return 0 if successful, or -1 if an error occurred
301  @see bufferevent_disable()
302  */
303 int bufferevent_disable_hard(struct bufferevent *bufev, short event);
304 
305 /** Internal: Set up locking on a bufferevent. If lock is set, use it.
306  * Otherwise, use a new lock. */
307 int bufferevent_enable_locking(struct bufferevent *bufev, void *lock);
308 /** Internal: Increment the reference count on bufev. */
309 void bufferevent_incref(struct bufferevent *bufev);
310 /** Internal: Lock bufev and increase its reference count.
311  * unlocking it otherwise. */
312 void _bufferevent_incref_and_lock(struct bufferevent *bufev);
313 /** Internal: Decrement the reference count on bufev. Returns 1 if it freed
314  * the bufferevent.*/
315 int bufferevent_decref(struct bufferevent *bufev);
316 /** Internal: Drop the reference count on bufev, freeing as necessary, and
317  * unlocking it otherwise. Returns 1 if it freed the bufferevent. */
318 int _bufferevent_decref_and_unlock(struct bufferevent *bufev);
319 
320 /** Internal: If callbacks are deferred and we have a read callback, schedule
321  * a readcb. Otherwise just run the readcb. */
322 void _bufferevent_run_readcb(struct bufferevent *bufev);
323 /** Internal: If callbacks are deferred and we have a write callback, schedule
324  * a writecb. Otherwise just run the writecb. */
325 void _bufferevent_run_writecb(struct bufferevent *bufev);
326 /** Internal: If callbacks are deferred and we have an eventcb, schedule
327  * it to run with events "what". Otherwise just run the eventcb. */
328 void _bufferevent_run_eventcb(struct bufferevent *bufev, short what);
329 
330 /** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in
331  * which case add ev with no timeout. */
332 int _bufferevent_add_event(struct event *ev, const struct timeval *tv);
333 
334 /* =========
335  * These next functions implement timeouts for bufferevents that aren't doing
336  * anything else with ev_read and ev_write, to handle timeouts.
337  * ========= */
338 /** Internal use: Set up the ev_read and ev_write callbacks so that
339  * the other "generic_timeout" functions will work on it. Call this from
340  * the constructor function. */
341 void _bufferevent_init_generic_timeout_cbs(struct bufferevent *bev);
342 /** Internal use: Delete the ev_read and ev_write callbacks if they're pending.
343  * Call this from the destructor function. */
344 int _bufferevent_del_generic_timeout_cbs(struct bufferevent *bev);
345 /** Internal use: Add or delete the generic timeout events as appropriate.
346  * (If an event is enabled and a timeout is set, we add the event. Otherwise
347  * we delete it.) Call this from anything that changes the timeout values,
348  * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */
349 int _bufferevent_generic_adj_timeouts(struct bufferevent *bev);
350 
351 /** Internal use: We have just successfully read data into an inbuf, so
352  * reset the read timeout (if any). */
353 #define BEV_RESET_GENERIC_READ_TIMEOUT(bev) \
354  do { \
355  if (evutil_timerisset(&(bev)->timeout_read)) \
356  event_add(&(bev)->ev_read, &(bev)->timeout_read); \
357  } while (0)
358 /** Internal use: We have just successfully written data from an inbuf, so
359  * reset the read timeout (if any). */
360 #define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev) \
361  do { \
362  if (evutil_timerisset(&(bev)->timeout_write)) \
363  event_add(&(bev)->ev_write, &(bev)->timeout_write); \
364  } while (0)
365 #define BEV_DEL_GENERIC_READ_TIMEOUT(bev) \
366  event_del(&(bev)->ev_read)
367 #define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev) \
368  event_del(&(bev)->ev_write)
369 
370 
371 /** Internal: Given a bufferevent, return its corresponding
372  * bufferevent_private. */
373 #define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev)
374 
375 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
376 #define BEV_LOCK(b) _EVUTIL_NIL_STMT
377 #define BEV_UNLOCK(b) _EVUTIL_NIL_STMT
378 #else
379 /** Internal: Grab the lock (if any) on a bufferevent */
380 #define BEV_LOCK(b) do { \
381  struct bufferevent_private *locking = BEV_UPCAST(b); \
382  EVLOCK_LOCK(locking->lock, 0); \
383  } while (0)
384 
385 /** Internal: Release the lock (if any) on a bufferevent */
386 #define BEV_UNLOCK(b) do { \
387  struct bufferevent_private *locking = BEV_UPCAST(b); \
388  EVLOCK_UNLOCK(locking->lock, 0); \
389  } while (0)
390 #endif
391 
392 
393 /* ==== For rate-limiting. */
394 
395 int _bufferevent_decrement_write_buckets(struct bufferevent_private *bev,
396  ev_ssize_t bytes);
397 int _bufferevent_decrement_read_buckets(struct bufferevent_private *bev,
398  ev_ssize_t bytes);
399 ev_ssize_t _bufferevent_get_read_max(struct bufferevent_private *bev);
400 ev_ssize_t _bufferevent_get_write_max(struct bufferevent_private *bev);
401 
402 #ifdef __cplusplus
403 }
404 #endif
405 
406 
407 #endif /* _BUFFEREVENT_INTERNAL_H_ */
int errno_pending
Set to the current socket errno if we have deferred callbacks and an events callback is pending...
Definition: bufferevent-internal.h:172
int(* enable)(struct bufferevent *, short)
Enables one or more of EV_READ|EV_WRITE on a bufferevent.
Definition: bufferevent-internal.h:230
unsigned connection_refused
Flag: set if a connect failed prematurely; this is a hack for getting around the bufferevent abstract...
Definition: bufferevent-internal.h:155
int(* adj_timeouts)(struct bufferevent *)
Called when the timeouts on the bufferevent have changed.
Definition: bufferevent-internal.h:244
A single evbuffer callback for an evbuffer.
Definition: evbuffer-internal.h:60
ev_ssize_t min_share
The smallest number of bytes that any member of the group should be limited to read or write at a tim...
Definition: bufferevent-internal.h:100
unsigned read_suspended
True iff we don't want to read from any member of the group.until the token bucket refills...
Definition: bufferevent-internal.h:75
struct deferred_cb deferred
Used to implement deferred callbacks.
Definition: bufferevent-internal.h:178
Definition: bufferevent-internal.h:66
const char * type
The name of the bufferevent's type.
Definition: bufferevent-internal.h:213
struct bufferevent_rate_limit * rate_limiting
Rate-limiting information for this bufferevent.
Definition: bufferevent-internal.h:191
unsigned pending_unsuspend_write
True iff we were unable to suspend one of the bufferevents in the group for writing the last time we ...
Definition: bufferevent-internal.h:86
void * lock
Lock for this bufferevent.
Definition: bufferevent-internal.h:188
Structure to represent a single event.
Definition: event_struct.h:87
int refcnt
Current reference count for this bufferevent.
Definition: bufferevent-internal.h:184
ev_uint64_t total_read
Total number of bytes read or written in this group since last reset.
Definition: bufferevent-internal.h:91
unsigned connecting
Flag: set if we are currently busy connecting.
Definition: bufferevent-internal.h:152
struct event master_refill_event
Timeout event that goes off once a tick, when the bucket is ready to refill.
Definition: bufferevent-internal.h:103
unsigned own_lock
If set, we should free the lock when we free the bufferevent.
Definition: bufferevent-internal.h:143
Data structures for bufferevents.
bufferevent_suspend_flags write_suspended
If set, writing is suspended until one or more conditions are over.
Definition: bufferevent-internal.h:168
int dns_error
The DNS error code for bufferevent_socket_connect_hostname.
Definition: bufferevent-internal.h:175
Functions for multi-threaded applications using Libevent.
#define evutil_socket_t
A type wide enough to hold the output of "socket()" or "accept()".
Definition: util.h:278
unsigned readcb_pending
Flag: set if we have deferred callbacks and a read callback is pending.
Definition: bufferevent-internal.h:147
int n_members
The number of bufferevents in the group.
Definition: bufferevent-internal.h:96
unsigned writecb_pending
Flag: set if we have deferred callbacks and a write callback is pending.
Definition: bufferevent-internal.h:150
Parts of the bufferevent structure that are shared among all bufferevent types, but not exposed in bu...
Definition: bufferevent-internal.h:135
A token bucket is an internal structure that tracks how many bytes we are currently willing to read o...
Definition: ratelim-internal.h:38
Configuration info for a token bucket or set of token buckets.
Definition: ratelim-internal.h:48
void(* destruct)(struct bufferevent *)
Free any storage and deallocate any extra data or structures used in this implementation.
Definition: bufferevent-internal.h:241
void * lock
Lock to protect the members of this group.
Definition: bufferevent-internal.h:107
off_t mem_offset
At what offset into the implementation type will we find a bufferevent structure? ...
Definition: bufferevent-internal.h:224
Possible data types for a control callback.
Definition: bufferevent-internal.h:202
Common convenience functions for cross-platform portability and related socket manipulations.
enum bufferevent_options options
The options this bufferevent was constructed with.
Definition: bufferevent-internal.h:181
short eventcb_pending
Set to the events pending if we have deferred callbacks and an events callback is pending...
Definition: bufferevent-internal.h:158
int(* flush)(struct bufferevent *, short, enum bufferevent_flush_mode)
Called to flush data.
Definition: bufferevent-internal.h:247
TAILQ_HEAD(rlim_group_member_list, bufferevent_private) members
List of all members in the group.
bufferevent_suspend_flags read_suspended
If set, read is suspended until one or more conditions are over.
Definition: bufferevent-internal.h:163
struct evbuffer_cb_entry * read_watermarks_cb
Evbuffer callback to enforce watermarks on input.
Definition: bufferevent-internal.h:140
struct ev_token_bucket rate_limit
Current limits for the group.
Definition: bufferevent-internal.h:70
struct bufferevent_rate_limit_group * group
The rate-limiting group for this bufferevent, or NULL if it is only rate-limited on its own...
Definition: bufferevent-internal.h:120
A deferred_cb is a callback that can be scheduled to run as part of an event_base's event_loop...
Definition: defer-internal.h:42
bufferevent_flush_mode
Flags that can be passed into filters to let them know how to deal with the incoming data...
Definition: bufferevent.h:490
unsigned pending_unsuspend_read
True iff we were unable to suspend one of the bufferevents in the group for reading the last time we ...
Definition: bufferevent-internal.h:82
int(* ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *)
Called to access miscellaneous fields.
Definition: bufferevent-internal.h:250
Shared implementation of a bufferevent.
Definition: bufferevent_struct.h:70
bufferevent_options
Options that can be specified when creating a bufferevent.
Definition: bufferevent.h:148
Definition: event-internal.h:167
Implementation table for a bufferevent: holds function pointers and other information to make the var...
Definition: bufferevent-internal.h:211
int(* disable)(struct bufferevent *, short)
Disables one or more of EV_READ|EV_WRITE on a bufferevent.
Definition: bufferevent-internal.h:236
struct bufferevent bev
The underlying bufferevent structure.
Definition: bufferevent-internal.h:137
Fields for rate-limiting a single bufferevent.
Definition: bufferevent-internal.h:111
unsigned write_suspended
True iff we don't want to write from any member of the group.until the token bucket refills...
Definition: bufferevent-internal.h:78