2 * Copyright (c) 2008-2012 Niels Provos and Nick Mathewson
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 #ifndef BUFFEREVENT_INTERNAL_H_INCLUDED_
27 #define BUFFEREVENT_INTERNAL_H_INCLUDED_
33 #include "event2/event-config.h"
34 #include "event2/event_struct.h"
35 #include "evconfig-private.h"
36 #include "event2/util.h"
37 #include "defer-internal.h"
38 #include "evthread-internal.h"
39 #include "event2/thread.h"
40 #include "ratelim-internal.h"
41 #include "event2/bufferevent_struct.h"
43 /* These flags are reasons that we might be declining to actually enable
44 reading or writing on a bufferevent.
47 /* On a all bufferevents, for reading: used when we have read up to the
50 On a filtering bufferevent, for writing: used when the underlying
51 bufferevent's write buffer has been filled up to its watermark
54 #define BEV_SUSPEND_WM 0x01
55 /* On a base bufferevent: when we have emptied a bandwidth buckets */
56 #define BEV_SUSPEND_BW 0x02
57 /* On a base bufferevent: when we have emptied the group's bandwidth bucket. */
58 #define BEV_SUSPEND_BW_GROUP 0x04
59 /* On a socket bufferevent: can't do any operations while we're waiting for
60 * name lookup to finish. */
61 #define BEV_SUSPEND_LOOKUP 0x08
62 /* On a base bufferevent, for reading: used when a filter has choked this
63 * (underlying) bufferevent because it has stopped reading from it. */
64 #define BEV_SUSPEND_FILT_READ 0x10
66 typedef ev_uint16_t bufferevent_suspend_flags;
68 struct bufferevent_rate_limit_group {
69 /** List of all members in the group */
70 LIST_HEAD(rlim_group_member_list, bufferevent_private) members;
71 /** Current limits for the group. */
72 struct ev_token_bucket rate_limit;
73 struct ev_token_bucket_cfg rate_limit_cfg;
75 /** True iff we don't want to read from any member of the group.until
76 * the token bucket refills. */
77 unsigned read_suspended : 1;
78 /** True iff we don't want to write from any member of the group.until
79 * the token bucket refills. */
80 unsigned write_suspended : 1;
81 /** True iff we were unable to suspend one of the bufferevents in the
82 * group for reading the last time we tried, and we should try
84 unsigned pending_unsuspend_read : 1;
85 /** True iff we were unable to suspend one of the bufferevents in the
86 * group for writing the last time we tried, and we should try
88 unsigned pending_unsuspend_write : 1;
91 /** Total number of bytes read or written in this group since last
93 ev_uint64_t total_read;
94 ev_uint64_t total_written;
97 /** The number of bufferevents in the group. */
100 /** The smallest number of bytes that any member of the group should
101 * be limited to read or write at a time. */
102 ev_ssize_t min_share;
103 ev_ssize_t configured_min_share;
105 /** Timeout event that goes off once a tick, when the bucket is ready
107 struct event master_refill_event;
109 /** Seed for weak random number generator. Protected by 'lock' */
110 struct evutil_weakrand_state weakrand_seed;
112 /** Lock to protect the members of this group. This lock should nest
113 * within every bufferevent lock: if you are holding this lock, do
114 * not assume you can lock another bufferevent. */
118 /** Fields for rate-limiting a single bufferevent. */
119 struct bufferevent_rate_limit {
120 /* Linked-list elements for storing this bufferevent_private in a
123 * Note that this field is supposed to be protected by the group
125 LIST_ENTRY(bufferevent_private) next_in_group;
126 /** The rate-limiting group for this bufferevent, or NULL if it is
127 * only rate-limited on its own. */
128 struct bufferevent_rate_limit_group *group;
130 /* This bufferevent's current limits. */
131 struct ev_token_bucket limit;
132 /* Pointer to the rate-limit configuration for this bufferevent.
133 * Can be shared. XXX reference-count this? */
134 struct ev_token_bucket_cfg *cfg;
136 /* Timeout event used when one this bufferevent's buckets are
138 struct event refill_bucket_event;
141 /** Parts of the bufferevent structure that are shared among all bufferevent
142 * types, but not exposed in bufferevent_struct.h. */
143 struct bufferevent_private {
144 /** The underlying bufferevent structure. */
145 struct bufferevent bev;
147 /** Evbuffer callback to enforce watermarks on input. */
148 struct evbuffer_cb_entry *read_watermarks_cb;
150 /** If set, we should free the lock when we free the bufferevent. */
151 unsigned own_lock : 1;
153 /** Flag: set if we have deferred callbacks and a read callback is
155 unsigned readcb_pending : 1;
156 /** Flag: set if we have deferred callbacks and a write callback is
158 unsigned writecb_pending : 1;
159 /** Flag: set if we are currently busy connecting. */
160 unsigned connecting : 1;
161 /** Flag: set if a connect failed prematurely; this is a hack for
162 * getting around the bufferevent abstraction. */
163 unsigned connection_refused : 1;
164 /** Set to the events pending if we have deferred callbacks and
165 * an events callback is pending. */
166 short eventcb_pending;
168 /** If set, read is suspended until one or more conditions are over.
169 * The actual value here is a bitfield of those conditions; see the
170 * BEV_SUSPEND_* flags above. */
171 bufferevent_suspend_flags read_suspended;
173 /** If set, writing is suspended until one or more conditions are over.
174 * The actual value here is a bitfield of those conditions; see the
175 * BEV_SUSPEND_* flags above. */
176 bufferevent_suspend_flags write_suspended;
178 /** Set to the current socket errno if we have deferred callbacks and
179 * an events callback is pending. */
182 /** The DNS error code for bufferevent_socket_connect_hostname */
185 /** Used to implement deferred callbacks */
186 struct event_callback deferred;
188 /** The options this bufferevent was constructed with */
189 enum bufferevent_options options;
191 /** Current reference count for this bufferevent. */
194 /** Lock for this bufferevent. Shared by the inbuf and the outbuf.
195 * If NULL, locking is disabled. */
198 /** No matter how big our bucket gets, don't try to read more than this
199 * much in a single read operation. */
200 ev_ssize_t max_single_read;
202 /** No matter how big our bucket gets, don't try to write more than this
203 * much in a single write operation. */
204 ev_ssize_t max_single_write;
206 /** Rate-limiting information for this bufferevent */
207 struct bufferevent_rate_limit *rate_limiting;
210 /** Possible operations for a control callback. */
211 enum bufferevent_ctrl_op {
214 BEV_CTRL_GET_UNDERLYING,
218 /** Possible data types for a control callback */
219 union bufferevent_ctrl_data {
225 Implementation table for a bufferevent: holds function pointers and other
226 information to make the various bufferevent types work.
228 struct bufferevent_ops {
229 /** The name of the bufferevent's type. */
231 /** At what offset into the implementation type will we find a
232 bufferevent structure?
234 Example: if the type is implemented as
235 struct bufferevent_x {
237 struct bufferevent bev;
239 then mem_offset should be offsetof(struct bufferevent_x, bev)
243 /** Enables one or more of EV_READ|EV_WRITE on a bufferevent. Does
244 not need to adjust the 'enabled' field. Returns 0 on success, -1
247 int (*enable)(struct bufferevent *, short);
249 /** Disables one or more of EV_READ|EV_WRITE on a bufferevent. Does
250 not need to adjust the 'enabled' field. Returns 0 on success, -1
253 int (*disable)(struct bufferevent *, short);
255 /** Detatches the bufferevent from related data structures. Called as
256 * soon as its reference count reaches 0. */
257 void (*unlink)(struct bufferevent *);
259 /** Free any storage and deallocate any extra data or structures used
260 in this implementation. Called when the bufferevent is
263 void (*destruct)(struct bufferevent *);
265 /** Called when the timeouts on the bufferevent have changed.*/
266 int (*adj_timeouts)(struct bufferevent *);
268 /** Called to flush data. */
269 int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode);
271 /** Called to access miscellaneous fields. */
272 int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
276 extern const struct bufferevent_ops bufferevent_ops_socket;
277 extern const struct bufferevent_ops bufferevent_ops_filter;
278 extern const struct bufferevent_ops bufferevent_ops_pair;
280 #define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket)
281 #define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter)
282 #define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair)
285 extern const struct bufferevent_ops bufferevent_ops_async;
286 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)
288 #define BEV_IS_ASYNC(bevp) 0
291 /** Initialize the shared parts of a bufferevent. */
292 int bufferevent_init_common_(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options);
294 /** For internal use: temporarily stop all reads on bufev, until the conditions
295 * in 'what' are over. */
296 void bufferevent_suspend_read_(struct bufferevent *bufev, bufferevent_suspend_flags what);
297 /** For internal use: clear the conditions 'what' on bufev, and re-enable
298 * reading if there are no conditions left. */
299 void bufferevent_unsuspend_read_(struct bufferevent *bufev, bufferevent_suspend_flags what);
301 /** For internal use: temporarily stop all writes on bufev, until the conditions
302 * in 'what' are over. */
303 void bufferevent_suspend_write_(struct bufferevent *bufev, bufferevent_suspend_flags what);
304 /** For internal use: clear the conditions 'what' on bufev, and re-enable
305 * writing if there are no conditions left. */
306 void bufferevent_unsuspend_write_(struct bufferevent *bufev, bufferevent_suspend_flags what);
308 #define bufferevent_wm_suspend_read(b) \
309 bufferevent_suspend_read_((b), BEV_SUSPEND_WM)
310 #define bufferevent_wm_unsuspend_read(b) \
311 bufferevent_unsuspend_read_((b), BEV_SUSPEND_WM)
314 Disable a bufferevent. Equivalent to bufferevent_disable(), but
315 first resets 'connecting' flag to force EV_WRITE down for sure.
317 XXXX this method will go away in the future; try not to add new users.
318 See comment in evhttp_connection_reset_() for discussion.
320 @param bufev the bufferevent to be disabled
321 @param event any combination of EV_READ | EV_WRITE.
322 @return 0 if successful, or -1 if an error occurred
323 @see bufferevent_disable()
325 int bufferevent_disable_hard_(struct bufferevent *bufev, short event);
327 /** Internal: Set up locking on a bufferevent. If lock is set, use it.
328 * Otherwise, use a new lock. */
329 int bufferevent_enable_locking_(struct bufferevent *bufev, void *lock);
330 /** Internal: Increment the reference count on bufev. */
331 void bufferevent_incref_(struct bufferevent *bufev);
332 /** Internal: Lock bufev and increase its reference count.
333 * unlocking it otherwise. */
334 void bufferevent_incref_and_lock_(struct bufferevent *bufev);
335 /** Internal: Decrement the reference count on bufev. Returns 1 if it freed
337 int bufferevent_decref_(struct bufferevent *bufev);
338 /** Internal: Drop the reference count on bufev, freeing as necessary, and
339 * unlocking it otherwise. Returns 1 if it freed the bufferevent. */
340 int bufferevent_decref_and_unlock_(struct bufferevent *bufev);
342 /** Internal: If callbacks are deferred and we have a read callback, schedule
343 * a readcb. Otherwise just run the readcb. Ignores watermarks. */
344 void bufferevent_run_readcb_(struct bufferevent *bufev, int options);
345 /** Internal: If callbacks are deferred and we have a write callback, schedule
346 * a writecb. Otherwise just run the writecb. Ignores watermarks. */
347 void bufferevent_run_writecb_(struct bufferevent *bufev, int options);
348 /** Internal: If callbacks are deferred and we have an eventcb, schedule
349 * it to run with events "what". Otherwise just run the eventcb.
350 * See bufferevent_trigger_event for meaning of "options". */
351 void bufferevent_run_eventcb_(struct bufferevent *bufev, short what, int options);
353 /** Internal: Run or schedule (if deferred or options contain
354 * BEV_TRIG_DEFER_CALLBACKS) I/O callbacks specified in iotype.
355 * Must already hold the bufev lock. Honors watermarks unless
356 * BEV_TRIG_IGNORE_WATERMARKS is in options. */
357 static inline void bufferevent_trigger_nolock_(struct bufferevent *bufev, short iotype, int options);
359 /* Making this inline since all of the common-case calls to this function in
360 * libevent use constant arguments. */
362 bufferevent_trigger_nolock_(struct bufferevent *bufev, short iotype, int options)
364 if ((iotype & EV_READ) && ((options & BEV_TRIG_IGNORE_WATERMARKS) ||
365 evbuffer_get_length(bufev->input) >= bufev->wm_read.low))
366 bufferevent_run_readcb_(bufev, options);
367 if ((iotype & EV_WRITE) && ((options & BEV_TRIG_IGNORE_WATERMARKS) ||
368 evbuffer_get_length(bufev->output) <= bufev->wm_write.low))
369 bufferevent_run_writecb_(bufev, options);
372 /** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in
373 * which case add ev with no timeout. */
374 int bufferevent_add_event_(struct event *ev, const struct timeval *tv);
377 * These next functions implement timeouts for bufferevents that aren't doing
378 * anything else with ev_read and ev_write, to handle timeouts.
380 /** Internal use: Set up the ev_read and ev_write callbacks so that
381 * the other "generic_timeout" functions will work on it. Call this from
382 * the constructor function. */
383 void bufferevent_init_generic_timeout_cbs_(struct bufferevent *bev);
384 /** Internal use: Add or delete the generic timeout events as appropriate.
385 * (If an event is enabled and a timeout is set, we add the event. Otherwise
386 * we delete it.) Call this from anything that changes the timeout values,
387 * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */
388 int bufferevent_generic_adj_timeouts_(struct bufferevent *bev);
390 enum bufferevent_options bufferevent_get_options_(struct bufferevent *bev);
392 /** Internal use: We have just successfully read data into an inbuf, so
393 * reset the read timeout (if any). */
394 #define BEV_RESET_GENERIC_READ_TIMEOUT(bev) \
396 if (evutil_timerisset(&(bev)->timeout_read)) \
397 event_add(&(bev)->ev_read, &(bev)->timeout_read); \
399 /** Internal use: We have just successfully written data from an inbuf, so
400 * reset the read timeout (if any). */
401 #define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev) \
403 if (evutil_timerisset(&(bev)->timeout_write)) \
404 event_add(&(bev)->ev_write, &(bev)->timeout_write); \
406 #define BEV_DEL_GENERIC_READ_TIMEOUT(bev) \
407 event_del(&(bev)->ev_read)
408 #define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev) \
409 event_del(&(bev)->ev_write)
412 /** Internal: Given a bufferevent, return its corresponding
413 * bufferevent_private. */
414 #define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev)
416 #ifdef EVENT__DISABLE_THREAD_SUPPORT
417 #define BEV_LOCK(b) EVUTIL_NIL_STMT_
418 #define BEV_UNLOCK(b) EVUTIL_NIL_STMT_
420 /** Internal: Grab the lock (if any) on a bufferevent */
421 #define BEV_LOCK(b) do { \
422 struct bufferevent_private *locking = BEV_UPCAST(b); \
423 EVLOCK_LOCK(locking->lock, 0); \
426 /** Internal: Release the lock (if any) on a bufferevent */
427 #define BEV_UNLOCK(b) do { \
428 struct bufferevent_private *locking = BEV_UPCAST(b); \
429 EVLOCK_UNLOCK(locking->lock, 0); \
434 /* ==== For rate-limiting. */
436 int bufferevent_decrement_write_buckets_(struct bufferevent_private *bev,
438 int bufferevent_decrement_read_buckets_(struct bufferevent_private *bev,
440 ev_ssize_t bufferevent_get_read_max_(struct bufferevent_private *bev);
441 ev_ssize_t bufferevent_get_write_max_(struct bufferevent_private *bev);
443 int bufferevent_ratelim_init_(struct bufferevent_private *bev);
450 #endif /* BUFFEREVENT_INTERNAL_H_INCLUDED_ */