external/bsd/libevent/dist/bufferevent-internal.h

   1 /*      $NetBSD: bufferevent-internal.h,v 1.2 2013/04/11 16:56:41 christos Exp $        */
   2 /*
   3  * Copyright (c) 2008-2012 Niels Provos and Nick Mathewson
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27 #ifndef _BUFFEREVENT_INTERNAL_H_
  28 #define _BUFFEREVENT_INTERNAL_H_
  29
  30 #ifdef __cplusplus
  31 extern "C" {
  32 #endif
  33
  34 #include "event2/event-config.h"
  35 #include "event2/util.h"
  36 #include "defer-internal.h"
  37 #include "evthread-internal.h"
  38 #include "event2/thread.h"
  39 #include "ratelim-internal.h"
  40 #include "event2/bufferevent_struct.h"
  41
  42 /* These flags are reasons that we might be declining to actually enable
  43    reading or writing on a bufferevent.
  44  */
  45
  46 /* On a all bufferevents, for reading: used when we have read up to the
  47    watermark value.
  48
  49    On a filtering bufferevent, for writing: used when the underlying
  50    bufferevent's write buffer has been filled up to its watermark
  51    value.
  52 */
  53 #define BEV_SUSPEND_WM 0x01
  54 /* On a base bufferevent: when we have emptied a bandwidth buckets */
  55 #define BEV_SUSPEND_BW 0x02
  56 /* On a base bufferevent: when we have emptied the group's bandwidth bucket. */
  57 #define BEV_SUSPEND_BW_GROUP 0x04
  58 /* On a socket bufferevent: can't do any operations while we're waiting for
  59  * name lookup to finish. */
  60 #define BEV_SUSPEND_LOOKUP 0x08
  61 /* On a base bufferevent, for reading: used when a filter has choked this
  62  * (underlying) bufferevent because it has stopped reading from it. */
  63 #define BEV_SUSPEND_FILT_READ 0x10
  64
  65 typedef ev_uint16_t bufferevent_suspend_flags;
  66
  67 struct bufferevent_rate_limit_group {
  68         /** List of all members in the group */
  69         TAILQ_HEAD(rlim_group_member_list, bufferevent_private) members;
  70         /** Current limits for the group. */
  71         struct ev_token_bucket rate_limit;
  72         struct ev_token_bucket_cfg rate_limit_cfg;
  73
  74         /** True iff we don't want to read from any member of the group.until
  75          * the token bucket refills.  */
  76         unsigned read_suspended : 1;
  77         /** True iff we don't want to write from any member of the group.until
  78          * the token bucket refills.  */
  79         unsigned write_suspended : 1;
  80         /** True iff we were unable to suspend one of the bufferevents in the
  81          * group for reading the last time we tried, and we should try
  82          * again. */
  83         unsigned pending_unsuspend_read : 1;
  84         /** True iff we were unable to suspend one of the bufferevents in the
  85          * group for writing the last time we tried, and we should try
  86          * again. */
  87         unsigned pending_unsuspend_write : 1;
  88
  89         /*@{*/
  90         /** Total number of bytes read or written in this group since last
  91          * reset. */
  92         ev_uint64_t total_read;
  93         ev_uint64_t total_written;
  94         /*@}*/
  95
  96         /** The number of bufferevents in the group. */
  97         int n_members;
  98
  99         /** The smallest number of bytes that any member of the group should
 100          * be limited to read or write at a time. */
 101         ev_ssize_t min_share;
 102         ev_ssize_t configured_min_share;
 103
 104         /** Timeout event that goes off once a tick, when the bucket is ready
 105          * to refill. */
 106         struct event master_refill_event;
 107         /** Lock to protect the members of this group.  This lock should nest
 108          * within every bufferevent lock: if you are holding this lock, do
 109          * not assume you can lock another bufferevent. */
 110         void *lock;
 111 };
 112
 113 /** Fields for rate-limiting a single bufferevent. */
 114 struct bufferevent_rate_limit {
 115         /* Linked-list elements for storing this bufferevent_private in a
 116          * group.
 117          *
 118          * Note that this field is supposed to be protected by the group
 119          * lock */
 120         TAILQ_ENTRY(bufferevent_private) next_in_group;
 121         /** The rate-limiting group for this bufferevent, or NULL if it is
 122          * only rate-limited on its own. */
 123         struct bufferevent_rate_limit_group *group;
 124
 125         /* This bufferevent's current limits. */
 126         struct ev_token_bucket limit;
 127         /* Pointer to the rate-limit configuration for this bufferevent.
 128          * Can be shared.  XXX reference-count this? */
 129         struct ev_token_bucket_cfg *cfg;
 130
 131         /* Timeout event used when one this bufferevent's buckets are
 132          * empty. */
 133         struct event refill_bucket_event;
 134 };
 135
 136 /** Parts of the bufferevent structure that are shared among all bufferevent
 137  * types, but not exposed in bufferevent_struct.h. */
 138 struct bufferevent_private {
 139         /** The underlying bufferevent structure. */
 140         struct bufferevent bev;
 141
 142         /** Evbuffer callback to enforce watermarks on input. */
 143         struct evbuffer_cb_entry *read_watermarks_cb;
 144
 145         /** If set, we should free the lock when we free the bufferevent. */
 146         unsigned own_lock : 1;
 147
 148         /** Flag: set if we have deferred callbacks and a read callback is
 149          * pending. */
 150         unsigned readcb_pending : 1;
 151         /** Flag: set if we have deferred callbacks and a write callback is
 152          * pending. */
 153         unsigned writecb_pending : 1;
 154         /** Flag: set if we are currently busy connecting. */
 155         unsigned connecting : 1;
 156         /** Flag: set if a connect failed prematurely; this is a hack for
 157          * getting around the bufferevent abstraction. */
 158         unsigned connection_refused : 1;
 159         /** Set to the events pending if we have deferred callbacks and
 160          * an events callback is pending. */
 161         short eventcb_pending;
 162
 163         /** If set, read is suspended until one or more conditions are over.
 164          * The actual value here is a bitfield of those conditions; see the
 165          * BEV_SUSPEND_* flags above. */
 166         bufferevent_suspend_flags read_suspended;
 167
 168         /** If set, writing 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 write_suspended;
 172
 173         /** Set to the current socket errno if we have deferred callbacks and
 174          * an events callback is pending. */
 175         int errno_pending;
 176
 177         /** The DNS error code for bufferevent_socket_connect_hostname */
 178         int dns_error;
 179
 180         /** Used to implement deferred callbacks */
 181         struct deferred_cb deferred;
 182
 183         /** The options this bufferevent was constructed with */
 184         enum bufferevent_options options;
 185
 186         /** Current reference count for this bufferevent. */
 187         int refcnt;
 188
 189         /** Lock for this bufferevent.  Shared by the inbuf and the outbuf.
 190          * If NULL, locking is disabled. */
 191         void *lock;
 192
 193         /** Rate-limiting information for this bufferevent */
 194         struct bufferevent_rate_limit *rate_limiting;
 195 };
 196
 197 /** Possible operations for a control callback. */
 198 enum bufferevent_ctrl_op {
 199         BEV_CTRL_SET_FD,
 200         BEV_CTRL_GET_FD,
 201         BEV_CTRL_GET_UNDERLYING,
 202         BEV_CTRL_CANCEL_ALL
 203 };
 204
 205 /** Possible data types for a control callback */
 206 union bufferevent_ctrl_data {
 207         void *ptr;
 208         evutil_socket_t fd;
 209 };
 210
 211 /**
 212    Implementation table for a bufferevent: holds function pointers and other
 213    information to make the various bufferevent types work.
 214 */
 215 struct bufferevent_ops {
 216         /** The name of the bufferevent's type. */
 217         const char *type;
 218         /** At what offset into the implementation type will we find a
 219             bufferevent structure?
 220
 221             Example: if the type is implemented as
 222             struct bufferevent_x {
 223                int extra_data;
 224                struct bufferevent bev;
 225             }
 226             then mem_offset should be offsetof(struct bufferevent_x, bev)
 227         */
 228         off_t mem_offset;
 229
 230         /** Enables one or more of EV_READ|EV_WRITE on a bufferevent.  Does
 231             not need to adjust the 'enabled' field.  Returns 0 on success, -1
 232             on failure.
 233          */
 234         int (*enable)(struct bufferevent *, short);
 235
 236         /** Disables one or more of EV_READ|EV_WRITE on a bufferevent.  Does
 237             not need to adjust the 'enabled' field.  Returns 0 on success, -1
 238             on failure.
 239          */
 240         int (*disable)(struct bufferevent *, short);
 241
 242         /** Free any storage and deallocate any extra data or structures used
 243             in this implementation.
 244          */
 245         void (*destruct)(struct bufferevent *);
 246
 247         /** Called when the timeouts on the bufferevent have changed.*/
 248         int (*adj_timeouts)(struct bufferevent *);
 249
 250         /** Called to flush data. */
 251         int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode);
 252
 253         /** Called to access miscellaneous fields. */
 254         int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
 255
 256 };
 257
 258 extern const struct bufferevent_ops bufferevent_ops_socket;
 259 extern const struct bufferevent_ops bufferevent_ops_filter;
 260 extern const struct bufferevent_ops bufferevent_ops_pair;
 261
 262 #define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket)
 263 #define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter)
 264 #define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair)
 265
 266 #ifdef WIN32
 267 extern const struct bufferevent_ops bufferevent_ops_async;
 268 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)
 269 #else
 270 #define BEV_IS_ASYNC(bevp) 0
 271 #endif
 272
 273 /** Initialize the shared parts of a bufferevent. */
 274 int bufferevent_init_common(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options);
 275
 276 /** For internal use: temporarily stop all reads on bufev, until the conditions
 277  * in 'what' are over. */
 278 void bufferevent_suspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
 279 /** For internal use: clear the conditions 'what' on bufev, and re-enable
 280  * reading if there are no conditions left. */
 281 void bufferevent_unsuspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
 282
 283 /** For internal use: temporarily stop all writes on bufev, until the conditions
 284  * in 'what' are over. */
 285 void bufferevent_suspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
 286 /** For internal use: clear the conditions 'what' on bufev, and re-enable
 287  * writing if there are no conditions left. */
 288 void bufferevent_unsuspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
 289
 290 #define bufferevent_wm_suspend_read(b) \
 291         bufferevent_suspend_read((b), BEV_SUSPEND_WM)
 292 #define bufferevent_wm_unsuspend_read(b) \
 293         bufferevent_unsuspend_read((b), BEV_SUSPEND_WM)
 294
 295 /*
 296   Disable a bufferevent.  Equivalent to bufferevent_disable(), but
 297   first resets 'connecting' flag to force EV_WRITE down for sure.
 298
 299   XXXX this method will go away in the future; try not to add new users.
 300     See comment in evhttp_connection_reset() for discussion.
 301
 302   @param bufev the bufferevent to be disabled
 303   @param event any combination of EV_READ | EV_WRITE.
 304   @return 0 if successful, or -1 if an error occurred
 305   @see bufferevent_disable()
 306  */
 307 int bufferevent_disable_hard(struct bufferevent *bufev, short event);
 308
 309 /** Internal: Set up locking on a bufferevent.  If lock is set, use it.
 310  * Otherwise, use a new lock. */
 311 int bufferevent_enable_locking(struct bufferevent *bufev, void *lock);
 312 /** Internal: Increment the reference count on bufev. */
 313 void bufferevent_incref(struct bufferevent *bufev);
 314 /** Internal: Lock bufev and increase its reference count.
 315  * unlocking it otherwise. */
 316 void _bufferevent_incref_and_lock(struct bufferevent *bufev);
 317 /** Internal: Decrement the reference count on bufev.  Returns 1 if it freed
 318  * the bufferevent.*/
 319 int bufferevent_decref(struct bufferevent *bufev);
 320 /** Internal: Drop the reference count on bufev, freeing as necessary, and
 321  * unlocking it otherwise.  Returns 1 if it freed the bufferevent. */
 322 int _bufferevent_decref_and_unlock(struct bufferevent *bufev);
 323
 324 /** Internal: If callbacks are deferred and we have a read callback, schedule
 325  * a readcb.  Otherwise just run the readcb. */
 326 void _bufferevent_run_readcb(struct bufferevent *bufev);
 327 /** Internal: If callbacks are deferred and we have a write callback, schedule
 328  * a writecb.  Otherwise just run the writecb. */
 329 void _bufferevent_run_writecb(struct bufferevent *bufev);
 330 /** Internal: If callbacks are deferred and we have an eventcb, schedule
 331  * it to run with events "what".  Otherwise just run the eventcb. */
 332 void _bufferevent_run_eventcb(struct bufferevent *bufev, short what);
 333
 334 /** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in
 335  * which case add ev with no timeout. */
 336 int _bufferevent_add_event(struct event *ev, const struct timeval *tv);
 337
 338 /* =========
 339  * These next functions implement timeouts for bufferevents that aren't doing
 340  * anything else with ev_read and ev_write, to handle timeouts.
 341  * ========= */
 342 /** Internal use: Set up the ev_read and ev_write callbacks so that
 343  * the other "generic_timeout" functions will work on it.  Call this from
 344  * the constructor function. */
 345 void _bufferevent_init_generic_timeout_cbs(struct bufferevent *bev);
 346 /** Internal use: Delete the ev_read and ev_write callbacks if they're pending.
 347  * Call this from the destructor function. */
 348 int _bufferevent_del_generic_timeout_cbs(struct bufferevent *bev);
 349 /** Internal use: Add or delete the generic timeout events as appropriate.
 350  * (If an event is enabled and a timeout is set, we add the event.  Otherwise
 351  * we delete it.)  Call this from anything that changes the timeout values,
 352  * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */
 353 int _bufferevent_generic_adj_timeouts(struct bufferevent *bev);
 354
 355 /** Internal use: We have just successfully read data into an inbuf, so
 356  * reset the read timeout (if any). */
 357 #define BEV_RESET_GENERIC_READ_TIMEOUT(bev)                             \
 358         do {                                                            \
 359                 if (evutil_timerisset(&(bev)->timeout_read))            \
 360                         event_add(&(bev)->ev_read, &(bev)->timeout_read); \
 361         } while (/*CONSTCOND*/0)
 362 /** Internal use: We have just successfully written data from an inbuf, so
 363  * reset the read timeout (if any). */
 364 #define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev)                            \
 365         do {                                                            \
 366                 if (evutil_timerisset(&(bev)->timeout_write))           \
 367                         event_add(&(bev)->ev_write, &(bev)->timeout_write); \
 368         } while (/*CONSTCOND*/0)
 369 #define BEV_DEL_GENERIC_READ_TIMEOUT(bev)       \
 370                 event_del(&(bev)->ev_read)
 371 #define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev)      \
 372                 event_del(&(bev)->ev_write)
 373
 374
 375 /** Internal: Given a bufferevent, return its corresponding
 376  * bufferevent_private. */
 377 #define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev)
 378
 379 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
 380 #define BEV_LOCK(b) _EVUTIL_NIL_STMT
 381 #define BEV_UNLOCK(b) _EVUTIL_NIL_STMT
 382 #else
 383 /** Internal: Grab the lock (if any) on a bufferevent */
 384 #define BEV_LOCK(b) do {                                                \
 385                 struct bufferevent_private *locking =  BEV_UPCAST(b);   \
 386                 EVLOCK_LOCK(locking->lock, 0);                          \
 387         } while (/*CONSTCOND*/0)
 388
 389 /** Internal: Release the lock (if any) on a bufferevent */
 390 #define BEV_UNLOCK(b) do {                                              \
 391                 struct bufferevent_private *locking =  BEV_UPCAST(b);   \
 392                 EVLOCK_UNLOCK(locking->lock, 0);                        \
 393         } while (/*CONSTCOND*/0)
 394 #endif
 395
 396
 397 /* ==== For rate-limiting. */
 398
 399 int _bufferevent_decrement_write_buckets(struct bufferevent_private *bev,
 400     ev_ssize_t bytes);
 401 int _bufferevent_decrement_read_buckets(struct bufferevent_private *bev,
 402     ev_ssize_t bytes);
 403 ev_ssize_t _bufferevent_get_read_max(struct bufferevent_private *bev);
 404 ev_ssize_t _bufferevent_get_write_max(struct bufferevent_private *bev);
 405
 406 #ifdef __cplusplus
 407 }
 408 #endif
 409
 410
 411 #endif /* _BUFFEREVENT_INTERNAL_H_ */