release/src/router/libevent/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"
  39
  40 /* These flags are reasons that we might be declining to actually enable
  41    reading or writing on a bufferevent.
  42  */
  43
  44 /* On a all bufferevents, for reading: used when we have read up to the
  45    watermark value.
  46
  47    On a filtering bufferevent, for writing: used when the underlying
  48    bufferevent's write buffer has been filled up to its watermark
  49    value.
  50 */
  51 #define BEV_SUSPEND_WM 0x01
  52 /* On a base bufferevent: when we have emptied a bandwidth buckets */
  53 #define BEV_SUSPEND_BW 0x02
  54 /* On a base bufferevent: when we have emptied the group's bandwidth bucket. */
  55 #define BEV_SUSPEND_BW_GROUP 0x04
  56 /* On a socket bufferevent: can't do any operations while we're waiting for
  57  * name lookup to finish. */
  58 #define BEV_SUSPEND_LOOKUP 0x08
  59 /* On a base bufferevent, for reading: used when a filter has choked this
  60  * (underlying) bufferevent because it has stopped reading from it. */
  61 #define BEV_SUSPEND_FILT_READ 0x10
  62
  63 typedef ev_uint16_t bufferevent_suspend_flags;
  64
  65 struct bufferevent_rate_limit_group {
  66         /** List of all members in the group */
  67         TAILQ_HEAD(rlim_group_member_list, bufferevent_private) members;
  68         /** Current limits for the group. */
  69         struct ev_token_bucket rate_limit;
  70         struct ev_token_bucket_cfg rate_limit_cfg;
  71
  72         /** True iff we don't want to read from any member of the group.until
  73          * the token bucket refills.  */
  74         unsigned read_suspended : 1;
  75         /** True iff we don't want to write from any member of the group.until
  76          * the token bucket refills.  */
  77         unsigned write_suspended : 1;
  78         /** True iff we were unable to suspend one of the bufferevents in the
  79          * group for reading the last time we tried, and we should try
  80          * again. */
  81         unsigned pending_unsuspend_read : 1;
  82         /** True iff we were unable to suspend one of the bufferevents in the
  83          * group for writing the last time we tried, and we should try
  84          * again. */
  85         unsigned pending_unsuspend_write : 1;
  86
  87         /*@{*/
  88         /** Total number of bytes read or written in this group since last
  89          * reset. */
  90         ev_uint64_t total_read;
  91         ev_uint64_t total_written;
  92         /*@}*/
  93
  94         /** The number of bufferevents in the group. */
  95         int n_members;
  96
  97         /** The smallest number of bytes that any member of the group should
  98          * be limited to read or write at a time. */
  99         ev_ssize_t min_share;
 100         /** Timeout event that goes off once a tick, when the bucket is ready
 101          * to refill. */
 102         struct event master_refill_event;
 103         /** Lock to protect the members of this group.  This lock should nest
 104          * within every bufferevent lock: if you are holding this lock, do
 105          * not assume you can lock another bufferevent. */
 106         void *lock;
 107 };
 108
 109 /** Fields for rate-limiting a single bufferevent. */
 110 struct bufferevent_rate_limit {
 111         /* Linked-list elements for storing this bufferevent_private in a
 112          * group.
 113          *
 114          * Note that this field is supposed to be protected by the group
 115          * lock */
 116         TAILQ_ENTRY(bufferevent_private) next_in_group;
 117         /** The rate-limiting group for this bufferevent, or NULL if it is
 118          * only rate-limited on its own. */
 119         struct bufferevent_rate_limit_group *group;
 120
 121         /* This bufferevent's current limits. */
 122         struct ev_token_bucket limit;
 123         /* Pointer to the rate-limit configuration for this bufferevent.
 124          * Can be shared.  XXX reference-count this? */
 125         struct ev_token_bucket_cfg *cfg;
 126
 127         /* Timeout event used when one this bufferevent's buckets are
 128          * empty. */
 129         struct event refill_bucket_event;
 130 };
 131
 132 /** Parts of the bufferevent structure that are shared among all bufferevent
 133  * types, but not exposed in bufferevent_struct.h. */
 134 struct bufferevent_private {
 135         /** The underlying bufferevent structure. */
 136         struct bufferevent bev;
 137
 138         /** Evbuffer callback to enforce watermarks on input. */
 139         struct evbuffer_cb_entry *read_watermarks_cb;
 140
 141         /** If set, we should free the lock when we free the bufferevent. */
 142         unsigned own_lock : 1;
 143
 144         /** Flag: set if we have deferred callbacks and a read callback is
 145          * pending. */
 146         unsigned readcb_pending : 1;
 147         /** Flag: set if we have deferred callbacks and a write callback is
 148          * pending. */
 149         unsigned writecb_pending : 1;
 150         /** Flag: set if we are currently busy connecting. */
 151         unsigned connecting : 1;
 152         /** Flag: set if a connect failed prematurely; this is a hack for
 153          * getting around the bufferevent abstraction. */
 154         unsigned connection_refused : 1;
 155         /** Set to the events pending if we have deferred callbacks and
 156          * an events callback is pending. */
 157         short eventcb_pending;
 158
 159         /** If set, read is suspended until one or more conditions are over.
 160          * The actual value here is a bitfield of those conditions; see the
 161          * BEV_SUSPEND_* flags above. */
 162         bufferevent_suspend_flags read_suspended;
 163
 164         /** If set, writing is suspended until one or more conditions are over.
 165          * The actual value here is a bitfield of those conditions; see the
 166          * BEV_SUSPEND_* flags above. */
 167         bufferevent_suspend_flags write_suspended;
 168
 169         /** Set to the current socket errno if we have deferred callbacks and
 170          * an events callback is pending. */
 171         int errno_pending;
 172
 173         /** The DNS error code for bufferevent_socket_connect_hostname */
 174         int dns_error;
 175
 176         /** Used to implement deferred callbacks */
 177         struct deferred_cb deferred;
 178
 179         /** The options this bufferevent was constructed with */
 180         enum bufferevent_options options;
 181
 182         /** Current reference count for this bufferevent. */
 183         int refcnt;
 184
 185         /** Lock for this bufferevent.  Shared by the inbuf and the outbuf.
 186          * If NULL, locking is disabled. */
 187         void *lock;
 188
 189         /** Rate-limiting information for this bufferevent */
 190         struct bufferevent_rate_limit *rate_limiting;
 191 };
 192
 193 /** Possible operations for a control callback. */
 194 enum bufferevent_ctrl_op {
 195         BEV_CTRL_SET_FD,
 196         BEV_CTRL_GET_FD,
 197         BEV_CTRL_GET_UNDERLYING
 198 };
 199
 200 /** Possible data types for a control callback */
 201 union bufferevent_ctrl_data {
 202         void *ptr;
 203         evutil_socket_t fd;
 204 };
 205
 206 /**
 207    Implementation table for a bufferevent: holds function pointers and other
 208    information to make the various bufferevent types work.
 209 */
 210 struct bufferevent_ops {
 211         /** The name of the bufferevent's type. */
 212         const char *type;
 213         /** At what offset into the implementation type will we find a
 214             bufferevent structure?
 215
 216             Example: if the type is implemented as
 217             struct bufferevent_x {
 218                int extra_data;
 219                struct bufferevent bev;
 220             }
 221             then mem_offset should be offsetof(struct bufferevent_x, bev)
 222         */
 223         off_t mem_offset;
 224
 225         /** Enables one or more of EV_READ|EV_WRITE on a bufferevent.  Does
 226             not need to adjust the 'enabled' field.  Returns 0 on success, -1
 227             on failure.
 228          */
 229         int (*enable)(struct bufferevent *, short);
 230
 231         /** Disables one or more of EV_READ|EV_WRITE on a bufferevent.  Does
 232             not need to adjust the 'enabled' field.  Returns 0 on success, -1
 233             on failure.
 234          */
 235         int (*disable)(struct bufferevent *, short);
 236
 237         /** Free any storage and deallocate any extra data or structures used
 238             in this implementation.
 239          */
 240         void (*destruct)(struct bufferevent *);
 241
 242         /** Called when the timeouts on the bufferevent have changed.*/
 243         int (*adj_timeouts)(struct bufferevent *);
 244
 245         /** Called to flush data. */
 246         int (*flush)(struct bufferevent *, short, enum bufferevent_flush_mode);
 247
 248         /** Called to access miscellaneous fields. */
 249         int (*ctrl)(struct bufferevent *, enum bufferevent_ctrl_op, union bufferevent_ctrl_data *);
 250
 251 };
 252
 253 extern const struct bufferevent_ops bufferevent_ops_socket;
 254 extern const struct bufferevent_ops bufferevent_ops_filter;
 255 extern const struct bufferevent_ops bufferevent_ops_pair;
 256
 257 #define BEV_IS_SOCKET(bevp) ((bevp)->be_ops == &bufferevent_ops_socket)
 258 #define BEV_IS_FILTER(bevp) ((bevp)->be_ops == &bufferevent_ops_filter)
 259 #define BEV_IS_PAIR(bevp) ((bevp)->be_ops == &bufferevent_ops_pair)
 260
 261 #ifdef WIN32
 262 extern const struct bufferevent_ops bufferevent_ops_async;
 263 #define BEV_IS_ASYNC(bevp) ((bevp)->be_ops == &bufferevent_ops_async)
 264 #else
 265 #define BEV_IS_ASYNC(bevp) 0
 266 #endif
 267
 268 /** Initialize the shared parts of a bufferevent. */
 269 int bufferevent_init_common(struct bufferevent_private *, struct event_base *, const struct bufferevent_ops *, enum bufferevent_options options);
 270
 271 /** For internal use: temporarily stop all reads on bufev, until the conditions
 272  * in 'what' are over. */
 273 void bufferevent_suspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
 274 /** For internal use: clear the conditions 'what' on bufev, and re-enable
 275  * reading if there are no conditions left. */
 276 void bufferevent_unsuspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what);
 277
 278 /** For internal use: temporarily stop all writes on bufev, until the conditions
 279  * in 'what' are over. */
 280 void bufferevent_suspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
 281 /** For internal use: clear the conditions 'what' on bufev, and re-enable
 282  * writing if there are no conditions left. */
 283 void bufferevent_unsuspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what);
 284
 285 #define bufferevent_wm_suspend_read(b) \
 286         bufferevent_suspend_read((b), BEV_SUSPEND_WM)
 287 #define bufferevent_wm_unsuspend_read(b) \
 288         bufferevent_unsuspend_read((b), BEV_SUSPEND_WM)
 289
 290 /** Internal: Set up locking on a bufferevent.  If lock is set, use it.
 291  * Otherwise, use a new lock. */
 292 int bufferevent_enable_locking(struct bufferevent *bufev, void *lock);
 293 /** Internal: Increment the reference count on bufev. */
 294 void bufferevent_incref(struct bufferevent *bufev);
 295 /** Internal: Lock bufev and increase its reference count.
 296  * unlocking it otherwise. */
 297 void _bufferevent_incref_and_lock(struct bufferevent *bufev);
 298 /** Internal: Decrement the reference count on bufev.  Returns 1 if it freed
 299  * the bufferevent.*/
 300 int bufferevent_decref(struct bufferevent *bufev);
 301 /** Internal: Drop the reference count on bufev, freeing as necessary, and
 302  * unlocking it otherwise.  Returns 1 if it freed the bufferevent. */
 303 int _bufferevent_decref_and_unlock(struct bufferevent *bufev);
 304
 305 /** Internal: If callbacks are deferred and we have a read callback, schedule
 306  * a readcb.  Otherwise just run the readcb. */
 307 void _bufferevent_run_readcb(struct bufferevent *bufev);
 308 /** Internal: If callbacks are deferred and we have a write callback, schedule
 309  * a writecb.  Otherwise just run the writecb. */
 310 void _bufferevent_run_writecb(struct bufferevent *bufev);
 311 /** Internal: If callbacks are deferred and we have an eventcb, schedule
 312  * it to run with events "what".  Otherwise just run the eventcb. */
 313 void _bufferevent_run_eventcb(struct bufferevent *bufev, short what);
 314
 315 /** Internal: Add the event 'ev' with timeout tv, unless tv is set to 0, in
 316  * which case add ev with no timeout. */
 317 int _bufferevent_add_event(struct event *ev, const struct timeval *tv);
 318
 319 /* =========
 320  * These next functions implement timeouts for bufferevents that aren't doing
 321  * anything else with ev_read and ev_write, to handle timeouts.
 322  * ========= */
 323 /** Internal use: Set up the ev_read and ev_write callbacks so that
 324  * the other "generic_timeout" functions will work on it.  Call this from
 325  * the constructor function. */
 326 void _bufferevent_init_generic_timeout_cbs(struct bufferevent *bev);
 327 /** Internal use: Delete the ev_read and ev_write callbacks if they're pending.
 328  * Call this from the destructor function. */
 329 int _bufferevent_del_generic_timeout_cbs(struct bufferevent *bev);
 330 /** Internal use: Add or delete the generic timeout events as appropriate.
 331  * (If an event is enabled and a timeout is set, we add the event.  Otherwise
 332  * we delete it.)  Call this from anything that changes the timeout values,
 333  * that enabled EV_READ or EV_WRITE, or that disables EV_READ or EV_WRITE. */
 334 int _bufferevent_generic_adj_timeouts(struct bufferevent *bev);
 335
 336 /** Internal use: We have just successfully read data into an inbuf, so
 337  * reset the read timeout (if any). */
 338 #define BEV_RESET_GENERIC_READ_TIMEOUT(bev)                             \
 339         do {                                                            \
 340                 if (evutil_timerisset(&(bev)->timeout_read))            \
 341                         event_add(&(bev)->ev_read, &(bev)->timeout_read); \
 342         } while (0)
 343 /** Internal use: We have just successfully written data from an inbuf, so
 344  * reset the read timeout (if any). */
 345 #define BEV_RESET_GENERIC_WRITE_TIMEOUT(bev)                            \
 346         do {                                                            \
 347                 if (evutil_timerisset(&(bev)->timeout_write))           \
 348                         event_add(&(bev)->ev_write, &(bev)->timeout_write); \
 349         } while (0)
 350 #define BEV_DEL_GENERIC_READ_TIMEOUT(bev)       \
 351                 event_del(&(bev)->ev_read)
 352 #define BEV_DEL_GENERIC_WRITE_TIMEOUT(bev)      \
 353                 event_del(&(bev)->ev_write)
 354
 355
 356 /** Internal: Given a bufferevent, return its corresponding
 357  * bufferevent_private. */
 358 #define BEV_UPCAST(b) EVUTIL_UPCAST((b), struct bufferevent_private, bev)
 359
 360 #ifdef _EVENT_DISABLE_THREAD_SUPPORT
 361 #define BEV_LOCK(b) _EVUTIL_NIL_STMT
 362 #define BEV_UNLOCK(b) _EVUTIL_NIL_STMT
 363 #else
 364 /** Internal: Grab the lock (if any) on a bufferevent */
 365 #define BEV_LOCK(b) do {                                                \
 366                 struct bufferevent_private *locking =  BEV_UPCAST(b);   \
 367                 EVLOCK_LOCK(locking->lock, 0);                          \
 368         } while (0)
 369
 370 /** Internal: Release the lock (if any) on a bufferevent */
 371 #define BEV_UNLOCK(b) do {                                              \
 372                 struct bufferevent_private *locking =  BEV_UPCAST(b);   \
 373                 EVLOCK_UNLOCK(locking->lock, 0);                        \
 374         } while (0)
 375 #endif
 376
 377
 378 /* ==== For rate-limiting. */
 379
 380 int _bufferevent_decrement_write_buckets(struct bufferevent_private *bev,
 381     ev_ssize_t bytes);
 382 int _bufferevent_decrement_read_buckets(struct bufferevent_private *bev,
 383     ev_ssize_t bytes);
 384 ev_ssize_t _bufferevent_get_read_max(struct bufferevent_private *bev);
 385 ev_ssize_t _bufferevent_get_write_max(struct bufferevent_private *bev);
 386
 387 #ifdef __cplusplus
 388 }
 389 #endif
 390
 391
 392 #endif /* _BUFFEREVENT_INTERNAL_H_ */