src/main/connection.c

   1 /*
   2  *   This program is free software; you can redistribute it and/or modify
   3  *   it under the terms of the GNU General Public License as published by
   4  *   the Free Software Foundation; either version 2 of the License, or
   5  *   (at your option) any later version.
   6  *
   7  *   This program is distributed in the hope that it will be useful,
   8  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  *   GNU General Public License for more details.
  11  *
  12  *   You should have received a copy of the GNU General Public License
  13  *   along with this program; if not, write to the Free Software
  14  *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  15  */
  16
  17 /**
  18  * @file connection.c
  19  * @brief Handle pools of connections (threads, sockets, etc.)
  20  * @note This API must be used by all modules in the public distribution that
  21  * maintain pools of connections.
  22  *
  23  * @copyright 2012  The FreeRADIUS server project
  24  * @copyright 2012  Alan DeKok <aland@deployingradius.com>
  25  */
  26 RCSID("$Id$")
  27
  28 #include <freeradius-devel/radiusd.h>
  29
  30 #include <freeradius-devel/connection.h>
  31
  32 #include <freeradius-devel/rad_assert.h>
  33
  34 typedef struct fr_connection fr_connection_t;
  35
  36 static int fr_connection_pool_check(fr_connection_pool_t *pool);
  37
  38 /** An individual connection within the connection pool
  39  *
  40  * Defines connection counters, timestamps, and holds a pointer to the
  41  * connection handle itself.
  42  *
  43  * @see fr_connection_pool_t
  44  */
  45 struct fr_connection {
  46         fr_connection_t *prev;          //!< Previous connection in list.
  47         fr_connection_t *next;          //!< Next connection in list.
  48
  49         time_t          created;        //!< Time connection was created.
  50         time_t          last_used;      //!< Last time the connection was
  51                                         //!< reserved.
  52
  53         int             num_uses;       //!< Number of times the connection
  54                                         //!< has been reserved.
  55         int             in_use;         //!< Whether the connection is currently
  56                                         //!< reserved.
  57         int             number;         //!< Unique ID assigned when the
  58                                         //!< connection is created, these will
  59                                         //!< monotonically increase over the
  60                                         //!< lifetime of the connection pool.
  61         void            *connection;    //!< Pointer to whatever the module
  62                                         //!< uses for a connection handle.
  63 };
  64
  65 /** A connection pool
  66  *
  67  * Defines the configuration of the connection pool, all the counters and
  68  * timestamps related to the connection pool, the mutex that stops multiple
  69  * threads leaving the pool in an inconsistent state, and the callbacks
  70  * required to open, close and check the status of connections within the pool.
  71  *
  72  * @see fr_connection
  73  */
  74 struct fr_connection_pool_t {
  75         int             start;          //!< Number of initial connections
  76         int             min;            //!< Minimum number of concurrent
  77                                         //!< connections to keep open.
  78         int             max;            //!< Maximum number of concurrent
  79                                         //!< connections to allow.
  80         int             spare;          //!< Number of spare connections to try
  81                                         //!< and maintain.
  82         int             cleanup_delay;  //!< How long a connection can go unused
  83                                         //!< for before it's closed
  84                                         //!< (0 is infinite).
  85         int             max_uses;       //!< Maximum number of times a
  86                                         //!< connection can be used before being
  87                                         //!< closed.
  88         int             lifetime;       //!< How long a connection can be open
  89                                         //!< before being closed (irrespective
  90                                         //!< of whether it's idle or not).
  91         int             idle_timeout;   //!< How long a connection can be idle
  92                                         //!< before being closed.
  93
  94         int             trigger;        //!< If true execute connection triggers
  95                                         //!< associated with the connection
  96                                         //!< pool.
  97
  98         int             spread;         //!< If true requests will be spread
  99                                         //!< across all connections, instead of
 100                                         //!< re-using the most recently used
 101                                         //!< connections first.
 102
 103         time_t          last_checked;   //!< Last time we pruned the connection
 104                                         //!< pool.
 105         time_t          last_spawned;   //!< Last time we spawned a connection.
 106         time_t          last_failed;    //!< Last time we tried to spawn a
 107                                         //!< a connection but failed.
 108         time_t          last_complained;//!< Last time we complained about
 109                                         //!< configuration parameters.
 110         time_t          last_throttled; //!< Last time we refused to spawn a
 111                                         //!< connection because the last
 112                                         //!< connection failed, or we were
 113                                         //!< already spawning a connection.
 114         time_t          last_at_max;    //!< Last time we hit the maximum number
 115                                         //!< of allowed connections.
 116
 117         unsigned int    count;          //!< Number of connections spawned over
 118                                         //!< the lifetime of the pool.
 119         int             num;            //!< Number of connections in the pool.
 120         int             active;         //!< Number of currently reserved
 121                                         //!< connections.
 122
 123         fr_connection_t *head;          //!< Start of the connection list.
 124         fr_connection_t *tail;          //!< End of the connection list.
 125
 126         int             spawning;       //!< Whether we are currently attempting
 127                                         //!< to spawn a new connection.
 128
 129 #ifdef HAVE_PTHREAD_H
 130         pthread_mutex_t mutex;          //!< Mutex used to keep consistent state
 131                                         //!< when making modifications in
 132                                         //!< threaded mode.
 133 #endif
 134
 135         CONF_SECTION    *cs;            //!< Configuration section holding
 136                                         //!< the section of parsed config file
 137                                         //!< that relates to this pool.
 138         void            *ctx;           //!< Pointer to context data that will
 139                                         //!< be passed to callbacks.
 140
 141         char            *log_prefix;    //!< Log prefix to prepend to all log
 142                                         //!< messages created by the connection
 143                                         //!< pool code.
 144
 145         fr_connection_create_t  create; //!< Function used to create new
 146                                         //!< connections.
 147         fr_connection_alive_t   alive;  //!< Function used to check status
 148                                         //!< of connections.
 149         fr_connection_delete_t  delete; //!< Function used to close existing
 150                                         //!< connections.
 151 };
 152
 153 #define LOG_PREFIX "rlm_%s (%s)"
 154 #ifndef HAVE_PTHREAD_H
 155 #define pthread_mutex_lock(_x)
 156 #define pthread_mutex_unlock(_x)
 157 #endif
 158
 159 static const CONF_PARSER connection_config[] = {
 160         { "start",    PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, start),
 161           0, "5" },
 162         { "min",      PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, min),
 163           0, "5" },
 164         { "max",      PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, max),
 165           0, "10" },
 166         { "spare",    PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, spare),
 167           0, "3" },
 168         { "uses",     PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, max_uses),
 169           0, "0" },
 170         { "lifetime", PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, lifetime),
 171           0, "0" },
 172         { "cleanup_delay", PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, cleanup_delay),
 173           0, "5" },
 174         { "idle_timeout",  PW_TYPE_INTEGER, offsetof(fr_connection_pool_t, idle_timeout),
 175           0, "60" },
 176         { "spread", PW_TYPE_BOOLEAN, offsetof(fr_connection_pool_t, spread),
 177           0, "no" },
 178         { NULL, -1, 0, NULL, NULL }
 179 };
 180
 181 /** Removes a connection from the connection list
 182  *
 183  * @note Must be called with the mutex held.
 184  *
 185  * @param[in,out] pool to modify.
 186  * @param[in] this Connection to delete.
 187  */
 188 static void fr_connection_unlink(fr_connection_pool_t *pool,
 189                                  fr_connection_t *this)
 190 {
 191         if (this->prev) {
 192                 rad_assert(pool->head != this);
 193                 this->prev->next = this->next;
 194         } else {
 195                 rad_assert(pool->head == this);
 196                 pool->head = this->next;
 197         }
 198         if (this->next) {
 199                 rad_assert(pool->tail != this);
 200                 this->next->prev = this->prev;
 201         } else {
 202                 rad_assert(pool->tail == this);
 203                 pool->tail = this->prev;
 204         }
 205
 206         this->prev = this->next = NULL;
 207 }
 208
 209 /** Adds a connection to the head of the connection list
 210  *
 211  * @note Must be called with the mutex held.
 212  *
 213  * @param[in,out] pool to modify.
 214  * @param[in] this Connection to add.
 215  */
 216 static void fr_connection_link_head(fr_connection_pool_t *pool,
 217                                     fr_connection_t *this)
 218 {
 219         rad_assert(pool != NULL);
 220         rad_assert(this != NULL);
 221         rad_assert(pool->head != this);
 222         rad_assert(pool->tail != this);
 223
 224         if (pool->head) {
 225                 pool->head->prev = this;
 226         }
 227
 228         this->next = pool->head;
 229         this->prev = NULL;
 230         pool->head = this;
 231         if (!pool->tail) {
 232                 rad_assert(this->next == NULL);
 233                 pool->tail = this;
 234         } else {
 235                 rad_assert(this->next != NULL);
 236         }
 237 }
 238
 239 /** Adds a connection to the tail of the connection list
 240  *
 241  * @note Must be called with the mutex held.
 242  *
 243  * @param[in,out] pool to modify.
 244  * @param[in] this Connection to add.
 245  */
 246 static void fr_connection_link_tail(fr_connection_pool_t *pool,
 247                                     fr_connection_t *this)
 248 {
 249         rad_assert(pool != NULL);
 250         rad_assert(this != NULL);
 251         rad_assert(pool->head != this);
 252         rad_assert(pool->tail != this);
 253
 254         if (pool->tail) {
 255                 pool->tail->next = this;
 256         }
 257         this->prev = pool->tail;
 258         this->next = NULL;
 259         pool->tail = this;
 260         if (!pool->head) {
 261                 rad_assert(this->prev == NULL);
 262                 pool->head = this;
 263         } else {
 264                 rad_assert(this->prev != NULL);
 265         }
 266 }
 267
 268
 269 /** Spawns a new connection
 270  *
 271  * Spawns a new connection using the create callback, and returns it for
 272  * adding to the connection list.
 273  *
 274  * @note Will call the 'open' trigger.
 275  * @note Must be called with the mutex free.
 276  *
 277  * @param[in] pool to modify.
 278  * @param[in] now Current time.
 279  * @return the new connection struct or NULL on error.
 280  */
 281 static fr_connection_t *fr_connection_spawn(fr_connection_pool_t *pool,
 282                                             time_t now)
 283 {
 284         fr_connection_t *this;
 285         void *conn;
 286
 287         rad_assert(pool != NULL);
 288
 289         /*
 290          *      Prevent all threads from blocking if the resource
 291          *      were managing connections for appears to be unavailable.
 292          */
 293         if ((pool->num == 0) && pool->spawning) {
 294                 return NULL;
 295         }
 296
 297         pthread_mutex_lock(&pool->mutex);
 298         rad_assert(pool->num <= pool->max);
 299
 300         if ((pool->last_failed == now) || pool->spawning) {
 301                 int complain = false;
 302
 303                 if (pool->last_throttled != now) {
 304                         complain = true;
 305
 306                         pool->last_throttled = now;
 307                 }
 308
 309                 pthread_mutex_unlock(&pool->mutex);
 310
 311                 if (complain) {
 312                         if (pool->spawning) {
 313                                 ERROR("%s: Cannot open new connection, "
 314                                        "connection spawning already in "
 315                                        "progress", pool->log_prefix);
 316                         } else {
 317                                 ERROR("%s: Last connection failed, "
 318                                        "throttling connection spawn",
 319                                        pool->log_prefix);
 320                         }
 321                 }
 322
 323                 return NULL;
 324         }
 325
 326         pool->spawning = true;
 327
 328         /*
 329          *      Unlock the mutex while we try to open a new
 330          *      connection.  If there are issues with the back-end,
 331          *      opening a new connection may take a LONG time.  In
 332          *      that case, we want the other connections to continue
 333          *      to be used.
 334          */
 335         pthread_mutex_unlock(&pool->mutex);
 336
 337         INFO("%s: Opening additional connection (%i)",
 338                pool->log_prefix, pool->count);
 339
 340         this = rad_malloc(sizeof(*this));
 341         memset(this, 0, sizeof(*this));
 342
 343         /*
 344          *      This may take a long time, which prevents other
 345          *      threads from releasing connections.  We don't care
 346          *      about other threads opening new connections, as we
 347          *      already have no free connections.
 348          */
 349         conn = pool->create(pool->ctx);
 350         if (!conn) {
 351                 ERROR("%s: Opening connection failed (%i)",
 352                        pool->log_prefix, pool->count);
 353
 354                 pool->last_failed = now;
 355                 free(this);
 356                 pool->spawning = false; /* atomic, so no lock is needed */
 357                 return NULL;
 358         }
 359
 360         this->created = now;
 361         this->connection = conn;
 362
 363         /*
 364          *      And lock the mutex again while we link the new
 365          *      connection back into the pool.
 366          */
 367         pthread_mutex_lock(&pool->mutex);
 368
 369         this->number = pool->count++;
 370         this->last_used = now;
 371         fr_connection_link_head(pool, this);
 372         pool->num++;
 373         pool->spawning = false;
 374         pool->last_spawned = time(NULL);
 375
 376         pthread_mutex_unlock(&pool->mutex);
 377
 378         if (pool->trigger) exec_trigger(NULL, pool->cs, "open", true);
 379
 380         return this;
 381 }
 382
 383 /** Add a new connection to the pool
 384  *
 385  * If conn is not NULL will attempt to add that connection handle to the pool.
 386  * If conn is NULL will attempt to spawn a new connection using the create
 387  * callback.
 388  *
 389  * @note Will call the 'open' trigger.
 390  *
 391  * @param[in,out] pool to add connection to.
 392  * @param[in] conn to add.
 393  * @return 0 if the connection wasn't added else 1.
 394  */
 395 int fr_connection_add(fr_connection_pool_t *pool, void *conn)
 396 {
 397         fr_connection_t *this;
 398
 399         if (!pool) return 0;
 400
 401         pthread_mutex_lock(&pool->mutex);
 402
 403         if (!conn) {
 404                 conn = pool->create(pool->ctx);
 405                 if (!conn) {
 406                         pthread_mutex_unlock(&pool->mutex);
 407                         return 0;
 408                 }
 409
 410                 INFO("%s: Opening connection successful (%i)",
 411                        pool->log_prefix, pool->count);
 412         }
 413
 414         /*
 415          *      Too many connections: can't add it.
 416          */
 417         if (pool->num >= pool->max) {
 418                 pthread_mutex_unlock(&pool->mutex);
 419                 return 0;
 420         }
 421
 422         this = rad_malloc(sizeof(*this));
 423         memset(this, 0, sizeof(*this));
 424
 425         this->created = time(NULL);
 426         this->connection = conn;
 427
 428         this->number = pool->count++;
 429         this->last_used = time(NULL);
 430         fr_connection_link_head(pool, this);
 431         pool->num++;
 432
 433         pthread_mutex_unlock(&pool->mutex);
 434
 435         if (pool->trigger) exec_trigger(NULL, pool->cs, "open", true);
 436
 437         return 1;
 438 }
 439
 440 /** Close an existing connection.
 441  *
 442  * Removes the connection from the list, calls the delete callback to close
 443  * the connection, then frees memory allocated to the connection.
 444  *
 445  * @note Will call the 'close' trigger.
 446  * @note Must be called with the mutex held.
 447  *
 448  * @param[in,out] pool to modify.
 449  * @param[in,out] this Connection to delete.
 450
 451  */
 452 static void fr_connection_close(fr_connection_pool_t *pool,
 453                                 fr_connection_t *this)
 454 {
 455         if (pool->trigger) exec_trigger(NULL, pool->cs, "close", true);
 456
 457         rad_assert(this->in_use == false);
 458
 459         fr_connection_unlink(pool, this);
 460         pool->delete(pool->ctx, this->connection);
 461         rad_assert(pool->num > 0);
 462         pool->num--;
 463         free(this);
 464 }
 465
 466 /** Find a connection handle in the connection list
 467  *
 468  * Walks over the list of connections searching for a specified connection
 469  * handle and returns the first connection that contains that pointer.
 470  *
 471  * @note Will lock mutex and only release mutex if connection handle
 472  * is not found, so will usually return will mutex held.
 473  * @note Must be called with the mutex free.
 474  *
 475  * @param[in] pool to search in.
 476  * @param[in] conn handle to search for.
 477  * @return the connection containing the specified handle, or NULL if non is
 478  * found.
 479  */
 480 static fr_connection_t *fr_connection_find(fr_connection_pool_t *pool, void *conn)
 481 {
 482         fr_connection_t *this;
 483
 484         if (!pool || !conn) return NULL;
 485
 486         pthread_mutex_lock(&pool->mutex);
 487
 488         /*
 489          *      FIXME: This loop could be avoided if we passed a 'void
 490          *      **connection' instead.  We could use "offsetof" in
 491          *      order to find top of the parent structure.
 492          */
 493         for (this = pool->head; this != NULL; this = this->next) {
 494                 if (this->connection == conn) return this;
 495         }
 496
 497         pthread_mutex_unlock(&pool->mutex);
 498         return NULL;
 499 }
 500
 501 /** Delete a connection from the connection pool.
 502  *
 503  * Resolves the connection handle to a connection, then (if found)
 504  * closes, unlinks and frees that connection.
 505  *
 506  * @note Must be called with the mutex free.
 507  *
 508  * @param[in,out] pool Connection pool to modify.
 509  * @param[in] conn to delete.
 510  * @return 0 if the connection could not be found, else 1.
 511  */
 512 int fr_connection_del(fr_connection_pool_t *pool, void *conn)
 513 {
 514         fr_connection_t *this;
 515
 516         this = fr_connection_find(pool, conn);
 517         if (!this) return 0;
 518
 519         /*
 520          *      If it's in use, release it.
 521          */
 522         if (this->in_use) {
 523                 rad_assert(this->in_use == true);
 524                 this->in_use = false;
 525
 526                 rad_assert(pool->active > 0);
 527                 pool->active--;
 528         }
 529
 530         INFO("%s: Deleting connection (%i)", pool->log_prefix,
 531                this->number);
 532
 533         fr_connection_close(pool, this);
 534         fr_connection_pool_check(pool);
 535         return 1;
 536 }
 537
 538 /** Delete a connection pool
 539  *
 540  * Closes, unlinks and frees all connections in the connection pool, then frees
 541  * all memory used by the connection pool.
 542  *
 543  * @note Will call the 'stop' trigger.
 544  * @note Must be called with the mutex free.
 545  *
 546  * @param[in,out] pool to delete.
 547  */
 548 void fr_connection_pool_delete(fr_connection_pool_t *pool)
 549 {
 550         fr_connection_t *this, *next;
 551
 552         if (!pool) return;
 553
 554         DEBUG("%s: Removing connection pool", pool->log_prefix);
 555
 556         pthread_mutex_lock(&pool->mutex);
 557
 558         for (this = pool->head; this != NULL; this = next) {
 559                 next = this->next;
 560
 561                 INFO("%s: Closing connection (%i)", pool->log_prefix,
 562                        this->number);
 563
 564                 fr_connection_close(pool, this);
 565         }
 566
 567         if (pool->trigger) exec_trigger(NULL, pool->cs, "stop", true);
 568
 569         rad_assert(pool->head == NULL);
 570         rad_assert(pool->tail == NULL);
 571         rad_assert(pool->num == 0);
 572
 573         free(pool->log_prefix);
 574         free(pool);
 575 }
 576
 577 /** Create a new connection pool
 578  *
 579  * Allocates structures used by the connection pool, initialises the various
 580  * configuration options and counters, and sets the callback functions.
 581  *
 582  * Will also spawn the number of connections specified by the 'start'
 583  * configuration options.
 584  *
 585  * @note Will call the 'start' trigger.
 586  *
 587  * @param[in] parent configuration section containing a 'pool' subsection.
 588  * @param[in] ctx pointer to pass to callbacks.
 589  * @param[in] c Callback to create new connections.
 590  * @param[in] a Callback to check the status of connections.
 591  * @param[in] d Callback to delete connections.
 592  * @param[in] prefix to prepend to all log message, if NULL will create prefix
 593  *      from parent conf section names.
 594  * @return A new connection pool or NULL on error.
 595  */
 596 fr_connection_pool_t *fr_connection_pool_init(CONF_SECTION *parent,
 597                                               void *ctx,
 598                                               fr_connection_create_t c,
 599                                               fr_connection_alive_t a,
 600                                               fr_connection_delete_t d,
 601                                               char *prefix)
 602 {
 603         int i, lp_len;
 604         fr_connection_pool_t *pool;
 605         fr_connection_t *this;
 606         CONF_SECTION *modules;
 607         CONF_SECTION *cs;
 608         char const *cs_name1, *cs_name2;
 609         time_t now = time(NULL);
 610
 611         if (!parent || !ctx || !c || !d) return NULL;
 612
 613         cs = cf_section_sub_find(parent, "pool");
 614         if (!cs) cs = cf_section_sub_find(parent, "limit");
 615
 616         pool = rad_malloc(sizeof(*pool));
 617         memset(pool, 0, sizeof(*pool));
 618
 619         pool->cs = cs;
 620         pool->ctx = ctx;
 621         pool->create = c;
 622         pool->alive = a;
 623         pool->delete = d;
 624
 625         pool->head = pool->tail = NULL;
 626
 627 #ifdef HAVE_PTHREAD_H
 628         pthread_mutex_init(&pool->mutex, NULL);
 629 #endif
 630
 631         if (!prefix) {
 632                 modules = cf_item_parent(cf_sectiontoitem(parent));
 633                 if (modules) {
 634                         cs_name1 = cf_section_name1(modules);
 635                         if (cs_name1 && (strcmp(cs_name1, "modules") == 0)) {
 636                                 cs_name1 = cf_section_name1(parent);
 637                                 cs_name2 = cf_section_name2(parent);
 638                                 if (!cs_name2) {
 639                                         cs_name2 = cs_name1;
 640                                 }
 641
 642                                 lp_len = (sizeof(LOG_PREFIX) - 4) + strlen(cs_name1) + strlen(cs_name2);
 643                                 pool->log_prefix = rad_malloc(lp_len);
 644                                 snprintf(pool->log_prefix, lp_len, LOG_PREFIX, cs_name1,
 645                                          cs_name2);
 646                         }
 647                 } else {                /* not a module configuration */
 648                         cs_name1 = cf_section_name1(parent);
 649
 650                         pool->log_prefix = strdup(cs_name1);
 651                 }
 652         } else {
 653                 pool->log_prefix = strdup(prefix);
 654         }
 655
 656         DEBUG("%s: Initialising connection pool", pool->log_prefix);
 657
 658         if (cs) {
 659                 if (cf_section_parse(cs, pool, connection_config) < 0) {
 660                         goto error;
 661                 }
 662
 663                 if (cf_section_sub_find(cs, "trigger")) pool->trigger = true;
 664         } else {
 665                 pool->start = 5;
 666                 pool->min = 5;
 667                 pool->max = 10;
 668                 pool->spare = 3;
 669                 pool->cleanup_delay = 5;
 670                 pool->idle_timeout = 60;
 671         }
 672
 673         /*
 674          *      Some simple limits
 675          */
 676         if (pool->max > 1024) pool->max = 1024;
 677         if (pool->start > pool->max) pool->start = pool->max;
 678         if (pool->spare > (pool->max - pool->min)) {
 679                 pool->spare = pool->max - pool->min;
 680         }
 681         if ((pool->lifetime > 0) && (pool->idle_timeout > pool->lifetime)) {
 682                 pool->idle_timeout = 0;
 683         }
 684
 685         /*
 686          *      Create all of the connections, unless the admin says
 687          *      not to.
 688          */
 689         for (i = 0; i < pool->start; i++) {
 690                 this = fr_connection_spawn(pool, now);
 691                 if (!this) {
 692                 error:
 693                         fr_connection_pool_delete(pool);
 694                         return NULL;
 695                 }
 696         }
 697
 698         if (pool->trigger) exec_trigger(NULL, pool->cs, "start", true);
 699
 700         return pool;
 701 }
 702
 703
 704 /** Check whether a connection needs to be removed from the pool
 705  *
 706  * Will verify that the connection is within idle_timeout, max_uses, and
 707  * lifetime values. If it is not, the connection will be closed.
 708  *
 709  * @note Will only close connections not in use.
 710  * @note Must be called with the mutex held.
 711  *
 712  * @param[in,out] pool to modify.
 713  * @param[in,out] this Connection to manage.
 714  * @param[in] now Current time.
 715  * @return 0 if the connection was closed, otherwise 1.
 716  */
 717 static int fr_connection_manage(fr_connection_pool_t *pool,
 718                                 fr_connection_t *this,
 719                                 time_t now)
 720 {
 721         rad_assert(pool != NULL);
 722         rad_assert(this != NULL);
 723
 724         /*
 725          *      Don't terminated in-use connections
 726          */
 727         if (this->in_use) return 1;
 728
 729         if ((pool->max_uses > 0) &&
 730             (this->num_uses >= pool->max_uses)) {
 731                 DEBUG("%s: Closing expired connection (%i): Hit max_uses limit",
 732                       pool->log_prefix, this->number);
 733         do_delete:
 734                 if ((pool->num <= pool->min) &&
 735                     (pool->last_complained < now)) {
 736                         WARN("%s: You probably need to lower \"min\"", pool->log_prefix);
 737
 738                         pool->last_complained = now;
 739                 }
 740                 fr_connection_close(pool, this);
 741                 return 0;
 742         }
 743
 744         if ((pool->lifetime > 0) &&
 745             ((this->created + pool->lifetime) < now)) {
 746                 DEBUG("%s: Closing expired connection (%i) ", pool->log_prefix,
 747                       this->number);
 748                 goto do_delete;
 749         }
 750
 751         if ((pool->idle_timeout > 0) &&
 752             ((this->last_used + pool->idle_timeout) < now)) {
 753                 INFO("%s: Closing connection (%i): Hit idle_timeout, "
 754                        "was idle for %u seconds", pool->log_prefix, this->number,
 755                        (int) (now - this->last_used));
 756                 goto do_delete;
 757         }
 758
 759         return 1;
 760 }
 761
 762
 763 /** Check whether any connections needs to be removed from the pool
 764  *
 765  * Maintains the number of connections in the pool as per the configuration
 766  * parameters for the connection pool.
 767  *
 768  * @note Will only run checks the first time it's called in a given second,
 769  * to throttle connection spawning/closing.
 770  * @note Will only close connections not in use.
 771  * @note Must be called with the mutex held, will release mutex before
 772  * returning.
 773  *
 774  * @param[in,out] pool to manage.
 775  * @return 1
 776  */
 777 static int fr_connection_pool_check(fr_connection_pool_t *pool)
 778 {
 779         int spare, spawn;
 780         time_t now = time(NULL);
 781         fr_connection_t *this, *next;
 782
 783         if (pool->last_checked == now) {
 784                 pthread_mutex_unlock(&pool->mutex);
 785                 return 1;
 786         }
 787
 788         spare = pool->num - pool->active;
 789
 790         spawn = 0;
 791         if ((pool->num < pool->max) && (spare < pool->spare)) {
 792                 spawn = pool->spare - spare;
 793                 if ((spawn + pool->num) > pool->max) {
 794                         spawn = pool->max - pool->num;
 795                 }
 796                 if (pool->spawning) spawn = 0;
 797
 798                 if (spawn) {
 799                         pthread_mutex_unlock(&pool->mutex);
 800                         fr_connection_spawn(pool, now); /* ignore return code */
 801                         pthread_mutex_lock(&pool->mutex);
 802                 }
 803         }
 804
 805         /*
 806          *      We haven't spawned connections in a while, and there
 807          *      are too many spare ones.  Close the one which has been
 808          *      idle for the longest.
 809          */
 810         if ((now >= (pool->last_spawned + pool->cleanup_delay)) &&
 811             (spare > pool->spare)) {
 812                 fr_connection_t *idle;
 813
 814                 idle = NULL;
 815                 for (this = pool->tail; this != NULL; this = this->prev) {
 816                         if (this->in_use) continue;
 817
 818                         if (!idle ||
 819                            (this->last_used < idle->last_used)) {
 820                                 idle = this;
 821                         }
 822                 }
 823
 824                 rad_assert(idle != NULL);
 825
 826                 INFO("%s: Closing connection (%i): Too many "
 827                        "free connections (%d > %d)", pool->log_prefix,
 828                        idle->number, spare, pool->spare);
 829                 fr_connection_close(pool, idle);
 830         }
 831
 832         /*
 833          *      Pass over all of the connections in the pool, limiting
 834          *      lifetime, idle time, max requests, etc.
 835          */
 836         for (this = pool->head; this != NULL; this = next) {
 837                 next = this->next;
 838                 fr_connection_manage(pool, this, now);
 839         }
 840
 841         pool->last_checked = now;
 842         pthread_mutex_unlock(&pool->mutex);
 843
 844         return 1;
 845 }
 846
 847 /** Trigger connection check for a given connection or all connections
 848  *
 849  * If conn is not NULL then we call fr_connection_manage on the connection.
 850  * If conn is NULL we call fr_connection_pool_check on the pool.
 851  *
 852  * @note Only connections that are not in use will be closed.
 853  *
 854  * @see fr_connection_manage
 855  * @see fr_connection_pool_check
 856  * @param[in,out] pool to manage.
 857  * @param[in,out] conn to check.
 858  * @return 0 if the connection was closed, else 1.
 859  */
 860 int fr_connection_check(fr_connection_pool_t *pool, void *conn)
 861 {
 862         fr_connection_t *this;
 863         time_t now;
 864         int ret = 1;
 865
 866         if (!pool) return 1;
 867
 868         now = time(NULL);
 869         pthread_mutex_lock(&pool->mutex);
 870
 871         if (!conn) return fr_connection_pool_check(pool);
 872
 873         for (this = pool->head; this != NULL; this = this->next) {
 874                 if (this->connection == conn) {
 875                         ret = fr_connection_manage(pool, conn, now);
 876                         break;
 877                 }
 878         }
 879
 880         pthread_mutex_unlock(&pool->mutex);
 881
 882         return ret;
 883 }
 884
 885 /** Reserve a connection in the connection pool
 886  *
 887  * Will attempt to find an unused connection in the connection pool, if one is
 888  * found, will mark it as in in use increment the number of active connections
 889  * and return the connection handle.
 890  *
 891  * If no free connections are found will attempt to spawn a new one, conditional
 892  * on a connection spawning not already being in progress, and not being at the
 893  * 'max' connection limit.
 894  *
 895  * @note fr_connection_release must be called once the caller has finished
 896  * using the connection.
 897  *
 898  * @see fr_connection_release
 899  * @param[in,out] pool to reserve the connection from.
 900  * @return a pointer to the connection handle, or NULL on error.
 901  */
 902 void *fr_connection_get(fr_connection_pool_t *pool)
 903 {
 904         time_t now;
 905         fr_connection_t *this, *next;
 906
 907         if (!pool) return NULL;
 908
 909         pthread_mutex_lock(&pool->mutex);
 910
 911         now = time(NULL);
 912         for (this = pool->head; this != NULL; this = next) {
 913                 next = this->next;
 914
 915                 if (!this->in_use) goto do_return;
 916         }
 917
 918         if (pool->num == pool->max) {
 919                 int complain = false;
 920
 921                 /*
 922                  *      Rate-limit complaints.
 923                  */
 924                 if (pool->last_at_max != now) {
 925                         complain = true;
 926                         pool->last_at_max = now;
 927                 }
 928
 929                 pthread_mutex_unlock(&pool->mutex);
 930
 931                 if (complain) {
 932                         ERROR("%s: No connections available and at max "
 933                                "connection limit", pool->log_prefix);
 934                 }
 935
 936                 return NULL;
 937         }
 938
 939         pthread_mutex_unlock(&pool->mutex);
 940         this = fr_connection_spawn(pool, now);
 941         if (!this) return NULL;
 942         pthread_mutex_lock(&pool->mutex);
 943
 944 do_return:
 945         pool->active++;
 946         this->num_uses++;
 947         this->last_used = now;
 948         this->in_use = true;
 949
 950         pthread_mutex_unlock(&pool->mutex);
 951
 952         DEBUG("%s: Reserved connection (%i)", pool->log_prefix, this->number);
 953
 954         return this->connection;
 955 }
 956
 957 /** Release a connection
 958  *
 959  * Will mark a connection as unused and decrement the number of active
 960  * connections.
 961  *
 962  * @see fr_connection_get
 963  * @param[in,out] pool to release the connection in.
 964  * @param[in,out] conn to release.
 965  */
 966 void fr_connection_release(fr_connection_pool_t *pool, void *conn)
 967 {
 968         fr_connection_t *this;
 969
 970         this = fr_connection_find(pool, conn);
 971         if (!this) return;
 972
 973         rad_assert(this->in_use == true);
 974         this->in_use = false;
 975
 976         /*
 977          *      Determines whether the last used connection gets
 978          *      re-used first.
 979          */
 980         if (pool->spread) {
 981                 /*
 982                  *      Put it at the tail of the list, so
 983                  *      that it will get re-used last.
 984                  */
 985                 if (this != pool->tail) {
 986                         fr_connection_unlink(pool, this);
 987                         fr_connection_link_tail(pool, this);
 988                 }
 989         } else {
 990                 /*
 991                  *      Put it at the head of the list, so
 992                  *      that it will get re-used quickly.
 993                  */
 994                 if (this != pool->head) {
 995                         fr_connection_unlink(pool, this);
 996                         fr_connection_link_head(pool, this);
 997                 }
 998         }
 999
1000         rad_assert(pool->active > 0);
1001         pool->active--;
1002
1003         DEBUG("%s: Released connection (%i)", pool->log_prefix, this->number);
1004
1005         /*
1006          *      We mirror the "spawn on get" functionality by having
1007          *      "delete on release".  If there are too many spare
1008          *      connections, go manage the pool && clean some up.
1009          */
1010         fr_connection_pool_check(pool);
1011 }
1012
1013 /** Reconnect a suspected inviable connection
1014  *
1015  * This should be called by the module if it suspects that a connection is
1016  * not viable (e.g. the server has closed it).
1017  *
1018  * Will attempt to create a new connection handle using the create callback,
1019  * and if this is successful the new handle will be assigned to the existing
1020  * pool connection.
1021  *
1022  * If this is not successful, the connection will be removed from the pool.
1023  *
1024  * When implementing a module that uses the connection pool API, it is advisable
1025  * to pass a pointer to the pointer to the handle (void **conn)
1026  * to all functions which may call reconnect. This is so that if a new handle
1027  * is created and returned, the handle pointer can be updated up the callstack,
1028  * and a function higher up the stack doesn't attempt to use a now invalid
1029  * connection handle.
1030  *
1031  * @warning After calling reconnect the caller *MUST NOT* attempt to use
1032  * the old handle in any other operations, as its memory will have been freed.
1033  *
1034  * @see fr_connection_get
1035  * @param[in,out] pool to reconnect the connection in.
1036  * @param[in,out] conn to reconnect.
1037  * @return ew connection handle if successful else NULL.
1038  */
1039 void *fr_connection_reconnect(fr_connection_pool_t *pool, void *conn)
1040 {
1041         void *new_conn;
1042         fr_connection_t *this;
1043         int conn_number;
1044
1045         if (!pool || !conn) return NULL;
1046
1047         this = fr_connection_find(pool, conn);
1048         if (!this) return NULL;
1049
1050         conn_number = this->number;
1051
1052         rad_assert(this->in_use == true);
1053
1054         DEBUG("%s: Reconnecting (%i)", pool->log_prefix, conn_number);
1055
1056         new_conn = pool->create(pool->ctx);
1057         if (!new_conn) {
1058                 time_t now = time(NULL);
1059
1060                 if (pool->last_complained == now) {
1061                         now = 0;
1062                 } else {
1063                         pool->last_complained = now;
1064                 }
1065
1066                 this->in_use = false;
1067
1068                 rad_assert(pool->active > 0);
1069                 pool->active--;
1070
1071                 fr_connection_close(pool, this);
1072                 pthread_mutex_unlock(&pool->mutex);
1073
1074                 /*
1075                  *      Can't create a new socket.
1076                  *      Try grabbing a pre-existing one.
1077                  */
1078                 new_conn = fr_connection_get(pool);
1079                 if (new_conn) return new_conn;
1080
1081                 if (!now) return NULL;
1082
1083                 ERROR("%s: Failed to reconnect (%i), and no other "
1084                        "connections available", pool->log_prefix, conn_number);
1085
1086                 return NULL;
1087         }
1088
1089         pool->delete(pool->ctx, conn);
1090         this->connection = new_conn;
1091         pthread_mutex_unlock(&pool->mutex);
1092         return new_conn;
1093 }