source3/lib/server_prefork.h

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Common server globals
   4
   5    Copyright (C) Simo Sorce <idra@samba.org> 2011
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "system/network.h"
  22 #include <tevent.h>
  23 #include "lib/tsocket/tsocket.h"
  24
  25 struct prefork_pool;
  26
  27 enum pf_worker_status {
  28         PF_WORKER_NONE = 0,
  29         PF_WORKER_ALIVE,
  30         PF_WORKER_ACCEPTING,
  31         PF_WORKER_EXITING
  32 };
  33
  34 enum pf_server_cmds {
  35         PF_SRV_MSG_NONE = 0,
  36         PF_SRV_MSG_EXIT
  37 };
  38
  39 /**
  40 * @brief This structure is shared between the controlling parent and the
  41 *        the child. The parent can only write to the 'cmds' and
  42 *        'allowed_clients' variables, while a child is running.
  43 *        The child can change 'status', and 'num_clients'.
  44 *        All other variables are initialized by the parent before forking the
  45 *        child.
  46 */
  47 struct pf_worker_data {
  48         pid_t pid;
  49         enum pf_worker_status status;
  50         time_t started;
  51         time_t last_used;
  52         int num_clients;
  53
  54         enum pf_server_cmds cmds;
  55         int allowed_clients;
  56 };
  57
  58 /**
  59 * @brief This is the 'main' function called by a child right after the fork.
  60 *        It is daemon specific and should initialize and perform whatever
  61 *        operation the child is meant to do. Returning from this function will
  62 *        cause the termination of the child.
  63 *
  64 * @param ev             The event context
  65 * @param msg_ctx        The messaging context
  66 * @param pf             The mmaped area used to communicate with parent
  67 * @param listen_fd_size The number of file descriptors to monitor
  68 * @param listen_fds     The array of file descriptors
  69 * @param private_data   Private data that needs to be passed to the main
  70 *                       function from the calling parent.
  71 *
  72 * @return Returns the exit status to be reported to the parent via exit()
  73 */
  74 typedef int (prefork_main_fn_t)(struct tevent_context *ev,
  75                                 struct messaging_context *msg_ctx,
  76                                 struct pf_worker_data *pf,
  77                                 int child_id,
  78                                 int listen_fd_size,
  79                                 int *listen_fds,
  80                                 void *private_data);
  81
  82 /**
  83 * @brief Callback function for parents that also want to be called on sigchld
  84 *
  85 * @param ev_ctx         The event context
  86 * @param pool           The pool handler
  87 * @param private_data   Data private to the parent
  88 */
  89 typedef void (prefork_sigchld_fn_t)(struct tevent_context *ev_ctx,
  90                                     struct prefork_pool *pool,
  91                                     void *private_data);
  92
  93 /* ==== Functions used by controlling process ==== */
  94
  95 /**
  96 * @brief Creates the first pool of preforked processes
  97 *
  98 * @param mem_ctx        The memory context used to hold the pool structure
  99 * @param ev_ctx         The event context
 100 * @param msg_ctx        The messaging context
 101 * @param listen_fd_size The number of file descriptors to monitor
 102 * @param listen_fds     The array of file descriptors to monitor
 103 * @param min_children   Minimum number of children that must be available at
 104 *                       any given time
 105 * @param max_children   Maximum number of children that can be started. Also
 106 *                       determines the initial size of the pool.
 107 * @param main_fn        The children 'main' function to be called after fork
 108 * @param private_data   The children private data.
 109 * @param pf_pool        The allocated pool.
 110 *
 111 * @return True if it was successful, False otherwise.
 112 *
 113 * NOTE: each listen_fd is forced to non-blocking mode once handed over.
 114 * You should not toush listen_fds once you hand the to the prefork library.
 115 */
 116 bool prefork_create_pool(TALLOC_CTX *mem_ctx,
 117                          struct tevent_context *ev_ctx,
 118                          struct messaging_context *msg_ctx,
 119                          int listen_fd_size, int *listen_fds,
 120                          int min_children, int max_children,
 121                          prefork_main_fn_t *main_fn, void *private_data,
 122                          struct prefork_pool **pf_pool);
 123 /**
 124 * @brief Function used to attempt to expand the size of children.
 125 *
 126 * @param pfp            The pool structure.
 127 * @param new_max        The new max number of children.
 128 *
 129 * @return 0 if operation was successful
 130 *         ENOSPC if the mmap area could not be grown to the requested size
 131 *         EINVAL if the new max is invalid.
 132 *
 133 * NOTE: this function can easily fail if the mmap area cannot be enlarged.
 134 *       A well behaving parent MUST NOT error out if this happen.
 135 */
 136 int prefork_expand_pool(struct prefork_pool *pfp, int new_max);
 137
 138 /**
 139 * @brief Used to prefork a number of new children
 140 *
 141 * @param ev_ctx         The event context
 142 * @param msg_ctx        The messaging context
 143 * @param pfp            The pool structure
 144 * @param num_children   The number of children to be started
 145 *
 146 * @return The number of new children effectively forked.
 147 *
 148 * NOTE: This method does not expand the pool, if the max number of children
 149 *       has already been forked it will do nothing.
 150 */
 151 int prefork_add_children(struct tevent_context *ev_ctx,
 152                          struct messaging_context *msg_ctx,
 153                          struct prefork_pool *pfp,
 154                          int num_children);
 155 /**
 156 * @brief Commands a number of children to stop and exit
 157 *
 158 * @param msg_ctx        The messaging context.
 159 * @param pfp            The pool.
 160 * @param num_children   The number of children we need to retire.
 161 * @param age_limit      The minimum age a child has been active to be
 162 *                       considered for retirement. (Compared against the
 163 *                       'started' value in the pf_worker_data structure of the
 164 *                       children.
 165 *
 166 * @return Number of children that were signaled to stop
 167 *
 168 * NOTE: Only children that have no attached clients can be stopped.
 169 *       If all the available children are too young or are busy then it
 170 *       is possible that none will be asked to stop.
 171 */
 172 int prefork_retire_children(struct messaging_context *msg_ctx,
 173                             struct prefork_pool *pfp,
 174                             int num_children, time_t age_limit);
 175 /**
 176 * @brief Count the number of children
 177 *
 178 * @param pfp    The pool.
 179 * @param active Number of children currently active if not NULL
 180 *
 181 * @return The total number of children.
 182 */
 183 int prefork_count_children(struct prefork_pool *pfp, int *active);
 184
 185 /**
 186 * @brief Count the number of actual connections currently allowed
 187 *
 188 * @param pfp            The pool.
 189 *
 190 * @return The number of connections that can still be opened by clients
 191 *         with the current pool of children.
 192 */
 193 int prefork_count_allowed_connections(struct prefork_pool *pfp);
 194
 195 /**
 196 * @brief Increase the amount of clients each child is allowed to handle
 197 *        simultaneaously. It will allow each child to handle more than
 198 *        one client at a time, up to 'max' (currently set to 100).
 199 *
 200 * @param pfp    The pool.
 201 * @param max    Max number of allowed connections per child
 202 */
 203 void prefork_increase_allowed_clients(struct prefork_pool *pfp, int max);
 204
 205 /**
 206 * @brief Decrease the amount of clients each child is allowed to handle.
 207 *        Min is 1.
 208 *
 209 * @param pfp    The pool.
 210 */
 211 void prefork_decrease_allowed_clients(struct prefork_pool *pfp);
 212
 213 /**
 214 * @brief Reset the maximum allowd clients per child to 1.
 215 *        Does not reduce the number of clients actually beeing served by
 216 *        any given child, but prevents children from overcommitting from
 217 *        now on.
 218 *
 219 * @param pfp    The pool.
 220 */
 221 void prefork_reset_allowed_clients(struct prefork_pool *pfp);
 222
 223 /**
 224 * @brief Send a specific signal to all children.
 225 *        Used to send SIGHUP when a reload of the configuration is needed
 226 *        for example.
 227 *
 228 * @param pfp            The pool.
 229 * @param signal_num     The signal number to be sent.
 230 */
 231 void prefork_send_signal_to_all(struct prefork_pool *pfp, int signal_num);
 232
 233 /**
 234 * @brief Send a message to all children that the server changed something
 235 *        in the pool and they may want to take action.
 236 *
 237 * @param msg_ctx        The messaging context.
 238 * @param pfp            The pool.
 239 */
 240 void prefork_warn_active_children(struct messaging_context *msg_ctx,
 241                                   struct prefork_pool *pfp);
 242
 243 /**
 244 * @brief Sets the SIGCHLD callback
 245 *
 246 * @param pfp            The pool handler.
 247 * @param sigchld_fn     The callback function (pass NULL to unset).
 248 * @param private_data   Private data for the callback function.
 249 */
 250 void prefork_set_sigchld_callback(struct prefork_pool *pfp,
 251                                   prefork_sigchld_fn_t *sigchld_fn,
 252                                   void *private_data);
 253
 254 /* ==== Functions used by children ==== */
 255
 256 /**
 257 * @brief Try to listen and accept on one of the listening sockets.
 258 *        Asynchronusly tries to grab the lock and perform an accept.
 259 *        Will automatically update the 'status' of the child and handle
 260 *        all the locking/unlocking/timingout as necessary.
 261 *        Changes behavior depending on whether the child already has other
 262 *        client connections. If not it blocks on the lock call for periods of
 263 *        time. Otherwise it loops on the lock using a timer in order to allow
 264 *        processing of the other clients requests.
 265 *
 266 * @param mem_ctx        The memory context on whic to allocate the request
 267 * @param ev             The event context
 268 * @param pf             The child/parent shared structure
 269 * @param listen_fd_size The number of listening file descriptors
 270 * @param listen_fds     The array of listening file descriptors
 271 *
 272 * @return The tevent request pointer or NULL on allocation errors.
 273 */
 274 struct tevent_req *prefork_listen_send(TALLOC_CTX *mem_ctx,
 275                                         struct tevent_context *ev,
 276                                         struct pf_worker_data *pf,
 277                                         int listen_fd_size,
 278                                         int *listen_fds);
 279 /**
 280 * @brief Returns the file descriptor after the new client connection has
 281 *        been accepted.
 282 *
 283 * @param req            The request
 284 * @param mem_ctx        The memory context for cli_addr and srv_addr
 285 * @param fd             The new file descriptor.
 286 * @param srv_addr       The server address in tsocket_address format
 287 * @param cli_addr       The client address in tsocket_address format
 288 *
 289 * @return       The error in case the operation failed.
 290 */
 291 int prefork_listen_recv(struct tevent_req *req,
 292                         TALLOC_CTX *mem_ctx, int *fd,
 293                         struct tsocket_address **srv_addr,
 294                         struct tsocket_address **cli_addr);
 295