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