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