ctdb/common/srvid.h

   1 /*
   2    Message handler database based on srvid
   3
   4    Copyright (C) Amitay Isaacs  2015
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #ifndef __CTDB_SRVID_H__
  21 #define __CTDB_SRVID_H__
  22
  23 #include <talloc.h>
  24 #include <tdb.h>
  25
  26 /**
  27  * @file srvid.h
  28  *
  29  * @brief Database of message handlers based on srvid
  30  *
  31  * CTDB can be used to send messages between clients across nodes using
  32  * CTDB_REQ_MESSAGE. Clients register for messages based on srvid. CTDB itself
  33  * uses a small set of srvid messages. A large range (2^56) of srvid messages
  34  * is reserved for Samba.
  35  */
  36
  37 /**
  38  * @brief Message handler function
  39  *
  40  * To receive messages for a specific srvid, register a message handler function
  41  * for the srvid.
  42  */
  43 typedef void (*srvid_handler_fn)(uint64_t srvid, TDB_DATA data,
  44                                  void *private_data);
  45
  46 /**
  47  * @brief Abstract struct to store srvid message handler database
  48  */
  49 struct srvid_context;
  50
  51 /**
  52  * @brief Initialize srvid message handler database
  53  *
  54  * This returns a new srvid message handler database context. Freeing
  55  * this context will free all the memory associated with the hash table.
  56  *
  57  * @param[in] mem_ctx Talloc memory context
  58  * @param[out] result The new db_hash_context structure
  59  * @return 0 on success, errno on failure
  60  */
  61 int srvid_init(TALLOC_CTX *mem_ctx, struct srvid_context **result);
  62
  63 /**
  64  * @brief Register a message handler for a srvid
  65  *
  66  * The message handler is allocated using the specified talloc context. Freeing
  67  * this talloc context, removes the message handler.
  68  *
  69  * @param[in] srv The srvid message handler database context
  70  * @param[in] mem_ctx Talloc memory context for message handler
  71  * @param[in] srvid The srvid
  72  * @param[in] handler The message handler function for srvid
  73  * @param[in] private_data Private data for message handler function
  74  * @return 0 on success, errno on failure
  75  */
  76 int srvid_register(struct srvid_context *srv, TALLOC_CTX *mem_ctx,
  77                    uint64_t srvid, srvid_handler_fn handler,
  78                    void *private_data);
  79
  80 /**
  81  * @brief Unregister a message handler for a srvid
  82  *
  83  * @param[in] srv The srvid message handler database context
  84  * @param[in] srvid The srvid
  85  * @param[in] private_data Private data of message handler function
  86  * @return 0 on success, errno on failure
  87  */
  88 int srvid_deregister(struct srvid_context *srv, uint64_t srvid,
  89                      void *private_data);
  90
  91 /**
  92  * @brief Check if any message handler is registered for srvid
  93  *
  94  * If private_data is NULL, then check if there is any registration
  95  * for * specified srvid.  If private_data is not NULL, then check for
  96  * registration that matches the specified private data.
  97  *
  98  * @param[in] srv The srvid message handler database context
  99  * @param[in] srvid The srvid
 100  * @param[in] private_data Private data
 101  * @return 0 on success, errno on failure
 102  */
 103 int srvid_exists(struct srvid_context *srv, uint64_t srvid,
 104                  void *private_data);
 105
 106 /**
 107  * @brief Call message handlers for given srvid
 108  *
 109  * @param[in] srv The srvid message handler database context
 110  * @param[in] srvid The srvid
 111  * @param[in] srvid_all The srvid that gets all messages
 112  * @param[in] data The data passed to each message handler
 113  * @return 0 on success, errno on failure
 114  *
 115  * If srvid_all passed is 0, the message is not sent to message handlers
 116  * registered with special srvid to receive all messages.
 117  */
 118 int srvid_dispatch(struct srvid_context *srv, uint64_t srvid,
 119                    uint64_t srvid_all, TDB_DATA data);
 120
 121 #endif /* __CTDB_SRVID_H__ */