path: root/src/mds-registry/slave.h

/**
 * mds — A micro-display server
 * Copyright © 2014, 2015  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef MDS_MDS_REGISTRY_SLAVE_H
#define MDS_MDS_REGISTRY_SLAVE_H


#include <libmdsserver/hash-table.h>

#include <stdlib.h>
#include <stdint.h>
#include <pthread.h>
#include <time.h>
#include <signal.h>



#define SLAVE_T_VERSION  0

/**
 * Slave information, a thread waiting for protocols to become available
 */
typedef struct slave
{
  /**
   * Set of protocols for which to wait that they become available
   */
  hash_table_t* wait_set;
  
  /**
   * The ID of the waiting client
   */
  uint64_t client;
  
  /**
   * The ID of the waiting client
   */
  char* client_id;
  
  /**
   * The ID of the message that triggered the waiting
   */
  char* message_id;
  
  /**
   * The slave's node in the linked list of slaves
   */
  ssize_t node;
  
  /**
   * Whether the client has been closed
   */
  volatile sig_atomic_t closed;
  
  /**
   * The slave thread
   */
  pthread_t thread;
  
  /**
   * The time slave should die if its condition
   * has not be meet at that time
   */
  struct timespec dethklok;
  
  /**
   * Whether `dethklok` should apply
   */
  int timed;
  
} slave_t;



/**
 * Start a slave thread
 * 
 * @param   wait_set         Set of protocols for which to wait that they become available
 * @param   recv_client_id   The ID of the waiting client
 * @param   recv_message_id  The ID of the message that triggered the waiting
 * @return                   Non-zero on error
 */
int start_slave(hash_table_t* restrict wait_set, const char* restrict recv_client_id, const char* restrict recv_message_id);

/**
 * Start a slave thread with an already created slave
 * 
 * @param   slave  The slave
 * @return         Non-zero on error, `errno` will be set accordingly
 */
int start_created_slave(slave_t* restrict slave);

/**
 * Close all slaves associated with a client
 * 
 * @param  client  The client's ID
 */
void close_slaves(uint64_t client);

/**
 * Notify slaves that a protocol has become available
 * 
 * @param   command  The protocol
 * @return           Non-zero on error, `ernno`will be set accordingly
 */
int advance_slaves(char* command);

/**
 * Create a slave
 * 
 * @return  The slave
 */
slave_t* slave_create(hash_table_t* restrict wait_set, const char* restrict recv_client_id, const char* restrict recv_message_id);


/**
 * Initialise a slave
 * 
 * @param  this  Memory slot in which to store the new slave information
 */
void slave_initialise(slave_t* restrict this);

/**
 * Release all resources assoicated with a slave
 * 
 * @param  this  The slave information
 */
void slave_destroy(slave_t* restrict this);

/**
 * Calculate the buffer size need to marshal slave information
 * 
 * @param   this  The slave information
 * @return        The number of bytes to allocate to the output buffer
 */
size_t slave_marshal_size(const slave_t* restrict this) __attribute__((pure));

/**
 * Marshals slave information
 * 
 * @param   this  The slave information
 * @param   data  Output buffer for the marshalled data
 * @return        The number of bytes that have been written (everything will be written)
 */
size_t slave_marshal(const slave_t* restrict this, char* restrict data);

/**
 * Unmarshals slave information
 * 
 * @param   this  Memory slot in which to store the new slave information
 * @param   data  In buffer with the marshalled data
 * @return        Zero on error, `errno` will be set accordingly, otherwise the
 *                number of read bytes. Destroy the slave information on error.
 */
size_t slave_unmarshal(slave_t* restrict this, char* restrict data);

/**
 * Pretend to unmarshal slave information
 * 
 * @param   data  In buffer with the marshalled data
 * @return        The number of read bytes
 */
size_t slave_unmarshal_skip(char* restrict data) __attribute__((pure));


#endif