/* multiserver.h
 * Fork multiple times, create a socket for each.
 * The socket will accept accept()ed sockets from the main process.
 * After each finished request, it'll inform the main process.
 *  - UziMonkey <uzimonkey@gmail.com>
 */

#ifndef MULTISERVER_H_INCLUDED
#define MULTISERVER_H_INCLUDED

#include <sys/time.h>
#include <time.h>
#include <sys/types.h>

struct multiserver_worker {
	struct timeval access_time; /* Last time accessed */
	unsigned access_count;      /* Number of times accessed */
	pid_t pid;                  /* PID of worker process */
	int sock[2];                /* socketpair for communication */
	int free;                   /* Is the worker busy? */

	/* Previous and next nodes in linked list */
	struct multiserver_worker *prev, *next;
};

struct multiserver_pool {
	/* Head and tail of linked list */
	struct multiserver_worker *head, *tail;
	unsigned size;         /* How many workers in the pool */
	unsigned maximum_size; /* Maximum size pool can grow to */
	unsigned free;         /* How many free workers in the pool */
	
	struct timeval idle_timeout; /* How long do idle extra workers linger? */
	struct timeval access_time;  /* Last time pool was accessed */
	unsigned access_count;       /* Number of times pool was accessed */
};

/* Create a multiserver pool. */
struct multiserver_pool multiserver_create_pool(
		unsigned size, /* Size of the pool */
		unsigned maximum_size, /* Maximum size the pool can grow to */
		struct timeval *idle_timeout, /* Time idle extra processes are killed */
		void (*worker_func)(void) /* Function that does the work */
		);

/* Send a socket to a multiserver pool.
 * One of three things will happen:
 *  1: A free process will answer the call
 *  2: There are no free processes, and a new process will be spawned to answer.
 *  3: The pool is at its maximum size.  It's up to the caller to handle it.
 *
 * Returns: 0 if a process answered the socket, -1 if the pool was full
 */
int multiserver_send_job(
		struct multiserver_pool *pool, /* Pool to send to job to */
		int socket /* Client socket */
		);

/* Purge idle workers.  Should be called by the controller every so often.
 *
 * Returns: Number of workers purged or -1 on error.
 */
int multiserver_purge(
		struct multiserver_pool *pool /* Pool to purge */
		);

#endif /* MULTISERVER_H_INCLUDED */