/*
 * Copyright (C) 2014 University of Chicago.
 * See COPYRIGHT notice in top-level directory.
 *
*/

/* Implementation of a simple "resource" data structure for lps to get and
 * retrieve. Additionally allows 'reservations' of a resource for
 * later use, allowing claiming of the resource without requiring the LP to
 * reimplement resource functionality. General requests go through the
 * "general" pool (unreserved part of the resource and
 * reservation-specific requests go through their specific pools. */

#ifndef RESOURCE_H
#define RESOURCE_H

#include <stdint.h>

typedef struct resource_s resource;
typedef unsigned int resource_token_t;

/* initialize with avail capacity, all unreserved */
void resource_init(uint64_t avail, resource *r);

/* Acquire req units of the resource from the general pool. 
 * Returns 0 on success, 1 on failure (not enough available). */
int resource_get(uint64_t req, resource *r);

/* Release req units of the resource from the general pool. */
void resource_free(uint64_t req, resource *r);

/* Reservation functions, same return value as get. 
 * These functions expect exactly one caller per LP group as 
 * defined by the codes configuration 
 * TODO: "un-reserving" not yet supported */
int resource_reserve(uint64_t req, resource_token_t *tok, resource *r);

/* Acquire req units of the resource from a reserved pool */ 
int reserved_get(uint64_t req, resource_token_t tok, resource *r);

/* Release req units of the resource from the general pool. */
void reserved_free(uint64_t req, resource_token_t tok, resource *r);

#define MAX_RESERVE 8
struct resource_s {
    uint64_t avail;
    uint64_t reserved_avail[MAX_RESERVE];
    unsigned int num_tokens;
};


#endif /* end of include guard: RESOURCE_H */

/*
 * Local variables:
 *  c-indent-level: 4
 *  c-basic-offset: 4
 * End:
 *
 * vim: ts=8 sts=4 sw=4 expandtab
 */