comm.h

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/*
 * Copyright (c) 2017, 2018 Rafael Antoniello
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef MEDIAPROCESSORS_UTILS_SRC_COMM_H_
#define MEDIAPROCESSORS_UTILS_SRC_COMM_H_

#include <sys/types.h>
#include <inttypes.h>
#include <pthread.h>
#include <stdarg.h>

/* **** Definitions **** */

/* Forward definitions */
typedef struct log_ctx_s log_ctx_t;
typedef struct comm_ctx_s comm_ctx_t;

typedef enum comm_mode_enum {
    COMM_MODE_IPUT= 0,
    COMM_MODE_OPUT,
    COMM_MODE_MAX
} comm_mode_t;

typedef struct comm_if_s {
    char *scheme;
    comm_ctx_t* (*open)(const char *url, const char *local_url,
            comm_mode_t comm_mode, log_ctx_t *log_ctx, va_list arg);
    void (*close)(comm_ctx_t **ref_comm_ctx);
    int (*send)(comm_ctx_t *comm_ctx, const void *buf, size_t count,
            struct timeval *timeout);
    int (*recv)(comm_ctx_t *comm_ctx, void** ref_buf, size_t *ref_count,
            char **ref_from, struct timeval *timeout);
    int (*unblock)(comm_ctx_t *comm_ctx);
} comm_if_t;

typedef struct comm_ctx_s {
    const comm_if_t *comm_if;
    pthread_mutex_t api_mutex;
    log_ctx_t *log_ctx;
    comm_mode_t comm_mode;
    char* local_url;
    char* url;
} comm_ctx_t;

/* **** Prototypes **** */

int comm_module_open(log_ctx_t *log_ctx);

void comm_module_close();

int comm_module_opt(const char *tag, ...);

comm_ctx_t* comm_open(const char *url, const char *local_url,
        comm_mode_t comm_mode, log_ctx_t *log_ctx, ...);

void comm_close(comm_ctx_t **ref_comm_ctx);

int comm_send(comm_ctx_t *comm_ctx, const void *buf, size_t count,
        struct timeval *timeout);

int comm_recv(comm_ctx_t *comm_ctx, void** ref_buf, size_t *ref_count,
        char **ref_from, struct timeval* timeout);

int comm_unblock(comm_ctx_t* comm_ctx);

/* **** Communication module functions to integrate with an "external API" ****
 *
 * The set of functions below are provided to be integrated in an external
 * application with a typical send/receive interface and a control interface
 * implemented as an API.
 *
 * Let us call the 'control functions' to the following set:
 * - 'comm_open_external()';
 * - 'comm_close_external()';
 * - 'comm_reset_external()';
 * We will call the 'i/o functions' to:
 * - 'comm_send_external()'
 * - 'comm_recv_external()'.
 *
 * The calling application must be designed in order to make sure the
 * 'control functions' are never executed concurrently. That is, it should
 * define a critical section to provide that these functions are never executed
 * "at the same time", avoiding the potential problems of "opening" while
 * "closing", etc.
 *
 * In the case of 'i/o' functions, these may be executed asynchronously and
 * concurrently by the calling application, so these are designed to provide
 * secure means to be able to be executed at the same time as the
 * 'control functions' (for example, we should be able to read, write at the
 * same time another thread is requested to close or reset the same COMM
 * instance).
 * To make this possible, we use an external specific critical section (given
 * by the argument 'comm_ctx_mutex_external') to be used to
 * execute in mutual exclusion the "control functions" and the "i/o" functions.
 * Finally, it is to note that "unblocking" operation is not performed within
 * this critical section to avoid deadlocks, as i/o functions may
 * be defined as blocking operations.
 */

int comm_open_external(pthread_mutex_t *comm_ctx_mutex_external,
        const char *url, const char *local_url, comm_mode_t comm_mode,
        log_ctx_t *log_ctx, comm_ctx_t **ref_comm_ctx, ...);

void comm_close_external(pthread_mutex_t *comm_ctx_mutex_external,
        comm_ctx_t **ref_comm_ctx, log_ctx_t *log_ctx);

int comm_reset_external(pthread_mutex_t *comm_ctx_mutex_external,
        const char *new_url, const char *local_url, comm_mode_t comm_mode,
        log_ctx_t *log_ctx, comm_ctx_t **ref_comm_ctx_curr, ...);

int comm_recv_external(pthread_mutex_t *comm_ctx_mutex_external,
        comm_ctx_t **ref_comm_ctx, void** ref_buf, size_t *ref_count,
        char **ref_from, struct timeval* timeout, log_ctx_t *log_ctx);

#endif /* MEDIAPROCESSORS_UTILS_SRC_COMM_H_ */