/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2004-2008 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2005 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2007-2020 Cisco Systems, Inc.  All rights reserved.
 * Copyright (c) 2010-2015 Los Alamos National Security, LLC. All rights
 *                         reserved.
 * Copyright (c) 2016      Intel, Inc. All rights reserved.
 * Copyright (c) 2019      Sylabs, Inc. All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 *
 * These symbols are in a file by themselves to provide nice linker
 * semantics.  Since linkers generally pull in symbols by object
 * files, keeping these symbols as the only symbols in this file
 * prevents utility programs such as "ompi_info" from having to import
 * entire components just to query their version and parameters.
 */

#include "opal_config.h"

#include "opal/constants.h"
#include "opal/mca/shmem/shmem.h"
#include "shmem_mmap.h"

/**
 * public string showing the shmem ompi_mmap component version number
 */
const char *opal_shmem_mmap_component_version_string
    = "OPAL mmap shmem MCA component version " OPAL_VERSION;

int opal_shmem_mmap_relocate_backing_file = 0;
char *opal_shmem_mmap_backing_file_base_dir = NULL;
bool opal_shmem_mmap_nfs_warning = true;

/**
 * local functions
 */
static int mmap_register(void);
static int mmap_open(void);
static int mmap_close(void);
static int mmap_query(mca_base_module_t **module, int *priority);
static int mmap_runtime_query(mca_base_module_t **module, int *priority, const char *hint);

/**
 * instantiate the public struct with all of our public information
 * and pointers to our public functions in it
 */
opal_shmem_mmap_component_t mca_shmem_mmap_component = {
    .super =
        {
            .base_version =
                {
                    OPAL_SHMEM_BASE_VERSION_2_0_0,

                    /* component name and version */
                    .mca_component_name = "mmap",
                    MCA_BASE_MAKE_VERSION(component, OPAL_MAJOR_VERSION, OPAL_MINOR_VERSION,
                                          OPAL_RELEASE_VERSION),

                    .mca_open_component = mmap_open,
                    .mca_close_component = mmap_close,
                    .mca_query_component = mmap_query,
                    .mca_register_component_params = mmap_register,
                },
            /* MCA v2.0.0 component meta data */
            .base_data =
                {/* the component is checkpoint ready */
                 MCA_BASE_METADATA_PARAM_CHECKPOINT},
            .runtime_query = mmap_runtime_query,
        },
};

/* ////////////////////////////////////////////////////////////////////////// */
static int mmap_runtime_query(mca_base_module_t **module, int *priority, const char *hint)
{
    /* no run-time query needed for mmap, so this is easy */
    *priority = mca_shmem_mmap_component.priority;
    *module = (mca_base_module_t *) &opal_shmem_mmap_module.super;
    return OPAL_SUCCESS;
}

static int mmap_register(void)
{
    int ret;

    /* ////////////////////////////////////////////////////////////////////// */
    /* (default) priority - set high to make mmap the default */
    mca_shmem_mmap_component.priority = 50;
    ret = mca_base_component_var_register(&mca_shmem_mmap_component.super.base_version, "priority",
                                          "Priority for shmem mmap "
                                          "component (default: 50)",
                                          MCA_BASE_VAR_TYPE_INT, NULL, 0,
                                          MCA_BASE_VAR_FLAG_SETTABLE, OPAL_INFO_LVL_3,
                                          MCA_BASE_VAR_SCOPE_ALL_EQ,
                                          &mca_shmem_mmap_component.priority);
    if (0 > ret) {
        return ret;
    }

    /*
     * Do we want the "warning: your mmap file is on NFS!" message?  Per a
     * thread on the OMPI devel list
     * (https://www.open-mpi.org/community/lists/devel/2011/12/10054.php),
     * on some systems, it doesn't seem to matter.  But per older threads,
     * it definitely does matter on some systems.  Perhaps newer kernels
     * are smarter about this kind of stuff...?  Regardless, we should
     * provide the ability to turn off this message for systems where the
     * effect doesn't matter.
     */
    opal_shmem_mmap_nfs_warning = true;
    ret = mca_base_component_var_register(&mca_shmem_mmap_component.super.base_version,
                                          "enable_nfs_warning",
                                          "Enable the warning emitted when Open MPI detects "
                                          "that its shared memory backing file is located on "
                                          "a network filesystem (1 = enabled, 0 = disabled).",
                                          MCA_BASE_VAR_TYPE_BOOL, NULL, 0,
                                          MCA_BASE_VAR_FLAG_SETTABLE, OPAL_INFO_LVL_9,
                                          MCA_BASE_VAR_SCOPE_LOCAL, &opal_shmem_mmap_nfs_warning);
    if (0 > ret) {
        return ret;
    }

    opal_shmem_mmap_relocate_backing_file = 0;
    ret = mca_base_component_var_register(
        &mca_shmem_mmap_component.super.base_version, "relocate_backing_file",
        "Whether to change the default placement of backing files or not "
        "(Negative = try to relocate backing files to an area rooted at "
        "the path specified by "
        "shmem_mmap_backing_file_base_dir, but continue "
        "with the default path if the relocation fails, 0 = do not relocate, "
        "Positive = same as the negative option, but will fail if the "
        "relocation fails.",
        MCA_BASE_VAR_TYPE_INT, NULL, 0, MCA_BASE_VAR_FLAG_SETTABLE, OPAL_INFO_LVL_9,
        MCA_BASE_VAR_SCOPE_ALL_EQ, &opal_shmem_mmap_relocate_backing_file);
    if (0 > ret) {
        return ret;
    }

    opal_shmem_mmap_backing_file_base_dir = "/dev/shm";
    ret = mca_base_component_var_register(&mca_shmem_mmap_component.super.base_version,
                                          "backing_file_base_dir",
                                          "Specifies where backing files will be created when "
                                          "shmem_mmap_relocate_backing_file is in use.",
                                          MCA_BASE_VAR_TYPE_STRING, NULL, 0,
                                          MCA_BASE_VAR_FLAG_SETTABLE, OPAL_INFO_LVL_9,
                                          MCA_BASE_VAR_SCOPE_ALL_EQ,
                                          &opal_shmem_mmap_backing_file_base_dir);
    if (0 > ret) {
        return ret;
    }

    return OPAL_SUCCESS;
}

/* ////////////////////////////////////////////////////////////////////////// */
static int mmap_open(void)
{
    return OPAL_SUCCESS;
}

/* ////////////////////////////////////////////////////////////////////////// */
static int mmap_query(mca_base_module_t **module, int *priority)
{
    *priority = mca_shmem_mmap_component.priority;
    *module = (mca_base_module_t *) &opal_shmem_mmap_module.super;
    return OPAL_SUCCESS;
}

/* ////////////////////////////////////////////////////////////////////////// */
static int mmap_close(void)
{
    return OPAL_SUCCESS;
}