psm2.h

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/* Copyright (c) 2003-2014 Intel Corporation. All rights reserved. */

#ifndef PSM2_H
#define PSM2_H

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

/*!
 * @file psm.h
 */
/*!
 * @mainpage PSM2 API
 *
 * @brief PSM2 OPA Messaging Library
 *
 * The PSM2 OPA Messaging API, or PSM2 API, is Intel's low-level
 * user-level communications interface for the OPA family of products.
 * PSM2 users are enabled with mechanisms necessary to implement higher level
 * communications interfaces in parallel environments.
 *
 * Since PSM2 targets clusters of multicore processors, it internally implements
 * two levels of communication: intra-node shared memory communication and
 * inter-node OPA communication.  Both of these levels are encapsulated
 * below the interface and the user is free to assume that intra-node and
 * inter-node communication is transparently handled within PSM.
 *
 * @section compat Compatibility
 *
 * PSM2 can coexist with other QLogic/Pathscale software distributions, such as
 * OpenIB/OpenFabrics, which allows applications to simultaneously target
 * PSM-based and non PSM-based applications on a single node without changing
 * any system-level configuration.  However, PSM2 does not support running
 * PSM-based and non PSM-based communication within the same user process.
 *
 * While there are future plans to extend PSM2 to support multi-threaded
 * applications, PSM2
 * is currently a single-threaded library. This means that the user cannot make
 * @e any concurrent PSM2 library calls.  While threads may
 * be a valid execution model for the wider set of potential PSM2 clients,
 * applications should currently expect better effective use
 * of OPA resources (and hence better performance) by dedicating a
 * single PSM2 communication endpoint to every CPU core.
 *
 * Except where noted, PSM2 does not assume an SPMD (single program, multiple
 * data) parallel model and extends to MPMD (multiple program, multiple data)
 * environments in specific areas. However, PSM2 assumes the runtime environment
 * to be homogeneous on all nodes in bit width (32-bit or 64-bit) and endianness
 * (little or big) and will fail at startup if any of these assumptions do not
 * hold.  For homogeneous systems PSM2 can run either in 32-bit or 64-bit
 * environments.  Even though both environments should expect similar
 * performance from the API, PSM2 has chosen to favor 64-bit environments in
 * some minor areas.
 *
 * @section ep_model Endpoint Communication Model
 *
 * PSM2 follows an endpoint communication model where an endpoint is defined as
 * an object (or handle) instantiated to support sending and receiving messages
 * to other endpoints.  In order to prevent PSM2 from being tied to a particular
 * parallel model (such as SPMD), control over the parallel layout of endpoints
 * is retained by the user.  Opening endpoints (@ref psm2_ep_open) and
 * connecting endpoints to enable communication (@ref psm2_ep_connect) are two
 * decoupled mechanisms.  Users that do not dynamically change the number of
 * endpoints beyond parallel startup will probably lump both mechanisms
 * together at startup.  Users that wish to manipulate the location and amount
 * of endpoints at runtime can do so by explicitly connecting sets or subsets
 * of endpoints.
 *
 * As a side effect, this greater flexibility forces the user to cope with a
 * two-stage initialization process.  In the first stage of opening an endpoint
 * (@ref psm2_ep_open), a user obtains an opaque handle to the endpoint and a
 * globally distributable endpoint identifier (@ref psm2_epid_t).  Prior to the
 * second stage of connecting endpoints (@ref psm2_ep_connect), a user must
 * distribute all relevent endpoint identifiers through an out-of-band
 * mechanism.  Once the endpoint identifiers are successfully distributed to
 * all processes that wish to communicate, the user
 * connects all endpoint identifiers to the locally opened endpoint
 * (@ref psm2_ep_connect).  In connecting the endpoints, the user obtains an
 * opaque endpoint address (@ref psm2_epaddr_t), which is required for all PSM
 * communication primitives.
 *
 *
 * @section components PSM2 Components
 *
 * PSM2 exposes a single endpoint initialization model, but enables various
 * levels of communication functionality and semantics through @e components.
 * The first major component available in PSM2 is PSM2 Matched Queues
 * (@ref psm2_mq), and the second is PSM2 Active Message (@ref psm2_am).
 *
 * Matched Queues (MQ) present a queue-based communication model with the
 * distinction that queue consumers use a 3-tuple of metadata to match incoming
 * messages against a list of preposted receive buffers.  The MQ semantics are
 * sufficiently akin to MPI to cover the entire MPI-1.2 standard.
 *
 * The Active Message (AM) component presents a request/reply model where
 * the arrival of a message triggers the execution of consumer-provided
 * handler code. This can be used to implement many one-sided and two-sided
 * communications paradigms.
 *
 * With future releases of the PSM2 interface, more components will
 * be exposed to accomodate users that implement parallel communication
 * models that deviate from the Matched Queue semantics.  For example, PSM
 * plans to expose a connection management component to make it easier to
 * handle endpoint management for clients without their own connection
 * managers.
 *
 *
 * @section progress PSM2 Communication Progress Guarantees
 *
 * PSM2 internally ensures progress of both intra-node and inter-node messages,
 * but not autonomously.  This means that while performance does not depend
 * greatly on how the user decides to schedule communication progress,
 * explicit progress calls are required for correctness.  The @ref psm2_poll
 * function is available to make progress over all PSM2 components in a generic
 * manner.  For more information on making progress over many communication
 * operations in the MQ component, see the @ref mq_progress documentation.
 *
 *
 * @section completion PSM2 Completion semantics
 *
 * PSM2 implements the MQ component, which documents its own
 * message completion semantics (@ref mq_completion).
 *
 *
 * @section error_handling PSM2 Error handling
 *
 * PSM2 exposes a list of user and runtime errors enumerated in @ref psm2_error.
 * While most errors are fatal in that the user is not expected to be able to
 * recover from them, PSM2 still allows some level of control.  By
 * default, PSM2 returns all errors to the user but as a convenience, allows
 * users to either defer errors internally to PSM2 or to have PSM2 return all
 * errors to the user (callers to PSM2 functions).  PSM2 attempts to deallocate
 * its resources as a best effort, but exits are always non-collective with
 * respect to endpoints opened in other processes.  The user is expected to be
 * able to handle non-collective exits from any endpoint and in turn cleanly
 * and independently terminate the parallel environment.  Local error handling
 * can be handled in three modes:
 *
 * Errors and error handling can be individually registered either globally or
 * per-endpoint:
 * @li @b Per-endpoint error handling captures errors for functions where the
 * error scoping is determined to be over an endpoint.  This includes all
 * communication functions that include an EP or MQ handle as the first
 * parameter.
 *
 * @li @b Global error handling captures errors for functions where a
 * particular endpoint cannot be identified or for @ref psm2_ep_open, where
 * errors (if any) occur before the endpoint is opened.
 *
 * Error handling is controlled by registering error handlers (@ref
 * psm2_error_register_handler).  The global error handler can
 * be set at any time (even before @ref psm2_init), whereas a per-endpoint error
 * handler can be set as soon as a new endpoint is succesfully created.  If a
 * per-endpoint handle is not registered, the per-endpoint handler inherits
 * from the global error handler at time of open.
 *
 * PSM2 predefines two different mechanisms for handling errors:
 *
 * @li PSM-internal error handler (@ref PSM2_ERRHANDLER_PSM2_HANDLER)
 * @li No-op PSM2 error handler where errors are returned
 *     (@ref PSM2_ERRHANDLER_NO_HANDLER)
 *
 * The default PSM-internal error handler effectively frees the user from
 * explicitly handling the return values of ever PSM2 function but may not
 * return to the user in a function determined to have caused a fatal error.
 *
 * The No-op PSM2 error handler bypasses all error handling functionality and
 * always returns the error to the user.  The user can then use @ref
 * psm2_error_get_string to obtain a generic string from an error code (compared
 * to a more detailed error message available through registering of error
 * handlers).
 *
 * For even more control, users can register their own error handlers to have
 * access to more precise error strings and selectively control when an when
 * not to return to callers of PSM2 functions.  All error handlers shown defer
 * error handling to PSM2 for errors that are not recognized using @ref
 * psm2_error_defer.  Deferring an error from a custom error handler is
 * equivalent to relying on the default error handler.
 *
 * @section env_var Environment variables
 *
 * Some PSM2 behaviour can be controlled via environment variables.
 *
 * @li @b PSM2_DEVICES. PSM2 implements three devices for communication which
 * are, in order,  @c self, @c shm and @c hfi.  For PSM2 jobs that do not
 * require shared-memory communications, @b PSM2_DEVICES can be specified as @c
 * self, @c hfi.  Similarly, for shared-memory only jobs, the @c hfi device
 * can be disabled.  It is up to the user to ensure that the endpoint ids
 * passed in @ref psm2_ep_connect do not require a device that has been
 * explicitly disabled by the user.  In some instances, enabling only the
 * devices that are required may improve performance.
 *
 * @li @b PSM2_TRACEMASK. Depending on the value of the tracemask, various parts
 * of PSM2 will output debugging information.  With a default value of @c 0x1,
 * informative messages will be printed (this value should be considered a
 * minimum).  At @c 0x101, startup and finalization messages are added to the
 * output.  At @c 0x1c3, every communication event is logged and should hence
 * be used for extreme debugging only.
 */

/** @brief Local endpoint handle (opaque)
 *  @ingroup ep
 *
 * Handle returned to the user when a new local endpoint is created.  The
 * handle is a local handle to be used in all communication functions and is
 * not intended to globally identify the opened endpoint in any way.
 *
 * All open endpoint handles can be globally identified using the endpoint id
 * integral type (@ref psm2_epid_t) and all communication must use an endpoint
 * address (@ref psm2_epaddr_t) that can be obtained by connecting a local
 * endpoint to one or more endpoint identifiers.
 *
 * @remark The local endpoint handle is opaque to the user.  */
typedef struct psm2_ep *psm2_ep_t;

/** @brief MQ handle (opaque)
 * @ingroup mq
 *
 * Handle returned to the user when a new Matched queue is created (@ref
 * ps2m_mq_init).  */
typedef struct psm2_mq *psm2_mq_t;

/*! @defgroup init PSM2 Initialization and Maintenance
 * @{
 */
#define PSM2_VERNO       0x0201	/*!< Header-defined Version number */
#define PSM2_VERNO_MAJOR 0x02	/*!< Header-defined Major Version Number */
#define PSM2_VERNO_MINOR 0x01	/*!< Header-defined Minor Version Number */
#define PSM2_VERNO_COMPAT_MAJOR 0x01	/*!<PSM1 Major Version Number> */

/*! @brief PSM2 Error type
 */
enum psm2_error {
	/*! Interface-wide "ok", guaranteed to be 0. */
	PSM2_OK = 0,
	/*! No events progressed on @ref psm2_poll (not fatal) */
	PSM2_OK_NO_PROGRESS = 1,
	/*! Error in a function parameter */
	PSM2_PARAM_ERR = 3,
	/*! PSM2 ran out of memory */
	PSM2_NO_MEMORY = 4,
	/*! PSM2 has not been initialized by @ref psm2_init */
	PSM2_INIT_NOT_INIT = 5,
	/*! API version passed in @ref psm2_init is incompatible */
	PSM2_INIT_BAD_API_VERSION = 6,
	/*! PSM2 Could not set affinity */
	PSM2_NO_AFFINITY = 7,
	/*! PSM2 Unresolved internal error */
	PSM2_INTERNAL_ERR = 8,
	/*! PSM2 could not set up shared memory segment */
	PSM2_SHMEM_SEGMENT_ERR = 9,
	/*! PSM2 option is a read-only option */
	PSM2_OPT_READONLY = 10,
	/*! PSM2 operation timed out */
	PSM2_TIMEOUT = 11,
	/*! Too many endpoints */
	PSM2_TOO_MANY_ENDPOINTS = 12,

	/*! PSM2 is finalized */
	PSM2_IS_FINALIZED = 13,

	/*! Endpoint was closed */
	PSM2_EP_WAS_CLOSED = 20,
	/*! PSM2 Could not find an OPA Unit */
	PSM2_EP_NO_DEVICE = 21,
	/*! User passed a bad unit or port number */
	PSM2_EP_UNIT_NOT_FOUND = 22,
	/*! Failure in initializing endpoint */
	PSM2_EP_DEVICE_FAILURE = 23,
	/*! Error closing the endpoing error */
	PSM2_EP_CLOSE_TIMEOUT = 24,
	/*! No free ports could be obtained */
	PSM2_EP_NO_PORTS_AVAIL = 25,
	/*! Could not detect network connectivity */
	PSM2_EP_NO_NETWORK = 26,
	/*! Invalid Unique job-wide UUID Key */
	PSM2_EP_INVALID_UUID_KEY = 27,
	/*! Internal out of resources */
	PSM2_EP_NO_RESOURCES = 28,

	/*! Endpoint connect status unknown (because of other failures or if
	 * connect attempt timed out) */
	PSM2_EPID_UNKNOWN = 40,
	/*! Endpoint could not be reached by any PSM2 component */
	PSM2_EPID_UNREACHABLE = 41,
	/*! At least one of the connecting nodes was incompatible in endianess */
	PSM2_EPID_INVALID_NODE = 43,
	/*! At least one of the connecting nodes provided an invalid MTU */
	PSM2_EPID_INVALID_MTU = 44,
	/*! At least one of the connecting nodes provided a bad key */
	PSM2_EPID_INVALID_UUID_KEY = 45,
	/*! At least one of the connecting nodes is running an incompatible
	 * PSM2 protocol version */
	PSM2_EPID_INVALID_VERSION = 46,
	/*! At least one node provided garbled information */
	PSM2_EPID_INVALID_CONNECT = 47,
	/*! EPID was already connected */
	PSM2_EPID_ALREADY_CONNECTED = 48,
	/*! EPID is duplicated, network connectivity problem */
	PSM2_EPID_NETWORK_ERROR = 49,
	/*! EPID incompatible partition keys */
	PSM2_EPID_INVALID_PKEY = 50,
	/*! Unable to resolve path for endpoint */
	PSM2_EPID_PATH_RESOLUTION = 51,

	/*! MQ Non-blocking request is incomplete */
	PSM2_MQ_NO_COMPLETIONS = 60,
	/*! MQ Message has been truncated at the receiver */
	PSM2_MQ_TRUNCATION = 61,

	/*! AM reply error */
	PSM2_AM_INVALID_REPLY = 70,

	PSM2_ERROR_LAST = 80
};

/* Backwards header compatibility for a confusing error return name */
#define PSM2_MQ_INCOMPLETE PSM2_MQ_NO_COMPLETIONS

/*! @see psm2_error */
typedef enum psm2_error psm2_error_t;

/*! @brief PSM2 Error type
 */
enum psm2_component {
	/*! PSM2 core library */
	PSM2_COMPONENT_CORE = 0,
	/*! MQ component */
	PSM2_COMPONENT_MQ = 1,
	/*! AM component */
	PSM2_COMPONENT_AM = 2,
	/*! IB component */
	PSM2_COMPONENT_IB = 3
};

/*! @see psm2_component */
typedef enum psm2_component psm2_component_t;

/*! @brief PSM2 Path resolution mechanism
 */
enum psm2_path_res {
	/*! PSM2 no path resolution */
	PSM2_PATH_RES_NONE = 0,
	/*! Use OFED Plus for path resolution */
	PSM2_PATH_RES_OPP = 1,
	/*! Use OFED UMAD for path resolution */
	PSM2_PATH_RES_UMAD = 2
};

/*! @see psm2_path_resolution */
typedef enum psm2_path_res psm2_path_res_t;

/** @brief Initialize PSM2 interface
 *
 * Call to initialize the PSM2 library for a desired API revision number.
 *
 * @param[in,out] api_verno_major As input a pointer to an integer that holds
 *                                @ref PSM2_VERNO_MAJOR. As output, the pointer
 *                                is updated with the major revision number of
 *                                the loaded library.
 * @param[in,out] api_verno_minor As intput, a pointer to an integer that holds
 *                                @ref PSM2_VERNO_MINOR.  As output, the pointer
 *                                is updated with the minor revision number of
 *                                the loaded library.
 *
 * @pre The user has not called any other PSM2 library call except @ref
 *      psm2_error_register_handler to register a global error handler.
 *
 * @warning PSM2 initialization is a precondition for all functions used in the
 *          PSM2 library.
 *
 * @returns PSM2_OK The PSM2 interface could be opened and the desired API
 *                 revision can be provided.
 * @returns PSM2_INIT_BAD_API_VERSION The PSM2 library cannot compatibility for
 *                                   the desired API version.
 *
 * @verbatim
 * // In this example, we want to handle our own errors before doing init,
 * // since we don't want a fatal error if OPA is not found.
 * // Note that @ref psm2_error_register_handler (and @ref psm2_uuid_generate)
 * // are the only function that can be called before @ref psm2_init
 *
 * int try_to_initialize_psm() {
 *     int verno_major = PSM2_VERNO_MAJOR;
 *     int verno_minor = PSM2_VERNO_MINOR;
 *
 *     int err = psm2_error_register_handler(NULL,  // Global handler
 *                                  PSM2_ERRHANDLER_NO_HANDLER); // return errors
 *     if (err) {
 *        fprintf(stderr, "Couldn't register global handler: %s\n",
 *		          psm2_error_get_string(err));
 *        return -1;
 *     }
 *
 *     err = psm2_init(&verno_major, &verno_minor);
 *     if (err || verno_major > PSM2_VERNO_MAJOR) {
 *        if (err)
 *	      fprintf(stderr, "PSM2 initialization failure: %s\n",
 *	              psm2_error_get_string(err));
 *	  else
 *	      fprintf(stderr, "PSM2 loaded an unexpected/unsupported "
 *	                      "version (%d.%d)\n", verno_major, verno_minor);
 *	  return -1;
 *     }
 *
 *     // We were able to initialize PSM2 but will defer all further error
 *     // handling since most of the errors beyond this point will be fatal.
 *     int err = psm2_error_register_handler(NULL,  // Global handler
 *                                           PSM2_ERRHANDLER_PSM2_HANDLER);
 *     if (err) {
 *        fprintf(stderr, "Couldn't register global errhandler: %s\n",
 *		          psm2_error_get_string(err));
 *        return -1;
 *     }
 *     return 1;
 * }
 * @endverbatim
 */
psm2_error_t psm2_init(int *api_verno_major, int *api_verno_minor);

/** @brief Finalize PSM2 interface
 *
 * Single call to finalize PSM2 and close all unclosed endpoints
 *
 * @post The user guarantees not to make any further PSM2 calls, including @ref
 * psm2_init.
 *
 * @returns PSM2_OK Always returns @c PSM2_OK */
psm2_error_t psm2_finalize(void);

/** @brief Error handling opaque token
 *
 * A token is required for users that register their own handlers and wish to
 * defer further error handling to PSM. */
typedef struct psm2_error_token *psm2_error_token_t;

/** @brief Error handling function
 *
 * Users can handle errors explicitly instead of relying on PSM's own error
 * handler.  There is one global error handler and error handlers that can be
 * individually set for each opened endpoint.  By default, endpoints will
 * inherit the global handler registered at the time of open.
 *
 * @param[in] ep Handle associated to the endpoint over which the error occured
 *               or @c NULL if the error is being handled by the global error
 *               handler.
 * @param[in] error PSM2 error identifier
 * @param[in] error_string A descriptive error string of maximum length @ref
 *                         PSM2_ERRSTRING_MAXLEN.
 * @param[in] token Opaque PSM2 token associated with the particular event that
 *		    generated the error.  The token can be used to extract the
 *		    error string and can be passed to @ref psm2_error_defer to
 *		    defer any remaining or unhandled error handling to PSM.
 *
 * @post If the error handler returns, the error returned is propagated to the
 *       caller.  */
typedef psm2_error_t(*psm2_ep_errhandler_t) (psm2_ep_t ep,
					   const psm2_error_t error,
					   const char *error_string,
					   psm2_error_token_t token);

/* Obsolete names, only here for backwards compatibility */
#define PSM2_ERRHANDLER_DEFAULT	((psm2_ep_errhandler_t)-1)
#define PSM2_ERRHANDLER_NOP	((psm2_ep_errhandler_t)-2)

#define PSM2_ERRHANDLER_PSM_HANDLER  ((psm2_ep_errhandler_t)-1)
/**< PSM2 error handler as explained in @ref error_handling */

#define PSM2_ERRHANDLER_NO_HANDLER   ((psm2_ep_errhandler_t)-2)
/**< Bypasses the default PSM2 error handler and returns all errors to the user
 * (this is the default) */

#define PSM2_ERRSTRING_MAXLEN	512 /**< Maximum error string length. */

/** @brief PSM2 error handler registration
 *
 * Function to register error handlers on a global basis and on a per-endpoint
 * basis.  PSM2_ERRHANDLER_PSM2_HANDLER and PSM2_ERRHANDLER_NO_HANDLER are special
 * pre-defined handlers to respectively enable use of the default PSM-internal
 * handler or the no-handler that disables registered error handling and
 * returns all errors to the caller (both are documented in @ref
 * error_handling).
 *
 * @param[in] ep Handle of the endpoint over which the error handler should be
 *               registered.  With ep set to @c NULL, the behavior of the
 *               global error handler can be controlled.
 * @param[in] errhandler Handler to register.  Can be a user-specific error
 *                       handling function or PSM2_ERRHANDLER_PSM2_HANDLER or
 *                       PSM2_ERRHANDLER_NO_HANDLER.
 *
 * @remark When ep is set to @c NULL, this is the only function that can be
 * called before @ref psm2_init
 */
psm2_error_t
psm2_error_register_handler(psm2_ep_t ep, const psm2_ep_errhandler_t errhandler);

/** @brief PSM2 deferred error handler
 *
 * Function to handle fatal PSM2 errors if no error handler is installed or if
 * the user wishes to defer further error handling to PSM.  Depending on the
 * type of error, PSM2 may or may not return from the function call.
 *
 * @param[in] err_token Error token initially passed to error handler
 *
 * @pre The user is calling into the function because it has decided that PSM
 *      should handle an error case.
 *
 * @post The function may or may not return depending on the error
 */
psm2_error_t psm2_error_defer(psm2_error_token_t err_token);

/** @brief Get generic error string from error
 *
 * Function to return the default error string associated to a PSM2 error.
 *
 * While a more detailed and precise error string is usually available within
 * error handlers, this function is available to obtain an error string out of
 * an error handler context or when a no-op error handler is registered.
 *
 * @param[in] error PSM2 error
 */
const char *psm2_error_get_string(psm2_error_t error);

/** @brief Option key/pair structure
 *
 * Currently only used in MQ.
 */
struct psm2_optkey {
	uint32_t key;	/**< Option key */
	void *value;	/**< Option value */
};

/*! @} */

/*! @defgroup ep PSM2 Device Endpoint Management
 * @{
 */

/** @brief Endpoint ID
 *
 * Integral type of size 8 bytes that can be used by the user to globally
 * identify a successfully opened endpoint.  Although the contents of the
 * endpoint id integral type remains opaque to the user, unique network id and
 * OPA port number can be extracted using @ref psm2_epid_nid and @ref
 * psm2_epid_context.
 */
typedef uint64_t psm2_epid_t;

/** @brief Endpoint Address (opaque)
 *
 * Remote endpoint addresses are created when the user binds an endpoint ID
 * to a particular endpoint handle using @ref psm2_ep_connect.  A given endpoint
 * address is only guaranteed to be valid over a single endpoint.
 */
typedef struct psm2_epaddr *psm2_epaddr_t;

/** @brief PSM2 Unique UID
 *
 * PSM2 type equivalent to the DCE-1 uuid_t, used to uniquely identify an
 * endpoint within a particular job.  Since PSM2 does not participate in job
 * allocation and management, users are expected to generate a unique ID to
 * associate endpoints to a particular parallel or collective job.
 * @see psm2_uuid_generate
 */
typedef uint8_t psm2_uuid_t[16];

/** @brief Get Endpoint identifier's Unique Network ID */
uint64_t psm2_epid_nid(psm2_epid_t epid);

/** @brief Get Endpoint identifier's OPA context number */
uint64_t psm2_epid_context(psm2_epid_t epid);

/** @brief Get Endpoint identifier's OPA port (deprecated, use
 * @ref psm2_epid_context instead) */
uint64_t psm2_epid_port(psm2_epid_t epid);

/** @brief List the number of available OPA units
 *
 * Function used to determine the amount of locally available OPA units.
 * For @c N units, valid unit numbers in @ref psm2_ep_open are @c 0 to @c N-1.
 *
 * @returns PSM2_OK unless the user has not called @ref psm2_init
 */
psm2_error_t psm2_ep_num_devunits(uint32_t *num_units);

/** @brief Utility to generate UUIDs for @ref psm2_ep_open
 *
 * This function is available as a utility for generating unique job-wide ids.
 * See discussion in @ref psm2_ep_open for further information.
 *
 * @remark This function does not require PSM2 to be initialized.
 */
void psm2_uuid_generate(psm2_uuid_t uuid_out);

/* Affinity modes for the affinity member of struct psm2_ep_open_opts */
#define PSM2_EP_OPEN_AFFINITY_SKIP     0	/**< Disable setting affinity */
#define PSM2_EP_OPEN_AFFINITY_SET      1	/**< Enable setting affinity unless
					  already set */
#define PSM2_EP_OPEN_AFFINITY_FORCE    2	/**< Enable setting affinity regardless
					  of current affinity setting */

/* Default values for some constants */
#define PSM2_EP_OPEN_PKEY_DEFAULT    0xffffffffffffffffULL
				    /**< Default protection key */

/** @brief Endpoint Open Options
 *
 * These options are available for opening a PSM2 endpoint.  Each is
 * individually documented and setting each option to -1 or passing NULL as the
 * options parameter in @ref psm2_ep_open instructs PSM2 to use
 * implementation-defined defaults.
 *
 * Each option is documented in @ref psm2_ep_open
 */
struct psm2_ep_open_opts {
	int64_t timeout;	/**< timeout in nanoseconds to open device */
	int unit;		/**< OPA Unit ID to open on */
	int affinity;		/**< How PSM2 should set affinity */
	int shm_mbytes;	/**< Megabytes used for intra-node, deprecated */
	int sendbufs_num;	/**< Preallocated send buffers */
	uint64_t network_pkey;	/**< Network Protection Key (v1.01) */
	int port;		/**< IB port to use (1 to N) */
	int outsl;		/**< IB SL to use when sending pkts */
	uint64_t service_id;	/* IB Service ID to use for endpoint */
	psm2_path_res_t path_res_type;	/* Path resolution type */
	int senddesc_num;	/* Preallocated send descriptors */
	int imm_size;		/* Immediate data size for endpoint */
};

/** @brief OPA endpoint creation
 *
 * Function used to create a new local communication endpoint on an OPA
 * adapter.  The returned endpoint handle is required in all PSM2 communication
 * operations, as PSM2 can manage communication over multiple endpoints.  An
 * opened endpoint has no global context until the user connects the endpoint
 * to other global endpoints by way of @ref psm2_ep_connect.  All local endpoint
 * handles are globally identified by endpoint IDs (@ref psm2_epid_t) which are
 * also returned when an endpoint is opened.  It is assumed that the user can
 * provide an out-of-band mechanism to distribute the endpoint IDs in order to
 * establish connections between endpoints (@ref psm2_ep_connect for more
 * information).
 *
 * @param[in] unique_job_key Endpoint key, to uniquely identify the endpoint in
 *                           a parallel job.  It is up to the user to ensure
 *                           that the key is globally unique over a period long
 *                           enough to prevent duplicate keys over the same set
 *                           of endpoints (see comments below).
 *
 * @param[in] opts Open options of type @ref psm2_ep_open_opts
 *                 (see @ref psm2_ep_open_opts_get_defaults).
 *
 * @param[out] ep User-supplied storage to return a pointer to the newly
 *                created endpoint.  The returned pointer of type @ref psm2_ep_t
 *                is a local handle and cannot be used to globally identify the
 *                endpoint.
 * @param[out] epid User-supplied storage to return the endpoint ID associated
 *                  to the newly created local endpoint returned in the @c ep
 *                  handle.  The endpoint ID is an integral type suitable for
 *                  uniquely identifying the local endpoint.
 *
 * PSM2 does not internally verify the consistency of the uuid, it is up to the
 * user to ensure that the uid is unique enough not to collide with other
 * currently-running jobs.  Users can employ three mechanisms to obtain a uuid.
 *
 * 1. Use the supplied @ref psm2_uuid_generate utility
 *
 * 2. Use an OS or library-specific uuid generation utility, that complies with
 *    OSF DCE 1.1, such as @c uuid_generate on Linux or @c uuid_create on
 *    FreeBSD.
 *    (see http://www.opengroup.org/onlinepubs/009629399/uuid_create.htm)
 *
 * 3. Manually pack a 16-byte string using a utility such as /dev/random or
 *    other source with enough entropy and proper seeding to prevent two nodes
 *    from generating the same uuid_t.
 *
 * The following options are relevent when opening an endpoint:
 *   @li @c timeout establishes the amount of nanoseconds to wait before
 *                  failing to open a port (with -1, defaults to 15 secs).
 *   @li @c unit sets the OPA unit number to use to open a port (with
 *               -1, PSM2 determines the best unit to open the port).  If @c
 *               HFI_UNIT is set in the environment, this setting is ignored.
 *   @li @c affinity enables or disables PSM2 setting processor affinity.  The
 *                   option can be controlled to either disable (@ref
 *                   PSM2_EP_OPEN_AFFINITY_SKIP) or enable the affinity setting
 *                   only if it is already unset (@ref
 *                   PSM2_EP_OPEN_AFFINITY_SET) or regardless of affinity begin
 *                   set or not (@ref PSM2_EP_OPEN_AFFINITY_FORCE).
 *                   If @c HFI_NO_CPUAFFINITY is set in the environment, this
 *                   setting is ignored.
 *   @li @c shm_mbytes sets a maximum amount of megabytes that can be allocated
 *		       to each local endpoint ID connected through this
 *		       endpoint (with -1, defaults to 10 MB).
 *   @li @c sendbufs_num sets the number of send buffers that can be
 *                       pre-allocated for communication (with -1, defaults to
 *                       512 buffers of MTU size).
 *   @li @c network_pkey sets the protection key to employ for point-to-point
 *                       PSM2 communication.  Unless a specific value is used,
 *                       this parameter should be set to
 *                       PSM2_EP_OPEN_PKEY_DEFAULT.
 *
 * @warning Currently, PSM2 limits the user to calling @ref psm2_ep_open only
 * once per process and subsequent calls will fail.  Multiple endpoints per
 * process will be enabled in a future release.
 *
 * @verbatim
 * // In order to open an endpoint and participate in a job, each endpoint has
 * // to be distributed a unique 16-byte UUID key from an out-of-band source.
 * // Presumably this can come from the parallel spawning utility either
 * // indirectly through an implementors own spawning interface or as in this
 * // example, the UUID is set as a string in an environment variable
 * // propagated to all endpoints in the job.
 *
 * int try_to_open_psm2_endpoint(psm2_ep_t *ep, // output endpoint handle
 *                              psm2_epid_t *epid, // output endpoint identifier
 *                              int unit)  // unit of our choice
 * {
 *    psm2_ep_open_opts epopts;
 *    psm2_uuid_t job_uuid;
 *    char *c;
 *
 *    // Let PSM2 assign its default values to the endpoint options.
 *    psm2_ep_open_opts_get_defaults(&epopts);
 *
 *    // We want a stricter timeout and a specific unit
 *    epopts.timeout = 15*1e9;  // 15 second timeout
 *    epopts.unit = unit;	// We want a specific unit, -1 would let PSM
 *                              // choose the unit for us.
 *    epopts.port = port;	// We want a specific unit, <= 0 would let PSM
 *                              // choose the port for us.
 *    // We've already set affinity, don't let PSM2 do so if it wants to.
 *    if (epopts.affinity == PSM2_EP_OPEN_AFFINITY_SET)
 *       epopts.affinity = PSM2_EP_OPEN_AFFINITY_SKIP;
 *
 *    // ENDPOINT_UUID is set to the same value in the environment of all the
 *    // processes that wish to communicate over PSM2 and was generated by
 *    // the process spawning utility
 *    c = getenv("ENDPOINT_UUID");
 *    if (c && *c)
 *       implementor_string_to_16byte_packing(c, job_uuid);
 *    else {
 *       fprintf(stderr, "Can't find UUID for endpoint\n);
 *       return -1;
 *    }
 *
 *    // Assume we don't want to handle errors here.
 *    psm2_ep_open(job_uuid, &epopts, ep, epid);
 *    return 1;
 * }
 * @endverbatim
 */
psm2_error_t
psm2_ep_open(const psm2_uuid_t unique_job_key,
	    const struct psm2_ep_open_opts *opts, psm2_ep_t *ep,
	    psm2_epid_t *epid);

/** @brief Endpoint open default options.
 *
 * Function used to initialize the set of endpoint options to their default
 * values for use in @ref psm2_ep_open.
 *
 * @param[out] opts Endpoint Open options.
 *
 * @warning For portable operation, users should always call this function
 * prior to calling @ref psm2_ep_open.
 *
 * @return PSM2_OK If result could be updated
 * @return PSM2_INIT_NOT_INIT If psm has not been initialized.
 */
psm2_error_t
psm2_ep_open_opts_get_defaults(struct psm2_ep_open_opts *opts);

/** @brief Endpoint shared memory query
 *
 * Function used to determine if a remote endpoint shares memory with a
 * currently opened local endpiont.
 *
 * @param[in] ep Endpoint handle
 * @param[in] epid Endpoint ID
 *
 * @param[out] result Result is non-zero if the remote endpoint shares memory with the local
 * endpoint @c ep, or zero otherwise.
 *
 * @return PSM2_OK If result could be updated
 * @return PSM2_EPID_UNKNOWN If the epid is not recognized
 */
psm2_error_t
psm2_ep_epid_share_memory(psm2_ep_t ep, psm2_epid_t epid, int *result);

/** @brief Close endpoint
 * @param[in] ep PSM2 endpoint handle
 * @param[in] mode One of @ref PSM2_EP_CLOSE_GRACEFUL or @ref PSM2_EP_CLOSE_FORCE
 * @param[in] timeout How long to wait in nanoseconds if mode is
 *			PSM2_EP_CLOSE_GRACEFUL, 0 waits forever.  If @c mode is
 *			@ref PSM2_EP_CLOSE_FORCE, this parameter is ignored.
 *
 * The following errors are returned, others are handled by the per-endpoint
 * error handler:
 *
 * @return PSM2_OK  Endpoint was successfully closed without force or
 *                 successfully closed with force within the supplied timeout.
 * @return PSM2_EP_CLOSE_TIMEOUT Endpoint could not be successfully closed
 *                              within timeout.
 */
psm2_error_t psm2_ep_close(psm2_ep_t ep, int mode, int64_t timeout);

#define PSM2_EP_CLOSE_GRACEFUL	0   /**< Graceful mode in @ref psm2_ep_close */
#define PSM2_EP_CLOSE_FORCE	1   /**< Forceful mode in @ref psm2_ep_close */

/** @brief Provide mappings for network id to hostname
 *
 * Since PSM2 does not assume or rely on the availability of an external
 * networkid-to-hostname mapping service, users can provide one or more of
 * these mappings.  The @ref psm2_map_nid_hostname function allows a list of
 * network ids to be associated to hostnames.
 *
 * This function is not mandatory for correct operation but may allow PSM2 to
 * provide better diagnostics when remote endpoints are unavailable and can
 * otherwise only be identified by their network id.
 *
 * @param[in] num Number elements in @c nid and @c hostnames arrays
 * @param[in] nids User-provided array of network ids (i.e. OPA LIDs),
 *                 should be obtained by calling @ref psm2_epid_nid on each
 *                 epid.
 * @param[in] hostnames User-provided array of hostnames (array of
 *                      NUL-terimated strings) where each hostname index
 *                      maps to the provided nid hostname.
 *
 * @warning Duplicate nids may be provided in the input @c nids array, only
 *          the first corresponding hostname will be remembered.
 *
 * @pre The user may or may not have already provided a hostname mappings.
 * @post The user may free any dynamically allocated memory passed to the
 *       function.
 *
 */
psm2_error_t
psm2_map_nid_hostname(int num, const uint64_t *nids, const char **hostnames);

/** @brief Connect one or more remote endpoints to a local endpoint
 *
 * Function to non-collectively establish a connection to a set of endpoint IDs
 * and translate endpoint IDs into endpoint addresses.  Establishing a remote
 * connection with a set of remote endpoint IDs does not imply a collective
 * operation and the user is free to connect unequal sets on each process.
 * Similarly, a given endpoint address does not imply that a pairwise
 * communication context exists between the local endpoint and remote endpoint.
 *
 * @param[in] ep PSM2 endpoint handle
 *
 * @param[in] num_of_epid The amount of endpoints to connect to, which
 *                        also establishes the amount of elements contained in
 *                        all of the function's array-based parameters.
 *
 * @param[in] array_of_epid User-allocated array that contains @c num_of_epid
 *                          valid endpoint identifiers.  Each endpoint id (or
 *                          epid) has been obtained through an out-of-band
 *                          mechanism and each endpoint must have been opened
 *                          with the same uuid key.
 *
 * @param[in] array_of_epid_mask User-allocated array that contains
 *                          @c num_of_epid integers.  This array of masks
 *                          allows users to select which of the epids in @c
 *                          array_of_epid should be connected.  If the integer
 *                          at index i is zero, psm does not attempt to connect
 *                          to the epid at index i in @c array_of_epid.  If
 *                          this parameter is NULL, psm will try to connect to
 *                          each epid.
 *
 * @param[out] array_of_errors User-allocated array of at least @c num_of_epid
 *                             elements. If the function does not return
 *                             PSM2_OK, this array can be consulted for each
 *                             endpoint not masked off by @c array_of_epid_mask
 *                             to know why the endpoint could not be connected.
 *                             Endpoints that could not be connected because of
 *                             an unrelated failure will be marked as @ref
 *                             PSM2_EPID_UNKNOWN.  If the function returns
 *                             PSM2_OK, the errors for all endpoints will also
 *                             contain PSM2_OK.
 *
 * @param[out] array_of_epaddr User-allocated array of at least @c num_of_epid
 *                             elements of type psm2_epaddr_t.  Each
 *                             successfully connected endpoint is updated with
 *                             an endpoint address handle that corresponds to
 *                             the endpoint id at the same index in @c
 *                             array_of_epid.  Handles are only updated if the
 *                             endpoint could be connected and if its error in
 *                             array_of_errors is PSM2_OK.
 *
 * @param[in] timeout Timeout in nanoseconds after which connection attempts
 *                    will be abandoned.  Setting this value to 0 disables
 *                    timeout and waits until all endpoints have been
 *                    successfully connected or until an error is detected.
 *
 * @pre The user has opened a local endpoint and obtained a list of endpoint
 *      IDs to connect to a given endpoint handle using an out-of-band
 *      mechanism not provided by PSM.
 *
 * @post If the connect is successful, @c array_of_epaddr is updated with valid
 *       endpoint addresses.
 *
 * @post If unsuccessful, the user can query the return status of each
 *       individual remote endpoint in @c array_of_errors.
 *
 * @post The user can call into @ref psm2_ep_connect many times with the same
 *       endpoint ID and the function is guaranteed to return the same output
 *       parameters.
 *
 * @post PSM2 does not keep any reference to the arrays passed into the
 *       function and the caller is free to deallocate them.
 *
 * The error value with the highest importance is returned by
 * the function if some portion of the communication failed.  Users should
 * always refer to individual errors in @c array_of_errors whenever the
 * function cannot return PSM2_OK.
 *
 * @returns PSM2_OK  The entire set of endpoint IDs were successfully connected
 *                  and endpoint addresses are available for all endpoint IDs.
 *
 * @verbatim
 * int connect_endpoints(psm2_ep_t ep, int numep,
 *                       const psm2_epid_t *array_of_epid,
 *                       psm2_epaddr_t **array_of_epaddr_out)
 * {
 *     psm2_error_t *errors = (psm2_error_t *) calloc(numep, sizeof(psm2_error_t));
 *     if (errors == NULL)
 *         return -1;
 *
 *     psm2_epaddr_t *all_epaddrs =
 *              (psm2_epaddr_t *) calloc(numep, sizeof(psm2_epaddr_t));
 *
 *     if (all_epaddrs == NULL)
 *         return -1;
 *
 *     psm2_ep_connect(ep, numep, array_of_epid,
 *                    NULL, // We want to connect all epids, no mask needed
 *                    errors,
 *                    all_epaddrs,
 *                    30*e9); // 30 second timeout, <1 ns is forever
 *     *array_of_epaddr_out = all_epaddrs;
 *     free(errors);
 *     return 1;
 * }
 * @endverbatim */
psm2_error_t
psm2_ep_connect(psm2_ep_t ep, int num_of_epid, const psm2_epid_t *array_of_epid,
		   const int *array_of_epid_mask, psm2_error_t *array_of_errors,
		   psm2_epaddr_t *array_of_epaddr, int64_t timeout);

/** @brief Ensure endpoint communication progress
 *
 * Function to ensure progress for all PSM2 components instantiated on an
 * endpoint (currently, this only includes the MQ component).  The function
 * never blocks and is typically required in two cases:
 *
 * @li Allowing all PSM2 components instantiated over a given endpoint to make
 *     communication progress. Refer to @ref mq_progress for a detailed
 *     discussion on MQ-level progress issues.
 *
 * @li Cases where users write their own synchronization primitives that
 *     depend on remote communication (such as spinning on a memory location
 *     which's new value depends on ongoing communication).
 *
 * The poll function doesn't block, but the user can rely on the @ref
 * PSM2_OK_NO_PROGRESS return value to control polling behaviour in terms of
 * frequency (poll until an event happens) or execution environment (poll for a
 * while but yield to other threads of CPUs are oversubscribed).
 *
 * @returns PSM2_OK             Some communication events were progressed
 * @returns PSM2_OK_NO_PROGRESS Polling did not yield any communication progress
 *
 */
psm2_error_t psm2_poll(psm2_ep_t ep);

/** @brief Set a user-determined ep address label.
 *
 * @param[in] epaddr Endpoint address, obtained from @ref psm2_ep_connect
 * @param[in] epaddr_label_string User-allocated string to print when
 *                   identifying endpoint in error handling or other verbose
 *                   printing.  The NULL-terminated string must be allocated by
 *                   the user since PSM2 only keeps a pointer to the label.  If
 *                   users do not explicitly set a label for each endpoint,
 *                   endpoints will identify themselves as hostname:port.
 */
void psm2_epaddr_setlabel(psm2_epaddr_t epaddr,
			 const char *epaddr_label_string);

/** @brief Set a user-determined ep address context.
 *
 * @param[in] epaddr Endpoint address, obtained from @ref psm2_ep_connect
 * @param[in] ctxt   Opaque user defined state to associate with an endpoint
 *                   address. This state can be retrieved via
 *                   @ref psm2_epaddr_getctxt.
 */
void
psm2_epaddr_setctxt(psm2_epaddr_t epaddr, void *ctxt);

/** @brief Get the user-determined ep address context. Users can associate an
 *  opaque context with each endpoint via @ref psm2_epaddr_setctxt.
 *
 * @param[in] epaddr Endpoint address, obtained from @ref psm2_ep_connect.
 */
void *psm2_epaddr_getctxt(psm2_epaddr_t epaddr);

/* Below are all component specific options. The component object for each of
 * the options is also specified.
 */

/* PSM2_COMPONENT_CORE options */
/* PSM2 debug level */
#define PSM2_CORE_OPT_DEBUG     0x101
  /**< [@b uint32_t ] Set/Get the PSM2 debug level. This option can be set
   * before initializing the PSM2 library.
   *
   * component object: (null)
   * option value: PSM2 Debug mask to set or currently active debug level.
   */

/* PSM2 endpoint address context */
#define PSM2_CORE_OPT_EP_CTXT   0x102
  /**< [@b uint32_t ] Set/Get the context associated with a PSM2 endpoint
   * address (psm2_epaddr_t).
   *
   * component object: PSM2 endpoint (@ref psm2_epaddr_t) address.
   * option value: Context associated with PSM2 endpoint address.
   */

/* PSM2_COMPONENT_IB options */
/* Default service level to use to communicate with remote endpoints */
#define PSM2_IB_OPT_DF_SL 0x201
  /**< [@b uint32_t ] Default OPA SL to use for all remote communication.
   * If unset defaults to Service Level 0.
   *
   * component object: Opened PSM2 endpoint id (@ref psm2_ep_t).
   * option value: Default IB SL to use for endpoint. (0 <= SL < 15)
   */

/* Set IB service level to use for communication to an endpoint */
#define PSM2_IB_OPT_EP_SL 0x202
  /**< [@b uint32_t ] OPA SL to use for communication to specified
   * remote endpoint.
   *
   * component object: PSM2 endpoint (@ ref psm2_epaddr_t) address.
   * option value: SL used to communicate with remote endpoint. (0 <= SL < 15)
   */

/* PSM2_COMPONENT_MQ options (deprecates psm2_mq_set|getopt) */
/* MQ options that can be set in psm2_mq_init and psm2_{set,get}_opt */
#define PSM2_MQ_OPT_RNDV_IB_SZ       0x301
#define PSM2_MQ_RNDV_HFI_SZ          PSM2_MQ_OPT_RNDV_IB_SZ
#define PSM2_MQ_RNDV_IPATH_SZ        PSM2_MQ_OPT_RNDV_IB_SZ
  /**< [@b uint32_t ] Size at which to start enabling rendezvous
   * messaging for OPA messages (if unset, defaults to values
   * between 56000 and 72000 depending on the system configuration)
   *
   * component object: PSM2 Matched Queue (@ref psm2_mq_t).
   * option value: Size at which to switch to rendezvous protocol.
   */

#define PSM2_MQ_OPT_RNDV_SHM_SZ      0x302
#define PSM2_MQ_RNDV_SHM_SZ          PSM2_MQ_OPT_RNDV_SHM_SZ
  /**< [@b uint32_t ] Size at which to start enabling
   * rendezvous messaging for shared memory (intra-node) messages (If
   * unset, defaults to 64000 bytes).
   *
   * component object: PSM2 Matched Queue (@ref psm2_mq_t).
   * option value: Size at which to switch to rendezvous protocol.
   */

#define PSM2_MQ_OPT_SYSBUF_MYBYTES   0x303
#define PSM2_MQ_MAX_SYSBUF_MBYTES    PSM2_MQ_OPT_SYSBUF_MYBYTES
  /**< [@b uint32_t ] Maximum amount of bytes to allocate for unexpected
   * messages.
   *
   * component object: PSM2 Matched Queue (@ref psm2_mq_t).
   * option value: Deprecated; this option has no effect.
   */

/* PSM2_COMPONENT_AM options */
#define PSM2_AM_OPT_FRAG_SZ          0x401
#define PSM2_AM_MAX_FRAG_SZ          PSM2_AM_OPT_FRAG_SZ
/*!< [@b uint32_t ] Maximum active message fragment size that can be sent
 * for a given endpoint or across all endpoints. This value can only be
 * queried.
 *
 * component object: PSM2 endpoint (@ref psm2_epaddr_t) address. If NULL then
 *                   option value is the smalles fragment size across all
 *                   active endpoints.
 * option value: Maximum active message fragment size in bytes.
 */

#define PSM2_AM_OPT_NARGS 0x402
#define PSM2_AM_MAX_NARGS PSM2_AM_OPT_NARGS

/*!< [@b uint32_t ] Maximum number of message arguments that can be sent
 * for a given endpoint or across all endpoints. This value can only be
 * queried.
 *
 * component object: PSM2 endpoint (@ref psm2_epaddr_t) address. If NULL then
 *                   option value is the smalles fragment size across all
 *                   active endpoints.
 * option value: Maximum number of active message arguments.
 */

#define PSM2_AM_OPT_HANDLERS 0x403
#define PSM2_AM_MAX_HANDLERS PSM2_AM_OPT_HANDLERS
/*!< [@b uint32_t ] Maximum number of message handlers that can be registered
 * for a given endpoint or across all endpoints. This value can only be
 * queried.
 *
 * component object: PSM2 endpoint (@ref psm2_epaddr_t) address. If NULL then
 *                   option value is the smalles fragment size across all
 *                   active endpoints.
 * option value: Maximum number of active message handlers.
 */

/** @brief Set an option for a PSM2 component
 *
 * Function to set the value of a PSM2 component option
 *
 * @param[in] component Type of PSM2 component for which to set the option
 * @param[in] component_obj Opaque component specify object to apply the set
 *                          operation on. These are passed uninterpreted to the
 *                          appropriate component for interpretation.
 * @param[in] optname Name of component option to set. These are component
 *                    specific and passed uninterpreted to the appropriate
 *                    component for interpretation.
 * @param[in] optval Pointer to storage that contains the value to be updated
 *                   for the supplied option.  It is up to the user to
 *                   ensure that the pointer points to a memory location with a
 *                   correct size and format.
 * @param[in] optlen Size of the memory region pointed to by optval.
 *
 * @returns PSM2_OK if option could be set.
 * @returns PSM2_PARAM_ERR if the component or optname are not valid.
 * @returns PSM2_OPT_READONLY if the option to be set is a read-only option.
 *
 */
psm2_error_t
psm2_setopt(psm2_component_t component, const void *component_obj,
	   int optname, const void *optval, uint64_t optlen);

/** @brief Get an option for a PSM2 component
 *
 * Function to get the value of a PSM2 component option
 *
 * @param[in] component Type of PSM2 component for which to get the option
 * @param[in] component_obj Opaque component specify object to apply the get
 *                          operation on. These are passed uninterpreted to the
 *                          appropriate component for interpretation.
 * @param[in] optname Name of component option to get. These are component
 *                    specific and passed uninterpreted to the appropriate
 *                    component for interpretation.
 * @param[out] optval Pointer to storage that contains the value to be updated
 *                    for the supplied option.  It is up to the user to
 *                    ensure that the pointer points to a valid memory region.
 * @param[in,out] optlen This is a value result parameter initially containing
 *                      the size of the memory region pointed to by optval and
 *                      modified to return the actual size of optval.
 *
 * @returns PSM2_OK if option value could be retrieved successfully.
 * @returns PSM2_PARAM_ERR if the component or optname are not valid.
 * @returns PSM2_NO_MEMORY if the memory region optval is of insufficient size.
 *                         optlen contains the required memory region size for
 *                         optname value.
 *
 */
psm2_error_t
psm2_getopt(psm2_component_t component, const void *component_obj,
	   int optname, void *optval, uint64_t *optlen);

/** @brief Datatype for end-point information */
typedef struct psm2_epinfo {
	psm2_ep_t ep;		/**< The ep for this end-point*/
	psm2_epid_t epid;	/**< The epid for this end-point */
	psm2_uuid_t uuid;	/**< The UUID for this end-point */
	uint16_t jkey;		/**< The job key for this end-point */
	char uuid_str[64];	/**< String representation of the UUID for this end-point */
} psm2_epinfo_t;

/** @brief Datatype for end-point connection */
typedef struct psm2_epconn {
	psm2_epaddr_t addr;	/**< The epaddr for this connection */
	psm2_ep_t ep;		/**< The ep for this connection */
	psm2_mq_t mq;		/**< The mq for this connection */
} psm2_epconn_t;

/** @brief Query PSM2 for end-point information.
 *
 * Function to query PSM2 for end-point information. This allows retrieval of
 * end-point information in cases where the caller does not have access to the
 * results of psm2_ep_open().  In single-rail mode PSM2 will use a single
 * end-point. In multi-rail mode, PSM2 will use an end-point per rail.
 *
 * @param[in,out] num_of_epinfo On input, sizes the available number of entries
 *                              in array_of_epinfo.  On output, specifies the
 *                              returned number of entries in array_of_epinfo.
 * @param[out] array_of_epinfo Returns end-point information structures.
 *
 * @pre PSM2 is initialized and the end-point has been opened.
 *
 * @returns PSM2_OK indicates success.
 * @returns PSM2_PARAM_ERR if input num_if_epinfo is less than or equal to zero.
 * @returns PSM2_EP_WAS_CLOSED if PSM2 end-point is closed or does not exist.
 */
psm2_error_t psm2_ep_query(int *num_of_epinfo, psm2_epinfo_t *array_of_epinfo);

/** @brief Query PSM2 for end-point connections.
 *
 * Function to query PSM2 for end-point connections. This allows retrieval of
 * end-point connnections in cases where the caller does not have access to the
 * results of psm2_ep_connect().  The epid values can be found using
 * psm2_ep_query() so that each PSM2 process can determine its own epid. These
 * values can then be distributed across the PSM2 process so that each PSM
 * process knows the epid for all other PSM2 processes.
 *
 * @param[in] epid The epid of a PSM2 process.
 * @param[out] epconn The connection information for that PSM2 process.
 *
 * @pre PSM2 is initialized and the end-point has been connected to this epid.
 *
 * @returns PSM2_OK indicates success.
 * @returns PSM2_EP_WAS_CLOSED if PSM2 end-point is closed or does not exist.
 * @returns PSM2_EPID_UNKNOWN if the epid value is not known to PSM.
 */
psm2_error_t psm2_ep_epid_lookup(psm2_epid_t epid, psm2_epconn_t *epconn);

/*! @} */

#ifdef __cplusplus
} /* extern "C" */
#endif
#endif