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//
// Copyright 2017 Garrett D'Amore <garrett@damore.org>
// Copyright 2017 Capitar IT Group BV <info@capitar.com>
// Copyright 2017 Staysail Systems, Inc. <info@staysail.tech>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#ifndef CORE_AIO_H
#define CORE_AIO_H
#include "core/defs.h"
#include "core/list.h"
#include "core/taskq.h"
#include "core/thread.h"
typedef struct nni_aio_ops nni_aio_ops;
typedef void (*nni_aio_cancelfn)(nni_aio *, int);
// An nni_aio is an async I/O handle.
struct nni_aio {
int a_result; // Result code (nng_errno)
size_t a_count; // Bytes transferred (I/O only)
nni_time a_expire; // Absolute timeout
nni_duration a_timeout; // Relative timeout
// These fields are private to the aio framework.
nni_cv a_cv;
unsigned a_fini : 1; // shutting down (no new operations)
unsigned a_done : 1; // operation has completed
unsigned a_pend : 1; // completion routine pending
unsigned a_active : 1; // aio was started
unsigned a_expiring : 1; // expiration callback in progress
unsigned a_waiting : 1; // a thread is waiting for this to finish
unsigned a_synch : 1; // run completion synchronously
nni_task a_task;
// Read/write operations.
nni_iov a_iov[4];
int a_niov;
// Message operations.
nni_msg *a_msg;
// Connect/accept operations.
void *a_endpt; // opaque endpoint handle
void *a_pipe; // opaque pipe handle
// Resolver operations.
nni_sockaddr *a_addr;
// User scratch data. Consumers may store values here, which
// must be preserved by providers and the framework.
void *a_user_data[4];
// Operation inputs & outputs. Up to 4 inputs and 4 outputs may be
// specified. The semantics of these will vary, and depend on the
// specific operation.
void *a_inputs[4];
void *a_outputs[4];
// Provider-use fields.
nni_aio_cancelfn a_prov_cancel;
void * a_prov_data;
nni_list_node a_prov_node;
void * a_prov_extra[4]; // Extra data used by provider
// Expire node.
nni_list_node a_expire_node;
};
// nni_aio_init initializes an aio object. The callback is called with
// the supplied argument when the operation is complete. If NULL is
// supplied for the callback, then nni_aio_wake is used in its place,
// and the aio is used for the argument.
extern int nni_aio_init(nni_aio **, nni_cb, void *);
// nni_aio_fini finalizes the aio, releasing resources (locks)
// associated with it. The caller is responsible for ensuring that any
// associated I/O is unscheduled or complete. This is safe to call
// on zero'd memory.
extern void nni_aio_fini(nni_aio *);
// nni_aio_fini_cb finalizes the aio WITHOUT waiting for it to complete.
// This is intended exclusively for finalizing an AIO from a completion
// callack for that AIO. It is important that the caller ensure that nothing
// else might be waiting for that AIO or using it.
extern void nni_aio_fini_cb(nni_aio *);
// nni_aio_stop cancels any unfinished I/O, running completion callbacks,
// but also prevents any new operations from starting (nni_aio_start will
// return NNG_ESTATE). This should be called before nni_aio_fini(). The
// best pattern is to call nni_aio_stop on all linked aios, before calling
// nni_aio_fini on any of them. This function will block until any
// callbacks are executed, and therefore it should never be executed
// from a callback itself. (To abort operations without blocking
// use nni_aio_cancel instead.)
extern void nni_aio_stop(nni_aio *);
// nni_aio_set_data sets user data. This should only be done by the
// consumer, initiating the I/O. The intention is to be able to store
// additional data for use when the operation callback is executed.
// The index represents the "index" at which to store the data. A maximum
// of 4 elements can be stored with the (index >= 0 && index < 4).
extern void nni_aio_set_data(nni_aio *, int, void *);
// nni_aio_get_data returns the user data that was previously stored
// with nni_aio_set_data.
extern void *nni_aio_get_data(nni_aio *, int);
// nni_set_input sets input parameters on the AIO. The semantic details
// of this will be determined by the specific AIO operation. AIOs can
// carry up to 4 input parameters.
extern void nni_aio_set_input(nni_aio *, int, void *);
// nni_get_input returns the input value stored by nni_aio_set_input.
extern void *nni_aio_get_input(nni_aio *, int);
// nni_set_output sets output results on the AIO, allowing providers to
// return results to consumers. The semantic details are determined by
// the AIO operation. Up to 4 outputs can be carried on an AIO.
extern void nni_aio_set_output(nni_aio *, int, void *);
// nni_get_output returns an output previously stored on the AIO.
extern void *nni_aio_get_output(nni_aio *, int);
// XXX: These should be refactored in terms of the generic inputs and
// outputs.
extern void nni_aio_set_msg(nni_aio *, nni_msg *);
extern nni_msg *nni_aio_get_msg(nni_aio *);
extern void nni_aio_set_pipe(nni_aio *, void *);
extern void * nni_aio_get_pipe(nni_aio *);
extern void nni_aio_set_ep(nni_aio *, void *);
extern void * nni_aio_get_ep(nni_aio *);
// nni_aio_set_synch sets a synchronous completion flag on the AIO.
// When this is set, the next time the AIO is completed, the callback
// be run synchronously, from the thread calling the finish routine.
// It is important that this only be set when the provider knows that
// it is not holding any locks or resources when completing the operation,
// or when the consumer knows that the callback routine does not acquire
// any locks. Use with caution to avoid deadlocks. The flag is cleared
// automatically when the completion callback is executed. Some care has
// been taken so that other aio operations like aio_wait will work,
// although it is still an error to try waiting for an aio from that aio's
// completion callback.
void nni_aio_set_synch(nni_aio *);
// nni_aio_set_timeout sets the timeout (relative) when the AIO will
// be canceled. The cancelation does not happen until after nni_aio_start
// is called.
extern void nni_aio_set_timeout(nni_aio *, nni_duration);
// nni_aio_result returns the result code (0 on success, or an NNG errno)
// for the operation. It is only valid to call this when the operation is
// complete (such as when the callback is executed or after nni_aio_wait
// is performed).
extern int nni_aio_result(nni_aio *);
// nni_aio_count returns the number of bytes of data transferred, if any.
// As with nni_aio_result, it is only defined if the I/O operation has
// completed.
extern size_t nni_aio_count(nni_aio *);
// nni_aio_wait blocks the caller until the operation is complete.
// The operation must have already been started. This routine will
// block until the AIO, as well as any callback, has completed execution.
// If the callback routine reschedules the AIO, the wait may wind up
// waiting for the rescheduled operation; this is most often used in
// lieu of a callback to build synchronous constructs on top of AIOs.
extern void nni_aio_wait(nni_aio *);
// nni_aio_list_init creates a list suitable for use by providers using
// the a_prov_node member of the aio. These operations are not locked,
// but they do have some extra checks -- remove is idempotent for example,
// and append will perform any necessary remove first.
extern void nni_aio_list_init(nni_list *);
extern void nni_aio_list_append(nni_list *, nni_aio *);
extern void nni_aio_list_prepend(nni_list *, nni_aio *);
extern void nni_aio_list_remove(nni_aio *);
extern int nni_aio_list_active(nni_aio *);
// nni_aio_finish is called by the provider when an operation is complete.
extern void nni_aio_finish(nni_aio *, int, size_t);
extern void nni_aio_finish_error(nni_aio *, int);
extern void nni_aio_finish_pipe(nni_aio *, void *);
extern void nni_aio_finish_msg(nni_aio *, nni_msg *);
// nni_aio_cancel is used to cancel an operation. Any pending I/O or
// timeouts are canceled if possible, and the callback will be returned
// with the indicated result (NNG_ECLOSED or NNG_ECANCELED is recommended.)
extern void nni_aio_cancel(nni_aio *, int rv);
extern int nni_aio_start(nni_aio *, nni_aio_cancelfn, void *);
// nni_aio_stop is used to abort all further operations on the AIO.
// When this is executed, no further operations or callbacks will be
// executed, and if callbacks or I/O is in progress this will block
// until they are either canceled or aborted. (Question: why not just
// nni_fini?)
// extern void nni_aio_stop(nni_aio *);
extern int nni_aio_sys_init(void);
extern void nni_aio_sys_fini(void);
#endif // CORE_AIO_H
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