инициализация потока трассировки, сброс и завершение работы процесса (TRACING) (trace stream initialization, flush, and shutdown from a process (TRACING))
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
posix_trace_create, posix_trace_create_withlog,
posix_trace_flush, posix_trace_shutdown — trace stream
initialization, flush, and shutdown from a process (TRACING)
Синопсис (Synopsis)
#include <sys/types.h>
#include <trace.h>
int posix_trace_create(pid_t pid,
const trace_attr_t *restrict attr,
trace_id_t *restrict trid);
int posix_trace_create_withlog(pid_t pid,
const trace_attr_t *restrict attr, int file_desc,
trace_id_t *restrict trid);
int posix_trace_flush(trace_id_t trid);
int posix_trace_shutdown(trace_id_t trid);
Описание (Description)
The posix_trace_create() function shall create an active trace
stream. It allocates all the resources needed by the trace stream
being created for tracing the process specified by pid in
accordance with the attr argument. The attr argument represents
the initial attributes of the trace stream and shall have been
initialized by the function posix_trace_attr_init() prior to the
posix_trace_create() call. If the argument attr is NULL, the
default attributes shall be used. The attr attributes object
shall be manipulated through a set of functions described in the
posix_trace_attr family of functions. If the attributes of the
object pointed to by attr are modified later, the attributes of
the trace stream shall not be affected. The creation-time
attribute of the newly created trace stream shall be set to the
value of the system clock, if the Timers option is not supported,
or to the value of the CLOCK_REALTIME clock, if the Timers option
is supported.
The pid argument represents the target process to be traced. If
the process executing this function does not have appropriate
privileges to trace the process identified by pid, an error shall
be returned. If the pid argument is zero, the calling process
shall be traced.
The posix_trace_create() function shall store the trace stream
identifier of the new trace stream in the object pointed to by
the trid argument. This trace stream identifier shall be used in
subsequent calls to control tracing. The trid argument may only
be used by the following functions:
posix_trace_clear() posix_trace_getnext_event()
posix_trace_eventid_equal() posix_trace_shutdown()
posix_trace_eventid_get_name() posix_trace_start()
posix_trace_eventtypelist_getnext_id() posix_trace_stop()
posix_trace_eventtypelist_rewind() posix_trace_timedgetnext_event()
posix_trace_get_attr() posix_trace_trid_eventid_open()
posix_trace_get_status() posix_trace_trygetnext_event()
If the Trace Event Filter option is supported, the following
additional functions may use the trid argument:
posix_trace_get_filter() posix_trace_set_filter()
In particular, notice that the operations normally used by a
trace analyzer process, such as posix_trace_rewind() or
posix_trace_close(), cannot be invoked using the trace stream
identifier returned by the posix_trace_create() function.
A trace stream shall be created in a suspended state. If the
Trace Event Filter option is supported, its trace event type
filter shall be empty.
The posix_trace_create() function may be called multiple times
from the same or different processes, with the system-wide limit
indicated by the runtime invariant value {TRACE_SYS_MAX}, which
has the minimum value {_POSIX_TRACE_SYS_MAX}.
The trace stream identifier returned by the posix_trace_create()
function in the argument pointed to by trid is valid only in the
process that made the function call. If it is used from another
process, that is a child process, in functions defined in
POSIX.1‐2008, these functions shall return with the error
[EINVAL].
The posix_trace_create_withlog() function shall be equivalent to
posix_trace_create(), except that it associates a trace log with
this stream. The file_desc argument shall be the file descriptor
designating the trace log destination. The function shall fail if
this file descriptor refers to a file with a file type that is
not compatible with the log policy associated with the trace log.
The list of the appropriate file types that are compatible with
each log policy is implementation-defined.
The posix_trace_create_withlog() function shall return in the
parameter pointed to by trid the trace stream identifier, which
uniquely identifies the newly created trace stream, and shall be
used in subsequent calls to control tracing. The trid argument
may only be used by the following functions:
posix_trace_clear() posix_trace_get_status()
posix_trace_eventid_equal() posix_trace_getnext_event()
posix_trace_eventid_get_name() posix_trace_shutdown()
posix_trace_eventtypelist_getnext_id() posix_trace_start()
posix_trace_eventtypelist_rewind() posix_trace_stop()
posix_trace_flush() posix_trace_timedgetnext_event()
posix_trace_get_attr() posix_trace_trid_eventid_open()
If the Trace Event Filter option is supported, the following
additional functions may use the trid argument:
posix_trace_get_filter() posix_trace_set_filter()
In particular, notice that the operations normally used by a
trace analyzer process, such as posix_trace_rewind() or
posix_trace_close(), cannot be invoked using the trace stream
identifier returned by the posix_trace_create_withlog() function.
The posix_trace_flush() function shall initiate a flush operation
which copies the contents of the trace stream identified by the
argument trid into the trace log associated with the trace stream
at the creation time. If no trace log has been associated with
the trace stream pointed to by trid, this function shall return
an error. The termination of the flush operation can be polled by
the posix_trace_get_status() function. During the flush
operation, it shall be possible to trace new trace events up to
the point when the trace stream becomes full. After flushing is
completed, the space used by the flushed trace events shall be
available for tracing new trace events.
If flushing the trace stream causes the resulting trace log to
become full, the trace log full policy shall be applied. If the
trace log-full-policy attribute is set, the following occurs:
POSIX_TRACE_UNTIL_FULL
The trace events that have not yet been flushed shall be
discarded.
POSIX_TRACE_LOOP
The trace events that have not yet been flushed shall be
written to the beginning of the trace log, overwriting
previous trace events stored there.
POSIX_TRACE_APPEND
The trace events that have not yet been flushed shall be
appended to the trace log.
The posix_trace_shutdown() function shall stop the tracing of
trace events in the trace stream identified by trid, as if
posix_trace_stop() had been invoked. The posix_trace_shutdown()
function shall free all the resources associated with the trace
stream.
The posix_trace_shutdown() function shall not return until all
the resources associated with the trace stream have been freed.
When the posix_trace_shutdown() function returns, the trid
argument becomes an invalid trace stream identifier. A call to
this function shall unconditionally deallocate the resources
regardless of whether all trace events have been retrieved by the
analyzer process. Any thread blocked on one of the
trace_getnext_event() functions (which specified this trid)
before this call is unblocked with the error [EINVAL].
If the process exits, invokes a member of the exec family of
functions, or is terminated, the trace streams that the process
had created and that have not yet been shut down, shall be
automatically shut down as if an explicit call were made to the
posix_trace_shutdown() function.
For an active trace stream with log, when the
posix_trace_shutdown() function is called, all trace events that
have not yet been flushed to the trace log shall be flushed, as
in the posix_trace_flush() function, and the trace log shall be
closed.
When a trace log is closed, all the information that may be
retrieved later from the trace log through the trace interface
shall have been written to the trace log. This information
includes the trace attributes, the list of trace event types
(with the mapping between trace event names and trace event type
identifiers), and the trace status.
In addition, unspecified information shall be written to the
trace log to allow detection of a valid trace log during the
posix_trace_open() operation.
The posix_trace_shutdown() function shall not return until all
trace events have been flushed.
Возвращаемое значение (Return value)
Upon successful completion, these functions shall return a value
of zero. Otherwise, they shall return the corresponding error
number.
The posix_trace_create() and posix_trace_create_withlog()
functions store the trace stream identifier value in the object
pointed to by trid, if successful.
Ошибки (Error)
The posix_trace_create() and posix_trace_create_withlog()
functions shall fail if:
EAGAIN No more trace streams can be started now. {TRACE_SYS_MAX}
has been exceeded.
EINTR The operation was interrupted by a signal. No trace stream
was created.
EINVAL One or more of the trace parameters specified by the attr
parameter is invalid.
ENOMEM The implementation does not currently have sufficient
memory to create the trace stream with the specified
parameters.
EPERM The caller does not have appropriate privileges to trace
the process specified by pid.
ESRCH The pid argument does not refer to an existing process.
The posix_trace_create_withlog() function shall fail if:
EBADF The file_desc argument is not a valid file descriptor open
for writing.
EINVAL The file_desc argument refers to a file with a file type
that does not support the log policy associated with the
trace log.
ENOSPC No space left on device. The device corresponding to the
argument file_desc does not contain the space required to
create this trace log.
The posix_trace_flush() and posix_trace_shutdown() functions
shall fail if:
EINVAL The value of the trid argument does not correspond to an
active trace stream with log.
EFBIG The trace log file has attempted to exceed an
implementation-defined maximum file size.
ENOSPC No space left on device.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
The posix_trace_create(), posix_trace_create_withlog(),
posix_trace_flush(), and posix_trace_shutdown() functions may be
removed in a future version.
Смотри также (See also)
clock_getres(3p), exec(1p), posix_trace_attr_destroy(3p),
posix_trace_clear(3p), posix_trace_close(3p),
posix_trace_eventid_equal(3p),
posix_trace_eventtypelist_getnext_id(3p),
posix_trace_get_attr(3p), posix_trace_get_filter(3p),
posix_trace_getnext_event(3p), posix_trace_start(3p),
posix_trace_start(3p), time(3p)
The Base Definitions volume of POSIX.1‐2017, sys_types.h(0p),
trace.h(0p)
