функции управления временем для синхронизации положения в архиве и интервала обновления между одним или несколькими приложениями (time control functions for synchronizing the archive position and update interval between one or more applications)
Имя (Name)
pmTimeConnect, pmTimeDisconnect, pmTimeRecv, pmTimeSendAck,
pmTimeShowDialog - time control functions for synchronizing the
archive position and update interval between one or more
applications
Синопсис C (C Synopsis)
#include <pcp/pmtime.h>
int pmTimeConnect(int port, pmTime *state);
int pmTimeDisconnect(int fd);
int pmTimeSendAck(int fd, struct timeval *fetchTime);
int pmTimeShowDialog(int fd, int show);
int pmTimeRecv(int fd, pmTime *state);
cc ... -lpcp_gui
Описание (Description)
These functions form part of the Performance Metrics Applications
Programming Interface (PMAPI) and are intended to provide a
uniform mechanism for applications to both replay archive data
and report live data in a time synchronized manner.
The pmTime structure has the following fields:
typedef struct {
unsigned int magic;
unsigned int length;
pm_tctl_command command;
pm_tctl_source source;
pm_tctl_state state;
pm_tctl_mode mode;
struct timeval delta;
struct timeval position;
struct timeval start; /* archive only */
struct timeval end; /* archive only */
char data[0]; /* arbitrary length info (TZ) */
} pmTime;
In the simplest case, the application should call pmTimeConnect
to connect to the time control server, pmtime(1), and then
repeatedly call pmTimeRecv in the main loop of the application.
On success, pmTimeConnect returns a non-negative file descriptor.
In applications which have multiple threads of control, rather
than simply blocking in pmTimeRecv, the file descriptor may be
used in calls to select(2). In graphical applications, the file
descriptor may be used to interface with the event loop.
The port parameter to pmTimeConnect is the port number of the
socket on which the time control server is (or will be) listening
for new connections.
The state parameter to pmTimeConnect is used to initialize a new
time control server or to pass additional information to an
existing time control server. The start and finish fields
indicate the chronological bounds interesting to the application.
The showdialog field indicates whether the time control server
should initially show or hide the dialog. The position, delta,
and data fields indicate the initial archive position, update
interval, time zone string and time zone label string.
pmTimeRecv blocks until the time control server sends a command
message. It then updates the state parameter and returns one of
the PM_TCTL command identifiers.
The PM_TCTL_SET command indicates the application should seek to
the archive position (see pmSetMode(3)) returned in the position
field of the state parameter.
The PM_TCTL_STEP command indicates the application should perform
an update, i.e. advance (or rewind, if delta is negative) to the
time indicated by position and then fetch new metric values,
update the display or whatever. In order for several application
to remain synchronized, the time control server will wait until
all applications have acknowledged that they have completed the
step command. Applications should call pmTimeSendAck when the
step command has been processed. Note that PM_TCTL_STEP is the
only command that requires an explicit acknowledgement.
The PM_TCTL_VCRMODE command is used by the time control server to
indicate the current VCR mode.
The value is returned in the vcrmode field of the state parameter
passed to pmTimeRecv, and remains valid until the next
PM_TCTL_VCRMODE command is received.
The PM_TCTL_TZ command indicates the application should use a new
time- zone, as indicated in the tz and tzlabel fields of the
state parameter.
The PM_TCTL_BOUNDS command is sent to all applications when the
time control server changes its chronological bounds. This may
occur when a new application connects to the time control server
or the user changes the bounds manually. Most applications will
ignore this command.
The PM_TCTL_SHOWDIALOG command will be sent to all applications
when the visibility of the time control server changes. This
allows applications to alter the text in menus or buttons to
reflect this change. Applications may change the visibility of
the time control dialog using the pmTimeShowDialog function. The
initial visibility is determined when the time control dialog is
first created by an application calling pmTimeConnect with the
showdialog field in the state parameter set to the desired value.
The pmTimeDisconnect function may be used to close the command
socket to the time control server. This is useful when
applications need to change the connection mode, e.g. to divorce
the current time control server and connect to a new one.
Смотри также (See also)
pmtime(1), PMAPI(3) and pmSetMode(3).
