NAME

       pmTimeConnect, pmTimeDisconnect, pmTimeRecv, pmTimeSendAck, pmTimeShowDialog - time control functions for
       synchronizing the archive position and update interval between one or more applications

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

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.

SEE ALSO

       pmtime(1), PMAPI(3) and pmSetMode(3).