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Configuration-sync.cfg.md

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sync.cfg is a configuration file that contains information that can change, when switching between master and slave hosts. Eg. eodMng process uses this file to determine master and slave hosts (via cfg.eodOrder field). If master site fails, one can easily revert synchronisation order, just by modifying sync.cfg contents of system.cfg:

...
[group:kdb]
  [[core.eodMng]]
    type = q:eodMng
    qsd = eodMng.qsd
   ...
   .cfg.eodMngList = ((eodMng(core.eodMng), hdb(core.hdb), rdb(core.rdb)),
                     (eodMng(prod2.eodMng), hdb(prod2.hdb), rdb(prod2.rdb))) 
   ...

Content of sync.cfg:

[group:kdb]
  [[core.eodMng]]
    cfg.eodOrder = core.eodMng, prod2.eodMng

During each end-of-day, eodMng process reads sync.cfg and refreshes value of .cfg.eodOrder. If one wants to revert order of hosts, .cfg.eodOrder needs to be changed:

[group:kdb]
  [[core.eodMng]]
    .cfg.eodOrder = prod2.eodMng, core.eodMng

Change will be visible for eodMng during nearest end-of-day.

sync.cfg interface

Variables used in sync.cfg are defined in regular qsd files. The only difference is that sync.cfg variables have special validator syncOnly():

cfg.eodOrder = <type(LIST SYMBOL), isComponent(), syncOnly()>

Such validator marks variable to be defined in sync.cfg (instead of system.cfg). These variables can be defined only in sync.cfg – definig them in any other config file will result in error message.

cfgRdr provides following interface functions to use sync.cfg:

Function Notes
.cr.loadSyncCfg[] Loads sync.cfg. This function can be called every time the file was changed
.cr.getSyncCfgField[serviceId;section;field] Gets field value from sync.cfg. Arguments and result of this function are exactly the same as in .cr.getCfgField