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Altair FlowTracer Developer Guide
Runtime Change Propagation Control
The patented technique of Runtime Change Propagation Control (RCPC) provides the ability to stop the propagation of insignificant changes through the flow.
vovbarrier

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Altair FlowTracer Developer Guide
- FlowTracer Roles
  When using FlowTracer in large deployments, three main roles emerge: Administrator, Developer and User. In smaller organizations, a given person may have multiple roles, but the duties of each role still exist.
- Environment Management
  To ensure the correct and repeatable behavior of the tools, the environment must be controlled. This chapter explains how VOV supports multiple reusable environments.
- Execute Jobs From the Command Line
- Flowbuilding
  The trace is built using a combination of techniques.
- Flow Description Language (FDL)
- Tool Integration
- Integrate Difficult Tools
- Runtime Change Propagation Control
  The patented technique of Runtime Change Propagation Control (RCPC) provides the ability to stop the propagation of insignificant changes through the flow.
- Flow Library
  FlowTracer captures your design in design flows described by Flow.tcl files. The Flow Library is meant to help users locate and deploy instances of packaged flows bound to their specific design data.
- Files, Equivalences, Exclusions
  The files used in a project reside in one or more directories spread all around your filesystems. Each logical name defined in the equiv.tcl file implicitly declares the root of a workspace. You can browse the workspaces using the browser interface.
- Makefile Conversion
- Advanced Tasker Topics
- Resource Management
  The Resource Map Set represents the collection of resource maps that have been assigned to a project and the constraints associated with such resources.
- CGI Interface
- Events
  Every change in the trace is recorded as an event, which is then sent to all clients that subscribe to them.
- Miscellaneous

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vovbarrier

vovbarrier in shell scripts

While writing shell scripts, you may also find that the script vovbarrier may be useful. For example, the following code is also equivalent to a simple implementation of clevercopy:

#!/bin/csh -f
VovInput $1 || exit $status
vovbarrier $1 $2
exit $status

VovBarrier in C and C++

RCPC is implemented with the procedure VovBarrier() that has been added to VIL, and with the tool vovbarrier. In both cases, the key argument is the action to be performed on the barrier, which is either "STOP" or "PROPAGATE".

There are three options for a tool to control change propagation on one of its outputs:

Call VovBarrier( ..., "STOP"); This does not invalidate the fanouts of the output file immediately, allowing time to erect a barrier so the output file is not invalidated by invalidating this tool.
Call VovBarrier(..., "PROPAGATE"); This invalidates the fanouts of the output file immediately, but also erects a barrier so the output file won't be invalidated by invalidating this tool.
Do not call VovBarrier(...); This invalidates the fanouts of the output file immediately, allowing the file to be invalidated in the future if this tool is invalidated.