|1. Metadata Scanning||
Before anything else can happen, vcp must take the source repository
spec, something like cvs:module/dir/... and use the appropriate
repository interface (cvs log in this case) to extract the metadata.
The metadata is currently kept all in memory; if you run in to a repository so big that this is troublesome, do the transfer in phases or pester us to provide a swap file capability for this data.
In the case of a RevML source, it is not practical to scan the input for metadata alone (the RevML may be coming from the standard input, for instance), so all of the files in a RevML source file are extracted during the scanning phase, as mentioned in VCP::Source::revml.
|2. Sorting and Change Aggregation||
The order that the soruce repository presents revisions in is often not
the order they need to be inserted in, so the destination driver
(VCP::Dest::p4, for example) is given the opportunity to sort the
This is primarily used to do change number aggregation when converting from a repository that does not provide change set metadata (like CVS) to one that does (like p4).
This is also important when generating RevML files because the order of appearance of files in a log file may hinge on exactly when the files were inserted along with their names, at least in the case of CVS. Sorting the revisions provides for consistent RevML files, which is important in testing situations.
|3. File transfer.||
The final stage is to do the file transfer. When the entire source file
is available, it is simply added to the result repository in the correct
For incremental transfers an extra step is taken to ensure that incremental transfers leave no gaps. The base revision is backfilled from the destination repository (using the process for backfilling described in phase 1 above) and compared to the base revision from the source repository.
Currently, vcp shells out to command line tools like cvs and p4. This is a least common denominator approach that allows VCP to operate at a safe distance from the underlying implementations. It is also the primary bottleneck in transferring files. We will gladly accept donations of drivers that use direct library interfaces or remote procedure call (SOAP, RMI, etc., etc.) techniques to speed this process up.
Barrie Slaymaker <email@example.com>
Copyright (c) 2000, 2001, 2002 Perforce Software, Inc. All rights reserved.
|perl v5.20.3||VCP::PROCESS (3)||2004-11-04|