“Integration” is the term used by Perforce to describe the action of moving changes from one part of the depot to another. It is most commonly done in conjunction with creating and maintaining branches. An integration is done when you want to initially populate a branch, and it is done when you want to move subsequent changes in the branch from the parent to the child, or from the child to the parent. A common example of this is periodically integrating changes from the vendor FreeBSD tree to your child branch tree, allowing you to keep up to date with changes in the FreeBSD tree. The Perforce server tracks the changes in each tree and knows when there are changes that can be integrated from one tree to another.

The common way to do an integration is with the following command:

% p4 integrate -b branchname

branchname is the name given to a branch spec, as discussed in the previous section. This command will instruct Perforce to look for changes in the branch parent that are not yet in the child. From those changes it will prepare a list of diffs to move. If the integration is being done for the first time on a branch (for example doing an initial population operation), then the parent files will simply be copied to the child location on the local machine.

Once the integration operation is done, you must run p4 resolve to accept the changes and resolve possible conflicts. Conflicts can arise from overlapping changes that happened in both the parent and child copy of a file. Usually, however, there are no conflicts, and Perforce can quickly figure out how to merge the changes together. Use the following commands to do a resolve operation:

% p4 resolve -as
% p4 resolve

The first invocation will instruct Perforce to automatically merge the changes together and accept files that have no conflicts. The second invocation will allow you to inspect each file that has a possible conflict and resolve it by hand if needed.

Once all of the integrated files have been resolved, they need to be committed back to the repository. This is done via p4 submit, explained in the next section.