project: Use dicts to keep track of copyfiles and linkfiles

This avoids copying/linking the same file/link multiple times if a
copyfile/linkfile element with the same values has been specifed
multiple times. This can happen when including a common manifest that
uses an extend-project element that has a copyfile/linkfile element.

This uses dicts rather than sets to store the copyfiles and linkfiles to
make sure the order they are specified in the manifest is maintained.
For Python 3.7+, maintaining the order that keys are added to dicts is
guaranteed, and for Python 3.6 it happened to be true.

The _CopyFile class and the _LinkFile class are changed to inherit from
NamedTuple to be able to store them in dicts.

Change-Id: I9f5a80298b875251a81c5fe7d353e262d104fae4
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/525322
Reviewed-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Tested-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Commit-Queue: Peter Kjellerstedt <peter.kjellerstedt@axis.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/docs/manifest-format.md b/docs/manifest-format.md
index d1a11cc9..42e1ab18 100644
--- a/docs/manifest-format.md
+++ b/docs/manifest-format.md
@@ -453,10 +453,14 @@ Intermediate paths must not be symlinks either.
 
 Parent directories of "dest" will be automatically created if missing.
 
+The files are copied in the order they are specified in the manifests.
+If multiple elements specify the same source and destination, they will
+only be applied as one, based on the first occurence. Files are copied
+before any links specified via linkfile elements are created.
+
 ### Element linkfile
 
-It's just like copyfile and runs at the same time as copyfile but
-instead of copying it creates a symlink.
+It's just like copyfile, but instead of copying it creates a symlink.
 
 The symlink is created at "dest" (relative to the top of the tree) and
 points to the path specified by "src" which is a path in the project.
@@ -466,6 +470,11 @@ Parent directories of "dest" will be automatically created if missing.
 The symlink target may be a file or directory, but it may not point outside
 of the repo client.
 
+The links are created in the order they are specified in the manifests.
+If multiple elements specify the same source and destination, they will
+only be applied as one, based on the first occurence. Links are created
+after any files specified via copyfile elements are copied.
+
 ### Element remove-project
 
 Deletes a project from the internal manifest table, possibly