cmCPackArchiveGenerator: support multithreaded compression

4 files changed, 38 insertions, 0 deletions

diff --git a/Help/cpack_gen/archive.rst b/Help/cpack_gen/archive.rst
index e9904ae..3656aa2 100644
--- a/Help/cpack_gen/archive.rst
+++ b/Help/cpack_gen/archive.rst
@@ -51,3 +51,25 @@ Variables specific to CPack Archive generator
   Enable component packaging. If enabled (ON), then the archive generator
   creates  multiple packages. The default is OFF, which means that a single
   package containing files of all components is generated.
+
+Variables used by CPack Archive generator
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These variables are used by the Archive generator, but are also available to
+CPack generators which are essentially archives at their core. These include:
+
+  - :cpack_gen:`CPack Cygwin Generator`
+  - :cpack_gen:`CPack FreeBSD Generator`
+
+.. variable:: CPACK_ARCHIVE_THREADS
+
+  The number of threads to use when performing the compression. If set to
+  ``0``, the number of available cores on the machine will be used instead.
+  The default is ``1`` which limits compression to a single thread. Note that
+  not all compression modes support threading in all environments. Currently,
+  only the XZ compression may support it.
+
+.. note::
+
+    Official CMake binaries available on ``cmake.org`` ship with a ``liblzma``
+    that does not support parallel compression.
diff --git a/Help/cpack_gen/cygwin.rst b/Help/cpack_gen/cygwin.rst
index 1c5f7af..c65653e 100644
--- a/Help/cpack_gen/cygwin.rst
+++ b/Help/cpack_gen/cygwin.rst
@@ -3,6 +3,11 @@ CPack Cygwin Generator
 
 Cygwin CPack generator (Cygwin).
 
+Variables affecting the CPack Cygwin generator
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  - :variable:`CPACK_ARCHIVE_THREADS`
+
 Variables specific to CPack Cygwin generator
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/Help/cpack_gen/freebsd.rst b/Help/cpack_gen/freebsd.rst
index a8dd320..47a7784 100644
--- a/Help/cpack_gen/freebsd.rst
+++ b/Help/cpack_gen/freebsd.rst
@@ -3,6 +3,11 @@ CPack FreeBSD Generator
 
 The built in (binary) CPack FreeBSD (pkg) generator (Unix only)
 
+Variables affecting the CPack FreeBSD (pkg) generator
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  - :variable:`CPACK_ARCHIVE_THREADS`
+
 Variables specific to CPack FreeBSD (pkg) generator
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/Help/release/dev/parallel-lzma-compression.rst b/Help/release/dev/parallel-lzma-compression.rst
new file mode 100644
index 0000000..12b7102
--- /dev/null
+++ b/Help/release/dev/parallel-lzma-compression.rst
@@ -0,0 +1,6 @@
+parallel-lzma-compression
+-------------------------
+
+* The :cpack_gen:`CPack Archive Generator`'s ``TXZ`` format learned the
+  :variable:`CPACK_ARCHIVE_THREADS` variable to enable parallel compression.
+  Requires support in the ``liblzma`` used by CMake.