Merge topic 'cpack-zstd-parallel'

525faec4e9 CPack: Add parallel zstd compression
215c4efd3e cmArchiveWrite: Factor out thread count selection
29f63129be CPack: Format CPACK_THREADS compression methods as a definition list

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !7003

3 files changed, 57 insertions, 31 deletions

diff --git a/Help/release/dev/cpack-zstd-parallel.rst b/Help/release/dev/cpack-zstd-parallel.rst
new file mode 100644
index 0000000..da22625
--- /dev/null
+++ b/Help/release/dev/cpack-zstd-parallel.rst
@@ -0,0 +1,6 @@
+cpack-zstd-parallel
+-------------------
+
+* CPack now supports the :variable:`CPACK_THREADS` option for ``zstd``
+  compression when compiled with libarchive 3.6 or higher.  It is
+  supported by official CMake binaries available on ``cmake.org``.
diff --git a/Modules/CPack.cmake b/Modules/CPack.cmake
index 6650f7c..5a22be5 100644
--- a/Modules/CPack.cmake
+++ b/Modules/CPack.cmake
@@ -304,14 +304,25 @@ installers.  The most commonly-used variables are:
 
   By default ``CPACK_THREADS`` is set to ``1``.
 
-  Currently only ``xz`` compression *may* take advantage of multiple cores.
-  Other compression methods ignore this value and use only one thread.
+  The following compression methods may take advantage of multiple cores:
+
+  ``xz``
+    Supported if CMake is built with a ``liblzma`` that supports
+    parallel compression.
+
+    .. versionadded:: 3.21
 
-  .. versionadded:: 3.21
+      Official CMake binaries available on ``cmake.org`` now ship
+      with a ``liblzma`` that supports parallel compression.
+      Older versions did not.
 
-    Official CMake binaries available on ``cmake.org`` now ship
-    with a ``liblzma`` that supports parallel compression.
-    Older versions did not.
+  ``zstd``
+    .. versionadded:: 3.24
+
+    Supported if CMake is built with libarchive 3.6 or higher.
+    Official CMake binaries available on ``cmake.org`` support it.
+
+  Other compression methods ignore this value and use only one thread.
 
 Variables for Source Package Generators
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/Source/cmArchiveWrite.cxx b/Source/cmArchiveWrite.cxx
index 9e0d80c..cfde37c 100644
--- a/Source/cmArchiveWrite.cxx
+++ b/Source/cmArchiveWrite.cxx
@@ -95,6 +95,19 @@ cmArchiveWrite::cmArchiveWrite(std::ostream& os, Compress c,
   , Verbose(false)
   , Format(format)
 {
+  // Upstream fixed an issue with their integer parsing in 3.4.0
+  // which would cause spurious errors to be raised from `strtoull`.
+
+  if (numThreads < 1) {
+    int upperLimit = (numThreads == 0) ? std::numeric_limits<int>::max()
+                                       : std::abs(numThreads);
+
+    numThreads =
+      cm::clamp<int>(std::thread::hardware_concurrency(), 1, upperLimit);
+  }
+
+  std::string sNumThreads = std::to_string(numThreads);
+
   switch (c) {
     case CompressNone:
       if (archive_write_add_filter_none(this->Archive) != ARCHIVE_OK) {
@@ -150,36 +163,23 @@ cmArchiveWrite::cmArchiveWrite(std::ostream& os, Compress c,
         return;
       }
 
-      {
 #if ARCHIVE_VERSION_NUMBER >= 3004000
-        // Upstream fixed an issue with their integer parsing in 3.4.0
-        // which would cause spurious errors to be raised from `strtoull`.
-
-        if (numThreads < 1) {
-          int upperLimit = (numThreads == 0) ? std::numeric_limits<int>::max()
-                                             : std::abs(numThreads);
-
-          numThreads =
-            cm::clamp<int>(std::thread::hardware_concurrency(), 1, upperLimit);
-        }
 
 #  ifdef _AIX
-        // FIXME: Using more than 2 threads creates an empty archive.
-        // Enforce this limit pending further investigation.
-        numThreads = std::min(numThreads, 2);
+      // FIXME: Using more than 2 threads creates an empty archive.
+      // Enforce this limit pending further investigation.
+      if (numThreads > 2) {
+        numThreads = 2;
+        sNumThreads = std::to_string(numThreads);
+      }
 #  endif
-
-        std::string sNumThreads = std::to_string(numThreads);
-
-        if (archive_write_set_filter_option(this->Archive, "xz", "threads",
-                                            sNumThreads.c_str()) !=
-            ARCHIVE_OK) {
-          this->Error = cmStrCat("archive_compressor_xz_options: ",
-                                 cm_archive_error_string(this->Archive));
-          return;
-        }
-#endif
+      if (archive_write_set_filter_option(this->Archive, "xz", "threads",
+                                          sNumThreads.c_str()) != ARCHIVE_OK) {
+        this->Error = cmStrCat("archive_compressor_xz_options: ",
+                               cm_archive_error_string(this->Archive));
+        return;
       }
+#endif
 
       break;
     case CompressZstd:
@@ -188,6 +188,15 @@ cmArchiveWrite::cmArchiveWrite(std::ostream& os, Compress c,
                                cm_archive_error_string(this->Archive));
         return;
       }
+
+#if ARCHIVE_VERSION_NUMBER >= 3006000
+      if (archive_write_set_filter_option(this->Archive, "zstd", "threads",
+                                          sNumThreads.c_str()) != ARCHIVE_OK) {
+        this->Error = cmStrCat("archive_compressor_zstd_options: ",
+                               cm_archive_error_string(this->Archive));
+        return;
+      }
+#endif
       break;
   }