feat(itkPipeline): add --threads flag

Common flag to specify the threads used by the pipeline, if supported.

Author: thewtex

include/itkPipeline.h

@@ -25,6 +25,13 @@
 #include "itkMacro.h"
 #include "itkImage.h"
 #include "itkVectorImage.h"
+#include "itkConfigure.h"
+#if defined(ITK_USE_PTHREADS) || defined(ITK_USE_WIN32_THREADS)
+#define ITK_WASM_PIPELINE_USE_THREADS 1
+#endif
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+#include "itkMultiThreaderBase.h"
+#endif
 
 #include "glaze/glaze.hpp"
 
@@ -164,6 +171,16 @@ class WebAssemblyInterface_EXPORT Pipeline : public CLI::App
     return m_UseMemoryIO;
   }
 
+  int
+  get_threads() const
+  {
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+    return m_Threads;
+#else
+    return 1;
+#endif
+  }
+
   int
   get_argc() const
   {
@@ -198,6 +215,9 @@ class WebAssemblyInterface_EXPORT Pipeline : public CLI::App
   int         m_argc;
   char **     m_argv;
   std::string m_Version;
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+  int         m_Threads;
+#endif
 };
 
 

src/itkPipeline.cxx

@@ -31,6 +31,9 @@ Pipeline ::Pipeline(std::string name, std::string description, int argc, char **
   , m_argc(argc)
   , m_argv(argv)
   , m_Version("0.1.0")
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+  , m_Threads(8)
+#endif
 {
   this->footer("Enjoy ITK!");
 
@@ -39,17 +42,39 @@ Pipeline ::Pipeline(std::string name, std::string description, int argc, char **
   this->add_flag("--memory-io", m_UseMemoryIO, "Use itk-wasm memory IO")->group("");
   this->set_version_flag("--version", m_Version);
 
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+  this->add_option("--threads", m_Threads, "Number of threads to use for processing")->group("");
+#endif
+
   // Set m_UseMemoryIO before it is used by other memory parsers
   this->preparse_callback([this](size_t arg) {
     m_UseMemoryIO = false;
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+    m_Threads = 8; // Reset to default
+#endif
     for (int ii = 0; ii < this->m_argc; ++ii)
     {
       const std::string arg(this->m_argv[ii]);
       if (arg == "--memory-io")
       {
         m_UseMemoryIO = true;
       }
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+      if (arg == "--threads" && ii + 1 < this->m_argc)
+      {
+        try {
+          m_Threads = std::stoi(this->m_argv[ii + 1]);
+        } catch (...) {
+          // Keep default value if parsing fails
+        }
+      }
+#endif
     }
+#ifdef ITK_WASM_PIPELINE_USE_THREADS
+    // Set ITK's global number of threads
+    itk::MultiThreaderBase::SetGlobalDefaultNumberOfThreads(m_Threads);
+    std::cout << "m_Threads: " << m_Threads << std::endl;
+#endif
   });
 
 #ifndef ITK_WASM_NO_FILESYSTEM_IO