Fix: Python API: bpy.app.is_job_running('SHADER_COMPILATION')

Shader compilation no longer uses the `WM_job` API.
Add a `GPU_shader_batch_is_compiling` function to query if there's any
shader compilation happening, and update `bpy_app_is_job_running` to
handle this as a special case.

Pull Request: https://projects.blender.org/blender/blender/pulls/143559

source/blender/gpu/GPU_shader.hh

@@ -109,6 +109,10 @@ blender::Vector<GPUShader *> GPU_shader_batch_finalize(BatchHandle &handle);
  * WARNING: The handle will be invalidated by this call.
  */
 void GPU_shader_batch_cancel(BatchHandle &handle);
+/**
+ *  Returns true if there's any batch still being compiled.
+ */
+bool GPU_shader_batch_is_compiling();
 /**
  *  Wait until all the requested batches have been compiled.
  */

source/blender/gpu/intern/gpu_shader.cc

@@ -393,6 +393,11 @@ void GPU_shader_batch_cancel(BatchHandle &handle)
   GPUBackend::get()->get_compiler()->batch_cancel(handle);
 }
 
+bool GPU_shader_batch_is_compiling()
+{
+  return GPUBackend::get()->get_compiler()->is_compiling();
+}
+
 void GPU_shader_batch_wait_for_all()
 {
   GPUBackend::get()->get_compiler()->wait_for_all();
@@ -1170,22 +1175,34 @@ void ShaderCompiler::do_work(void *work_payload)
   compilation_finished_notification_.notify_all();
 }
 
+bool ShaderCompiler::is_compiling_impl()
+{
+  /* The mutex should be locked befor calling this function. */
+  BLI_assert(!mutex_.try_lock());
+
+  if (!compilation_queue_.is_empty()) {
+    return true;
+  }
+
+  for (Batch *batch : batches_.values()) {
+    if (!batch->is_ready()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool ShaderCompiler::is_compiling()
+{
+  std::unique_lock lock(mutex_);
+  return is_compiling_impl();
+}
+
 void ShaderCompiler::wait_for_all()
 {
   std::unique_lock lock(mutex_);
-  compilation_finished_notification_.wait(lock, [&]() {
-    if (!compilation_queue_.is_empty()) {
-      return false;
-    }
-
-    for (Batch *batch : batches_.values()) {
-      if (!batch->is_ready()) {
-        return false;
-      }
-    }
-
-    return true;
-  });
+  compilation_finished_notification_.wait(lock, [&]() { return !is_compiling_impl(); });
 }
 
 /** \} */

source/blender/gpu/intern/gpu_shader_private.hh

@@ -270,6 +270,8 @@ class ShaderCompiler {
 
   BatchHandle next_batch_handle_ = 1;
 
+  bool is_compiling_impl();
+
  protected:
   /* Must be called earlier from the destructor of the subclass if the compilation process relies
    * on subclass resources. */
@@ -300,6 +302,7 @@ class ShaderCompiler {
 
   bool specialization_batch_is_ready(SpecializationBatchHandle &handle);
 
+  bool is_compiling();
   void wait_for_all();
 };
 

source/blender/python/intern/bpy_app.cc

@@ -42,6 +42,8 @@
 #include "BKE_global.hh"
 #include "BKE_main.hh"
 
+#include "GPU_shader.hh"
+
 #include "UI_interface_icons.hh"
 
 #include "MEM_guardedalloc.h"
@@ -595,6 +597,11 @@ static PyObject *bpy_app_is_job_running(PyObject * /*self*/, PyObject *args, PyO
     return nullptr;
   }
   wmWindowManager *wm = static_cast<wmWindowManager *>(G_MAIN->wm.first);
+  if (job_type_enum.value == WM_JOB_TYPE_SHADER_COMPILATION) {
+    /* Shader compilation no longer uses the WM_job API, so we handle this as a special case
+     * to avoid breaking the Python API. */
+    return PyBool_FromLong(GPU_shader_batch_is_compiling());
+  }
   return PyBool_FromLong(WM_jobs_has_running_type(wm, job_type_enum.value));
 }