Use backend delegates for work vectors

Author: zatkins-dev

interface/ceed.c

@@ -28,7 +28,7 @@ static struct {
 } backends[32];
 static size_t num_backends;
 
-#define CEED_FTABLE_ENTRY(class, method) {#class #method, offsetof(struct class##_private, method)}
+#define CEED_FTABLE_ENTRY(class, method) { #class #method, offsetof(struct class##_private, method) }
 /// @endcond
 
 /// @file
@@ -858,7 +858,7 @@ int CeedClearWorkVectors(Ceed ceed, CeedSize min_len) {
     CeedSize vec_len;
     CeedCall(CeedVectorGetLength(ceed->work_vectors->vecs[i], &vec_len));
     if (vec_len < min_len) {
-      ceed->ref_count += 2;  // Note: increase ref_count to prevent Ceed destructor from triggering
+      ceed->ref_count += 2;  // Note: increase ref_count to prevent Ceed destructor from triggering again
       CeedCall(CeedVectorDestroy(&ceed->work_vectors->vecs[i]));
       ceed->ref_count -= 1;  // Note: restore ref_count
       ceed->work_vectors->num_vecs--;
@@ -890,6 +890,16 @@ int CeedGetWorkVector(Ceed ceed, CeedSize len, CeedVector *vec) {
   CeedInt    i = 0;
   CeedScalar usage_mb;
 
+  if (!ceed->VectorCreate) {
+    Ceed delegate;
+
+    CeedCall(CeedGetObjectDelegate(ceed, &delegate, "Vector"));
+    CeedCheck(delegate, ceed, CEED_ERROR_UNSUPPORTED, "Backend does not implement VectorCreate");
+    CeedCall(CeedGetWorkVector(delegate, len, vec));
+    CeedCall(CeedDestroy(&delegate));
+    return CEED_ERROR_SUCCESS;
+  }
+
   if (!ceed->work_vectors) CeedCall(CeedWorkVectorsCreate(ceed));
 
   // Search for big enough work vector
@@ -936,6 +946,16 @@ int CeedGetWorkVector(Ceed ceed, CeedSize len, CeedVector *vec) {
   @ref Backend
 **/
 int CeedRestoreWorkVector(Ceed ceed, CeedVector *vec) {
+  if (!ceed->VectorCreate) {
+    Ceed delegate;
+
+    CeedCall(CeedGetObjectDelegate(ceed, &delegate, "Vector"));
+    CeedCheck(delegate, ceed, CEED_ERROR_UNSUPPORTED, "Backend does not implement VectorCreate");
+    CeedCall(CeedRestoreWorkVector(delegate, vec));
+    CeedCall(CeedDestroy(&delegate));
+    return CEED_ERROR_SUCCESS;
+  }
+
   for (CeedInt i = 0; i < ceed->work_vectors->num_vecs; i++) {
     if (*vec == ceed->work_vectors->vecs[i]) {
       CeedCheck(ceed->work_vectors->is_in_use[i], ceed, CEED_ERROR_ACCESS, "Work vector %" CeedSize_FMT " was not checked out but is being returned");