kernel: Add check if the chainstate maanger is busy loading blocks

src/kernel/bitcoinkernel.cpp

@@ -1448,3 +1448,8 @@ kernel_Transaction* kernel_get_transaction_by_index(kernel_Block* block_, uint64
     return reinterpret_cast<kernel_Transaction*>(new CTransaction{*(**block).vtx[index]});
 }
 
+bool kernel_loading_blocks(kernel_ChainstateManager* chainman)
+{
+    return cast_chainstate_manager(chainman)->m_blockman.LoadingBlocks();
+}
+

src/kernel/bitcoinkernel.h

@@ -1389,6 +1389,17 @@ kernel_ByteArray* BITCOINKERNEL_WARN_UNUSED_RESULT kernel_copy_transaction_data(
     kernel_Transaction* transaction
 ) BITCOINKERNEL_ARG_NONNULL(1);
 
+/**
+ * @brief Check if the chainstate manager is busy loading blocks from disk. This
+ * may be the case when reindexing, or importing block files from disk.
+ *
+ * @param[in] chainman Non-null.
+ * @return             True if the chainstate manager is busy loading blocks.
+ */
+bool BITCOINKERNEL_WARN_UNUSED_RESULT kernel_loading_blocks(
+    kernel_ChainstateManager* chainman
+) BITCOINKERNEL_ARG_NONNULL(1);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus

src/kernel/bitcoinkernel_wrapper.h

@@ -756,6 +756,11 @@ class ChainMan
         return kernel_import_blocks(m_context.m_context.get(), m_chainman, c_paths.data(), c_paths.size());
     }
 
+    bool LoadingBlocks() const noexcept
+    {
+        return kernel_loading_blocks(m_chainman);
+    }
+
     bool ProcessBlockHeader(BlockHeader& header) const noexcept
     {
         return kernel_chainstate_manager_process_block_header(m_context.m_context.get(), m_chainman, header.m_block_header.get());

src/test/kernel/test_kernel.cpp

@@ -689,6 +689,7 @@ void chainman_reindex_chainstate_test(TestDirectory& test_directory)
     std::vector<std::string> import_files;
     import_files.push_back(test_directory.m_directory / "blocks" / "blk00000.dat");
     chainman->ImportBlocks(import_files);
+    assert(!chainman->LoadingBlocks());
 }
 
 int main()