Dedicated result/error handling

taocpp · Dec 17, 2024 · e902534 · e902534
1 parent 3225097
commit e902534
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Showing 5 changed files with 41 additions and 22 deletions.
diff --git a/include/tao/pq/connection.hpp b/include/tao/pq/connection.hpp
@@ -87,13 +87,15 @@ namespace tao::pq
       void cancel();
 
       [[nodiscard]] auto get_result( const std::chrono::steady_clock::time_point end ) -> std::unique_ptr< PGresult, decltype( &PQclear ) >;
+      [[nodiscard]] auto get_fatal_error( const std::chrono::steady_clock::time_point end ) -> std::unique_ptr< PGresult, decltype( &PQclear ) >;
+      void consume_empty_result( const std::chrono::steady_clock::time_point end );
+
       [[nodiscard]] auto get_copy_data( char*& buffer, const std::chrono::steady_clock::time_point end ) -> std::size_t;
       [[nodiscard]] auto get_copy_data( char*& buffer ) -> std::size_t;
 
       void put_copy_data( const char* buffer, const std::size_t size );
       void put_copy_end( const char* error_message = nullptr );
 
-      void clear_results( const std::chrono::steady_clock::time_point end );
       void clear_copy_data( const std::chrono::steady_clock::time_point end );
 
       // pass-key idiom

diff --git a/src/lib/pq/connection.cpp b/src/lib/pq/connection.cpp
@@ -301,6 +301,29 @@ namespace tao::pq
       return result;
    }
 
+   auto connection::get_fatal_error( const std::chrono::steady_clock::time_point end ) -> std::unique_ptr< PGresult, decltype( &PQclear ) >
+   {
+      auto result = connection::get_result( end );
+      if( !result ) {
+         throw std::runtime_error( "unable to obtain result" );
+      }
+
+      const auto status = PQresultStatus( result.get() );
+      if( status != PGRES_FATAL_ERROR ) {
+         throw std::runtime_error( std::format( "unexpected result status: {}", PQresStatus( status ) ) );
+      }
+
+      return result;
+   }
+
+   void connection::consume_empty_result( const std::chrono::steady_clock::time_point end )
+   {
+      if( const auto result = connection::get_result( end ) ) {
+         const auto status = PQresultStatus( result.get() );
+         throw std::runtime_error( std::format( "unexpected result status: {}", PQresStatus( status ) ) );
+      }
+   }
+
    auto connection::get_copy_data( char*& buffer, const std::chrono::steady_clock::time_point end ) -> std::size_t
    {
       while( true ) {
@@ -378,12 +401,6 @@ namespace tao::pq
       }
    }
 
-   void connection::clear_results( const std::chrono::steady_clock::time_point end )
-   {
-      while( connection::get_result( end ) ) {
-      }
-   }
-
    void connection::clear_copy_data( const std::chrono::steady_clock::time_point end )
    {
       char* ptr;
@@ -540,7 +557,7 @@ namespace tao::pq
       const auto result = connection::get_result( end );
       switch( PQresultStatus( result.get() ) ) {
          case PGRES_COMMAND_OK:
-            connection::clear_results( end );
+            connection::consume_empty_result( end );
             break;
 
          case PGRES_TUPLES_OK:
@@ -550,7 +567,7 @@ namespace tao::pq
             TAO_PQ_INTERNAL_UNREACHABLE;  // LCOV_EXCL_LINE
 
          default:
-            connection::clear_results( end );
+            connection::consume_empty_result( end );
             internal::throw_sqlstate( result.get() );
       }
 

diff --git a/src/lib/pq/table_reader.cpp b/src/lib/pq/table_reader.cpp
@@ -36,15 +36,15 @@ namespace tao::pq
 
          case PGRES_COMMAND_OK:
          case PGRES_TUPLES_OK:
-            m_transaction->connection()->clear_results( end );
+            m_transaction->connection()->consume_empty_result( end );
             throw std::runtime_error( "expected COPY TO statement" );
 
          case PGRES_EMPTY_QUERY:
-            m_transaction->connection()->clear_results( end );
+            m_transaction->connection()->consume_empty_result( end );
             throw std::runtime_error( "unexpected empty query" );
 
          default:
-            m_transaction->connection()->clear_results( end );
+            m_transaction->connection()->consume_empty_result( end );
             internal::throw_sqlstate( result.get() );
       }
    }

diff --git a/src/lib/pq/table_writer.cpp b/src/lib/pq/table_writer.cpp
@@ -33,28 +33,29 @@ namespace tao::pq
    void table_writer::check_result()
    {
       const auto end = m_transaction->connection()->timeout_end();
-      auto result = m_transaction->connection()->get_result( end );
+      const auto result = m_transaction->connection()->get_result( end );
       switch( PQresultStatus( result.get() ) ) {
          case PGRES_COPY_IN:
             break;
 
          case PGRES_COPY_OUT:
             m_transaction->connection()->cancel();
             m_transaction->connection()->clear_copy_data( end );
-            m_transaction->connection()->clear_results( end );
+            std::ignore = m_transaction->connection()->get_fatal_error( end );
+            m_transaction->connection()->consume_empty_result( end );
             throw std::runtime_error( "unexpected COPY TO statement" );
 
          case PGRES_COMMAND_OK:
          case PGRES_TUPLES_OK:
-            m_transaction->connection()->clear_results( end );
+            m_transaction->connection()->consume_empty_result( end );
             throw std::runtime_error( "expected COPY FROM statement" );
 
          case PGRES_EMPTY_QUERY:
-            m_transaction->connection()->clear_results( end );
+            m_transaction->connection()->consume_empty_result( end );
             throw std::runtime_error( "unexpected empty query" );
 
          default:
-            m_transaction->connection()->clear_results( end );
+            m_transaction->connection()->consume_empty_result( end );
             internal::throw_sqlstate( result.get() );
       }
    }

diff --git a/src/lib/pq/transaction.cpp b/src/lib/pq/transaction.cpp
@@ -173,12 +173,14 @@ namespace tao::pq
       switch( PQresultStatus( result.get() ) ) {
          case PGRES_COPY_IN:
             m_connection->put_copy_end( "unexpected COPY FROM statement" );
+            result = m_connection->get_fatal_error( end );
             break;
 
          case PGRES_COPY_OUT:
             m_connection->cancel();
             m_connection->clear_copy_data( end );
-            m_connection->clear_results( end );
+            std::ignore = m_connection->get_fatal_error( end );
+            m_connection->consume_empty_result( end );
             throw std::runtime_error( "unexpected COPY TO statement" );
 
          case PGRES_SINGLE_TUPLE:
@@ -190,10 +192,7 @@ namespace tao::pq
          default:;
       }
 
-      while( auto next = m_connection->get_result( end ) ) {
-         result = std::move( next );
-      }
-
+      m_connection->consume_empty_result( end );
       return pq::result( result.release() );
    }