Method __call_reducer__

crates/bindings-cpp/src/internal/Module.cpp:461–516

}

Status Module::__call_reducer__(
    uint32_t id,
    uint64_t sender_0, uint64_t sender_1, uint64_t sender_2, uint64_t sender_3,
    uint64_t conn_id_0, uint64_t conn_id_1,
    Timestamp timestamp,
    BytesSource args_source,
    BytesSink error_sink
) {
    // Clear any previous error state
    SpacetimeDB::Internal::clear_reducer_error();

    // Check if reducer ID is valid
    if (id >= g_reducer_handlers.size()) {
        fprintf(stderr, "ERROR: Invalid reducer ID %u (have %zu reducers)\n", 
                id, g_reducer_handlers.size());
        
        // Write error message
        std::string error = "Invalid reducer ID: " + std::to_string(id);
        WriteBytes(error_sink, std::vector<uint8_t>(error.begin(), error.end()));
        return StatusCode::NO_SUCH_REDUCER;
    }
    
    // Create reducer context
    std::array<uint8_t, 32> sender_bytes{};
    // Pack the 4 uint64_t parts into 32 bytes
    std::memcpy(sender_bytes.data(), &sender_0, 8);
    std::memcpy(sender_bytes.data() + 8, &sender_1, 8);
    std::memcpy(sender_bytes.data() + 16, &sender_2, 8);
    std::memcpy(sender_bytes.data() + 24, &sender_3, 8);
    
    Identity sender_identity(sender_bytes);
    
    // Create connection ID if provided
    std::optional<ConnectionId> connection_id;
    if (conn_id_0 != 0 || conn_id_1 != 0) {
        // ConnectionId is 128-bit (two 64-bit parts)
        connection_id = ConnectionId(u128(conn_id_1, conn_id_0));
    }
    
    ReducerContext ctx(sender_identity, connection_id, timestamp);
    
    // Get the handler
    const auto& handler_info = g_reducer_handlers[id];
    
    // Call the reducer handler
    handler_info.handler(ctx, args_source);
    
    // Check if the reducer failed gracefully
    if (SpacetimeDB::Internal::has_reducer_error()) {
        std::string error_msg = SpacetimeDB::Internal::get_reducer_error();
        WriteBytes(error_sink, std::vector<uint8_t>(error_msg.begin(), error_msg.end()));
        return StatusCode::HOST_CALL_FAILURE;
    }

    return StatusCode::OK;
}

// Dispatch function for views with ViewContext (has sender)