move [R] warnings out of destructor path (#797)

Co-authored-by: simonpcouch <[email protected]>

NEWS.md

@@ -1,5 +1,9 @@
 # odbc (development version)
 
+* Raises "Cancelling previous query" warnings from R rather than from Rcpp when 
+ a connection has a current result to avoid possible incorrect resource 
+ unwinds with `options(warn = 2)` (#797).
+
 * New `odbc::snowflake()` makes it easier to connect to Snowflake, 
  automatically handling authentication correctly on platforms that provide 
  Snowflake-native OAuth credentials (@atheriel, #662).

R/RcppExports.R

@@ -13,6 +13,10 @@ odbc_connect <- function(connection_string, timezone = "", timezone_out = "", en
  .Call(`_odbc_odbc_connect`, connection_string, timezone, timezone_out, encoding, bigint, timeout, r_attributes_)
 }
 
+has_result <- function(p) {
+ .Call(`_odbc_has_result`, p)
+}
+
 connection_info <- function(p) {
  .Call(`_odbc_connection_info`, p)
 }

R/dbi-connection.R

@@ -81,6 +81,9 @@ setMethod("dbDisconnect", "OdbcConnection",
 #' @export
 setMethod("dbSendQuery", c("OdbcConnection", "character"),
  function(conn, statement, params = NULL, ..., immediate = FALSE) {
+ if (has_result(conn@ptr)) {
+ cli::cli_warn("Cancelling previous query")
+ }
  OdbcResult(
  connection = conn,
  statement = statement,
@@ -109,6 +112,9 @@ setMethod("dbExecute", c("OdbcConnection", "character"),
 #' @export
 setMethod("dbSendStatement", c("OdbcConnection", "character"),
  function(conn, statement, params = NULL, ..., immediate = FALSE) {
+ if (has_result(conn@ptr)) {
+ cli::cli_warn("Cancelling previous query")
+ }
  OdbcResult(
  connection = conn,
  statement = statement,

src/RcppExports.cpp

@@ -48,6 +48,17 @@ BEGIN_RCPP
  return rcpp_result_gen;
 END_RCPP
 }
+// has_result
+bool has_result(connection_ptr const& p);
+RcppExport SEXP _odbc_has_result(SEXP pSEXP) {
+BEGIN_RCPP
+ Rcpp::RObject rcpp_result_gen;
+ Rcpp::RNGScope rcpp_rngScope_gen;
+ Rcpp::traits::input_parameter< connection_ptr const& >::type p(pSEXP);
+ rcpp_result_gen = Rcpp::wrap(has_result(p));
+ return rcpp_result_gen;
+END_RCPP
+}
 // connection_info
 Rcpp::List connection_info(connection_ptr const& p);
 RcppExport SEXP _odbc_connection_info(SEXP pSEXP) {
@@ -365,6 +376,7 @@ static const R_CallMethodDef CallEntries[] = {
  {"_odbc_list_drivers_", (DL_FUNC) &_odbc_list_drivers_, 0},
  {"_odbc_list_data_sources_", (DL_FUNC) &_odbc_list_data_sources_, 0},
  {"_odbc_odbc_connect", (DL_FUNC) &_odbc_odbc_connect, 7},
+ {"_odbc_has_result", (DL_FUNC) &_odbc_has_result, 1},
  {"_odbc_connection_info", (DL_FUNC) &_odbc_connection_info, 1},
  {"_odbc_connection_quote", (DL_FUNC) &_odbc_connection_quote, 1},
  {"_odbc_connection_release", (DL_FUNC) &_odbc_connection_release, 1},

src/connection.cpp

@@ -73,6 +73,11 @@ std::string get_info_or_empty(connection_ptr const& p, short type) {
  }
 }
 
+// [[Rcpp::export]]
+bool has_result(connection_ptr const& p) {
+ return (*p)->has_result();
+}
+
 // [[Rcpp::export]]
 Rcpp::List connection_info(connection_ptr const& p) {
  SQLUINTEGER getdata_ext;

src/odbc_connection.cpp

@@ -4,24 +4,25 @@
 
 namespace odbc {
 
-void odbc_connection::cancel_current_result(bool quiet) {
+void odbc_connection::cancel_current_result() {
  if (current_result_ == nullptr) {
  return;
  }
 
- if (!quiet) {
- Rcpp::warning("Cancelling previous query");
- }
  current_result_->statement()->cancel();
  current_result_ = nullptr;
 }
 
+bool odbc_connection::has_result() const {
+ return current_result_ != nullptr;
+}
+
 void odbc_connection::set_current_result(odbc_result* r) {
  if (r == current_result_) {
  return;
  }
 
- cancel_current_result(r == nullptr);
+ cancel_current_result();
  current_result_ = r;
 }
 

src/odbc_connection.h

@@ -38,8 +38,9 @@ class odbc_connection {
  bool supports_transactions() const;
  bool get_data_any_order() const;
 
- void cancel_current_result(bool quiet);
+ void cancel_current_result();
  void set_current_result(odbc_result* r);
+ bool has_result() const;
 
  cctz::time_zone timezone() const;
  std::string timezone_out_str() const;

src/odbc_result.cpp

@@ -16,7 +16,7 @@ odbc_result::odbc_result(
  bound_(false),
  output_encoder_(Iconv(c_->encoding(), "UTF-8")) {
 
- c_->cancel_current_result(false);
+ c_->cancel_current_result();
 
  if (immediate) {
  s_ = std::make_shared<nanodbc::statement>();