Add a signal handler to print crashes, plus extra logging (#59)

src/motherduck_destination.cpp

@@ -1,5 +1,7 @@
 #include "duckdb.hpp"
 #include "motherduck_destination_server.hpp"
+#include <csignal>
+#include <execinfo.h>
 #include <grpcpp/grpcpp.h>
 #include <string>
 
@@ -39,7 +41,15 @@ void download_motherduck_extension() {
   }
 }
 
+void logCrash(int sig) {
+  std::cerr << "Crash signal " << sig << std::endl;
+  std::exit(sig);
+}
+
 int main(int argc, char **argv) {
+  std::signal(SIGSEGV, logCrash);
+  std::signal(SIGABRT, logCrash);
+
   std::string port = "50052";
   for (auto i = 1; i < argc; i++) {
     if (strcmp(argv[i], "--port") == 0) {

src/motherduck_destination_server.cpp

@@ -204,10 +204,16 @@ grpc::Status DestinationSdkImpl::DescribeTable(
         find_property(request->configuration(), MD_PROP_DATABASE);
     std::unique_ptr<duckdb::Connection> con =
         get_connection(request->configuration(), db_name);
+    mdlog::info("Endpoint <DescribeTable>: got connection");
     table_def table_name{db_name, get_schema_name(request),
                          get_table_name(request)};
 
+    mdlog::info("Endpoint <DescribeTable>: schema name <" +
+                table_name.schema_name + ">");
+    mdlog::info("Endpoint <DescribeTable>: table name <" +
+                table_name.table_name + ">");
     if (!table_exists(*con, table_name)) {
+      mdlog::info("Endpoint <DescribeTable>: table not found");
       response->set_not_found(true);
       return ::grpc::Status(::grpc::StatusCode::OK, "");
     }

src/sql_generator.cpp

@@ -102,19 +102,23 @@ bool table_exists(duckdb::Connection &con, const table_def &table) {
   const std::string err =
       "Could not find whether table <" + table.to_escaped_string() + "> exists";
   auto statement = con.Prepare(query);
+  mdlog::info("    prepared table_exists query for table " + table.table_name);
   if (statement->HasError()) {
     throw std::runtime_error(err + " (at bind step): " + statement->GetError());
   }
   duckdb::vector<duckdb::Value> params = {duckdb::Value(table.db_name),
                                           duckdb::Value(table.schema_name),
                                           duckdb::Value(table.table_name)};
   auto result = statement->Execute(params, false);
+  mdlog::info("    executed table_exists query for table " + table.table_name);
 
   if (result->HasError()) {
     throw std::runtime_error(err + ": " + result->GetError());
   }
   auto materialized_result = duckdb::unique_ptr_cast<
       duckdb::QueryResult, duckdb::MaterializedQueryResult>(std::move(result));
+  mdlog::info("    materialized table_exists results for table " +
+              table.table_name);
   return materialized_result->RowCount() > 0;
 }