Swallow commit() exception in MiniSQLite destructor, improve state check

sqlwriter.cc

@@ -225,12 +225,10 @@ void MiniSQLite::execPrep(const std::string& table, std::vector<std::unordered_m
 
 void MiniSQLite::begin()
 {
-  d_intransaction=true;
   exec("begin");
 }
 void MiniSQLite::commit()
 {
-  d_intransaction=false;
   exec("commit");
 }
 
@@ -239,6 +237,11 @@ void MiniSQLite::cycle()
   exec("commit;begin");
 }
 
+bool MiniSQLite::inTransaction()
+{
+  return sqlite3_get_autocommit(d_sqlite) == 0;
+}
+
 bool MiniSQLite::haveTable(const string& table)
 {
   return !getSchema(table).empty();
@@ -437,8 +440,14 @@ vector<std::unordered_map<string, MiniSQLite::outvar_t>> SQLiteWriter::queryGen(
 MiniSQLite::~MiniSQLite()
 {
   // needs to close down d_sqlite3
-  if(d_intransaction)
-    commit();
+  if(inTransaction()) {
+    try {
+      commit();
+    } catch (std::runtime_error &e) {
+      // don't have a good way to report e
+      // transaction will be rolled back instead
+    }
+  }
 
   for(auto& stmt: d_stmts)
     if(stmt.second)

sqlwriter.hh

@@ -55,7 +55,7 @@ private:
   std::unordered_map<std::string, sqlite3_stmt*> d_stmts;
   std::vector<std::vector<std::string>> d_rows; // for exec()
   static int helperFunc(void* ptr, int cols, char** colvals, char** colnames);
-  bool d_intransaction{false};
+  bool inTransaction();
   bool haveTable(const std::string& table);
 };
 

testrunner.cc

@@ -349,6 +349,62 @@ TEST_CASE("readonly test") {
   unlink(fname.c_str());
 }
 
+TEST_CASE("MiniSQLite destructor commits") {
+  const char* name = "testrunner-dtor.sqlite3";
+
+  unlink(name);
+
+  {
+    MiniSQLite ms(name);
+    ms.begin();
+    ms.exec("create table top (role, playing, game)");
+    ms.exec("insert into top values ('d', '&', 'd')");
+  }
+
+  {
+    MiniSQLite ms(name);
+    CHECK(ms.exec("select count(*) from top").at(0).at(0) == "1");
+  }
+
+  unlink(name);
+}
+
+TEST_CASE("MiniSQLite destructor commit failure is ignored") {
+  const char* name = "testrunner-dtor.sqlite3";
+
+  unlink(name);
+
+  {
+    MiniSQLite ms(name);
+    ms.begin();
+    unlink(name);
+  }
+
+  unlink(name);
+}
+
+TEST_CASE("MiniSQLite destructor is not confused by rollback query") {
+  CHECK_NOTHROW([](){
+    MiniSQLite ms(":memory:");
+
+    ms.begin();
+    ms.exec("rollback");
+  }());
+}
+
+TEST_CASE("MiniSQLite destructor is not confused by rollback caused by error") {
+  CHECK_THROWS([](){
+    MiniSQLite ms(":memory:");
+
+    ms.begin();
+    ms.exec("create table foo (bar)");
+    ms.exec("pragma max_page_count=5");
+
+    // error happens here: 'database or disk is full'
+    ms.exec("insert into foo values (zeroblob(1000000))");
+  }());
+}
+
 TEST_CASE("test scale") {
   unlink("testrunner-example.sqlite3");
   {