Multiple rollbacks

doc/ref_cpp/data/shared_group_ref.yaml

@@ -235,7 +235,9 @@ CATEGORIES:
       SUMMARY  : &g_shared_group_rollback_summary
                  Rollback a transaction.
       DESCR    : &g_shared_group_rollback_descr
-                 This method closes a transaction and discards all changes done to the shared group.
+                 This method closes a transaction and discards all changes done to the shared group,
+                 unless a commit has already been done. It is ok to call rollback multiple times. 
+                 Any additional calls to rollback following a commit or rollback are treated as no-ops.
       EXAMPLES:
       - CODE   : ex_cpp_shared_group_rollback
         DESCR  :
@@ -297,7 +299,9 @@ CATEGORIES:
   - g_shared_group_end_read:
       NAMES    : end_read
       SUMMARY  : &g_shared_group_end_read_summary
-                 Terminate read transaction.
+                 Terminate read transaction. It is ok to call end_read multiple times, the
+                 first call will terminate the transaction. Any additional calls are treated
+                 as no-ops
       DESCR    : &g_shared_group_end_read_descr
                  This method terminates the read transaction.
       EXAMPLES:

src/tightdb/group_shared.cpp

@@ -350,6 +350,8 @@ const Group& SharedGroup::begin_read()
 
 void SharedGroup::end_read() TIGHTDB_NOEXCEPT
 {
+    if (!m_group.is_attached()) return;
+
     TIGHTDB_ASSERT(m_transact_stage == transact_Reading);
     TIGHTDB_ASSERT(m_version != numeric_limits<size_t>::max());
 
@@ -480,24 +482,26 @@ void SharedGroup::commit()
 // rollback() does not handle all cases.
 void SharedGroup::rollback() TIGHTDB_NOEXCEPT
 {
-    TIGHTDB_ASSERT(m_transact_stage == transact_Writing);
+    if (m_group.is_attached()) {
+        TIGHTDB_ASSERT(m_transact_stage == transact_Writing);
 
 #ifdef TIGHTDB_ENABLE_REPLICATION
-    if (Replication* repl = m_group.get_replication())
-        repl->rollback_write_transact(*this);
+        if (Replication* repl = m_group.get_replication())
+            repl->rollback_write_transact(*this);
 #endif
 
-    SharedInfo* info = m_file_map.get_addr();
+        SharedInfo* info = m_file_map.get_addr();
 
-    // Release write lock
-    info->writemutex.unlock();
+        // Release write lock
+        info->writemutex.unlock();
 
-    // Clear all changes made during transaction
-    m_group.detach();
+        // Clear all changes made during transaction
+        m_group.detach();
 
 #ifdef TIGHTDB_DEBUG
-    m_transact_stage = transact_Ready;
+        m_transact_stage = transact_Ready;
 #endif
+    }
 }
 
 

test/test_shared.cpp

@@ -1322,3 +1322,20 @@ TEST(Shared_MixedWithNonShared)
     }
     File::remove("test.tightdb");
 }
+
+
+TEST(MultipleRollbacks) 
+{
+    SharedGroup sg("test.tightdb");    
+    sg.begin_write();
+    sg.rollback();
+    sg.rollback();
+}
+
+TEST(MultipleEndReads) 
+{
+    SharedGroup sg("test.tightdb");    
+    sg.begin_read();
+    sg.end_read();
+    sg.end_read();
+}