obj: introduce pmemobj_tx_set_failure_event

This function can be used to disable or enable aborting tx
in case of an error (for example when allocation fails).

This patch also introduces pmemobj_tx_get_failure_event
which allows to query current setting of a transaction.

doc/libpmemobj/pmemobj_tx_begin.3.md

@@ -8,7 +8,7 @@ date: pmemobj API version 2.3
 ...
 
 [comment]: <> (SPDX-License-Identifier: BSD-3-Clause)
-[comment]: <> (Copyright 2017-2019, Intel Corporation)
+[comment]: <> (Copyright 2017-2020, Intel Corporation)
 
 [comment]: <> (pmemobj_tx_begin.3 -- man page for transactional object manipulation)
 
@@ -37,7 +37,10 @@ date: pmemobj API version 2.3
 **pmemobj_tx_log_intents_max_size**(),
 
 **pmemobj_tx_set_user_data**(),
-**pmemobj_tx_get_user_data**()
+**pmemobj_tx_get_user_data**(),
+
+**pmemobj_tx_set_failure_event**(),
+**pmemobj_tx_get_failure_event**()
 - transactional object manipulation
 
 # SYNOPSIS #
@@ -72,6 +75,9 @@ size_t pmemobj_tx_log_intents_max_size(size_t nintents);
 
 void pmemobj_tx_set_user_data(void *data);
 void *pmemobj_tx_get_user_data(void);
+
+void pmemobj_tx_set_failure_event(enum pobj_tx_failure_event event);
+enum pobj_tx_failure_event pmemobj_tx_get_failure_event(void);
 ```
 
 # DESCRIPTION #
@@ -412,6 +418,17 @@ If **pmemobj_tx_set_user_data**() was not called for a current transaction,
 during **TX_STAGE_WORK** or **TX_STAGE_ONABORT** or **TX_STAGE_ONCOMMIT** or
 **TX_STAGE_FINALLY**.
 
+**pmemobj_tx_set_failure_event**() specifies what should happen in case of an error
+within the transaction. It only affects functions which take a NO_ABORT flag.
+If **pmemobj_tx_set_failure_event**() is called with POBJ_TX_FAILURE_RETURN a NO_ABORT
+flag is implicitly passed to all functions which accept this flag. If called
+with POBJ_TX_FAILURE_ABORT then all functions abort the transaction (unless NO_ABORT
+flag is passed explicitly). This setting is inherited by inner transactions. It does
+not affect any of the outer transactions. Aborting on failure is the default behaviour.
+**pmemobj_tx_get_failure_event**() returns failure event for the current transaction.
+Both **pmemobj_tx_set_failure_event**() and **pmemobj_tx_get_failure_event**()
+must be called during **TX_STAGE_WORK**.
+
 # RETURN VALUE #
 
 The **pmemobj_tx_stage**() function returns the stage of the current transaction

src/include/libpmemobj/tx_base.h

@@ -50,6 +50,11 @@ enum pobj_log_type {
 	TX_LOG_TYPE_INTENT,
 };
 
+enum pobj_tx_failure_event {
+	POBJ_TX_FAILURE_ABORT,
+	POBJ_TX_FAILURE_RETURN,
+};
+
 #if !defined(pmdk_use_attr_deprec_with_msg) && defined(__COVERITY__)
 #define pmdk_use_attr_deprec_with_msg 0
 #endif
@@ -424,6 +429,20 @@ void pmemobj_tx_set_user_data(void *data);
  */
 void *pmemobj_tx_get_user_data(void);
 
+/*
+ * Sets the failure behaviour of transactional functions.
+ *
+ * This function must be called during TX_STAGE_WORK.
+ */
+void pmemobj_tx_set_failure_event(enum pobj_tx_failure_event event);
+
+/*
+ * Returns failure event for the current transaction.
+ *
+ * This function must be called during TX_STAGE_WORK.
+ */
+enum pobj_tx_failure_event pmemobj_tx_get_failure_event(void);
+
 #ifdef __cplusplus
 }
 #endif

src/libpmemobj/libpmemobj.def

@@ -1,6 +1,6 @@
 ;;;; Begin Copyright Notice
 ; SPDX-License-Identifier: BSD-3-Clause
-; Copyright 2015-2018, Intel Corporation
+; Copyright 2015-2020, Intel Corporation
 ;;;;  End Copyright Notice
 
 LIBRARY libpmemobj
@@ -96,6 +96,8 @@ EXPORTS
 	pmemobj_tx_log_intents_max_size
 	pmemobj_tx_set_user_data
 	pmemobj_tx_get_user_data
+	pmemobj_tx_set_failure_event
+	pmemobj_tx_get_failure_event
 	pmemobj_memcpy
 	pmemobj_memcpy_persist
 	pmemobj_memmove

src/libpmemobj/libpmemobj.link.in

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: BSD-3-Clause
-# Copyright 2014-2019, Intel Corporation
+# Copyright 2014-2020, Intel Corporation
 #
 #
 # src/libpmemobj.link -- linker link file for libpmemobj
@@ -87,6 +87,8 @@ LIBPMEMOBJ_1.0 {
 		pmemobj_tx_log_intents_max_size;
 		pmemobj_tx_set_user_data;
 		pmemobj_tx_get_user_data;
+		pmemobj_tx_set_failure_event;
+		pmemobj_tx_get_failure_event;
 		pmemobj_memcpy;
 		pmemobj_memcpy_persist;
 		pmemobj_memmove;