diff --git a/extra/exports b/extra/exports
index efbe17eef29ca2c76c9d85cdfdd2dec9dd05a008..7456b584cd4b7f6c78378a5bbf595cad548c0977 100644
--- a/extra/exports
+++ b/extra/exports
@@ -100,6 +100,7 @@ box_txn_id
box_txn_rollback
box_txn_rollback_to_savepoint
box_txn_savepoint
+box_txn_set_isolation
box_txn_set_timeout
box_update
box_upsert
diff --git a/src/box/box.cc b/src/box/box.cc
index 675dc601048914ecc1daadaa012a0cdfe0c9bd0d..814b1779ca3565ef586511b8a4f285b061b95f32 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1263,6 +1263,40 @@ box_check_txn_timeout(void)
return timeout;
}
+/**
+ * Get and check isolation level from config, converting number or string to
+ * enum txn_isolation_level.
+ * @return isolation level or txn_isolation_level_MAX is case of error.
+ */
+static enum txn_isolation_level
+box_check_txn_isolation(void)
+{
+ uint32_t level;
+ if (cfg_isnumber("txn_isolation")) {
+ level = cfg_geti("txn_isolation");
+ } else {
+ const char *str_level = cfg_gets("txn_isolation");
+ level = strindex(txn_isolation_level_strs, str_level,
+ txn_isolation_level_MAX);
+ if (level == txn_isolation_level_MAX)
+ level = strindex(txn_isolation_level_aliases, str_level,
+ txn_isolation_level_MAX);
+ }
+ if (level >= txn_isolation_level_MAX) {
+ diag_set(ClientError, ER_CFG, "txn_isolation",
+ "must be one of "
+ "box.txn_isolation_level (keys or values)");
+ return txn_isolation_level_MAX;
+ }
+ if (level == TXN_ISOLATION_DEFAULT) {
+ diag_set(ClientError, ER_CFG, "txn_isolation",
+ "cannot set default transaction isolation "
+ "to 'default'");
+ return txn_isolation_level_MAX;
+ }
+ return (enum txn_isolation_level)level;
+}
+
void
box_check_config(void)
{
@@ -1310,6 +1344,8 @@ box_check_config(void)
diag_raise();
if (box_check_txn_timeout() < 0)
diag_raise();
+ if (box_check_txn_isolation() == txn_isolation_level_MAX)
+ diag_raise();
}
int
@@ -2174,6 +2210,16 @@ box_set_txn_timeout(void)
return 0;
}
+int
+box_set_txn_isolation(void)
+{
+ enum txn_isolation_level level = box_check_txn_isolation();
+ if (level == txn_isolation_level_MAX)
+ return -1;
+ txn_default_isolation = level;
+ return 0;
+}
+
/* }}} configuration bindings */
/**
diff --git a/src/box/box.h b/src/box/box.h
index 2338e6bf24f55309a32b7fad179ade17c310130c..b53a0aad977beb9b54a9648dfd67a9fb1d395f20 100644
--- a/src/box/box.h
+++ b/src/box/box.h
@@ -279,6 +279,12 @@ void box_set_replication_anon(void);
void box_set_net_msg_max(void);
int box_set_crash(void);
int box_set_txn_timeout(void);
+/**
+ * Set default isolation level from cfg option txn_isolation.
+ * @return 0 on success, -1 on error.
+ */
+int
+box_set_txn_isolation(void);
int
box_set_prepared_stmt_cache_size(void);
diff --git a/src/box/lua/cfg.cc b/src/box/lua/cfg.cc
index 5ea23917d3b4fed086e0d30ed3c354d72fc4538e..b3f2f333c7c40ec16047d203ce0c731d88d609f6 100644
--- a/src/box/lua/cfg.cc
+++ b/src/box/lua/cfg.cc
@@ -404,6 +404,14 @@ lbox_cfg_set_txn_timeout(struct lua_State *L)
return 0;
}
+static int
+lbox_cfg_set_txn_isolation(struct lua_State *L)
+{
+ if (box_set_txn_isolation() != 0)
+ luaT_error(L);
+ return 0;
+}
+
void
box_lua_cfg_init(struct lua_State *L)
{
@@ -444,6 +452,7 @@ box_lua_cfg_init(struct lua_State *L)
{"cfg_set_sql_cache_size", lbox_set_prepared_stmt_cache_size},
{"cfg_set_crash", lbox_cfg_set_crash},
{"cfg_set_txn_timeout", lbox_cfg_set_txn_timeout},
+ {"cfg_set_txn_isolation", lbox_cfg_set_txn_isolation},
{NULL, NULL}
};
diff --git a/src/box/lua/load_cfg.lua b/src/box/lua/load_cfg.lua
index 7bc2f83bf3f589d8b84a6f1db2f68ca6304cb83c..7d86dd1b2813f323d96b3073f205dd6a4b1cb820 100644
--- a/src/box/lua/load_cfg.lua
+++ b/src/box/lua/load_cfg.lua
@@ -115,6 +115,7 @@ local default_cfg = {
net_msg_max = 768,
sql_cache_size = 5 * 1024 * 1024,
txn_timeout = 365 * 100 * 86400,
+ txn_isolation = "best-effort",
}
-- cfg variables which are covered by modules
@@ -207,6 +208,7 @@ local template_cfg = {
read_only = 'boolean',
hot_standby = 'boolean',
memtx_use_mvcc_engine = 'boolean',
+ txn_isolation = 'string, number',
worker_pool_threads = 'number',
election_mode = 'string',
election_timeout = 'number',
@@ -336,6 +338,7 @@ local dynamic_cfg = {
net_msg_max = private.cfg_set_net_msg_max,
sql_cache_size = private.cfg_set_sql_cache_size,
txn_timeout = private.cfg_set_txn_timeout,
+ txn_isolation = private.cfg_set_txn_isolation,
}
-- dynamically settable options, which should be reverted in case
@@ -670,6 +673,7 @@ local box_cfg_guard_whitelist = {
ctl = true;
watch = true;
broadcast = true;
+ txn_isolation_level = true;
NULL = true;
};
diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
index 154e98ed71eb52660395d4bb9bb4f160c5b37302..a03515524324e9b764598c7c1cb0eff3de5a2388 100644
--- a/src/box/lua/schema.lua
+++ b/src/box/lua/schema.lua
@@ -73,6 +73,8 @@ ffi.cdef[[
box_txn_begin();
int
box_txn_set_timeout(double timeout);
+ int
+ box_txn_set_isolation(uint32_t level);
/** \endcond public */
/** \cond public */
int
@@ -336,8 +338,48 @@ local function feedback_save_event(event)
end
end
+-- Public isolation level map string -> number.
+box.txn_isolation_level = {
+ ['default'] = 0,
+ ['DEFAULT'] = 0,
+ ['read-committed'] = 1,
+ ['READ_COMMITTED'] = 1,
+ ['read-confirmed'] = 2,
+ ['READ_CONFIRMED'] = 2,
+ ['best-effort'] = 3,
+ ['BEST_EFFORT'] = 3,
+}
+
+-- Create private isolation level map anything-correct -> number.
+local function create_txn_isolation_level_map()
+ local res = {}
+ for k,v in pairs(box.txn_isolation_level) do
+ res[k] = v
+ res[v] = v
+ end
+ return res
+end
+
+-- Private isolation level map anything-correct -> number.
+local txn_isolation_level_map = create_txn_isolation_level_map()
+box.internal.txn_isolation_level_map = txn_isolation_level_map
+
+-- Convert to numeric the value of txn isolation level, raise if failed.
+local function normalize_txn_isolation_level(txn_isolation)
+ txn_isolation = txn_isolation_level_map[txn_isolation]
+ if txn_isolation == nil then
+ box.error(box.error.ILLEGAL_PARAMS,
+ "txn_isolation must be one of box.txn_isolation_level" ..
+ " (keys or values)")
+ end
+ return txn_isolation
+end
+
+box.internal.normalize_txn_isolation_level = normalize_txn_isolation_level
+
box.begin = function(options)
local timeout
+ local txn_isolation
if options then
check_param(options, 'options', 'table')
timeout = options.timeout
@@ -345,6 +387,10 @@ box.begin = function(options)
box.error(box.error.ILLEGAL_PARAMS,
"timeout must be a number greater than 0")
end
+ txn_isolation = options.txn_isolation
+ if txn_isolation ~= nil then
+ txn_isolation = normalize_txn_isolation_level(txn_isolation)
+ end
end
if builtin.box_txn_begin() == -1 then
box.error()
@@ -352,6 +398,11 @@ box.begin = function(options)
if timeout then
assert(builtin.box_txn_set_timeout(timeout) == 0)
end
+ if txn_isolation and
+ builtin.box_txn_set_isolation(txn_isolation) ~= 0 then
+ box.rollback()
+ box.error()
+ end
end
box.is_in_txn = builtin.box_txn
diff --git a/src/box/memtx_tx.c b/src/box/memtx_tx.c
index c8a36fc4c3be59e3ac676f8a466652781bf28d89..3b490790fd4779e88db1f66c5bde732428db2bad 100644
--- a/src/box/memtx_tx.c
+++ b/src/box/memtx_tx.c
@@ -2007,6 +2007,13 @@ memtx_tx_tuple_clarify_impl(struct txn *txn, struct space *space,
static bool
detect_whether_prepared_ok(struct txn *txn)
{
+ if (txn == NULL)
+ return false;
+ else if (txn->isolation == TXN_ISOLATION_READ_COMMITTED)
+ return true;
+ else if (txn->isolation == TXN_ISOLATION_READ_CONFIRMED)
+ return false;
+ assert(txn->isolation == TXN_ISOLATION_BEST_EFFORT);
/*
* The best effort that we can make is to determine whether the
* transaction is read-only or not. For read only (including autocommit
@@ -2014,7 +2021,7 @@ detect_whether_prepared_ok(struct txn *txn)
* ignoring prepared. For read-write transaction we should see prepared
* changes in order to avoid conflicts.
*/
- return txn != NULL && !stailq_empty(&txn->stmts);
+ return !stailq_empty(&txn->stmts);
}
/**
diff --git a/src/box/txn.c b/src/box/txn.c
index fa9cab707ee1315d2df803226e92dc1c4dd6facb..af009c90b1937d279786f95729468cb1fcfa3231 100644
--- a/src/box/txn.c
+++ b/src/box/txn.c
@@ -45,6 +45,22 @@ double too_long_threshold;
/** Last prepare-sequence-number that was assigned to prepared TX. */
int64_t txn_last_psn = 0;
+enum txn_isolation_level txn_default_isolation = TXN_ISOLATION_BEST_EFFORT;
+
+const char *txn_isolation_level_strs[txn_isolation_level_MAX] = {
+ "DEFAULT",
+ "READ_COMMITTED",
+ "READ_CONFIRMED",
+ "BEST_EFFORT",
+};
+
+const char *txn_isolation_level_aliases[txn_isolation_level_MAX] = {
+ "default",
+ "read-committed",
+ "read-confirmed",
+ "best-effort",
+};
+
/* Txn cache. */
static struct stailq txn_cache = {NULL, &txn_cache.first};
@@ -352,6 +368,7 @@ txn_begin(void)
txn->psn = 0;
txn->rv_psn = 0;
txn->status = TXN_INPROGRESS;
+ txn->isolation = txn_default_isolation;
txn->signature = TXN_SIGNATURE_UNKNOWN;
txn->engine = NULL;
txn->engine_tx = NULL;
@@ -1183,6 +1200,29 @@ box_txn_set_timeout(double timeout)
return 0;
}
+int
+box_txn_set_isolation(uint32_t level)
+{
+ if (level >= txn_isolation_level_MAX) {
+ diag_set(ClientError, ER_ILLEGAL_PARAMS,
+ "unknown isolation level");
+ return -1;
+ }
+ struct txn *txn = in_txn();
+ if (txn == NULL) {
+ diag_set(ClientError, ER_NO_TRANSACTION);
+ return -1;
+ }
+ if (!stailq_empty(&txn->stmts)) {
+ diag_set(ClientError, ER_ACTIVE_TRANSACTION);
+ return -1;
+ }
+ if (level == TXN_ISOLATION_DEFAULT)
+ level = txn_default_isolation;
+ txn->isolation = level;
+ return 0;
+}
+
struct txn_savepoint *
txn_savepoint_new(struct txn *txn, const char *name)
{
diff --git a/src/box/txn.h b/src/box/txn.h
index de57b51d686b0bbf78cb72c678de4013539bedb2..491387d02ad754b8d4bfc032f5c4c928c3d316eb 100644
--- a/src/box/txn.h
+++ b/src/box/txn.h
@@ -146,6 +146,51 @@ enum {
TXN_SIGNATURE_ABORT = JOURNAL_ENTRY_ERR_MIN - 4,
};
+/** \cond public */
+/**
+ * When a transaction calls `commit`, this action can last for some time until
+ * redo data is written to WAL. While such a `commit` call is in progress we
+ * call changes of such a transaction as 'committed', and when the process is
+ * finished - we call the changes as 'confirmed'. One of the main options of
+ * a transaction is to see or not to see 'committed' changes.
+ * Note that now there are different terminologies in different places. This
+ * enum uses new 'committed' and 'confirmed' states of transactions. Meanwhile
+ * in engined the first state is usually called as 'prepared', and the second
+ * as 'committed' or 'completed'.
+ * Warning: this enum is exposed in lua via ffi, and thus any change in items
+ * must be correspondingly modified on ffi.cdef(), see schema.lua.
+ */
+enum txn_isolation_level {
+ /** Take isolation level from global default_isolation_level. */
+ TXN_ISOLATION_DEFAULT,
+ /** Allow to read committed, but not confirmed changes. */
+ TXN_ISOLATION_READ_COMMITTED,
+ /** Allow to read only confirmed changes. */
+ TXN_ISOLATION_READ_CONFIRMED,
+ /** Determine isolation level automatically. */
+ TXN_ISOLATION_BEST_EFFORT,
+ /** Upper bound of valid values. */
+ txn_isolation_level_MAX,
+};
+
+/** \endcond public */
+
+/**
+ * Common enum strings: uppercase letters, underscores.
+ */
+extern const char *txn_isolation_level_strs[txn_isolation_level_MAX];
+
+/**
+ * Aliases: lowercase letters, hyphens.
+ */
+extern const char *txn_isolation_level_aliases[txn_isolation_level_MAX];
+
+/**
+ * The level that is set for a transaction by default.
+ * Cannot be TXN_ISOLATION_DEFAULT since it senseless.
+ */
+extern enum txn_isolation_level txn_default_isolation;
+
/**
* Convert a result of a transaction execution to an error installed into the
* current diag.
@@ -364,6 +409,11 @@ struct txn {
int64_t rv_psn;
/** Status of the TX */
enum txn_status status;
+ /**
+ * Isolation level of TX. Can't be TXN_ISOLATION_DEFAULT since setting
+ * this value actually uses txn_default_isolation
+ */
+ enum txn_isolation_level isolation;
/** List of statements in a transaction. */
struct stailq stmts;
/** Number of new rows without an assigned LSN. */
@@ -880,6 +930,17 @@ box_txn_alloc(size_t size);
API_EXPORT int
box_txn_set_timeout(double timeout);
+/**
+ * Set an isolation @a level for a transaction.
+ * Must be called before the first DML.
+ * The level must be of enun txn_isolation_level values.
+ * @retval 0 if success
+ * @retval -1 if failed, diag is set.
+ *
+ */
+API_EXPORT int
+box_txn_set_isolation(uint32_t level);
+
/** \endcond public */
typedef struct txn_savepoint box_txn_savepoint_t;
diff --git a/test/app-tap/init_script.result b/test/app-tap/init_script.result
index b7e2ce09cb4505a6414171b7ccc62002552cdb3b..5fae022ea1c3a08b0793c5ba5d6a76e14db64d40 100644
--- a/test/app-tap/init_script.result
+++ b/test/app-tap/init_script.result
@@ -46,6 +46,7 @@ slab_alloc_granularity:8
sql_cache_size:5242880
strip_core:true
too_long_threshold:0.5
+txn_isolation:best-effort
txn_timeout:3153600000
vinyl_bloom_fpr:0.05
vinyl_cache:134217728
diff --git a/test/box-luatest/gh_6930_mvcc_isolation_levels_test.lua b/test/box-luatest/gh_6930_mvcc_isolation_levels_test.lua
new file mode 100644
index 0000000000000000000000000000000000000000..94b670e95e937886878f1501194cf330e579493a
--- /dev/null
+++ b/test/box-luatest/gh_6930_mvcc_isolation_levels_test.lua
@@ -0,0 +1,176 @@
+local server = require('test.luatest_helpers.server')
+local t = require('luatest')
+
+local g = t.group()
+
+g.before_all = function()
+ g.server = server:new{
+ alias = 'default',
+ box_cfg = {memtx_use_mvcc_engine = true}
+ }
+ g.server:start()
+end
+
+g.after_all = function()
+ g.server:drop()
+end
+
+g.test_mvcc_isolation_level_errors = function()
+ g.server:exec(function()
+ local t = require('luatest')
+ t.assert_error_msg_content_equals(
+ "Illegal parameters, txn_isolation must be one of " ..
+ "box.txn_isolation_level (keys or values)",
+ function() box.begin{txn_isolation = 'avadakedavra'} end)
+ t.assert_error_msg_content_equals(
+ "Incorrect value for option 'txn_isolation': must " ..
+ "be one of box.txn_isolation_level (keys or values)",
+ function() box.cfg{txn_isolation = 'avadakedavra'} end)
+ t.assert_error_msg_content_equals(
+ "Illegal parameters, txn_isolation must be one of " ..
+ "box.txn_isolation_level (keys or values)",
+ function() box.begin{txn_isolation = false} end)
+ t.assert_error_msg_content_equals(
+ "Incorrect value for option 'txn_isolation': " ..
+ "should be one of types string, number",
+ function() box.cfg{txn_isolation = false} end)
+ t.assert_error_msg_content_equals(
+ "Illegal parameters, txn_isolation must be one of " ..
+ "box.txn_isolation_level (keys or values)",
+ function() box.begin{txn_isolation = 8} end)
+ t.assert_error_msg_content_equals(
+ "Incorrect value for option 'txn_isolation': must " ..
+ "be one of box.txn_isolation_level (keys or values)",
+ function() box.cfg{txn_isolation = 8} end)
+ t.assert_error_msg_content_equals(
+ "Incorrect value for option 'txn_isolation': " ..
+ "cannot set default transaction isolation to 'default'",
+ function() box.cfg{txn_isolation = 'default'} end)
+ end)
+end
+
+g.before_test('test_mvcc_isolation_level_basics', function()
+ g.server:exec(function()
+ local s = box.schema.space.create('test')
+ s:create_index('primary')
+ end)
+end)
+
+g.test_mvcc_isolation_level_basics = function()
+ g.server:exec(function()
+ local t = require('luatest')
+ local fiber = require('fiber')
+ local s = box.space.test
+
+ local f = fiber.create(function()
+ fiber.self():set_joinable(true)
+ s:insert{1}
+ end)
+
+ t.assert_equals(s:select(), {})
+ t.assert_equals(s:count(), 0)
+
+ box.begin()
+ local res1 = s:select()
+ local res2 = s:count()
+ box.commit()
+ t.assert_equals(res1, {})
+ t.assert_equals(res2, 0)
+
+ local expect0 = {'default', 'read-confirmed', 'best-effort',
+ box.txn_isolation_level.DEFAULT,
+ box.txn_isolation_level.READ_CONFIRMED,
+ box.txn_isolation_level.BEST_EFFORT,
+ box.txn_isolation_level['default'],
+ box.txn_isolation_level['read-confirmed'],
+ box.txn_isolation_level['best-effort']}
+
+ for _,level in pairs(expect0) do
+ box.begin{txn_isolation = level}
+ res1 = s:select()
+ res2 = s:count()
+ box.commit()
+ t.assert_equals(res1, {})
+ t.assert_equals(res2, 0)
+ end
+
+ local expect0 = {'read-confirmed', 'best-effort',
+ box.txn_isolation_level.READ_CONFIRMED,
+ box.txn_isolation_level.BEST_EFFORT,
+ box.txn_isolation_level['read-confirmed'],
+ box.txn_isolation_level['best-effort']}
+
+ for _,level in pairs(expect0) do
+ box.cfg{txn_isolation = level}
+ box.begin{}
+ res1 = s:select()
+ res2 = s:count()
+ box.commit()
+ t.assert_equals(res1, {})
+ t.assert_equals(res2, 0)
+ box.begin{txn_isolation = 'default'}
+ res1 = s:select()
+ res2 = s:count()
+ box.commit()
+ t.assert_equals(res1, {})
+ t.assert_equals(res2, 0)
+ box.cfg{txn_isolation = 'best-effort'}
+ end
+
+ local expect1 = {'read-committed',
+ box.txn_isolation_level.READ_COMMITTED,
+ box.txn_isolation_level['read-committed']}
+
+ for _,level in pairs(expect1) do
+ box.begin{txn_isolation = level}
+ res1 = s:select()
+ res2 = s:count()
+ box.commit()
+ t.assert_equals(res1, {{1}})
+ t.assert_equals(res2, 1)
+ end
+
+ for _,level in pairs(expect1) do
+ box.cfg{txn_isolation = level}
+ box.begin{txn_isolation = level}
+ res1 = s:select()
+ res2 = s:count()
+ box.commit()
+ t.assert_equals(res1, {{1}})
+ t.assert_equals(res2, 1)
+ -- txn_isolation does not affect autocommit select,
+ -- which is always run as read-confirmed
+ t.assert_equals(s:select(), {})
+ t.assert_equals(s:count(), 0)
+ box.cfg{txn_isolation = 'best-effort'}
+ end
+
+ -- With default best-effort isolation RO->RW transaction can be aborted:
+ box.begin()
+ res1 = s:select(1) -- read confirmed {}
+ s:replace{2}
+ t.assert_error_msg_content_equals(
+ "Transaction has been aborted by conflict",
+ function() box.commit() end)
+ t.assert_equals(res1, {})
+
+ -- But using 'read-committed' allows to avoid conflict:
+ box.begin{txn_isolation = 'read-committed'}
+ res1 = s:select(1) -- read confirmed {{1}}
+ s:replace{2}
+ box.commit()
+ t.assert_equals(res1, {{1}})
+ t.assert_equals(s:select{}, {{1}, {2}})
+
+ f:join()
+ end)
+end
+
+g.after_test('test_mvcc_isolation_level_basics', function()
+ g.server:exec(function()
+ local s = box.space.test
+ if s then
+ s:drop()
+ end
+ end)
+end)
diff --git a/test/box/admin.result b/test/box/admin.result
index f5d6e6e7b6f3af7aef0d2ebf8e9546beee4bb3c1..7e47dc1cb6e8651ef219156acaa89e969758d144 100644
--- a/test/box/admin.result
+++ b/test/box/admin.result
@@ -113,6 +113,8 @@ cfg_filter(box.cfg)
- true
- - too_long_threshold
- 0.5
+ - - txn_isolation
+ - best-effort
- - txn_timeout
- 3153600000
- - vinyl_bloom_fpr
diff --git a/test/box/cfg.result b/test/box/cfg.result
index 8e953a04509c28da858394729b18b74fbc0b754f..157fe1d976630842b174dbb3ffda18ee1b204ebd 100644
--- a/test/box/cfg.result
+++ b/test/box/cfg.result
@@ -101,6 +101,8 @@ cfg_filter(box.cfg)
| - true
| - - too_long_threshold
| - 0.5
+ | - - txn_isolation
+ | - best-effort
| - - txn_timeout
| - 3153600000
| - - vinyl_bloom_fpr
@@ -234,6 +236,8 @@ cfg_filter(box.cfg)
| - true
| - - too_long_threshold
| - 0.5
+ | - - txn_isolation
+ | - best-effort
| - - txn_timeout
| - 3153600000
| - - vinyl_bloom_fpr
diff --git a/test/box/misc.result b/test/box/misc.result
index cfb0151b638388a5438c303a66bca379d6ccfad5..776b14b2f7064f86a88d5a19ea65648f529246a0 100644
--- a/test/box/misc.result
+++ b/test/box/misc.result
@@ -105,6 +105,7 @@ t
- stat
- tuple
- txn_id
+ - txn_isolation_level
- unprepare
- watch
...