[Tarantool-patches] [PATCH] replication: add support of qsync to the snapshot machinery

[Leonid Vasiliev]

Add commit:

replication: add a test for "replication: add support of qsync to the
snapshot machinery"

[TO BE SQUASHED INTO THE PREVIOUS COMMIT]

diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index 6721221..4194777 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -257,6 +257,9 @@ target_link_libraries(swim_errinj.test unit swim)
  add_executable(merger.test merger.test.c)
  target_link_libraries(merger.test unit core box)

+add_executable(snap_quorum_delay.test snap_quorum_delay.cc)
+target_link_libraries(snap_quorum_delay.test box core unit)
+
  #
  # Client for popen.test
  add_executable(popen-child popen-child.c)
diff --git a/test/unit/snap_quorum_delay.cc b/test/unit/snap_quorum_delay.cc
new file mode 100644
index 0000000..7a20067
--- /dev/null
+++ b/test/unit/snap_quorum_delay.cc
@@ -0,0 +1,250 @@
+/*
+ * Copyright 2010-2020, Tarantool AUTHORS, please see AUTHORS file.
+ *
+ * Redistribution and use in source and iproto forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above
+ *    copyright notice, this list of conditions and the
+ *    following disclaimer.
+ *
+ * 2. Redistributions in iproto form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * <COPYRIGHT HOLDER> OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include "unit.h"
+#include "gc.h"
+#include "memory.h"
+#include "txn.h"
+#include "txn_limbo.h"
+
+/**
+ * This test is only about delay in snapshot machinery (needed
+ * for qsync replication). It doesn't test the snapshot
+ * machinery, txn_limbo or something else and uses some tricks
+ * around txn_limbo.
+ * The logic of the test is as folows:
+ * In fiber_1 ("txn_fiber"):
+ *	- start a transaction.
+ *	- push the transaction to the limbo.
+ *	- start wait confirm (yield).
+ * In fiber_2 ("main"):
+ *	- do a snapshot.
+ *	- start wait while the last transaction
+ *	  from the limbo will be completed.
+ * In fiber_3 ("confirm_fiber"):
+ *	- confirm the transaction (remove the transaction from
+ *				   the limbo and wakeup fiber_1).
+ * In fiber_1 ("txn_fiber"):
+ *	- confirm/rollback/hung the transaction.
+ * In fiber_2 ("main"):
+ *	- check_results
+ */
+
+extern int replication_synchro_quorum;
+extern double replication_synchro_timeout;
+
+namespace /* local symbols */ {
+
+int test_result;
+
+/**
+ * Variations of a transaction completion.
+ */
+enum process_type {
+	TXN_PROCESS_COMMIT,
+	TXN_PROCESS_ROLLBACK,
+	TXN_PROCESS_TIMEOUT
+};
+
+/**
+ * Some fake values needed for work with the limbo
+ * (to push a transaction to the limbo and simulate confirm).
+ */
+const int fake_lsn = 1;
+const int instace_id = 1;
+const int relay_id = 2;
+
+int
+trg_cb(struct trigger *trigger, void *event)
+{
+	(void)event;
+	bool *check_trg = (bool *)trigger->data;
+	*check_trg = true;
+	return 0;
+}
+
+int
+txn_process_func(va_list ap)
+{
+	bool *check_trg = va_arg(ap, bool *);
+	enum process_type process_type = (enum process_type)va_arg(ap, int);
+	struct txn *txn = txn_begin();
+	txn->fiber = fiber();
+	/* Set the TXN_WAIT_ACK flag to simulate a sync transaction.*/
+	txn_set_flag(txn, TXN_WAIT_ACK);
+	/*
+	 * The true way to push the transaction to limbo is to call
+	 * txn_commit() for sync transaction. But, if txn_commit()
+	 * will be called now, the transaction will not be pushed to
+	 * the limbo because this is the case txn_commit_nop().
+	 * Instead, we push the transaction to the limbo manually
+	 * and call txn_commit (or another) later.
+	 */
+	struct txn_limbo_entry *entry = txn_limbo_append(&txn_limbo,
+							 instace_id, txn);
+	/*
+	 * The trigger is used to verify that the transaction has been
+	 * completed.
+	 */
+	struct trigger trg;
+	trigger_create(&trg, trg_cb, check_trg, NULL);
+
+	switch (process_type) {
+	case TXN_PROCESS_COMMIT:
+		txn_on_commit(txn, &trg);
+		break;
+	case TXN_PROCESS_ROLLBACK:
+		txn_on_rollback(txn, &trg);
+		break;
+	case TXN_PROCESS_TIMEOUT:
+		break;
+	default:
+		unreachable();
+	}
+
+	txn_limbo_assign_lsn(&txn_limbo, entry, fake_lsn);
+	txn_limbo_wait_complete(&txn_limbo, entry);
+
+	switch (process_type) {
+	case TXN_PROCESS_COMMIT:
+		txn_commit(txn);
+		break;
+	case TXN_PROCESS_ROLLBACK:
+		txn_rollback(txn);
+		break;
+	case TXN_PROCESS_TIMEOUT:
+		fiber_yield();
+		break;
+	default:
+		unreachable();
+	}
+	return 0;
+}
+
+int
+txn_confirm_func(va_list ap)
+{
+	/*
+	 * We shouldn't react on gc_wait_cleanup() yield
+	 * inside gc_checkpoint().
+	 */
+	fiber_sleep(0);
+	txn_limbo_ack(&txn_limbo, relay_id, fake_lsn);
+	return 0;
+}
+
+
+void
+test_snap_delay_common(enum process_type process_type)
+{
+	plan(1);
+
+	/*
+	 * We need to clear the limbo vclock before the new test
+	 * variation because the same fake lsn will be used.
+	 */
+	vclock_clear(&txn_limbo.vclock);
+	vclock_create(&txn_limbo.vclock);
+
+	bool check_trg = false;
+	struct fiber *txn_fiber = fiber_new("txn_fiber", txn_process_func);
+	fiber_start(txn_fiber, &check_trg, process_type);
+
+	struct fiber *confirm_entry = fiber_new("confirm_fiber",
+						txn_confirm_func);
+	fiber_wakeup(confirm_entry);
+
+	switch (process_type) {
+	case TXN_PROCESS_COMMIT:
+		ok(gc_checkpoint() == 0 && check_trg,
+		   "check snapshot delay confirm");
+		break;
+	case TXN_PROCESS_ROLLBACK:
+		ok(gc_checkpoint() == -1 && check_trg,
+		   "check snapshot delay rollback");
+		break;
+	case TXN_PROCESS_TIMEOUT:
+		ok(gc_checkpoint() == -1, "check snapshot delay timeout");
+		/* join the "hung" fiber */
+		fiber_set_joinable(txn_fiber, true);
+		fiber_cancel(txn_fiber);
+		fiber_join(txn_fiber);
+		break;
+	default:
+		unreachable();
+	}
+	check_plan();
+}
+
+void
+test_snap_delay_timeout()
+{
+	/* Set the timeout to a small value for the test. */
+	replication_synchro_timeout = 0.01;
+	test_snap_delay_common(TXN_PROCESS_TIMEOUT);
+}
+
+int
+test_snap_delay(va_list ap)
+{
+	header();
+	plan(3);
+	(void)ap;
+	replication_synchro_quorum = 2;
+
+	test_snap_delay_common(TXN_PROCESS_COMMIT);
+	test_snap_delay_common(TXN_PROCESS_ROLLBACK);
+	test_snap_delay_timeout();
+
+	ev_break(loop(), EVBREAK_ALL);
+	footer();
+	test_result = check_plan();
+	return 0;
+}
+} /* end of anonymous namespace */
+
+int
+main(void)
+{
+	memory_init();
+	fiber_init(fiber_c_invoke);
+	gc_init();
+	txn_limbo_init();
+
+	struct fiber *main_fiber = fiber_new("main", test_snap_delay);
+	assert(main_fiber != NULL);
+	fiber_wakeup(main_fiber);
+	ev_run(loop(), 0);
+
+	gc_free();
+	fiber_free();
+	memory_free();
+	return test_result;
+}
diff --git a/test/unit/snap_quorum_delay.result 
b/test/unit/snap_quorum_delay.result
new file mode 100644
index 0000000..6ca2133
--- /dev/null
+++ b/test/unit/snap_quorum_delay.result
@@ -0,0 +1,12 @@
+	*** test_snap_delay ***
+1..3
+    1..1
+    ok 1 - check snapshot delay confirm
+ok 1 - subtests
+    1..1
+    ok 1 - check snapshot delay rollback
+ok 2 - subtests
+    1..1
+    ok 1 - check snapshot delay timeout
+ok 3 - subtests
+	*** test_snap_delay: done ***