Do not allow run concurrent sweep instances

Author: Artyom Ivanov

src/include/firebird/impl/msg/jrd.h

@@ -987,3 +987,4 @@ FB_IMPL_MSG(JRD, 984, incompatible_format_patterns, -901, "HY", "000", "@1 incom
 FB_IMPL_MSG(JRD, 985, only_one_pattern_can_be_used, -901, "HY", "000", "Can use only one of these patterns @1")
 FB_IMPL_MSG(JRD, 986, can_not_use_same_pattern_twice, -901, "HY", "000", "Cannot use the same pattern twice: @1")
 FB_IMPL_MSG(JRD, 987, sysf_invalid_gen_uuid_version, -833, "42", "000", "Invalid GEN_UUID version (@1). Must be 4 or 7")
+FB_IMPL_MSG(JRD, 988, sweep_concurrent_instance, -901, "42", "000", "Another instance of sweep is already running")

src/include/gen/Firebird.pas

@@ -5740,6 +5740,7 @@ 	IProfilerStatsImpl = class(IProfilerStats)
 	 isc_only_one_pattern_can_be_used = 335545305;
 	 isc_can_not_use_same_pattern_twice = 335545306;
 	 isc_sysf_invalid_gen_uuid_version = 335545307;
+	 isc_sweep_concurrent_instance = 335545308;
 	 isc_gfix_db_name = 335740929;
 	 isc_gfix_invalid_sw = 335740930;
 	 isc_gfix_incmp_sw = 335740932;

src/jrd/Database.cpp

@@ -316,7 +316,7 @@ namespace Jrd
 			if (old & DBB_sweep_in_progress)
 			{
 				clearSweepStarting();
-				return false;
+				ERR_post(Arg::Gds(isc_sweep_concurrent_instance));
 			}
 
 			if (dbb_flags.compareExchange(old, old | DBB_sweep_in_progress))
@@ -336,7 +336,7 @@ namespace Jrd
 				fb_utils::init_status(tdbb->tdbb_status_vector);
 
 				dbb_flags &= ~DBB_sweep_in_progress;
-				return false;
+				ERR_post(Arg::Gds(isc_sweep_concurrent_instance));
 			}
 		}
 		else

src/jrd/Database.h

@@ -657,7 +657,8 @@ class Database : public pool_alloc<type_dbb>
 
 	// returns true if sweeper thread could start
 	bool allowSweepThread(thread_db* tdbb);
-	// returns true if sweep could run
+	// Returns true if sweep could run.
+	// Exception can be thrown if another sweep instance is already running.
 	bool allowSweepRun(thread_db* tdbb);
 	// reset sweep flag and release sweep lock
 	void clearSweepFlags(thread_db* tdbb);