#1339 Fix issue with cleaning up iterator resources for systems that …

…match nothing

distr/flecs.c

@@ -34173,6 +34173,7 @@ int flecs_query_finalize_terms(
     }
 
     bool cacheable = true;
+    bool match_nothing = true;
     for (i = 0; i < term_count; i ++) {
         ecs_term_t *term = &terms[i];
         bool prev_is_or = i && term[-1].oper == EcsOr;
@@ -34183,6 +34184,11 @@ int flecs_query_finalize_terms(
             return -1;
         }
 
+        if (term->src.id != EcsIsEntity) {
+            /* If term doesn't match 0 entity, query doesn't match nothing */
+            match_nothing = false;
+        }
+
         if (scope_nesting) {
             /* Terms inside a scope are not cacheable */
             ECS_BIT_CLEAR16(term->flags_, EcsTermIsCacheable);
@@ -34509,6 +34515,9 @@ int flecs_query_finalize_terms(
         cacheable && (cacheable_terms == term_count) &&
             !desc->order_by_callback);
 
+    /* If none of the terms match a source, the query matches nothing */
+    ECS_BIT_COND(q->flags, EcsQueryMatchNothing, match_nothing);
+
     for (i = 0; i < q->term_count; i ++) {
         ecs_term_t *term = &q->terms[i];
         /* Post process term names in case they were used to create variables */
@@ -62641,7 +62650,10 @@ ecs_entity_t flecs_run_intern(
 
     ecs_run_action_t run = system_data->run;
     if (run) {
-        if (!system_data->query->term_count) {
+        /* If system query matches nothing, the system run callback doesn't have
+         * anything to iterate, so the iterator resources don't get cleaned up
+         * automatically, so clean it up here. */
+        if (system_data->query->flags & EcsQueryMatchNothing) {
             it->next = flecs_default_next_callback; /* Return once */
             run(it);
             ecs_iter_fini(&qit);

distr/flecs.h

@@ -461,17 +461,18 @@ extern "C" {
 #define EcsQueryMatchOnlyThis         (1u << 12u) /* Query only has terms with $this source */
 #define EcsQueryMatchOnlySelf         (1u << 13u) /* Query has no terms with up traversal */
 #define EcsQueryMatchWildcards        (1u << 14u) /* Query matches wildcards */
-#define EcsQueryHasCondSet            (1u << 15u) /* Query has conditionally set fields */
-#define EcsQueryHasPred               (1u << 16u) /* Query has equality predicates */
-#define EcsQueryHasScopes             (1u << 17u) /* Query has query scopes */
-#define EcsQueryHasRefs               (1u << 18u) /* Query has terms with static source */
-#define EcsQueryHasOutTerms           (1u << 19u) /* Query has [out] terms */
-#define EcsQueryHasNonThisOutTerms    (1u << 20u) /* Query has [out] terms with no $this source */
-#define EcsQueryHasMonitor            (1u << 21u) /* Query has monitor for change detection */
-#define EcsQueryIsTrivial             (1u << 22u) /* Query can use trivial evaluation function */
-#define EcsQueryHasCacheable          (1u << 23u) /* Query has cacheable terms */
-#define EcsQueryIsCacheable           (1u << 24u) /* All terms of query are cacheable */
-#define EcsQueryHasTableThisVar       (1u << 25u) /* Does query have $this table var */
+#define EcsQueryMatchNothing          (1u << 15u) /* Query matches nothing */
+#define EcsQueryHasCondSet            (1u << 16u) /* Query has conditionally set fields */
+#define EcsQueryHasPred               (1u << 17u) /* Query has equality predicates */
+#define EcsQueryHasScopes             (1u << 18u) /* Query has query scopes */
+#define EcsQueryHasRefs               (1u << 19u) /* Query has terms with static source */
+#define EcsQueryHasOutTerms           (1u << 20u) /* Query has [out] terms */
+#define EcsQueryHasNonThisOutTerms    (1u << 21u) /* Query has [out] terms with no $this source */
+#define EcsQueryHasMonitor            (1u << 22u) /* Query has monitor for change detection */
+#define EcsQueryIsTrivial             (1u << 23u) /* Query can use trivial evaluation function */
+#define EcsQueryHasCacheable          (1u << 24u) /* Query has cacheable terms */
+#define EcsQueryIsCacheable           (1u << 25u) /* All terms of query are cacheable */
+#define EcsQueryHasTableThisVar       (1u << 26u) /* Does query have $this table var */
 #define EcsQueryCacheYieldEmptyTables (1u << 27u) /* Does query cache empty tables */
 
 ////////////////////////////////////////////////////////////////////////////////

include/flecs/private/api_flags.h

@@ -146,17 +146,18 @@ extern "C" {
 #define EcsQueryMatchOnlyThis         (1u << 12u) /* Query only has terms with $this source */
 #define EcsQueryMatchOnlySelf         (1u << 13u) /* Query has no terms with up traversal */
 #define EcsQueryMatchWildcards        (1u << 14u) /* Query matches wildcards */
-#define EcsQueryHasCondSet            (1u << 15u) /* Query has conditionally set fields */
-#define EcsQueryHasPred               (1u << 16u) /* Query has equality predicates */
-#define EcsQueryHasScopes             (1u << 17u) /* Query has query scopes */
-#define EcsQueryHasRefs               (1u << 18u) /* Query has terms with static source */
-#define EcsQueryHasOutTerms           (1u << 19u) /* Query has [out] terms */
-#define EcsQueryHasNonThisOutTerms    (1u << 20u) /* Query has [out] terms with no $this source */
-#define EcsQueryHasMonitor            (1u << 21u) /* Query has monitor for change detection */
-#define EcsQueryIsTrivial             (1u << 22u) /* Query can use trivial evaluation function */
-#define EcsQueryHasCacheable          (1u << 23u) /* Query has cacheable terms */
-#define EcsQueryIsCacheable           (1u << 24u) /* All terms of query are cacheable */
-#define EcsQueryHasTableThisVar       (1u << 25u) /* Does query have $this table var */
+#define EcsQueryMatchNothing          (1u << 15u) /* Query matches nothing */
+#define EcsQueryHasCondSet            (1u << 16u) /* Query has conditionally set fields */
+#define EcsQueryHasPred               (1u << 17u) /* Query has equality predicates */
+#define EcsQueryHasScopes             (1u << 18u) /* Query has query scopes */
+#define EcsQueryHasRefs               (1u << 19u) /* Query has terms with static source */
+#define EcsQueryHasOutTerms           (1u << 20u) /* Query has [out] terms */
+#define EcsQueryHasNonThisOutTerms    (1u << 21u) /* Query has [out] terms with no $this source */
+#define EcsQueryHasMonitor            (1u << 22u) /* Query has monitor for change detection */
+#define EcsQueryIsTrivial             (1u << 23u) /* Query can use trivial evaluation function */
+#define EcsQueryHasCacheable          (1u << 24u) /* Query has cacheable terms */
+#define EcsQueryIsCacheable           (1u << 25u) /* All terms of query are cacheable */
+#define EcsQueryHasTableThisVar       (1u << 26u) /* Does query have $this table var */
 #define EcsQueryCacheYieldEmptyTables (1u << 27u) /* Does query cache empty tables */
 
 ////////////////////////////////////////////////////////////////////////////////

src/addons/system/system.c

@@ -105,7 +105,10 @@ ecs_entity_t flecs_run_intern(
 
     ecs_run_action_t run = system_data->run;
     if (run) {
-        if (!system_data->query->term_count) {
+        /* If system query matches nothing, the system run callback doesn't have
+         * anything to iterate, so the iterator resources don't get cleaned up
+         * automatically, so clean it up here. */
+        if (system_data->query->flags & EcsQueryMatchNothing) {
             it->next = flecs_default_next_callback; /* Return once */
             run(it);
             ecs_iter_fini(&qit);

src/query/validator.c

@@ -1095,6 +1095,7 @@ int flecs_query_finalize_terms(
     }
 
     bool cacheable = true;
+    bool match_nothing = true;
     for (i = 0; i < term_count; i ++) {
         ecs_term_t *term = &terms[i];
         bool prev_is_or = i && term[-1].oper == EcsOr;
@@ -1105,6 +1106,11 @@ int flecs_query_finalize_terms(
             return -1;
         }
 
+        if (term->src.id != EcsIsEntity) {
+            /* If term doesn't match 0 entity, query doesn't match nothing */
+            match_nothing = false;
+        }
+
         if (scope_nesting) {
             /* Terms inside a scope are not cacheable */
             ECS_BIT_CLEAR16(term->flags_, EcsTermIsCacheable);
@@ -1431,6 +1437,9 @@ int flecs_query_finalize_terms(
         cacheable && (cacheable_terms == term_count) &&
             !desc->order_by_callback);
 
+    /* If none of the terms match a source, the query matches nothing */
+    ECS_BIT_COND(q->flags, EcsQueryMatchNothing, match_nothing);
+
     for (i = 0; i < q->term_count; i ++) {
         ecs_term_t *term = &q->terms[i];
         /* Post process term names in case they were used to create variables */

test/addons/project.json

@@ -109,7 +109,9 @@
                 "run_pipeline_multithreaded_tasks",
                 "pipeline_init_no_terms",
                 "pipeline_init_no_system_term",
-                "disable_component_from_immediate_system"
+                "disable_component_from_immediate_system",
+                "run_w_empty_query",
+                "run_w_0_src_query"
             ]
         }, {
             "id": "SystemMisc",

test/addons/src/Pipeline.c

@@ -3246,3 +3246,42 @@ void Pipeline_disable_component_from_immediate_system(void) {
 
     ecs_fini(world);
 }
+
+void Pipeline_run_w_empty_query(void) {
+    ecs_world_t *world = ecs_init();
+
+    ECS_COMPONENT(world, Position);
+
+    ecs_system(world, {
+        .entity = ecs_entity(world, {
+            .add = ecs_ids(ecs_pair(EcsDependsOn, EcsOnUpdate))
+        }),
+        .run = SysA
+    });
+
+    ecs_progress(world, 0);
+    test_int(sys_a_invoked, 1);
+
+    ecs_fini(world);
+}
+
+void Pipeline_run_w_0_src_query(void) {
+    ecs_world_t *world = ecs_init();
+
+    ECS_COMPONENT(world, Position);
+
+    ecs_system(world, {
+        .entity = ecs_entity(world, {
+            .add = ecs_ids(ecs_pair(EcsDependsOn, EcsOnUpdate))
+        }),
+        .query.terms = {
+            { ecs_id(Position), .src.id = EcsIsEntity }
+        },
+        .run = SysA
+    });
+
+    ecs_progress(world, 0);
+    test_int(sys_a_invoked, 1);
+
+    ecs_fini(world);
+}

test/addons/src/main.c

@@ -104,6 +104,8 @@ void Pipeline_run_pipeline_multithreaded_tasks(void);
 void Pipeline_pipeline_init_no_terms(void);
 void Pipeline_pipeline_init_no_system_term(void);
 void Pipeline_disable_component_from_immediate_system(void);
+void Pipeline_run_w_empty_query(void);
+void Pipeline_run_w_0_src_query(void);
 
 // Testsuite 'SystemMisc'
 void SystemMisc_invalid_not_without_id(void);
@@ -907,6 +909,14 @@ bake_test_case Pipeline_testcases[] = {
     {
         "disable_component_from_immediate_system",
         Pipeline_disable_component_from_immediate_system
+    },
+    {
+        "run_w_empty_query",
+        Pipeline_run_w_empty_query
+    },
+    {
+        "run_w_0_src_query",
+        Pipeline_run_w_0_src_query
     }
 };
 
@@ -2515,7 +2525,7 @@ static bake_test_suite suites[] = {
         "Pipeline",
         NULL,
         NULL,
-        83,
+        85,
         Pipeline_testcases
     },
     {

test/cpp/project.json

@@ -509,7 +509,8 @@
                 "register_twice_w_each",
                 "register_twice_w_run",
                 "register_twice_w_run_each",
-                "register_twice_w_each_run"
+                "register_twice_w_each_run",
+                "run_w_0_src_query"
             ]
         }, {
             "id": "Event",

test/cpp/src/System.cpp

@@ -1049,7 +1049,7 @@ void System_self_rate_filter(void) {
 
     int32_t count = 0;
 
-    auto sys = world.system<Position>("sys")
+    world.system<Position>("sys")
         .rate(2)
         .each([&](Position & p){
             count ++;
@@ -2310,3 +2310,18 @@ void System_register_twice_w_each_run(void) {
     sys2.run();
     test_int(count2, 1);
 }
+
+void System_run_w_0_src_query(void) {
+    flecs::world world;
+
+    int count = 0;
+
+    world.system()
+        .write<Position>()
+        .run([&](flecs::iter&){
+            count ++;
+        });
+
+    world.progress();
+    test_int(count, 1);
+}

test/cpp/src/main.cpp

@@ -492,6 +492,7 @@ void System_register_twice_w_each(void);
 void System_register_twice_w_run(void);
 void System_register_twice_w_run_each(void);
 void System_register_twice_w_each_run(void);
+void System_run_w_0_src_query(void);
 
 // Testsuite 'Event'
 void Event_evt_1_id_entity(void);
@@ -3242,6 +3243,10 @@ bake_test_case System_testcases[] = {
     {
         "register_twice_w_each_run",
         System_register_twice_w_each_run
+    },
+    {
+        "run_w_0_src_query",
+        System_run_w_0_src_query
     }
 };
 
@@ -6592,7 +6597,7 @@ static bake_test_suite suites[] = {
         "System",
         NULL,
         NULL,
-        72,
+        73,
         System_testcases
     },
     {

test/query/project.json

@@ -679,7 +679,9 @@
                 "ref_fields_static_src",
                 "ref_fields_variable_src",
                 "ref_fields_up_src",
-                "ref_fields_self_up_src"
+                "ref_fields_self_up_src",
+                "0_src_match_nothing",
+                "0_terms_match_nothing"
             ]
         }, {
             "id": "Combinations",

test/query/src/Basic.c

@@ -10741,3 +10741,38 @@ void Basic_ref_fields_self_up_src(void) {
 
     ecs_fini(world);
 }
+
+void Basic_0_src_match_nothing(void) {
+    ecs_world_t *world = ecs_mini();
+
+    ECS_COMPONENT(world, Position);
+
+    ecs_query_t *q = ecs_query(world, {
+        .terms = {{ .id = ecs_id(Position), .src.id = EcsIsEntity }},
+        .cache_kind = cache_kind
+    });
+
+    test_assert(q != NULL);
+    test_assert(q->flags & EcsQueryMatchNothing);
+
+    ecs_query_fini(q);
+
+    ecs_fini(world);
+}
+
+void Basic_0_terms_match_nothing(void) {
+    ecs_world_t *world = ecs_mini();
+
+    ECS_COMPONENT(world, Position);
+
+    ecs_query_t *q = ecs_query(world, {
+        .cache_kind = cache_kind
+    });
+
+    test_assert(q != NULL);
+    test_assert(q->flags & EcsQueryMatchNothing);
+
+    ecs_query_fini(q);
+
+    ecs_fini(world);
+}

test/query/src/main.c

@@ -668,6 +668,8 @@ void Basic_ref_fields_static_src(void);
 void Basic_ref_fields_variable_src(void);
 void Basic_ref_fields_up_src(void);
 void Basic_ref_fields_self_up_src(void);
+void Basic_0_src_match_nothing(void);
+void Basic_0_terms_match_nothing(void);
 
 // Testsuite 'Combinations'
 void Combinations_setup(void);
@@ -4682,6 +4684,14 @@ bake_test_case Basic_testcases[] = {
     {
         "ref_fields_self_up_src",
         Basic_ref_fields_self_up_src
+    },
+    {
+        "0_src_match_nothing",
+        Basic_0_src_match_nothing
+    },
+    {
+        "0_terms_match_nothing",
+        Basic_0_terms_match_nothing
     }
 };
 
@@ -10172,7 +10182,7 @@ static bake_test_suite suites[] = {
         "Basic",
         Basic_setup,
         NULL,
-        212,
+        214,
         Basic_testcases,
         1,
         Basic_params