erts: Add garbage_collection_info to process_info/2

This info request returns greater details about the current
gc state. This info is not included in the default process_info/1
as it would clutter the default printout with too much information.

6 files changed, 138 insertions, 53 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index ea04495574..4ad989cac1 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -256,6 +256,7 @@ atom functions
 atom function_clause
 atom garbage_collecting
 atom garbage_collection
+atom garbage_collection_info
 atom gc_end
 atom gc_start
 atom Ge='>='
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 1eb106a551..855ef8742a 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -589,7 +589,8 @@ static Eterm pi_args[] = {
     am_min_bin_vheap_size,
     am_current_location,
     am_current_stacktrace,
-    am_off_heap_message_queue
+    am_off_heap_message_queue,
+    am_garbage_collection_info
 };
 
 #define ERTS_PI_ARGS ((int) (sizeof(pi_args)/sizeof(Eterm)))
@@ -638,6 +639,7 @@ pi_arg2ix(Eterm arg)
     case am_current_location:			return 29;
     case am_current_stacktrace:			return 30;
     case am_off_heap_message_queue:		return 31;
+    case am_garbage_collection_info:		return 32;
     default:					return -1;
     }
 }
@@ -1395,6 +1397,32 @@ process_info_aux(Process *BIF_P,
 	break;
     }
 
+    case am_garbage_collection_info: {
+        Uint sz = 0, actual_sz = 0;
+
+        if (rp == BIF_P) {
+            sz += ERTS_PROCESS_GC_INFO_MAX_SIZE;
+        } else {
+            erts_process_gc_info(rp, &sz, NULL);
+            sz += 3;
+        }
+
+        hp = HAlloc(BIF_P, sz);
+        res = erts_process_gc_info(rp, &actual_sz, &hp);
+
+        /* We may have some extra space, fill with 0 tuples */
+        if (actual_sz <= sz - 3) {
+            for (; actual_sz < sz - 3; hp++, actual_sz++)
+                hp[0] = make_arityval(0);
+        } else {
+            for (; actual_sz < sz; hp++, actual_sz++)
+                hp[0] = make_arityval(0);
+            hp = HAlloc(BIF_P, 3);
+        }
+
+        break;
+    }
+
     case am_group_leader: {
 	int sz = NC_HEAP_SIZE(rp->group_leader);
 	hp = HAlloc(BIF_P, 3 + sz);
diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c
index 6cb37752bc..3399b1a9f2 100644
--- a/erts/emulator/beam/erl_gc.c
+++ b/erts/emulator/beam/erl_gc.c
@@ -2741,6 +2741,57 @@ erts_gc_info_request(Process *c_p)
     return ref;
 }
 
+Eterm
+erts_process_gc_info(Process *p, Uint *sizep, Eterm **hpp)
+{
+    ERTS_DECL_AM(bin_vheap_size);
+    ERTS_DECL_AM(bin_vheap_block_size);
+    ERTS_DECL_AM(bin_old_vheap_size);
+    ERTS_DECL_AM(bin_old_vheap_block_size);
+    Eterm tags[] = {
+        /* If you increase the number of elements here, make sure to update
+           any call sites as they may have stack allocations that depend
+           on the number of elements here. */
+        am_old_heap_block_size,
+        am_heap_block_size,
+        am_mbuf_size,
+        am_recent_size,
+        am_stack_size,
+        am_old_heap_size,
+        am_heap_size,
+        AM_bin_vheap_size,
+        AM_bin_vheap_block_size,
+        AM_bin_old_vheap_size,
+        AM_bin_old_vheap_block_size
+    };
+    UWord values[] = {
+        OLD_HEAP(p) ? OLD_HEND(p) - OLD_HEAP(p) : 0,
+        HEAP_SIZE(p),
+        MBUF_SIZE(p),
+        HIGH_WATER(p) - HEAP_START(p),
+        STACK_START(p) - p->stop,
+        OLD_HEAP(p) ? OLD_HTOP(p) - OLD_HEAP(p) : 0,
+        HEAP_TOP(p) - HEAP_START(p),
+        MSO(p).overhead,
+        BIN_VHEAP_SZ(p),
+        BIN_OLD_VHEAP(p),
+        BIN_OLD_VHEAP_SZ(p)
+    };
+
+    Eterm res = THE_NON_VALUE;
+
+    ERTS_CT_ASSERT(sizeof(values)/sizeof(*values) == sizeof(tags)/sizeof(*tags));
+    ERTS_CT_ASSERT(sizeof(values)/sizeof(*values) == ERTS_PROCESS_GC_INFO_MAX_TERMS);
+
+    res = erts_bld_atom_uword_2tup_list(hpp,
+                                        sizep,
+                                        sizeof(values)/sizeof(*values),
+                                        tags,
+                                        values);
+
+    return res;
+}
+
 #if defined(DEBUG) || defined(ERTS_OFFHEAP_DEBUG)
 
 static int
diff --git a/erts/emulator/beam/erl_gc.h b/erts/emulator/beam/erl_gc.h
index d603866cbf..2cedd9361f 100644
--- a/erts/emulator/beam/erl_gc.h
+++ b/erts/emulator/beam/erl_gc.h
@@ -132,6 +132,11 @@ typedef struct {
   Uint64 garbage_cols;
 } ErtsGCInfo;
 
+#define ERTS_PROCESS_GC_INFO_MAX_TERMS (11)  /* number of elements in process_gc_info*/
+#define ERTS_PROCESS_GC_INFO_MAX_SIZE                                   \
+    (ERTS_PROCESS_GC_INFO_MAX_TERMS * (2/*cons*/ + 3/*2-tuple*/ + BIG_UINT_HEAP_SIZE))
+Eterm erts_process_gc_info(struct process*, Uint *, Eterm **);
+
 void erts_gc_info(ErtsGCInfo *gcip);
 void erts_init_gc(void);
 int erts_garbage_collect_nobump(struct process*, int, Eterm*, int);
diff --git a/erts/emulator/beam/erl_trace.c b/erts/emulator/beam/erl_trace.c
index d02f1f7213..e47b1e4edc 100644
--- a/erts/emulator/beam/erl_trace.c
+++ b/erts/emulator/beam/erl_trace.c
@@ -2144,11 +2144,6 @@ void save_calls(Process *p, Export *e)
 void
 trace_gc(Process *p, Eterm what)
 {
-    ERTS_DECL_AM(bin_vheap_size);
-    ERTS_DECL_AM(bin_vheap_block_size);
-    ERTS_DECL_AM(bin_old_vheap_size);
-    ERTS_DECL_AM(bin_old_vheap_block_size);
-
     ErlHeapFragment *bp = NULL;
     ErlOffHeap *off_heap;
     ERTS_TRACER_REF_TYPE tracer_ref = ERTS_NULL_TRACER_REF;	/* Initialized
@@ -2159,55 +2154,22 @@ trace_gc(Process *p, Eterm what)
     Eterm msg = NIL;
     Uint size;
 
-    Eterm tags[] = {
-	am_old_heap_block_size,
-	am_heap_block_size,
-	am_mbuf_size,
-	am_recent_size,
-	am_stack_size,
-	am_old_heap_size,
-	am_heap_size,
-	AM_bin_vheap_size,
-	AM_bin_vheap_block_size,
-	AM_bin_old_vheap_size,
-	AM_bin_old_vheap_block_size
-    };
-
-    UWord values[] = {
-	OLD_HEAP(p) ? OLD_HEND(p) - OLD_HEAP(p) : 0,
-	HEAP_SIZE(p),
-	MBUF_SIZE(p),
-	HIGH_WATER(p) - HEAP_START(p),
-	STACK_START(p) - p->stop,
-	OLD_HEAP(p) ? OLD_HTOP(p) - OLD_HEAP(p) : 0,
-	HEAP_TOP(p) - HEAP_START(p),
-	MSO(p).overhead,
-	BIN_VHEAP_SZ(p),
-	BIN_OLD_VHEAP(p),
-	BIN_OLD_VHEAP_SZ(p)
-    };
 #define LOCAL_HEAP_SIZE						\
-    (sizeof(values)/sizeof(*values)) *				\
-	(2/*cons*/ + 3/*2-tuple*/ + BIG_UINT_HEAP_SIZE) +	\
+    (ERTS_PROCESS_GC_INFO_MAX_SIZE) +                           \
 	5/*4-tuple */ + TS_HEAP_WORDS
     DeclareTmpHeap(local_heap,LOCAL_HEAP_SIZE,p);
 #ifdef DEBUG
     Eterm* limit;
 #endif
 
-    ERTS_CT_ASSERT(sizeof(values)/sizeof(*values) == sizeof(tags)/sizeof(Eterm));
-
     UseTmpHeap(LOCAL_HEAP_SIZE,p);
 
     if (is_internal_port(ERTS_TRACER_PROC(p))) {
 	hp = local_heap;
 #ifdef DEBUG
 	size = 0;
-	(void) erts_bld_atom_uword_2tup_list(NULL,
-					    &size,
-					    sizeof(values)/sizeof(*values),
-					    tags,
-					    values);
+        (void) erts_process_gc_info(p, &size, NULL);
+
 	size += 5/*4-tuple*/ + TS_SIZE(p);
 #endif
     } else {
@@ -2218,11 +2180,8 @@ trace_gc(Process *p, Eterm what)
 			    ERTS_TRACE_FLAGS(p));
 
 	size = 0;
-	(void) erts_bld_atom_uword_2tup_list(NULL,
-					    &size,
-					    sizeof(values)/sizeof(*values),
-					    tags,
-					    values);
+        (void) erts_process_gc_info(p, &size, NULL);
+
 	size += 5/*4-tuple*/ + TS_SIZE(p);
 
 	hp = ERTS_ALLOC_SYSMSG_HEAP(size, &bp, &off_heap, tracer_ref);
@@ -2233,11 +2192,7 @@ trace_gc(Process *p, Eterm what)
     ASSERT(size <= LOCAL_HEAP_SIZE);
 #endif
 
-    msg = erts_bld_atom_uword_2tup_list(&hp,
-				       NULL,
-				       sizeof(values)/sizeof(*values),
-				       tags,
-				       values);
+    msg = erts_process_gc_info(p, NULL, &hp);
 
     msg = TUPLE4(hp, am_trace, p->common.id, what, msg);
     hp += 5;
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 97aa5e573e..bfd1e78bf0 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -41,6 +41,7 @@
 	 process_info_2_list/1, process_info_lock_reschedule/1,
 	 process_info_lock_reschedule2/1,
 	 process_info_lock_reschedule3/1,
+         process_info_garbage_collection/1,
 	 bump_reductions/1, low_prio/1, binary_owner/1, yield/1, yield2/1,
 	 process_status_exiting/1,
 	 otp_4725/1, bad_register/1, garbage_collect/1, otp_6237/1,
@@ -75,7 +76,9 @@ all() ->
      process_info_other_dist_msg, process_info_2_list,
      process_info_lock_reschedule,
      process_info_lock_reschedule2,
-     process_info_lock_reschedule3, process_status_exiting,
+     process_info_lock_reschedule3,
+     process_info_garbage_collection,
+     process_status_exiting,
      bump_reductions, low_prio, yield, yield2, otp_4725,
      bad_register, garbage_collect, process_info_messages,
      process_flag_badarg, process_flag_heap_size,
@@ -932,6 +935,48 @@ start_spawner() ->
 stop_spawner() ->
     ok.
 
+%% Tests erlang:process_info(Pid, garbage_collection_info)
+process_info_garbage_collection(_Config) ->
+    Parent = self(),
+    Pid = spawn_link(
+            fun() ->
+                    receive go -> ok end,
+                    (fun F(0) ->
+                             Parent ! deep,
+                             receive ok -> ok end,
+                             [];
+                         F(N) ->
+                             timer:sleep(1),
+                             [lists:seq(1,100) | F(N-1)]
+                     end)(1000),
+                    Parent ! shallow,
+                    receive done -> ok end
+            end),
+    {garbage_collection_info, Before} =
+        erlang:process_info(Pid, garbage_collection_info),
+    Pid ! go, receive deep -> ok end,
+    {_, Deep} = erlang:process_info(Pid, garbage_collection_info),
+    Pid ! ok, receive shallow -> ok end,
+    {_, After} = erlang:process_info(Pid, garbage_collection_info),
+    Pid ! done,
+
+    %% Do some general checks to see if everything seems to be roughly correct
+    ct:log("Before: ~p",[Before]),
+    ct:log("Deep: ~p",[Deep]),
+    ct:log("After: ~p",[After]),
+
+    %% Check stack_size
+    true = proplists:get_value(stack_size, Before) < proplists:get_value(stack_size, Deep),
+    true = proplists:get_value(stack_size, After) < proplists:get_value(stack_size, Deep),
+
+    %% Check used heap size
+    true = proplists:get_value(heap_size, Before) + proplists:get_value(old_heap_size, Before)
+        < proplists:get_value(heap_size, Deep) + proplists:get_value(old_heap_size, Deep),
+    true = proplists:get_value(heap_size, Before) + proplists:get_value(old_heap_size, Before)
+        < proplists:get_value(heap_size, After) + proplists:get_value(old_heap_size, After),
+
+    ok.
+
 %% Tests erlang:bump_reductions/1.
 bump_reductions(Config) when is_list(Config) ->
     erlang:garbage_collect(),