From f5138184479bd16c0ee0a5e583479378451401c8 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Wed, 10 Jun 2015 20:59:05 +0200
Subject: erts: Add erts_factory_trim_and_close

---
 erts/emulator/beam/erl_message.c | 25 +++++++++++++++++++++----
 erts/emulator/beam/erl_message.h |  1 +
 erts/emulator/beam/io.c          |  6 +-----
 3 files changed, 23 insertions(+), 9 deletions(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/erl_message.c b/erts/emulator/beam/erl_message.c
index 13e084ce10..f806d2c498 100644
--- a/erts/emulator/beam/erl_message.c
+++ b/erts/emulator/beam/erl_message.c
@@ -93,9 +93,6 @@ erts_resize_message_buffer(ErlHeapFragment *bp, Uint size,
 #endif
     ErlHeapFragment* nbp;
 
-    /* ToDo: Make use of 'used_size' to avoid realloc
-	when shrinking just a few words */
-
 #ifdef DEBUG
     {
 	Uint off_sz = size < bp->used_size ? size : bp->used_size;
@@ -110,8 +107,10 @@ erts_resize_message_buffer(ErlHeapFragment *bp, Uint size,
     }
 #endif
 
-    if (size == bp->used_size)
+    if (size >= (bp->used_size - bp->used_size / 16)) {
+        bp->used_size = size;
 	return bp;
+    }
 
 #ifdef HARD_DEBUG
     dbg_brefs = erts_alloc(ERTS_ALC_T_UNDEF, sizeof(Eterm *)*brefs_size);
@@ -1288,6 +1287,24 @@ void erts_factory_close(ErtsHeapFactory* factory)
     factory->mode = FACTORY_CLOSED;
 }
 
+void erts_factory_trim_and_close(ErtsHeapFactory* factory,
+				 Eterm *brefs, Uint brefs_size)
+{
+    if (factory->mode == FACTORY_HEAP_FRAGS) {
+        ErlHeapFragment* bp = factory->heap_frags;
+        if (bp->next == NULL) {
+            Uint used_sz = factory->hp - bp->mem;
+            ASSERT(used_sz <= bp->alloc_size);
+            factory->heap_frags = erts_resize_message_buffer(bp, used_sz,
+                                                             brefs, brefs_size);
+            factory->mode = FACTORY_CLOSED;
+            return;
+        }
+        /*else we don't trim multi fragmented messages for now */
+    }
+    erts_factory_close(factory);
+}
+
 void erts_factory_undo(ErtsHeapFactory* factory)
 {
     ErlHeapFragment* bp;
diff --git a/erts/emulator/beam/erl_message.h b/erts/emulator/beam/erl_message.h
index 39946f2a14..705ba5e506 100644
--- a/erts/emulator/beam/erl_message.h
+++ b/erts/emulator/beam/erl_message.h
@@ -79,6 +79,7 @@ void erts_factory_dummy_init(ErtsHeapFactory*);
 Eterm* erts_produce_heap(ErtsHeapFactory*, Uint need, Uint xtra);
 Eterm* erts_reserve_heap(ErtsHeapFactory*, Uint need);
 void erts_factory_close(ErtsHeapFactory*);
+void erts_factory_trim_and_close(ErtsHeapFactory*,Eterm *brefs, Uint brefs_size);
 void erts_factory_undo(ErtsHeapFactory*);
 
 #ifdef CHECK_FOR_HOLES
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index fb030d61f9..23f208c2eb 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -1407,12 +1407,8 @@ queue_port_sched_op_reply(Process *rp,
     hp += REF_THING_SIZE;
 
     msg = TUPLE2(hp, ref, msg);
-    hp += 3;
 
-    /* SVERK: We used to call erts_resize_message_buffer here
-     * to maybe realloc message.
-     */
-    erts_factory_close(factory);
+    erts_factory_trim_and_close(factory, &msg, 1);
 
     erts_queue_message(rp, rp_locksp, factory->heap_frags, msg, NIL);
 }
-- 
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