for heapdump=true builds, optionally generate dump on OOM

If the VM runs out of heap space and the "avian.heap.dump" system
property was specified at startup, the VM will write a heap dump to
the filename indicated by that property.  This dump may be analyzed
using e.g. DumpStats.java.

src/heap.cpp

@@ -69,6 +69,7 @@ void assert(Context*, bool);
 System* system(Context*);
 void* tryAllocate(Context* c, unsigned size);
 void free(Context* c, const void* p, unsigned size);
+void outOfMemory(Context*);
 
 #ifdef USE_ATOMIC_OPERATIONS
 inline void
@@ -359,7 +360,7 @@ class Segment {
               break;
             }
           } else {
-            abort(context);
+            outOfMemory(context);
           }
         }
       }
@@ -1708,7 +1709,8 @@ collect(Context* c)
   }
 }
 
-void* tryAllocate(Context* c, unsigned size)
+void*
+tryAllocate(Context* c, unsigned size)
 {
   ACQUIRE(c->lock);
 
@@ -1733,7 +1735,9 @@ void* tryAllocate(Context* c, unsigned size)
   return 0;
 }
 
-void free(Context* c, const void* p, unsigned size) {
+void
+free(Context* c, const void* p, unsigned size)
+{
   ACQUIRE(c->lock);
 
   if (DebugAllocation) {
@@ -1755,10 +1759,18 @@ void free(Context* c, const void* p, unsigned size) {
   c->count -= size;
 }
 
-void free_(Context* c, const void* p, unsigned size) {
+void
+free_(Context* c, const void* p, unsigned size)
+{
   free(c, p, size);
 }
 
+void
+outOfMemory(Context* c)
+{
+  c->client->outOfMemory();
+}
+
 class MyHeap: public Heap {
  public:
   MyHeap(System* system, unsigned limit):
@@ -1781,7 +1793,9 @@ class MyHeap: public Heap {
 
   virtual void* allocate(unsigned size) {
     void* p = local::tryAllocate(&c, size);
-    expect(c.system, p);
+    if (p == 0) {
+      c.client->outOfMemory();
+    }
     return p;
   }
 

src/heap.h

@@ -49,6 +49,7 @@ class Heap: public Allocator {
     virtual unsigned copiedSizeInWords(void*) = 0;
     virtual void copy(void*, void*) = 0;
     virtual void walk(void*, Walker*) = 0;
+    virtual void outOfMemory() = 0;
   };
 
   virtual void setClient(Client* client) = 0;

src/machine.cpp

@@ -2081,6 +2081,21 @@ class HeapClient: public Heap::Client {
     ::walk(m->rootThread, w, o, 0);
   }
 
+  virtual void outOfMemory() {
+#ifdef AVIAN_HEAPDUMP
+    const char* path = findProperty(m->rootThread, "avian.heap.dump");
+    if (path) {
+      FILE* out = vm::fopen(path, "wb");
+      if (out) {
+        dumpHeap(m->rootThread, out);
+        fclose(out);
+      }
+    }
+#endif//AVIAN_HEAPDUMP
+
+    abort(m->system);
+  }
+
   void dispose() {
     m->heap->free(this, sizeof(*this));
   }

test/extra/DumpStats.java

@@ -16,8 +16,9 @@ import java.util.Arrays;
  * heap dump generated by Avian's heapdump.cpp.  The output is a list
  * of classes (identified by number in the case of anonymous,
  * VM-internal classes), each followed by (1) the total memory
- * footprint of all instances of the class, and (2) the number of
+ * footprint of all instances of the class in machine words, and (2)
- * instances.  The output is ordered by instance memory footprint.
+ * the number of instances.  The output is ordered by instance memory
+ * footprint.
  */
 public class DumpStats {
   private static final int Root = 0;