Provide a way for iterating through all external strings referenced from the JS heap

test/cctest/test-heap-profiler.cc

Index: test/cctest/test-heap-profiler.cc
===================================================================
--- test/cctest/test-heap-profiler.cc	(revision 10391)
+++ test/cctest/test-heap-profiler.cc	(working copy)
@@ -855,7 +855,67 @@
   CHECK_EQ(NULL, v8::HeapProfiler::FindSnapshot(uid3));
 }
 
+class TestResource: public v8::String::ExternalStringResource {
+ public:
+  static const size_t max_length = 100;

[mnaganov (inactive), 2012/01/11 18:50:23]

kMaxLength

[yurys, 2012/01/11 19:50:13]

Done.

+  explicit TestResource(const char* data)
+    : data_(), length_(strlen(data)) {
+    if (length_ >= max_length) length_ = max_length - 1;
+    for (size_t i = 0; i < length_; i++) data_[i] = data[i];
+    data_[length_ + 1] = 0;
+  }
 
+  ~TestResource() {}
+  const uint16_t* data() const { return data_; }
+  size_t length() const { return length_; }
+ private:
+  uint16_t data_[max_length];
+  size_t length_;
+};
+
+class VisitorImpl : public v8::HeapProfiler::ExternalResourceVisitor {
+ public:
+  VisitorImpl(TestResource* r1, TestResource* r2)
+      : resource1_(r1),
+        resource2_(r2) {}
+  virtual ~VisitorImpl() {}
+  virtual void VisitExternalString(v8::Handle<v8::String> string) {
+    if (!string->IsExternal()) {
+      CHECK(string->IsExternalAscii());
+      return;
+    }
+    v8::String::ExternalStringResource* resource =
+        string->GetExternalStringResource();
+    CHECK(resource);
+    if (resource1_ == resource)

[mnaganov (inactive), 2012/01/11 18:50:23]

Perhaps, just use boolean flags? Modifying references looks too hackish.

[yurys, 2012/01/11 19:50:13]

Done.

+      resource1_ = NULL;
+    if (resource2_ == resource)
+      resource2_ = NULL;
+  }
+  void CheckVisitedResources() {
+    CHECK_EQ(NULL, resource1_);
+    CHECK_EQ(NULL, resource2_);
+  }
+
+ private:
+  v8::String::ExternalStringResource* resource1_;
+  v8::String::ExternalStringResource* resource2_;
+};
+
+TEST(VisitExternalStrings) {
+  v8::HandleScope scope;
+  LocalContext env;
+  TestResource* resource = new TestResource("Test string1");
+  v8::Local<v8::String> string1 = v8::String::NewExternal(resource);
+  TestResource* resource2 = new TestResource("Test string2");
+  v8::Local<v8::String> string2 = v8::String::NewExternal(resource2);
+
+  VisitorImpl visitor(resource, resource2);
+  v8::HeapProfiler::VisitExternalResources(&visitor);
+  visitor.CheckVisitedResources();
+}
+
+
 TEST(DocumentURL) {
   v8::HandleScope scope;
   LocalContext env;