Use ad hoc itoa function instead of OS::SNPrintF when serializing heap snapshots

src/profile-generator.cc

Index: src/profile-generator.cc
===================================================================
--- src/profile-generator.cc	(revision 11222)
+++ src/profile-generator.cc	(working copy)
@@ -3353,9 +3353,7 @@
       MaybeWriteChunk();
     }
   }
-  void AddNumber(int n) { AddNumberImpl<int>(n, "%d"); }
   void AddNumber(unsigned n) { AddNumberImpl<unsigned>(n, "%u"); }
-  void AddNumber(uint64_t n) { AddNumberImpl<uint64_t>(n, "%llu"); }
   void Finalize() {
     if (aborted_) return;
     ASSERT(chunk_pos_ < chunk_size_);
@@ -3510,6 +3508,30 @@
 }
 
 
+static char* itoa(int value, char* buffer) {

[mnaganov (inactive), 2012/04/04 10:03:31]

Have you tried IntToCString? It uses Vector, which has overrun asserts in debug
mode.

[alexeif, 2012/04/04 11:20:49]

I have more concerns regarding the checks in release mode.

[yurys, 2012/04/04 12:32:16]

IntToCString will place the number into the end of the buffer which wouldn't
work for us as we don't know number of digits beforehand. I switched this
implementation to Vector<char> so that we have overrun asserts in debug mode.

+  if (value < 0) {
+    *buffer = '-';
+    ++buffer;
+    value = -value;
+  }
+
+  int number_of_digits = 0;
+  int t = value;
+  do {
+    ++number_of_digits;
+  } while (t /= 10);
+
+  buffer += number_of_digits;
+  char* result = buffer;
+  do {
+    int last_digit = value % 10;
+    value /= 10;
+    *--buffer = '0' + last_digit;
+  } while (value);
+  return result;
+}
+
+
 void HeapSnapshotJSONSerializer::SerializeEdge(HeapGraphEdge* edge) {
   // The buffer needs space for 3 ints, 3 commas and \0
   static const int kBufferSize =
@@ -3522,10 +3544,15 @@
   STATIC_CHECK(sizeof(int) == sizeof(edge->type()));  // NOLINT
   STATIC_CHECK(sizeof(int) == sizeof(edge_name_or_index));  // NOLINT
   STATIC_CHECK(sizeof(int) == sizeof(GetNodeId(edge->to())));  // NOLINT
-  int result = OS::SNPrintF(buffer, ",%d,%d,%d",
-      edge->type(), edge_name_or_index, GetNodeId(edge->to()));
-  USE(result);
-  ASSERT(result != -1);
+  char* buffer_pos = buffer.start();
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(edge->type(), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(edge_name_or_index, buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(GetNodeId(edge->to()), buffer_pos);
+  *buffer_pos++ = '\0';
+  ASSERT(buffer_pos <= (buffer.start() + buffer.length()));
   writer_->AddString(buffer.start());
 }
 
@@ -3545,16 +3572,24 @@
   STATIC_CHECK(sizeof(int) == sizeof(entry->retained_size()));  // NOLINT
   STATIC_CHECK(sizeof(int) == sizeof(GetNodeId(entry->dominator())));  // NOLINT
   STATIC_CHECK(sizeof(int) == sizeof(children.length()));  // NOLINT
-  int result = OS::SNPrintF(buffer, "\n,%d,%d,%u,%d,%d,%d,%d",
-      entry->type(),
-      GetStringId(entry->name()),
-      entry->id(),
-      entry->self_size(),
-      entry->retained_size(),
-      GetNodeId(entry->dominator()),
-      children.length());
-  USE(result);
-  ASSERT(result != -1);
+  char* buffer_pos = buffer.start();
+  *buffer_pos++ = '\n';
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(entry->type(), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(GetStringId(entry->name()), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(entry->id(), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(entry->self_size(), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(entry->retained_size(), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(GetNodeId(entry->dominator()), buffer_pos);
+  *buffer_pos++ = ',';
+  buffer_pos = itoa(children.length(), buffer_pos);
+  *buffer_pos++ = '\0';
+  ASSERT(buffer_pos <= (buffer.start() + buffer.length()));
   writer_->AddString(buffer.start());
   for (int i = 0; i < children.length(); ++i) {
     SerializeEdge(&children[i]);