Histogram - Checks to cacth corruption in bucket ranges

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
===================================================================
--- base/metrics/histogram.cc	(revision 150971)
+++ base/metrics/histogram.cc	(working copy)
@@ -14,10 +14,13 @@
 #include <algorithm>
 #include <string>
 
+#include "base/compiler_specific.h"
+#include "base/debug/alias.h"
 #include "base/logging.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/pickle.h"
 #include "base/stringprintf.h"
+#include "base/string_util.h"
 #include "base/synchronization/lock.h"
 
 using std::string;
@@ -129,6 +132,29 @@
   return count == redundant_count_;
 }
 
+// TODO(rtenneti): delete this code after debugging.
+void CheckCorruption(const Histogram& histogram) {
+  const std::string& histogram_name = histogram.histogram_name();
+  char histogram_name_buf[128];
+  base::strlcpy(histogram_name_buf,
+                histogram_name.c_str(),
+                arraysize(histogram_name_buf));
+  base::debug::Alias(histogram_name_buf);
+
+  Sample previous_range = -1;  // Bottom range is always 0.
+  for (size_t index = 0; index < histogram.bucket_count(); ++index) {

[kaiwang, 2012/08/14 01:23:35]

index < histogram.bucket_count() + 1;

num of ranges is num of bucket plus 1

[ramant (doing other things), 2012/08/14 01:28:47]

kaewang and I have talked. We will leave this as is (similar to the code in
FindCorruption) to reduce the number of variables and to duplicate the exact
crashes as we were seeing.

[kaiwang, 2012/08/14 01:37:40]

This is temporary code, so I think it's not necessary to match the original
wrong behavior?

[kaiwang, 2012/08/14 01:40:13]

thinking it again, fix the behavior may lead to more CHECK failure. Just leave
it like this :)

[ramant (doing other things), 2012/08/14 01:49:45]

+1. I agree.

+    int new_range = histogram.ranges(index);
+    if (previous_range >= new_range) {
+      CHECK(false);  // Crash for the bucket order corruption.
+    }
+    previous_range = new_range;
+  }
+
+  if (!histogram.bucket_ranges()->HasValidChecksum()) {
+    CHECK(false);  // Crash for the checksum corruption.
+  }
+}
+
 Histogram* Histogram::FactoryGet(const string& name,
                                  Sample minimum,
                                  Sample maximum,
@@ -152,6 +178,8 @@
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
   }
+  // TODO(rtenneti): delete this code after debugging.
+  CheckCorruption(*histogram);
 
   CHECK_EQ(HISTOGRAM, histogram->histogram_type());
   CHECK(histogram->HasConstructionArguments(minimum, maximum, bucket_count));
@@ -704,6 +732,8 @@
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
   }
+  // TODO(rtenneti): delete this code after debugging.
+  CheckCorruption(*histogram);
 
   CHECK_EQ(LINEAR_HISTOGRAM, histogram->histogram_type());
   CHECK(histogram->HasConstructionArguments(minimum, maximum, bucket_count));
@@ -795,6 +825,8 @@
     histogram =
         StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
   }
+  // TODO(rtenneti): delete this code after debugging.
+  CheckCorruption(*histogram);
 
   CHECK_EQ(BOOLEAN_HISTOGRAM, histogram->histogram_type());
   return histogram;