Create a histogram serialization mechanism in components/metrics

components/metrics/chromeos/metric_sample.cc

Index: components/metrics/chromeos/metric_sample.cc
diff --git a/components/metrics/chromeos/metric_sample.cc b/components/metrics/chromeos/metric_sample.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6e80c67e92360607eb30be7a891649b5f41244db
--- /dev/null
+++ b/components/metrics/chromeos/metric_sample.cc
@@ -0,0 +1,186 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/metrics/chromeos/metric_sample.h"
+
+#include <string>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/stringprintf.h"
+
+namespace metrics {
+
+MetricSample::MetricSample(MetricSample::SampleType sample_type,
+                           const std::string& metric_name,
+                           const int sample,

[Alexei Svitkine (slow), 2014/05/13 19:52:42]

Nit: No need for primitive-typed params to be const. (Whereas it does make sense
for member variables).

[bsimonnet, 2014/05/13 21:28:00]

Done.

+                           const int min,
+                           const int max,
+                           const int bucket_count)
+    : type_(sample_type),
+      name_(metric_name),
+      sample_(sample),
+      min_(min),
+      max_(max),
+      bucket_count_(bucket_count) {
+}
+
+MetricSample::~MetricSample() {
+}
+
+bool MetricSample::IsValid() const {
+  return name().find(' ') == std::string::npos &&
+         name().find('\0') == std::string::npos && name().length() > 0;
+}
+
+std::string MetricSample::ToString() const {
+  if (type_ == CRASH) {
+    return base::StringPrintf("crash%c%s%c", '\0', name().c_str(), '\0');
+  } else if (type_ == SPARSE_HISTOGRAM) {
+    return base::StringPrintf(
+        "sparsehistogram%c%s %d%c", '\0', name().c_str(), sample_, '\0');

[Alexei Svitkine (slow), 2014/05/13 19:52:42]

Nit: Standardize on wrapping - you're using a different way to wrap here than in
the cases below.

[bsimonnet, 2014/05/13 21:28:00]

Done.

This formatting was produced by git cl format. Should I use it to format my CLs?

+  } else if (type_ == LINEAR_HISTOGRAM) {
+    return base::StringPrintf("linearhistogram%c%s %d %d%c",
+                              '\0',
+                              name().c_str(),
+                              sample_,
+                              max_,
+                              '\0');
+  } else if (type_ == HISTOGRAM) {
+    return base::StringPrintf("histogram%c%s %d %d %d %d%c",
+                              '\0',
+                              name().c_str(),
+                              sample_,
+                              min_,
+                              max_,
+                              bucket_count_,
+                              '\0');
+  } else {
+    // The type can only be USER_ACTION.
+    CHECK(type_ == USER_ACTION);
+    return base::StringPrintf("useraction%c%s%c", '\0', name().c_str(), '\0');
+  }
+}
+
+const int MetricSample::sample() const {
+  CHECK(type_ != USER_ACTION && type_ != CRASH);
+  return sample_;
+}
+
+const int MetricSample::min() const {
+  CHECK(type_ == HISTOGRAM);
+  return min_;
+}
+
+const int MetricSample::max() const {
+  CHECK(type_ == LINEAR_HISTOGRAM || type_ == HISTOGRAM);
+  return max_;
+}
+
+const int MetricSample::bucket_count() const {
+  CHECK(type_ == HISTOGRAM);
+  return bucket_count_;
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::CrashSample(
+    const std::string& crash_name) {
+  return scoped_ptr<MetricSample>(
+      new MetricSample(CRASH, crash_name, 0, 0, 0, 0));
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::HistogramSample(
+    const std::string& histogram_name,
+    int sample,
+    int min,
+    int max,
+    int bucket_count) {
+  return scoped_ptr<MetricSample>(new MetricSample(
+      HISTOGRAM, histogram_name, sample, min, max, bucket_count));
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::ReadHistogram(
+    const std::string& serialized_histogram) {
+  std::vector<std::string> parts;
+  base::SplitString(serialized_histogram, ' ', &parts);
+
+  if (parts.size() != 5)
+    return scoped_ptr<MetricSample>();
+  int sample, min, max, bucket_count;
+  if (parts[0].length() == 0 || !base::StringToInt(parts[1], &sample) ||
+      !base::StringToInt(parts[2], &min) ||
+      !base::StringToInt(parts[3], &max) ||
+      !base::StringToInt(parts[4], &bucket_count)) {
+    return scoped_ptr<MetricSample>();
+  }
+
+  return HistogramSample(parts[0], sample, min, max, bucket_count);
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::SparseHistogramSample(
+    const std::string& histogram_name,
+    int sample) {
+  return scoped_ptr<MetricSample>(
+      new MetricSample(SPARSE_HISTOGRAM, histogram_name, sample, 0, 0, 0));
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::ReadSparseHistogram(
+    const std::string& serialized_histogram) {
+  std::vector<std::string> parts;
+  base::SplitString(serialized_histogram, ' ', &parts);
+  if (parts.size() != 2)
+    return scoped_ptr<MetricSample>();
+  int sample;
+  if (parts[0].length() == 0 || !base::StringToInt(parts[1], &sample))

[Alexei Svitkine (slow), 2014/05/13 19:52:42]

Nit: .length() == 0 -> emtpty()

Change throughout, please.

[bsimonnet, 2014/05/13 21:28:00]

Done.

+    return scoped_ptr<MetricSample>();
+
+  return SparseHistogramSample(parts[0], sample);
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::LinearHistogramSample(
+    const std::string& histogram_name,
+    int sample,
+    int max) {
+  return scoped_ptr<MetricSample>(
+      new MetricSample(LINEAR_HISTOGRAM, histogram_name, sample, 0, max, 0));
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::ReadLinearHistogram(
+    const std::string& serialized_histogram) {
+  std::vector<std::string> parts;
+  int sample, max;
+  base::SplitString(serialized_histogram, ' ', &parts);
+  if (parts.size() != 3)
+    return scoped_ptr<MetricSample>();
+  if (parts[0].length() == 0 || !base::StringToInt(parts[1], &sample) ||
+      !base::StringToInt(parts[2], &max)) {
+    return scoped_ptr<MetricSample>();
+  }
+
+  return LinearHistogramSample(parts[0], sample, max);
+}
+
+// static
+scoped_ptr<MetricSample> MetricSample::UserActionSample(
+    const std::string& action_name) {
+  return scoped_ptr<MetricSample>(
+      new MetricSample(USER_ACTION, action_name, 0, 0, 0, 0));
+}
+
+bool MetricSample::IsEqual(const MetricSample* metric) {
+  CHECK(metric);

[Alexei Svitkine (slow), 2014/05/13 19:52:42]

Can the function take a const& to avoid needing to CHECK for NULL entirely?

[bsimonnet, 2014/05/13 21:28:00]

Done.

+  return type_ == metric->type_ && name_ == metric->name_ &&
+         sample_ == metric->sample_ && min_ == metric->min_ &&
+         max_ == metric->max_ && bucket_count_ == metric->bucket_count_;
+}
+
+}  // namespace metrics