Add DataReductionProxyExperimentsStats and UMA for measuring potentially non-compressed bytes.

components/data_reduction_proxy/core/browser/data_reduction_proxy_config_retrieval_params.cc

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_config_retrieval_params.cc
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_retrieval_params.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_retrieval_params.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9a85da734b21b611e356482d99d67a5f4bc837f8
--- /dev/null
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config_retrieval_params.cc
@@ -0,0 +1,268 @@
+// Copyright 2015 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/data_reduction_proxy/core/browser/data_reduction_proxy_config_retrieval_params.h"
+
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
+#include "base/prefs/pref_service.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
+#include "components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h"
+#include "components/variations/variations_associated_data.h"
+
+namespace {
+
+// The trial group prefix for which an experiment is considered enabled.
+const char kEnabled[] = "Enabled";
+
+// The minimum interval (in seconds) at which the config retrieval can occur.
+const int kConfigFetchMinimumIntervalSeconds = 300;
+
+// The default latency base for retrieving the config.
+const int kConfigFetchDefaultRoundtripMillisecondsBase = 100;
+
+// The default latency base for retrieving the config.
+const double kConfigFetchDefaultRoundtripMultiplier = 1.0;
+
+// The default latency base for retrieving the config.
+const int kConfigFetchDefaultRoundtripMillisecondsIncrement = 100;
+
+// The minimum Data Reduction Proxy configuration expiration.
+const int kConfigFetchMinimumExpirationSeconds = 5 * 60;
+
+// The default Data Reduction Proxy configuration expiration.
+const int kConfigFetchDefaultExpirationSeconds = 24 * 60 * 60;
+
+// Based on a histogram prefix |histogram| and |suffix|, retrieves the
+// histogram for the expanded histogram name. The histogram is identical to
+// the used in UMA_HISTOGRAM_COUNTS.
+base::HistogramBase* GetHistogramWithSuffix(const char* histogram, int suffix) {
+  std::string full_histogram_name = histogram + base::IntToString(suffix);
+  return base::Histogram::FactoryGet(
+      full_histogram_name, 1, 1000000, 50,
+      base::HistogramBase::kUmaTargetedHistogramFlag);
+}
+
+// Retrieves the boolean stored in |variation| from the field trial group
+// |group|. If the value is not present or cannot be parsed, returns
+// |default_value|.
+bool GetVariationBoolWithDefault(const char* group,
+                                 const char* variation,
+                                 bool default_value) {
+  std::string variation_value =
+      variations::GetVariationParamValue(group, variation);
+  int64 variation_numeric;
+  if (variation_value.empty() ||
+      !base::StringToInt64(variation_value, &variation_numeric)) {
+    return default_value;
+  }
+
+  return variation_numeric != 0;
+}
+
+// Retrieves the int64 stored in |variation| from the field trial group
+// |group|. If the value is not present, cannot be parsed, or is less than
+// |min_value|, returns |default_value|.
+int64 GetVariationInt64WithDefault(const char* group,
+                                   const char* variation,
+                                   int64 default_value,
+                                   int64 min_value) {
+  DCHECK(default_value >= min_value);
+  std::string variation_value =
+      variations::GetVariationParamValue(group, variation);
+  int64 variation_numeric;
+  if (variation_value.empty() ||
+      !base::StringToInt64(variation_value, &variation_numeric) ||
+      variation_numeric < min_value) {
+    return default_value;
+  }
+
+  return variation_numeric;
+}
+
+// Retrieves the double stored in |variation| from the field trial group
+// |group|. If the value is not present, cannot be parsed, or is less than
+// |min_value|, returns |default_value|.
+double GetVariationDoubleWithDefault(const char* group,
+                                     const char* variation,
+                                     double default_value,
+                                     double min_value) {
+  DCHECK(default_value >= min_value);
+  std::string variation_value =
+      variations::GetVariationParamValue(group, variation);
+  double variation_numeric;
+  if (variation_value.empty() ||
+      !base::StringToDouble(variation_value, &variation_numeric) ||
+      variation_numeric < min_value) {
+    return default_value;
+  }
+
+  return variation_numeric;
+}
+
+}  // namespace
+
+namespace data_reduction_proxy {
+
+const int kConfigFetchGroups = 10;
+
+const char kConfigFetchTrialGroup[] = "DataReductionProxyConfigFetchBytes";
+
+const char kConfigRoundtripMillisecondsBaseParam[] =
+    "config_roundtrip_milliseconds_base";
+
+const char kConfigRoundtripMultiplierParam[] = "config_roundtrip_multiplier";
+
+const char kConfigRoundtripMillisecondsIncrementParam[] =
+    "config_roundtrip_milliseconds_increment";
+
+const char kConfigExpirationSecondsParam[] = "config_expiration_seconds";
+
+const char kConfigAlwaysStaleParam[] = "always_stale";
+
+const int kConfigFetchBufferSeconds = 300;
+
+// static
+scoped_ptr<DataReductionProxyConfigRetrievalParams>
+DataReductionProxyConfigRetrievalParams::Create(PrefService* pref_service) {
+  std::string group_value =
+      base::FieldTrialList::FindFullName(kConfigFetchTrialGroup);
+  base::StringPiece group = group_value;
+  if (!group.starts_with(kEnabled))
+    return scoped_ptr<DataReductionProxyConfigRetrievalParams>();
+
+  base::Time now = base::Time::Now();
+  base::Time config_retrieve;
+  bool config_always_stale = GetVariationBoolWithDefault(
+      kConfigFetchTrialGroup, kConfigAlwaysStaleParam, false);
+  if (config_always_stale) {
+    config_retrieve = base::Time();
+  } else {
+    int64 config_retrieve_value =
+        pref_service->GetInt64(prefs::kSimulatedConfigRetrieveTime);
+    config_retrieve = base::Time::FromInternalValue(config_retrieve_value);
+    if (config_retrieve > now)
+      config_retrieve = base::Time();
+  }
+
+  int64 config_expiration_interval_seconds = GetVariationInt64WithDefault(
+      kConfigFetchTrialGroup, kConfigExpirationSecondsParam,
+      kConfigFetchDefaultExpirationSeconds,
+      kConfigFetchMinimumExpirationSeconds);
+  base::TimeDelta config_expiration_interval =
+      base::TimeDelta::FromSeconds(config_expiration_interval_seconds);
+  base::Time config_expiration = config_retrieve + config_expiration_interval;
+  std::vector<Variation> variations;
+  bool expired_config = (now > config_expiration);
+  if (expired_config) {
+    config_expiration = now + config_expiration_interval;
+
+    int64 config_roundtrip_milliseconds = GetVariationInt64WithDefault(
+        kConfigFetchTrialGroup, kConfigRoundtripMillisecondsBaseParam,
+        kConfigFetchDefaultRoundtripMillisecondsBase, 0);
+    double config_roundtrip_multiplier = GetVariationDoubleWithDefault(
+        kConfigFetchTrialGroup, kConfigRoundtripMultiplierParam,
+        kConfigFetchDefaultRoundtripMultiplier, 1.0);
+    int64 roundtrip_milliseconds_increment = GetVariationInt64WithDefault(
+        kConfigFetchTrialGroup, kConfigRoundtripMillisecondsIncrementParam,
+        kConfigFetchDefaultRoundtripMillisecondsIncrement, 0);
+
+    for (int params_index = 0; params_index < kConfigFetchGroups;
+         ++params_index) {
+      base::Time config_retrieved = now + base::TimeDelta::FromMilliseconds(
+                                              config_roundtrip_milliseconds);
+      variations.push_back(Variation(params_index, config_retrieved));
+      config_roundtrip_milliseconds *= config_roundtrip_multiplier;
+      config_roundtrip_milliseconds += roundtrip_milliseconds_increment;
+    }
+  }
+
+  return scoped_ptr<DataReductionProxyConfigRetrievalParams>(
+      new DataReductionProxyConfigRetrievalParams(expired_config, variations,
+                                                  config_expiration,
+                                                  config_expiration_interval));
+}
+
+DataReductionProxyConfigRetrievalParams::Variation::Variation(
+    int index,
+    const base::Time& simulated_config_retrieved)
+    : simulated_config_retrieved_(simulated_config_retrieved) {
+  lost_bytes_ocl_ = GetHistogramWithSuffix(
+      "DataReductionProxy.ConfigFetchLostBytesOCL_", index);
+  lost_bytes_rcl_ = GetHistogramWithSuffix(
+      "DataReductionProxy.ConfigFetchLostBytesCL_", index);
+  lost_bytes_diff_ = GetHistogramWithSuffix(
+      "DataReductionProxy.ConfigFetchLostBytesDiff_", index);
+}
+
+DataReductionProxyConfigRetrievalParams::ConfigState
+DataReductionProxyConfigRetrievalParams::Variation::GetState(
+    const base::Time& request_time,
+    const base::Time& config_expiration) const {
+  if (!simulated_config_retrieved_.is_null() &&
+      request_time < simulated_config_retrieved_) {
+    return DataReductionProxyConfigRetrievalParams::RETRIEVING;
+  } else if (request_time < config_expiration) {
+    return DataReductionProxyConfigRetrievalParams::VALID;
+  }
+
+  return DataReductionProxyConfigRetrievalParams::EXPIRED;
+}
+
+void DataReductionProxyConfigRetrievalParams::Variation::RecordStats(
+    int64 received_content_length,
+    int64 original_content_length) const {
+  lost_bytes_rcl_->Add(received_content_length);
+  lost_bytes_ocl_->Add(original_content_length);
+  lost_bytes_diff_->Add(original_content_length - received_content_length);
+}
+
+DataReductionProxyConfigRetrievalParams::
+    DataReductionProxyConfigRetrievalParams(
+        bool loaded_expired_config,
+        const std::vector<Variation>& variations,
+        const base::Time& config_expiration,
+        const base::TimeDelta& config_expiration_interval)
+    : loaded_expired_config_(loaded_expired_config),
+      config_expiration_(config_expiration),
+      config_expiration_interval_(config_expiration_interval),
+      variations_(variations) {
+  config_refresh_interval_ =
+      config_expiration_interval_ -
+      base::TimeDelta::FromSeconds(kConfigFetchBufferSeconds);
+  if (config_refresh_interval_.InSeconds() <
+      kConfigFetchMinimumIntervalSeconds) {
+    config_refresh_interval_ =
+        base::TimeDelta::FromSeconds(kConfigFetchMinimumIntervalSeconds);
+  }
+}
+
+DataReductionProxyConfigRetrievalParams::
+    ~DataReductionProxyConfigRetrievalParams() {
+}
+
+void DataReductionProxyConfigRetrievalParams::RecordStats(
+    const base::Time& request_time,
+    int64 received_content_length,
+    int64 original_content_length) const {
+  for (const auto& variation : variations_) {
+    switch (variation.GetState(request_time, config_expiration_)) {
+      case VALID:
+        break;
+      case RETRIEVING:
+      case EXPIRED:
+        variation.RecordStats(received_content_length, original_content_length);
+        break;
+      default:
+        NOTREACHED();
+    }
+  }
+}
+
+void DataReductionProxyConfigRetrievalParams::RefreshConfig() {
+  config_expiration_ = base::Time::Now() + config_expiration_interval_;
+}
+
+}  // namespace data_reduction_proxy