Refactor UKM interface for mojo-ification

components/ukm/ukm_recorder_impl.cc

Index: components/ukm/ukm_recorder_impl.cc
diff --git a/components/ukm/ukm_recorder_impl.cc b/components/ukm/ukm_recorder_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0ec456dd302c418f98c4f6b7f7515f0961b6529c
--- /dev/null
+++ b/components/ukm/ukm_recorder_impl.cc
@@ -0,0 +1,175 @@
+// Copyright 2017 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/ukm/ukm_recorder_impl.h"
+
+#include "base/metrics/field_trial.h"
+#include "base/metrics/field_trial_params.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/metrics/metrics_hashes.h"
+#include "base/strings/string_split.h"
+#include "components/metrics/proto/ukm/entry.pb.h"
+#include "components/metrics/proto/ukm/report.pb.h"
+#include "components/metrics/proto/ukm/source.pb.h"
+#include "components/ukm/ukm_source.h"
+
+namespace ukm {
+
+namespace {
+
+// Gets the list of whitelisted Entries as string. Format is a comma seperated
+// list of Entry names (as strings).
+std::string GetWhitelistEntries() {
+  return base::GetFieldTrialParamValueByFeature(kUkmFeature,
+                                                "WhitelistEntries");
+}
+
+// Gets the maximum number of Sources we'll keep in memory before discarding any
+// new ones being added.
+size_t GetMaxSources() {
+  constexpr size_t kDefaultMaxSources = 500;
+  return static_cast<size_t>(base::GetFieldTrialParamByFeatureAsInt(
+      kUkmFeature, "MaxSources", kDefaultMaxSources));
+}
+
+// Gets the maximum number of Entries we'll keep in memory before discarding any
+// new ones being added.
+size_t GetMaxEntries() {
+  constexpr size_t kDefaultMaxEntries = 5000;
+  return static_cast<size_t>(base::GetFieldTrialParamByFeatureAsInt(
+      kUkmFeature, "MaxEntries", kDefaultMaxEntries));
+}
+
+// True if we should record the initial_url field of the UKM Source proto.
+bool ShouldRecordInitialUrl() {
+  return base::GetFieldTrialParamByFeatureAsBool(kUkmFeature,
+                                                 "RecordInitialUrl", false);
+}
+
+enum class DroppedDataReason {
+  NOT_DROPPED = 0,
+  RECORDING_DISABLED = 1,
+  MAX_HIT = 2,
+  NOT_WHITELISTED = 3,
+  NUM_DROPPED_DATA_REASONS
+};
+
+void RecordDroppedSource(DroppedDataReason reason) {
+  UMA_HISTOGRAM_ENUMERATION(
+      "UKM.Sources.Dropped", static_cast<int>(reason),
+      static_cast<int>(DroppedDataReason::NUM_DROPPED_DATA_REASONS));
+}
+
+void RecordDroppedEntry(DroppedDataReason reason) {
+  UMA_HISTOGRAM_ENUMERATION(
+      "UKM.Entries.Dropped", static_cast<int>(reason),
+      static_cast<int>(DroppedDataReason::NUM_DROPPED_DATA_REASONS));
+}
+
+void StoreEntryProto(const mojom::UkmEntry& in, Entry* out) {
+  DCHECK(!out->has_source_id());
+  DCHECK(!out->has_event_hash());
+
+  out->set_source_id(in.source_id);
+  out->set_event_hash(in.event_hash);
+  for (const auto& metric : in.metrics) {
+    Entry::Metric* proto_metric = out->add_metrics();
+    proto_metric->set_metric_hash(metric->metric_hash);
+    proto_metric->set_value(metric->value);
+  }
+}
+
+}  // namespace
+
+UkmRecorderImpl::UkmRecorderImpl() : recording_enabled_(false) {}
+UkmRecorderImpl::~UkmRecorderImpl() = default;
+
+void UkmRecorderImpl::EnableRecording() {
+  recording_enabled_ = true;
+}
+
+void UkmRecorderImpl::DisableRecording() {
+  recording_enabled_ = false;
+}
+
+void UkmRecorderImpl::Purge() {
+  sources_.clear();
+  entries_.clear();
+}
+
+void UkmRecorderImpl::StoreRecordingsInReport(Report* report) {
+  for (const auto& kv : sources_) {
+    Source* proto_source = report->add_sources();
+    kv.second->PopulateProto(proto_source);
+    if (!ShouldRecordInitialUrl())
+      proto_source->clear_initial_url();
+  }
+  for (const auto& entry : entries_) {
+    Entry* proto_entry = report->add_entries();
+    StoreEntryProto(*entry, proto_entry);
+  }
+
+  UMA_HISTOGRAM_COUNTS_1000("UKM.Sources.SerializedCount", sources_.size());
+  UMA_HISTOGRAM_COUNTS_1000("UKM.Entries.SerializedCount", entries_.size());
+  sources_.clear();
+  entries_.clear();
+}
+
+void UkmRecorderImpl::UpdateSourceURL(ukm::SourceId source_id,
+                                      const GURL& url) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+
+  if (!recording_enabled_) {
+    RecordDroppedSource(DroppedDataReason::RECORDING_DISABLED);
+    return;
+  }
+
+  // Update the pre-existing source if there is any. This happens when the
+  // initial URL is different from the committed URL for the same source, e.g.,
+  // when there is redirection.
+  if (base::ContainsKey(sources_, source_id)) {
+    sources_[source_id]->UpdateUrl(url);
+    return;
+  }
+
+  if (sources_.size() >= GetMaxSources()) {
+    RecordDroppedSource(DroppedDataReason::MAX_HIT);
+    return;
+  }
+  std::unique_ptr<UkmSource> source = base::MakeUnique<UkmSource>();
+  source->set_id(source_id);
+  source->set_url(url);
+  sources_.insert(std::make_pair(source_id, std::move(source)));
+}
+
+void UkmRecorderImpl::AddEntry(mojom::UkmEntryPtr entry) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+
+  if (!recording_enabled_) {
+    RecordDroppedEntry(DroppedDataReason::RECORDING_DISABLED);
+    return;
+  }
+  if (entries_.size() >= GetMaxEntries()) {
+    RecordDroppedEntry(DroppedDataReason::MAX_HIT);
+    return;
+  }
+
+  if (!whitelisted_entry_hashes_.empty() &&
+      !base::ContainsKey(whitelisted_entry_hashes_, entry->event_hash)) {
+    RecordDroppedEntry(DroppedDataReason::NOT_WHITELISTED);
+    return;
+  }
+
+  entries_.push_back(std::move(entry));
+}
+
+void UkmRecorderImpl::StoreWhitelistedEntries() {
+  const auto entries =
+      base::SplitString(GetWhitelistEntries(), ",", base::TRIM_WHITESPACE,
+                        base::SPLIT_WANT_NONEMPTY);
+  for (const auto& entry_string : entries)
+    whitelisted_entry_hashes_.insert(base::HashMetricName(entry_string));
+}
+
+}  // namespace ukm