Basic UkmService implementation

components/ukm/ukm_service.cc

+// 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_service.h"
+
+#include <utility>
+
+#include "base/feature_list.h"
+#include "base/memory/ptr_util.h"
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/rand_util.h"
+#include "base/time/time.h"
+#include "components/metrics/metrics_log_uploader.h"
+#include "components/metrics/metrics_service_client.h"
+#include "components/metrics/proto/ukm/report.pb.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+#include "components/ukm/metrics_reporting_scheduler.h"
+#include "components/ukm/persisted_logs_metrics_impl.h"
+#include "components/ukm/ukm_pref_names.h"
+#include "components/variations/variations_associated_data.h"
+
+namespace ukm {
+
+namespace {
+
+const char kMimeType[] = "application/vnd.chrome.ukm";
+
+// Constants for the UKM rollout field trial.
+const char kUkmRolloutFieldTrialName[] = "UkmRollout";
+
+// Constant for the variations parameter name for the server URL
+const char kUkmRolloutServerUrlParam[] = "ServerUrl";
+
+// The UKM server's URL.
+const char kDefaultServerUrl[] = "https://clients4.google.com/ukm";
+
+// The delay, in seconds, after starting recording before doing expensive
+// initialization work.
+const int kInitializationDelaySeconds = 5;
+
+// The number of UKM logs that will be stored in PersistedLogs before logs
+// start being dropped.
+const int kMinPersistedLogs = 8;
+
+// The number of bytes UKM logs that will be stored in PersistedLogs before
+// logs start being dropped.
+// This ensures that a reasonable amount of history will be stored even if there
+// is a long series of very small logs.
+const int kMinPersistedBytes = 300000;
+
+// If an upload fails, and the transmission was over this byte count, then we
+// will discard the log, and not try to retransmit it.  We also don't persist
+// the log to the prefs for transmission during the next chrome session if this
+// limit is exceeded.
+const size_t kMaxLogRetransmitSize = 100 * 1024;
+
+std::string GetServerUrl() {
+  std::string server_url = variations::GetVariationParamValue(
+      kUkmRolloutFieldTrialName, kUkmRolloutServerUrlParam);

[Alexei Svitkine (slow), 2017/01/10 17:37:19]

Nit: Use GetVariationParamValueByFeature() and then you can remove
UkmRolloutFieldTrialName.

Also, I would just inline "ServerUrl" here since that's the only place you use
it.

[Steven Holte, 2017/01/10 22:52:45]

Done.

+  if (!server_url.empty())
+    return server_url;
+  return kDefaultServerUrl;
+}
+
+uint64_t LoadOrGenerateClientId(PrefService* pref_service) {
+  uint64_t client_id = pref_service->GetInteger(prefs::kUkmClientId);
+  if (!client_id) {

[Alexei Svitkine (slow), 2017/01/10 17:37:19]

What if 0 is legitimately generated? You can use  FindPreference() to see if it
exists.

(The other alternative is to explicitly disallow 0 and do a loop while
generating it to exclude 0's).

[Steven Holte, 2017/01/10 22:52:44]

Added the loop.

+    // Generate and store a new client id.
+    client_id = base::RandUint64();
+    pref_service->SetInteger(prefs::kUkmClientId, client_id);

[Alexei Svitkine (slow), 2017/01/10 17:37:19]

SetInt64() and GetInt64()

Integer may be 32 bit otherwise.

[Steven Holte, 2017/01/10 22:52:45]

Done.

+  }
+  return client_id;
+}
+
+}  // namespace
+
+const base::Feature kUkmFeature = {"Ukm", base::FEATURE_DISABLED_BY_DEFAULT};
+
+UkmService::UkmService(PrefService* pref_service,
+                       metrics::MetricsServiceClient* client)
+    : pref_service_(pref_service),
+      client_(client),
+      persisted_logs_(std::unique_ptr<ukm::PersistedLogsMetricsImpl>(
+                          new ukm::PersistedLogsMetricsImpl()),
+                      pref_service,
+                      prefs::kUkmPersistedLogs,
+                      kMinPersistedLogs,
+                      kMinPersistedBytes,
+                      kMaxLogRetransmitSize),
+      initialize_started_(false),
+      self_ptr_factory_(this) {
+  DCHECK(pref_service_);
+  DCHECK(client_);
+
+  persisted_logs_.DeserializeLogs();
+
+  base::Closure rotate_callback =
+      base::Bind(&UkmService::RotateLog, self_ptr_factory_.GetWeakPtr());
+  // MetricsServiceClient outlives UkmService, and
+  // MetricsReportingScheduler is tied to the lifetime of |this|.
+  const base::Callback<base::TimeDelta(void)>& get_upload_interval_callback =
+      base::Bind(&metrics::MetricsServiceClient::GetStandardUploadInterval,
+                 base::Unretained(client_));
+  scheduler_.reset(new ukm::MetricsReportingScheduler(
+      rotate_callback, get_upload_interval_callback));
+}
+
+UkmService::~UkmService() {}
+
+void UkmService::Initialize() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "UkmService::Initialize";
+  initialize_started_ = true;
+
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&UkmService::StartInitTask, self_ptr_factory_.GetWeakPtr()),
+      base::TimeDelta::FromSeconds(kInitializationDelaySeconds));
+}
+
+void UkmService::EnableReporting() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "UkmService::EnableReporting";
+  if (!initialize_started_)
+    Initialize();
+  scheduler_->Start();
+}
+
+void UkmService::DisableReporting() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "UkmService::DisableReporting";
+  scheduler_->UploadCancelled();
+  scheduler_->Stop();
+}
+
+// static
+void UkmService::RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterIntegerPref(prefs::kUkmClientId, 0);
+  registry->RegisterListPref(prefs::kUkmPersistedLogs);
+}
+
+void UkmService::StartInitTask() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "UkmService::StartInitTask";
+  client_id_ = LoadOrGenerateClientId(pref_service_);
+  client_->InitializeSystemProfileMetrics(base::Bind(
+      &UkmService::FinishedInitTask, self_ptr_factory_.GetWeakPtr()));
+}
+
+void UkmService::FinishedInitTask() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "UkmService::FinishedInitTask";
+  scheduler_->InitTaskComplete();
+}
+
+void UkmService::RotateLog() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!log_upload_in_progress_);
+  DVLOG(1) << "UkmService::RotateLog";
+  if (persisted_logs_.empty()) {
+    BuildAndStoreLog();
+  }
+  StartScheduledUpload();
+}
+
+void UkmService::BuildAndStoreLog() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "UkmService::BuildAndStoreLog";
+  Report report;
+  report.set_client_id(client_id_);
+  // TODO(holte): Populate system_profile.
+  // TODO(zhenw): Populate sources.
+  std::string serialized_log;
+  report.SerializeToString(&serialized_log);
+  persisted_logs_.StoreLog(serialized_log);
+}
+
+void UkmService::StartScheduledUpload() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!log_upload_in_progress_);
+  persisted_logs_.StageLog();
+  // TODO(holte): Handle data usage on cellular, etc.
+  if (!log_uploader_) {
+    log_uploader_ = client_->CreateUploader(
+        GetServerUrl(), kMimeType, base::Bind(&UkmService::OnLogUploadComplete,
+                                              self_ptr_factory_.GetWeakPtr()));
+  }
+  log_upload_in_progress_ = true;
+  log_uploader_->UploadLog(persisted_logs_.staged_log(),
+                           persisted_logs_.staged_log_hash());
+}
+
+void UkmService::OnLogUploadComplete(int response_code) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(log_upload_in_progress_);
+  DVLOG(1) << "UkmService::OnLogUploadComplete";
+  log_upload_in_progress_ = false;
+
+  UMA_HISTOGRAM_SPARSE_SLOWLY("UKM.Upload.ResponseCode", response_code);
+
+  bool upload_succeeded = response_code == 200;
+
+  // Provide boolean for error recovery (allow us to ignore response_code).
+  bool discard_log = false;
+  const size_t log_size_bytes = persisted_logs_.staged_log().length();
+  if (upload_succeeded) {
+    UMA_HISTOGRAM_COUNTS_10000("UKM.LogSize.OnSuccess", log_size_bytes / 1024);
+  } else if (log_size_bytes > kMaxLogRetransmitSize) {

[Alexei Svitkine (slow), 2017/01/10 17:37:19]

Nit: Wondering if we really need it? I would suggest leaving this logic out for
now until/if we find we need it.

[Steven Holte, 2017/01/10 22:52:44]

Done.

+    UMA_HISTOGRAM_COUNTS_1M("UKM.OversizeRejected.LogSize",
+                            static_cast<int>(log_size_bytes));
+    discard_log = true;
+  } else if (response_code == 400) {
+    // Bad syntax.  Retransmission won't work.
+    discard_log = true;
+  }
+
+  if (upload_succeeded || discard_log) {
+    persisted_logs_.DiscardStagedLog();
+    // Store the updated list to disk now that the removed log is uploaded.
+    persisted_logs_.SerializeLogs();
+  }
+
+  // Error 400 indicates a problem with the log, not with the server, so
+  // don't consider that a sign that the server is in trouble.
+  bool server_is_healthy = upload_succeeded || response_code == 400;
+  scheduler_->UploadFinished(server_is_healthy, !persisted_logs_.empty());
+}
+
+}  // namespace ukm