[CrOS Tether] Create HostScanCache, which caches scan results and inserts them into the network sta…

chromeos/components/tether/host_scanner.cc

 // 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 "chromeos/components/tether/host_scanner.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "chromeos/components/tether/device_id_tether_network_guid_map.h"
+#include "chromeos/components/tether/host_scan_cache.h"
 #include "chromeos/components/tether/tether_host_fetcher.h"
 #include "chromeos/network/network_state.h"
 #include "components/cryptauth/remote_device_loader.h"
 
 namespace chromeos {
 
 namespace tether {
 
 namespace {
 
 const char kDefaultCellCarrierName[] = "unknown-carrier";
 
 // Android signal strength is measured between 0 and 4 (inclusive), but Chrome
 // OS signal strength is measured between 0 and 100 (inclusive). In order to
 // convert between Android signal strength to Chrome OS signal strength, the
 // value must be multiplied by the below value.
 const int32_t kAndroidTetherHostToChromeOSSignalStrengthMultiplier = 25;
 
 int32_t ForceBetweenZeroAndOneHundred(int32_t value) {
   return std::min(std::max(value, 0), 100);
 }
 
 }  // namespace
 
 HostScanner::HostScanner(
     TetherHostFetcher* tether_host_fetcher,
     BleConnectionManager* connection_manager,
     HostScanDevicePrioritizer* host_scan_device_prioritizer,
     TetherHostResponseRecorder* tether_host_response_recorder,
-    NetworkStateHandler* network_state_handler,
     NotificationPresenter* notification_presenter,
-    DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map)
+    DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map,
+    HostScanCache* host_scan_cache)
     : tether_host_fetcher_(tether_host_fetcher),
       connection_manager_(connection_manager),
       host_scan_device_prioritizer_(host_scan_device_prioritizer),
       tether_host_response_recorder_(tether_host_response_recorder),
-      network_state_handler_(network_state_handler),
       notification_presenter_(notification_presenter),
       device_id_tether_network_guid_map_(device_id_tether_network_guid_map),
+      host_scan_cache_(host_scan_cache),
       is_fetching_hosts_(false),
       weak_ptr_factory_(this) {}
 
 HostScanner::~HostScanner() {}
 
 void HostScanner::StartScan() {
   if (host_scanner_operation_) {
     // If a scan is already active, do not continue.
     return;
   }
@@ skipping 20 matching lines @@
       tether_hosts, connection_manager_, host_scan_device_prioritizer_,
       tether_host_response_recorder_);
   host_scanner_operation_->AddObserver(this);
   host_scanner_operation_->Initialize();
 }
 
 void HostScanner::OnTetherAvailabilityResponse(
     std::vector<HostScannerOperation::ScannedDeviceInfo>&
         scanned_device_list_so_far,
     bool is_final_scan_result) {
-  most_recent_scan_results_ = scanned_device_list_so_far;
-
-  if (!scanned_device_list_so_far.empty()) {
-    // TODO(hansberry): Clear out old scanned hosts from NetworkStateHandler.
-    // TODO(khorimoto): Use UpdateTetherNetworkProperties if the network already
-    // exists.
+  if (scanned_device_list_so_far.empty()) {
+    // If a new scan is just starting up, remove existing cache entries; if they
+    // are still within range to communicate with the current device, they will
+    // show

[Ryan Hansberry, 2017/04/28 22:31:04]

Finish this sentence.

[Kyle Horimoto, 2017/04/28 22:45:04]

Done.

+    host_scan_cache_->ClearCacheExceptForActiveHost();
+  } else {
+    // Add all results received so far to the cache.
     for (auto& scanned_device_info : scanned_device_list_so_far) {
-      const DeviceStatus& status = scanned_device_info.device_status;
-      const cryptauth::RemoteDevice& remote_device =
-          scanned_device_info.remote_device;
-
-      const std::string carrier =
-          (!status.has_cell_provider() || status.cell_provider().empty())
-              ? kDefaultCellCarrierName
-              : status.cell_provider();
-
-      // If battery or signal strength are missing, assume they are 100. For
-      // battery percentage, force the value to be between 0 and 100. For signal
-      // strength, convert from Android signal strength to Chrome OS signal
-      // strength and force the value to be between 0 and 100.
-      const int32_t battery_percentage =
-          status.has_battery_percentage()
-              ? ForceBetweenZeroAndOneHundred(status.battery_percentage())
-              : 100;
-      const int32_t signal_strength =
-          status.has_connection_strength()
-              ? ForceBetweenZeroAndOneHundred(
-                    kAndroidTetherHostToChromeOSSignalStrengthMultiplier *
-                    status.connection_strength())
-              : 100;
-
-      // TODO(khorimoto): Pass a HasConnectedToHost parameter to this function.
-      network_state_handler_->AddTetherNetworkState(
-          device_id_tether_network_guid_map_->GetTetherNetworkGuidForDeviceId(
-              remote_device.GetDeviceId()),
-          remote_device.name, carrier, battery_percentage, signal_strength);
+      SetCacheEntry(scanned_device_info);
     }
 
     if (scanned_device_list_so_far.size() == 1) {
       notification_presenter_->NotifyPotentialHotspotNearby(
           scanned_device_list_so_far.at(0).remote_device);
     } else {
       notification_presenter_->NotifyMultiplePotentialHotspotsNearby();
     }
   }
 
   if (is_final_scan_result) {
     // If the final scan result has been received, the operation is finished.
     // Delete it.
     host_scanner_operation_->RemoveObserver(this);
     host_scanner_operation_.reset();
   }
 }
 
+void HostScanner::SetCacheEntry(
+    const HostScannerOperation::ScannedDeviceInfo& scanned_device_info) {
+  const DeviceStatus& status = scanned_device_info.device_status;
+  const cryptauth::RemoteDevice& remote_device =
+      scanned_device_info.remote_device;
+
+  // Use a sentinel value if carrier information is not available. This value is
+  // special-cased and replaced with a localized string in the settings UI.
+  const std::string carrier =
+      (!status.has_cell_provider() || status.cell_provider().empty())
+          ? kDefaultCellCarrierName
+          : status.cell_provider();
+
+  // If battery or signal strength are missing, assume they are 100. For
+  // battery percentage, force the value to be between 0 and 100. For signal
+  // strength, convert from Android signal strength to Chrome OS signal
+  // strength and force the value to be between 0 and 100.
+  const int32_t battery_percentage =
+      status.has_battery_percentage()
+          ? ForceBetweenZeroAndOneHundred(status.battery_percentage())
+          : 100;
+  const int32_t signal_strength =
+      status.has_connection_strength()
+          ? ForceBetweenZeroAndOneHundred(
+                kAndroidTetherHostToChromeOSSignalStrengthMultiplier *
+                status.connection_strength())
+          : 100;
+
+  host_scan_cache_->SetHostScanResult(
+      device_id_tether_network_guid_map_->GetTetherNetworkGuidForDeviceId(
+          remote_device.GetDeviceId()),
+      remote_device.name, carrier, battery_percentage, signal_strength);
+}
+
 }  // namespace tether
 
 }  // namespace chromeos