Add logging for slow device events, limit network UI update rate

chromeos/device_event_log.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/device_event_log.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "chromeos/device_event_log_impl.h"
 
 namespace chromeos {
 
 namespace device_event_log {
 
 namespace {
 
 const size_t kDefaultMaxEntries = 4000;
 
+const int kSlowMethodThresholdMs = 10;
+const int kVerySlowMethodThresholdMs = 50;
+
 DeviceEventLogImpl* g_device_event_log = NULL;
 
 }  // namespace
 
 const LogLevel kDefaultLogLevel = LOG_LEVEL_EVENT;
 
 void Initialize(size_t max_entries) {
   CHECK(!g_device_event_log);
   if (max_entries == 0)
     max_entries = kDefaultMaxEntries;
@@ skipping 46 matching lines @@
                                                int line,
                                                device_event_log::LogType type,
                                                device_event_log::LogLevel level)
     : file_(file), line_(line), type_(type), level_(level) {
 }
 
 DeviceEventLogInstance::~DeviceEventLogInstance() {
   device_event_log::AddEntry(file_, line_, type_, level_, stream_.str());
 }
 
+ScopedDeviceLogIfSlow::ScopedDeviceLogIfSlow(LogType type,
+                                             const char* file,
+                                             const std::string& name)
+    : file_(file), type_(type), name_(name) {
+}
+
+ScopedDeviceLogIfSlow::~ScopedDeviceLogIfSlow() {
+  if (timer_.Elapsed().InMilliseconds() >= kSlowMethodThresholdMs) {
+    LogLevel level(LOG_LEVEL_DEBUG);
+    if (timer_.Elapsed().InMilliseconds() >= kVerySlowMethodThresholdMs)
+      level = LOG_LEVEL_ERROR;
+    DEVICE_LOG(type_, level) << "@@@ Slow method: " << file_ << ":" << name_
+                             << ": " << timer_.Elapsed().InMilliseconds()
+                             << "ms";
+  }
+}
+
 }  // namespace internal
 
 }  // namespace device_event_log
 
 }  // namespace chromeos