Generalize network_event_log -> device_event_log

chromeos/device_event_log.h

Index: chromeos/device_event_log.h
diff --git a/chromeos/device_event_log.h b/chromeos/device_event_log.h
new file mode 100644
index 0000000000000000000000000000000000000000..ae7e80edb3ac5bf05e419b96f8a98ae2a155c394
--- /dev/null
+++ b/chromeos/device_event_log.h
@@ -0,0 +1,140 @@
+// 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.
+
+#ifndef CHROMEOS_DEVICE_EVENT_LOG_H_
+#define CHROMEOS_DEVICE_EVENT_LOG_H_
+
+#include <cstring>
+#include <sstream>
+
+#include "base/basictypes.h"
+#include "chromeos/chromeos_export.h"
+
+namespace chromeos {
+
+// These macros can be used to log chromeos device related events.
+// The following values should be used for |level| in these macros:
+//  ERROR Unexpected events, or device level failures. Use sparingly.
+//  USER  Events initiated directly by a user (or Chrome) action.
+//  EVENT Default event type.
+//  DEBUG Debugging details that are usually not interesting.
+// Examples:
+//  NET_LOG(EVENT) << "NetworkState Changed " << name << ": " << state;
+//  POWER_LOG(USER) << "Suspend requested";
+
+#define NET_LOG(level)                                       \
+  DEVICE_LOG(::chromeos::device_event_log::LOG_TYPE_NETWORK, \
+             ::chromeos::device_event_log::LOG_LEVEL_##level)
+#define POWER_LOG(level)                                   \
+  DEVICE_LOG(::chromeos::device_event_log::LOG_TYPE_POWER, \
+             ::chromeos::device_event_log::LOG_LEVEL_##level)
+
+// Generally prefer the above macros unless |level| is not constant.
+
+#define DEVICE_LOG(type, level)                                   \
+  ::chromeos::device_event_log::internal::DeviceEventLogInstance( \
+      __FILE__, __LINE__, type, level).stream()
+
+namespace device_event_log {
+
+// Used to specify the type of event.
+enum LogType {
+  // Shill / network configuration related events.
+  LOG_TYPE_NETWORK,
+  // Power manager related events.
+  LOG_TYPE_POWER,
+  // Use this in GetAsString for non NETWORK events (which are more frequent).
+  LOG_TYPE_NON_NETWORK,
+  // Use this in GetAsString for all events.
+  LOG_TYPE_ALL,
+};
+
+// Used to specify the detail level for logging. In GetAsString, used to
+// specify the maximum detail level (i.e. EVENT will include USER and ERROR).
+// See top-level comment for guidelines for each type.
+enum LogLevel {
+  LOG_LEVEL_ERROR = 0,
+  LOG_LEVEL_USER = 1,
+  LOG_LEVEL_EVENT = 2,
+  LOG_LEVEL_DEBUG = 3
+};
+
+// Used to specify which order to output event entries in GetAsString.
+enum StringOrder { OLDEST_FIRST, NEWEST_FIRST };
+
+// Initializes / shuts down device event logging. If |max_entries| = 0 the
+// default value will be used.
+CHROMEOS_EXPORT void Initialize(size_t max_entries);
+CHROMEOS_EXPORT void Shutdown();
+
+// If the global instance is initialized, adds an entry to it. Regardless of
+// whether the global instance was intitialzed, this logs the event to
+// LOG(ERROR) if |type| = ERROR or VLOG(1) otherwise.
+CHROMEOS_EXPORT void AddEntry(const char* file,
+                              int line,
+                              LogType type,
+                              LogLevel level,
+                              const std::string& event);
+
+// For backwards compatibility with network_event_log. Combines |event| and
+// |description| and calls AddEntry().
+CHROMEOS_EXPORT void AddEntryWithDescription(const char* file,
+                                             int line,
+                                             LogType type,
+                                             LogLevel level,
+                                             const std::string& event,
+                                             const std::string& description);
+
+// Outputs the log to a formatted string.
+// |order| determines which order to output the events.
+// |format| is a string that determines which elements to show. Elements
+// must be comma-separated, e.g. "time,desc".
+// Note: order of the format strings does not affect the output.
+//  "time" - Include a timestamp.
+//  "file" - Include file and line number.
+//  "type" - Include the event type.
+//  "html" - Include html tags.
+//  "json" - Return as JSON format
+// Only events matching |log_type| are included in the output.
+// Only events with |log_level| <= |max_level| are included in the output.
+// If |max_events| > 0, limits how many events are output.
+// If |json| is specified, returns a JSON list of dictionaries containing time,
+// level, file, event, and description.
+CHROMEOS_EXPORT std::string GetAsString(StringOrder order,
+                                        const std::string& format,
+                                        LogType log_type,
+                                        LogLevel max_level,
+                                        size_t max_events);
+
+CHROMEOS_EXPORT extern const LogLevel kDefaultLogLevel;
+
+namespace internal {
+
+class CHROMEOS_EXPORT DeviceEventLogInstance {
+ public:
+  DeviceEventLogInstance(const char* file,
+                         int line,
+                         device_event_log::LogType type,
+                         device_event_log::LogLevel level);
+  ~DeviceEventLogInstance();
+
+  std::ostream& stream() { return stream_; }
+
+ private:
+  const char* file_;
+  const int line_;
+  device_event_log::LogType type_;
+  device_event_log::LogLevel level_;
+  std::ostringstream stream_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeviceEventLogInstance);
+};
+
+}  // namespace internal
+
+}  // namespace device_event_log
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_DEVICE_EVENT_LOG_H_