Generalize the net module's LoadLog facility from a passive container, to an event stream (NetLog).

net/base/load_log.h

-// Copyright (c) 2009 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 NET_BASE_LOAD_LOG_H_
-#define NET_BASE_LOAD_LOG_H_
-
-#include <string>
-#include <vector>
-
-#include "base/ref_counted.h"
-#include "base/time.h"
-
-namespace net {
-
-// LoadLog stores information associated with an individual request. This
-// includes event traces (used to build up profiling information), error
-// return codes from network modules, and arbitrary text messages.
-//
-// Note that LoadLog is NOT THREADSAFE, however it is RefCountedThreadSafe so
-// that it can be AddRef() / Release() across threads.
-class LoadLog : public base::RefCountedThreadSafe<LoadLog> {
- public:
-   // TODO(eroman): Really, EventType and EventPhase should be
-   // Event::Type and Event::Phase, to be consisent with Entry.
-   // But there lots of consumers to change!
-  enum EventType {
-#define EVENT_TYPE(label) TYPE_ ## label,
-#include "net/base/load_log_event_type_list.h"
-#undef EVENT_TYPE
-  };
-
-  // The 'phase' of an event trace (whether it marks the beginning or end
-  // of an event.).
-  enum EventPhase {
-    PHASE_NONE,
-    PHASE_BEGIN,
-    // TODO(eroman): DEPRECATED: Use TYPE_STRING_LITERAL instead.
-    PHASE_END,
-  };
-
-  struct Event {
-    Event(EventType type, EventPhase phase) : type(type), phase(phase) {}
-    Event() {}
-
-    EventType type;
-    EventPhase phase;
-  };
-
-  struct Entry {
-    enum Type {
-      // This entry describes an event trace.
-      TYPE_EVENT,
-
-      // This entry describes a network error code that was returned.
-      TYPE_ERROR_CODE,
-
-      // This entry is a free-form std::string.
-      TYPE_STRING,
-
-      // This entry is a C-string literal.
-      TYPE_STRING_LITERAL,
-    };
-
-    Entry(base::TimeTicks time, int error_code)
-        : type(TYPE_ERROR_CODE), time(time), error_code(error_code) {
-    }
-
-    Entry(base::TimeTicks time, const Event& event)
-        : type(TYPE_EVENT), time(time), event(event) {
-    }
-
-    Entry(base::TimeTicks time, const std::string& string)
-        : type(TYPE_STRING), time(time), string(string) {
-    }
-
-    Entry(base::TimeTicks time, const char* literal)
-        : type(TYPE_STRING_LITERAL), time(time), literal(literal) {
-    }
-
-    Type type;
-    base::TimeTicks time;
-
-    // The following is basically a union, only one of them should be
-    // used depending on what |type| is.
-    Event event;          // valid when (type == TYPE_EVENT).
-    int error_code;       // valid when (type == TYPE_ERROR_CODE).
-    std::string string;   // valid when (type == TYPE_STRING).
-    const char* literal;  // valid when (type == TYPE_STRING_LITERAL).
-  };
-
-  // Ordered set of entries that were logged.
-  // TODO(eroman): use a StackVector or array to avoid allocations.
-  typedef std::vector<Entry> EntryList;
-
-  // Value for max_num_entries to indicate the LoadLog has no size limit.
-  static const size_t kUnbounded = static_cast<size_t>(-1);
-
-  // Creates a log, which can hold up to |max_num_entries| entries.
-  // If |max_num_entries| is |kUnbounded|, then the log can grow arbitrarily
-  // large.
-  //
-  // If entries are dropped because the log has grown too large, the final entry
-  // will be overwritten.
-  explicit LoadLog(size_t max_num_entries);
-
-  // --------------------------------------------------------------------------
-
-  // The public interface for adding events to the log are static methods.
-  // This makes it easier to deal with optionally NULL LoadLog.
-
-  // Adds an instantaneous event to the log.
-  // TODO(eroman): DEPRECATED: use AddStringLiteral() instead.
-  static void AddEvent(LoadLog* log, EventType event_type) {
-    if (log)
-      log->Add(Entry(base::TimeTicks::Now(), Event(event_type, PHASE_NONE)));
-  }
-
-  // Adds the start of an event to the log. Presumably this event type measures
-  // a time duration, and will be matched by a call to EndEvent(event_type).
-  static void BeginEvent(LoadLog* log, EventType event_type) {
-    if (log)
-      log->Add(Entry(base::TimeTicks::Now(), Event(event_type, PHASE_BEGIN)));
-  }
-
-  // Adds the end of an event to the log. Presumably this event type measures
-  // a time duration, and we are matching an earlier call to
-  // BeginEvent(event_type).
-  static void EndEvent(LoadLog* log, EventType event_type) {
-    if (log)
-      log->Add(Entry(base::TimeTicks::Now(), Event(event_type, PHASE_END)));
-  }
-
-  // |literal| should be a string literal (i.e. lives in static storage).
-  static void AddStringLiteral(LoadLog* log, const char* literal) {
-    if (log)
-      log->Add(Entry(base::TimeTicks::Now(), literal));
-  }
-
-  static void AddString(LoadLog* log, const std::string& string) {
-    if (log)
-      log->Add(Entry(base::TimeTicks::Now(), string));
-  }
-
-  static void AddErrorCode(LoadLog* log, int error) {
-    if (log)
-      log->Add(Entry(base::TimeTicks::Now(), error));
-  }
-
-  static bool IsUnbounded(const LoadLog* log) {
-    return log && log->is_unbounded();
-  }
-
-  // --------------------------------------------------------------------------
-
-  // Returns the list of all entries in the log.
-  const EntryList& entries() const {
-    return entries_;
-  }
-
-  // Returns the number of entries that were dropped from the log because the
-  // maximum size had been reached.
-  size_t num_entries_truncated() const {
-    return num_entries_truncated_;
-  }
-
-  // Returns the bound on the size of the log.
-  size_t max_num_entries() const {
-    return max_num_entries_;
-  }
-
-  bool is_unbounded() const {
-    return max_num_entries_ == kUnbounded;
-  }
-
-  // Returns a C-String symbolic name for |event|.
-  static const char* EventTypeToString(EventType event_type);
-
-  void Add(const Entry& entry);
-
-  // Copies all entries from |log|, appending it to the end of |this|.
-  void Append(const LoadLog* log);
-
- private:
-  friend class base::RefCountedThreadSafe<LoadLog>;
-
-  ~LoadLog() {}
-
-  EntryList entries_;
-  size_t num_entries_truncated_;
-  size_t max_num_entries_;;
-};
-
-}  // namespace net
-
-#endif  // NET_BASE_LOAD_LOG_H_