blob: e2c4611233e7a1fa6bb6146d6c63f302b76173e1 [file] [log] [blame]
// Copyright (c) 2012 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_LOG_NET_LOG_H_
#define NET_LOG_NET_LOG_H_
#include <stdint.h>
#include <string>
#include <vector>
#include "base/atomicops.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/strings/string16.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "net/base/net_export.h"
#include "net/log/net_log_capture_mode.h"
#include "net/log/net_log_entry.h"
#include "net/log/net_log_event_type.h"
#include "net/log/net_log_parameters_callback.h"
#include "net/log/net_log_source.h"
#include "net/log/net_log_source_type.h"
namespace base {
class Value;
}
namespace net {
// NetLog is the destination for log messages generated by the network stack.
// Each log message has a "source" field which identifies the specific entity
// that generated the message (for example, which URLRequest or which
// SpdySession).
//
// To avoid needing to pass in the "source ID" to the logging functions, NetLog
// is usually accessed through a NetLogWithSource, which will always pass in a
// specific source ID.
//
// All methods are thread safe, with the exception that no NetLog or
// NetLog::ThreadSafeObserver functions may be called by an observer's
// OnAddEntry() method. Doing so will result in a deadlock.
//
// For a broader introduction see the design document:
// https://sites.google.com/a/chromium.org/dev/developers/design-documents/network-stack/netlog
class NET_EXPORT NetLog {
public:
// An observer that is notified of entries added to the NetLog. The
// "ThreadSafe" prefix of the name emphasizes that this observer may be
// called from different threads then the one which added it as an observer.
class NET_EXPORT ThreadSafeObserver {
public:
// Constructs an observer that wants to see network events, with
// the specified minimum event granularity. A ThreadSafeObserver can only
// observe a single NetLog at a time.
//
// Observers will be called on the same thread an entry is added on,
// and are responsible for ensuring their own thread safety.
//
// Observers must stop watching a NetLog before either the observer or the
// NetLog is destroyed.
ThreadSafeObserver();
// Returns the capture mode for events this observer wants to
// receive. It is only valid to call this while observing a NetLog.
NetLogCaptureMode capture_mode() const;
// Returns the NetLog being watched, or nullptr if there is none.
NetLog* net_log() const;
// This method is called whenever an entry (event) was added to the NetLog
// being watched.
//
// OnAddEntry() is invoked on the thread which generated the NetLog entry,
// which may be different from the thread that added this observer.
//
// Whenever OnAddEntry() is invoked, the NetLog's mutex is held. The
// consequences of this are:
//
// * OnAddEntry() will never be called concurrently -- implementations
// can rely on this to avoid needing their own synchronization.
//
// * It is illegal for an observer to call back into the NetLog, or the
// observer itself, as this can result in deadlock or violating
// expectations of non re-entrancy into ThreadSafeObserver.
virtual void OnAddEntry(const NetLogEntry& entry) = 0;
protected:
virtual ~ThreadSafeObserver();
private:
friend class NetLog;
void OnAddEntryData(const NetLogEntryData& entry_data);
// Both of these values are only modified by the NetLog.
NetLogCaptureMode capture_mode_;
NetLog* net_log_;
DISALLOW_COPY_AND_ASSIGN(ThreadSafeObserver);
};
NetLog();
virtual ~NetLog();
// Emits a global event to the log stream, with its own unique source ID.
void AddGlobalEntry(NetLogEventType type);
void AddGlobalEntry(NetLogEventType type,
const NetLogParametersCallback& parameters_callback);
// Returns a unique ID which can be used as a source ID. All returned IDs
// will be unique and greater than 0.
uint32_t NextID();
// Returns true if there are any observers attached to the NetLog. This can be
// used as an optimization to avoid emitting log entries when there is no
// chance that the data will be consumed.
bool IsCapturing() const;
// Adds an observer and sets its log capture mode. The observer must not be
// watching any NetLog, including this one, when this is called.
//
// CAUTION: Think carefully before introducing a dependency on the
// NetLog. The order, format, and parameters in NetLog events are NOT
// guaranteed to be stable. As such, building a production feature that works
// by observing the NetLog is likely inappropriate. Just as you wouldn't build
// a feature by scraping the text output from LOG(INFO), you shouldn't do
// the same by scraping the logging data emitted to NetLog. Support for
// observers is an internal detail mainly used for testing and to write events
// to a file. Please consult a //net OWNER before using this outside of
// testing or serialization.
void AddObserver(ThreadSafeObserver* observer,
NetLogCaptureMode capture_mode);
// Sets the log capture mode of |observer| to |capture_mode|. |observer| must
// be watching |this|. NetLog implementations must call
// NetLog::OnSetObserverCaptureMode to update the observer's internal state.
void SetObserverCaptureMode(ThreadSafeObserver* observer,
NetLogCaptureMode capture_mode);
// Removes an observer.
//
// For thread safety reasons, it is recommended that this not be called in
// an object's destructor.
void RemoveObserver(ThreadSafeObserver* observer);
// Converts a time to the string format that the NetLog uses to represent
// times. Strings are used since integers may overflow.
static std::string TickCountToString(const base::TimeTicks& time);
// Returns a C-String symbolic name for |event_type|.
static const char* EventTypeToString(NetLogEventType event_type);
// Returns a dictionary that maps event type symbolic names to their enum
// values.
static std::unique_ptr<base::Value> GetEventTypesAsValue();
// Returns a C-String symbolic name for |source_type|.
static const char* SourceTypeToString(NetLogSourceType source_type);
// Returns a dictionary that maps source type symbolic names to their enum
// values.
static std::unique_ptr<base::Value> GetSourceTypesAsValue();
// Returns a C-String symbolic name for |event_phase|.
static const char* EventPhaseToString(NetLogEventPhase event_phase);
// Creates a NetLogParametersCallback that encapsulates a single bool.
// Warning: |name| must remain valid for the life of the callback.
static NetLogParametersCallback BoolCallback(const char* name, bool value);
// Warning: |name| must remain valid for the life of the callback.
static NetLogParametersCallback IntCallback(const char* name, int value);
// Creates a NetLogParametersCallback that encapsulates a single int64_t. The
// callback will return the value as a StringValue, since IntegerValues
// only support 32-bit values.
// Warning: |name| must remain valid for the life of the callback.
static NetLogParametersCallback Int64Callback(const char* name,
int64_t value);
// Creates a NetLogParametersCallback that encapsulates a single UTF8 string.
// Takes
// |value| as a pointer to avoid copying, and emphasize it must be valid for
// the life of the callback. |value| may not be NULL.
// Warning: |name| and |value| must remain valid for the life of the callback.
static NetLogParametersCallback StringCallback(const char* name,
const std::string* value);
static NetLogParametersCallback StringCallback(const char* name,
const char* value);
// Same as above, but takes in a UTF16 string.
static NetLogParametersCallback StringCallback(const char* name,
const base::string16* value);
private:
friend class NetLogWithSource;
void AddEntry(NetLogEventType type,
const NetLogSource& source,
NetLogEventPhase phase,
const NetLogParametersCallback* parameters_callback);
// Called whenever an observer is added or removed, to update
// |has_observers_|. Must have acquired |lock_| prior to calling.
void UpdateIsCapturing();
// Returns true if |observer| is watching this NetLog. Must
// be called while |lock_| is already held.
bool HasObserver(ThreadSafeObserver* observer);
// |lock_| protects access to |observers_|.
base::Lock lock_;
// Last assigned source ID. Incremented to get the next one.
base::subtle::Atomic32 last_id_;
// |is_capturing_| will be 0 when there are no observers watching the NetLog,
// 1 otherwise. Note that this is stored as an Atomic32 rather than a boolean
// so it can be accessed without needing a lock.
base::subtle::Atomic32 is_capturing_;
// |observers_| is a list of observers, ordered by when they were added.
// Pointers contained in |observers_| are non-owned, and must
// remain valid.
//
// |lock_| must be acquired whenever reading or writing to this.
//
// In practice |observers_| will be very small (<5) so O(n)
// operations on it are fine.
std::vector<ThreadSafeObserver*> observers_;
DISALLOW_COPY_AND_ASSIGN(NetLog);
};
// Creates a base::Value() to represent the byte string |raw| when adding it to
// the NetLog.
//
// When |raw| is an ASCII string, the returned value is a base::Value()
// containing that exact string. Otherwise it is represented by a
// percent-escaped version of the original string, along with a special prefix.
//
// This wrapper exists because base::Value strings are required to be UTF-8.
// Often times NetLog consumers just want to log a std::string, and that string
// may not be UTF-8.
NET_EXPORT base::Value NetLogStringValue(base::StringPiece raw);
} // namespace net
#endif // NET_LOG_NET_LOG_H_