src/system_wrappers/interface/trace.h

/*
 *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

// System independant wrapper for logging runtime information to file.
// Note: All log messages will be written to the same trace file.
// Note: If to many messages are written to file there will be a build up of
//       messages. Apply filtering to avoid that.
#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TRACE_H_
#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TRACE_H_

#include "common_types.h"
#include "typedefs.h"

#define WEBRTC_TRACE Trace::Add

namespace webrtc {
class Trace
{
public:

    // Increments the reference count to the trace.
    static void CreateTrace();
    // Decrements the reference count to the trace.
    static void ReturnTrace();
    // Note: any instance that writes to the trace file should increment and
    // decrement the reference count on construction and destruction
    // respectively

    // Specifies what type of messages should be written to the trace file. The
    // filter parameter is a bitmask where each message type is enumerated by
    // the TraceLevel enumerator. TODO (hellner) why is the
    // TraceLevel enumerator not defined in this file?
    static WebRtc_Word32 SetLevelFilter(const WebRtc_UWord32 filter);

    // Returns what type of messages are written to the trace file.
    static WebRtc_Word32 LevelFilter(WebRtc_UWord32& filter);

    // Sets the file name. If addFileCounter is false the same file will be
    // reused when it fills up. If it's true a new file with incremented name
    // will be used.
    static WebRtc_Word32 SetTraceFile(const char* fileName,
                                      const bool addFileCounter = false);

    // Returns the name of the file that the trace is currently writing to.
    static WebRtc_Word32 TraceFile(char fileName[1024]);

    // Registers callback to receive trace messages. TODO (hellner)
    // why not use OutStream instead? Why is TraceCallback not defined in this
    // file
    static WebRtc_Word32 SetTraceCallback(TraceCallback* callback);

    // Adds a trace message for writing to file. The message is put in a queue
    // for writing to file whenever possible for performance reasons. I.e. there
    // is a crash it is possible that the last, vital logs are not logged yet.
    // level is the the type of message to log. If that type of messages is
    // filtered it will not be written to file. module is an identifier for what
    // part of the code the message is comming.
    // id is an identifier that should be unique for that set of classes that
    // are associated (e.g. all instances owned by an engine).
    // msg and the elipsis are the same as e.g. sprintf.
    // TODO (hellner) Why is TraceModule not defined in this file?
    static void Add(const TraceLevel level,
                    const TraceModule module,
                    const WebRtc_Word32 id,
                    const char* msg, ...);

};
} // namespace webrtc
#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_TRACE_H_