/*

    File:       QLog.h

    Contains:   A simplistic logging package.

    Written by: DTS

    Copyright:  Copyright (c) 2010 Apple Inc. All Rights Reserved.

    Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc.

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                The Apple Software is provided by Apple on an "AS IS" basis. 

                APPLE MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING

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                THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN

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*/

#import <Foundation/Foundation.h>

@interface QLog : NSObject

{

    BOOL                _enabled;                                               // main thread write, any thread read

    int                 _logFile;                                               // main thread write, any thread read

    off_t               _logFileLength;                                         // main thread only, only valid if _logFile != -1

    BOOL                _loggingToStdErr;                                       // main thread write, any thread read

    NSUInteger          _optionsMask;                                           // main thread write, any thread read

    BOOL                _showViewer;                                            // main thread only

    NSMutableArray *    _logEntries;                                            // main thread only

    NSMutableArray *    _pendingEntries;                                        // any thread, protected by @synchronize (self)

}

+ (QLog *)log;                                                                  // any thread

    // Returns the singleton logging object.

- (void)flush;                                                                  // main thread only

    // Flushes any pending log entries to the logEntries array and also, if 

    // appropriate, to the log file or stderr.

- (void)clear;                                                                  // main thread only

    // Empties the logEntries array and, if appropriate, the log file.  Not 

    // much we can do about stderr (-:

// Preferences

@property (assign, readonly, getter=isEnabled) BOOL         enabled;            // any thread, observable, always changed by main thread

@property (assign, readonly, getter=isLoggingToFile) BOOL   loggingToFile;      // any thread, observable, always changed by main thread

@property (assign, readonly, getter=isLoggingToStdErr) BOOL loggingToStdErr;    // any thread, observable, always changed by main thread

@property (assign, readonly) NSUInteger                     optionsMask;        // any thread, observable, always changed by main thread

@property (assign, readonly) BOOL                           showViewer;         // main thread, observable, always changed by main thread

// User Default         Property

// ------------         --------

// qlogEnabled          enabled

// qlogLoggingToFile    loggingToFile

// qlogLoggingToStdErr  loggingToStdErr

// qlogOption0..31      optionsMask

// Log entry generation

// Some things to note:

// 

// o The -logOptions:xxx methods only log if the specified bit is set in 

//   optionsMask (that is, (optionsMask & (1 << option)) is not zero).

//

// o The format string is as implemented by +[NSString stringWithFormat:].

- (void)logWithFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1, 2);                             // any thread

- (void)logWithFormat:(NSString *)format arguments:(va_list)argList;                                // any thread

- (void)logOption:(NSUInteger)option withFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(2, 3);   // any thread

- (void)logOption:(NSUInteger)option withFormat:(NSString *)format arguments:(va_list)argList;      // any thread

// In memory log entries

// New entries are added to the end of this array and, as there's an upper limit 

// number of entries that will be held in memory, ald entries are removed from 

// the beginning.

@property (retain, readonly) NSMutableArray *               logEntries;         // observable, always changed by main thread

// In file log entries

- (NSInputStream *)streamForLogValidToLength:(off_t *)lengthPtr;                // main thread only

    // Returns an un-opened stream.  If lengthPtr is not NULL then, on return 

    // *lengthPtr contains the number of bytes in that stream that are 

    // guaranteed to be valid.

    //

    // This can only be called on the main thread but the resulting stream 

    // can be passed to any thread for processing.

@end