include/wvlog.h

   1 /* -*- Mode: C++ -*-
   2  * Worldvisions Weaver Software:
   3  *   Copyright (C) 1997-2002 Net Integration Technologies, Inc.
   4  *
   5  * A generic data-logger class with support for multiple receivers.  If
   6  * no WvLogRcv objects have been created (see wvlogrcv.h) the default is
   7  * to log to stderr.
   8  *
   9  * WvLog supports partial- and multiple-line log messages.  For example,
  10  *        log.print("test ");
  11  *        log.print("string\nfoo");
  12  * will print:
  13  *        appname(lvl): test string
  14  *        appname(lvl): foo
  15  */
  16 #ifndef __WVLOG_H
  17 #define __WVLOG_H
  18
  19 #include "wvstream.h"
  20 #include <errno.h>
  21 #ifdef _WIN32
  22 typedef int pid_t;
  23 #endif
  24
  25 class WvLog;
  26
  27 // a WvLogRcv registers itself with WvLog and prints, captures,
  28 // or transmits log messages.
  29 class WvLogRcvBase
  30 {
  31     friend class WvLog;
  32 protected:
  33     const char *appname(WvStringParm log) const;
  34     virtual void log(WvStringParm source, int loglevel,
  35                      const char *_buf, size_t len) = 0;
  36
  37 private:
  38     static void cleanup_on_fork(pid_t p);
  39     static void static_init();
  40
  41 public:
  42     bool force_new_line;
  43     WvLogRcvBase();
  44     virtual ~WvLogRcvBase();
  45 };
  46
  47
  48 DeclareWvList(WvLogRcvBase);
  49
  50 typedef wv::function<WvString(WvStringParm)> WvLogFilter;
  51
  52 /**
  53  * A WvLog stream accepts log messages from applications and forwards them
  54  * to all registered WvLogRcv's.
  55  */
  56 class WvLog : public WvStream
  57 {
  58     friend class WvLogRcvBase;
  59 public:
  60     enum LogLevel {
  61         Critical = 0,
  62         Error,
  63         Warning,
  64         Notice,
  65         Info,
  66         Debug, Debug1=Debug,
  67         Debug2,
  68         Debug3,
  69         Debug4,
  70         Debug5,
  71
  72         NUM_LOGLEVELS
  73     };
  74     WvString app;
  75
  76 protected:
  77     LogLevel loglevel;
  78     static WvLogRcvBaseList *receivers;
  79     static int num_receivers, num_logs;
  80     static WvLogRcvBase *default_receiver;
  81     WvLogFilter* filter;
  82
  83 public:
  84     WvLog(WvStringParm _app, LogLevel _loglevel = Info,
  85             WvLogFilter* filter = 0);
  86     WvLog(const WvLog &l);
  87     virtual ~WvLog();
  88
  89     /** fd==-1, but this stream is always ok */
  90     virtual bool isok() const;
  91
  92     /* always writable */
  93     virtual void pre_select(SelectInfo &si);
  94     virtual bool post_select(SelectInfo &si);
  95
  96     /**
  97      * change the loglevel.  This returns the object again, so you can
  98      * make convenient statements like log.lvl(WvLog::Warning).print(...)
  99      */
 100     WvLog &lvl(LogLevel _loglevel)
 101         { loglevel = _loglevel; return *this; }
 102
 103     /** change the loglevel and then print a message. */
 104     size_t operator() (LogLevel _loglevel, WvStringParm s)
 105     {
 106         LogLevel l = loglevel;
 107         size_t x = lvl(_loglevel).write(filter ? (*filter)(s) : s);
 108         lvl(l);
 109         return x;
 110     }
 111
 112     /** change the loglevel and then print a formatted message */
 113     size_t operator() (LogLevel _loglevel, WVSTRING_FORMAT_DECL)
 114     {
 115         LogLevel l = loglevel;
 116         size_t x;
 117         if (filter)
 118             x = lvl(_loglevel).print((*filter)(WvString(WVSTRING_FORMAT_CALL)));
 119         else
 120             x = lvl(_loglevel).print(WVSTRING_FORMAT_CALL);
 121         lvl(l);
 122         return x;
 123     }
 124
 125     /**
 126      * although these appear in WvStream, they need to be re-listed here
 127      * since the above operator()s caused them to be hidden
 128      */
 129     size_t operator() (WvStringParm s)
 130         { return WvStream::operator()(filter ? (*filter)(s) : s); }
 131     size_t operator() (WVSTRING_FORMAT_DECL)
 132         { return (filter ?
 133             WvStream::operator()((*filter)(WvString(WVSTRING_FORMAT_CALL))) :
 134             WvStream::operator()(WVSTRING_FORMAT_CALL) );
 135         }
 136
 137     /**
 138      * split off a new WvLog object with the requested loglevel.  This way
 139      * you can have log at two or more levels without having to retype
 140      * log.lvl(WvLog::blahblah) all the time.
 141      */
 142     WvLog split(LogLevel _loglevel) const
 143         { return WvLog(app, _loglevel, filter); }
 144
 145     /**
 146      * we override the unbuffered write function, so lines also include the
 147      * application and log level.
 148      */
 149     virtual size_t uwrite(const void *buf, size_t len);
 150
 151     /** a useful substitute for the normal C perror() function */
 152     void perror(WvStringParm s)
 153         { print("%s: %s\n", s, strerror(errno)); }
 154
 155 public:
 156     const char *wstype() const { return "WvLog"; }
 157 };
 158
 159
 160 #endif // __WVLOG_H