1// 2// GTMLogger.h 3// 4// Copyright 2007-2008 Google Inc. 5// 6// Licensed under the Apache License, Version 2.0 (the "License"); you may not 7// use this file except in compliance with the License. You may obtain a copy 8// of the License at 9// 10// http://www.apache.org/licenses/LICENSE-2.0 11// 12// Unless required by applicable law or agreed to in writing, software 13// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 14// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 15// License for the specific language governing permissions and limitations under 16// the License. 17// 18 19// Key Abstractions 20// ---------------- 21// 22// This file declares multiple classes and protocols that are used by the 23// GTMLogger logging system. The 4 main abstractions used in this file are the 24// following: 25// 26// * logger (GTMLogger) - The main logging class that users interact with. It 27// has methods for logging at different levels and uses a log writer, a log 28// formatter, and a log filter to get the job done. 29// 30// * log writer (GTMLogWriter) - Writes a given string to some log file, where 31// a "log file" can be a physical file on disk, a POST over HTTP to some URL, 32// or even some in-memory structure (e.g., a ring buffer). 33// 34// * log formatter (GTMLogFormatter) - Given a format string and arguments as 35// a va_list, returns a single formatted NSString. A "formatted string" could 36// be a string with the date prepended, a string with values in a CSV format, 37// or even a string of XML. 38// 39// * log filter (GTMLogFilter) - Given a formatted log message as an NSString 40// and the level at which the message is to be logged, this class will decide 41// whether the given message should be logged or not. This is a flexible way 42// to filter out messages logged at a certain level, messages that contain 43// certain text, or filter nothing out at all. This gives the caller the 44// flexibility to dynamically enable debug logging in Release builds. 45// 46// This file also declares some classes to handle the common log writer, log 47// formatter, and log filter cases. Callers can also create their own writers, 48// formatters, and filters and they can even build them on top of the ones 49// declared here. Keep in mind that your custom writer/formatter/filter may be 50// called from multiple threads, so it must be thread-safe. 51 52#import <Foundation/Foundation.h> 53#import "GTMDefines.h" 54 55// Predeclaration of used protocols that are declared later in this file. 56@protocol GTMLogWriter, GTMLogFormatter, GTMLogFilter; 57 58// GTMLogger 59// 60// GTMLogger is the primary user-facing class for an object-oriented logging 61// system. It is built on the concept of log formatters (GTMLogFormatter), log 62// writers (GTMLogWriter), and log filters (GTMLogFilter). When a message is 63// sent to a GTMLogger to log a message, the message is formatted using the log 64// formatter, then the log filter is consulted to see if the message should be 65// logged, and if so, the message is sent to the log writer to be written out. 66// 67// GTMLogger is intended to be a flexible and thread-safe logging solution. Its 68// flexibility comes from the fact that GTMLogger instances can be customized 69// with user defined formatters, filters, and writers. And these writers, 70// filters, and formatters can be combined, stacked, and customized in arbitrary 71// ways to suit the needs at hand. For example, multiple writers can be used at 72// the same time, and a GTMLogger instance can even be used as another 73// GTMLogger's writer. This allows for arbitrarily deep logging trees. 74// 75// A standard GTMLogger uses a writer that sends messages to standard out, a 76// formatter that smacks a timestamp and a few other bits of interesting 77// information on the message, and a filter that filters out debug messages from 78// release builds. Using the standard log settings, a log message will look like 79// the following: 80// 81// 2007-12-30 10:29:24.177 myapp[4588/0xa07d0f60] [lvl=1] foo=<Foo: 0x123> 82// 83// The output contains the date and time of the log message, the name of the 84// process followed by its process ID/thread ID, the log level at which the 85// message was logged (in the previous example the level was 1: 86// kGTMLoggerLevelDebug), and finally, the user-specified log message itself (in 87// this case, the log message was @"foo=%@", foo). 88// 89// Multiple instances of GTMLogger can be created, each configured their own 90// way. Though GTMLogger is not a singleton (in the GoF sense), it does provide 91// access to a shared (i.e., globally accessible) GTMLogger instance. This makes 92// it convenient for all code in a process to use the same GTMLogger instance. 93// The shared GTMLogger instance can also be configured in an arbitrary, and 94// these configuration changes will affect all code that logs through the shared 95// instance. 96 97// 98// Log Levels 99// ---------- 100// GTMLogger has 3 different log levels: Debug, Info, and Error. GTMLogger 101// doesn't take any special action based on the log level; it simply forwards 102// this information on to formatters, filters, and writers, each of which may 103// optionally take action based on the level. Since log level filtering is 104// performed at runtime, log messages are typically not filtered out at compile 105// time. The exception to this rule is that calls to the GTMLoggerDebug() macro 106// *ARE* filtered out of non-DEBUG builds. This is to be backwards compatible 107// with behavior that many developers are currently used to. Note that this 108// means that GTMLoggerDebug(@"hi") will be compiled out of Release builds, but 109// [[GTMLogger sharedLogger] logDebug:@"hi"] will NOT be compiled out. 110// 111// Standard loggers are created with the GTMLogLevelFilter log filter, which 112// filters out certain log messages based on log level, and some other settings. 113// 114// In addition to the -logDebug:, -logInfo:, and -logError: methods defined on 115// GTMLogger itself, there are also C macros that make usage of the shared 116// GTMLogger instance very convenient. These macros are: 117// 118// GTMLoggerDebug(...) 119// GTMLoggerInfo(...) 120// GTMLoggerError(...) 121// 122// Again, a notable feature of these macros is that GTMLogDebug() calls *will be 123// compiled out of non-DEBUG builds*. 124// 125// Standard Loggers 126// ---------------- 127// GTMLogger has the concept of "standard loggers". A standard logger is simply 128// a logger that is pre-configured with some standard/common writer, formatter, 129// and filter combination. Standard loggers are created using the creation 130// methods beginning with "standard". The alternative to a standard logger is a 131// regular logger, which will send messages to stdout, with no special 132// formatting, and no filtering. 133// 134// How do I use GTMLogger? 135// ---------------------- 136// The typical way you will want to use GTMLogger is to simply use the 137// GTMLogger*() macros for logging from code. That way we can easily make 138// changes to the GTMLogger class and simply update the macros accordingly. Only 139// your application startup code (perhaps, somewhere in main()) should use the 140// GTMLogger class directly in order to configure the shared logger, which all 141// of the code using the macros will be using. Again, this is just the typical 142// situation. 143// 144// To be complete, there are cases where you may want to use GTMLogger directly, 145// or even create separate GTMLogger instances for some reason. That's fine, 146// too. 147// 148// Examples 149// -------- 150// The following show some common GTMLogger use cases. 151// 152// 1. You want to log something as simply as possible. Also, this call will only 153// appear in debug builds. In non-DEBUG builds it will be completely removed. 154// 155// GTMLoggerDebug(@"foo = %@", foo); 156// 157// 2. The previous example is similar to the following. The major difference is 158// that the previous call (example 1) will be compiled out of Release builds 159// but this statement will not be compiled out. 160// 161// [[GTMLogger sharedLogger] logDebug:@"foo = %@", foo]; 162// 163// 3. Send all logging output from the shared logger to a file. We do this by 164// creating an NSFileHandle for writing associated with a file, and setting 165// that file handle as the logger's writer. 166// 167// NSFileHandle *f = [NSFileHandle fileHandleForWritingAtPath:@"/tmp/f.log" 168// create:YES]; 169// [[GTMLogger sharedLogger] setWriter:f]; 170// GTMLoggerError(@"hi"); // This will be sent to /tmp/f.log 171// 172// 4. Create a new GTMLogger that will log to a file. This example differs from 173// the previous one because here we create a new GTMLogger that is different 174// from the shared logger. 175// 176// GTMLogger *logger = [GTMLogger standardLoggerWithPath:@"/tmp/temp.log"]; 177// [logger logInfo:@"hi temp log file"]; 178// 179// 5. Create a logger that writes to stdout and does NOT do any formatting to 180// the log message. This might be useful, for example, when writing a help 181// screen for a command-line tool to standard output. 182// 183// GTMLogger *logger = [GTMLogger logger]; 184// [logger logInfo:@"%@ version 0.1 usage", progName]; 185// 186// 6. Send log output to stdout AND to a log file. The trick here is that 187// NSArrays function as composite log writers, which means when an array is 188// set as the log writer, it forwards all logging messages to all of its 189// contained GTMLogWriters. 190// 191// // Create array of GTMLogWriters 192// NSArray *writers = [NSArray arrayWithObjects: 193// [NSFileHandle fileHandleForWritingAtPath:@"/tmp/f.log" create:YES], 194// [NSFileHandle fileHandleWithStandardOutput], nil]; 195// 196// GTMLogger *logger = [GTMLogger standardLogger]; 197// [logger setWriter:writers]; 198// [logger logInfo:@"hi"]; // Output goes to stdout and /tmp/f.log 199// 200// For futher details on log writers, formatters, and filters, see the 201// documentation below. 202// 203// NOTE: GTMLogger is application level logging. By default it does nothing 204// with _GTMDevLog/_GTMDevAssert (see GTMDefines.h). An application can choose 205// to bridge _GTMDevLog/_GTMDevAssert to GTMLogger by providing macro 206// definitions in its prefix header (see GTMDefines.h for how one would do 207// that). 208// 209@interface GTMLogger : NSObject { 210 @private 211 id<GTMLogWriter> writer_; 212 id<GTMLogFormatter> formatter_; 213 id<GTMLogFilter> filter_; 214} 215 216// 217// Accessors for the shared logger instance 218// 219 220// Returns a shared/global standard GTMLogger instance. Callers should typically 221// use this method to get a GTMLogger instance, unless they explicitly want 222// their own instance to configure for their own needs. This is the only method 223// that returns a shared instance; all the rest return new GTMLogger instances. 224+ (id)sharedLogger; 225 226// Sets the shared logger instance to |logger|. Future calls to +sharedLogger 227// will return |logger| instead. 228+ (void)setSharedLogger:(GTMLogger *)logger; 229 230// 231// Creation methods 232// 233 234// Returns a new autoreleased GTMLogger instance that will log to stdout, using 235// the GTMLogStandardFormatter, and the GTMLogLevelFilter filter. 236+ (id)standardLogger; 237 238// Same as +standardLogger, but logs to stderr. 239+ (id)standardLoggerWithStderr; 240 241// Same as +standardLogger but levels >= kGTMLoggerLevelError are routed to 242// stderr, everything else goes to stdout. 243+ (id)standardLoggerWithStdoutAndStderr; 244 245// Returns a new standard GTMLogger instance with a log writer that will 246// write to the file at |path|, and will use the GTMLogStandardFormatter and 247// GTMLogLevelFilter classes. If |path| does not exist, it will be created. 248+ (id)standardLoggerWithPath:(NSString *)path; 249 250// Returns an autoreleased GTMLogger instance that will use the specified 251// |writer|, |formatter|, and |filter|. 252+ (id)loggerWithWriter:(id<GTMLogWriter>)writer 253 formatter:(id<GTMLogFormatter>)formatter 254 filter:(id<GTMLogFilter>)filter; 255 256// Returns an autoreleased GTMLogger instance that logs to stdout, with the 257// basic formatter, and no filter. The returned logger differs from the logger 258// returned by +standardLogger because this one does not do any filtering and 259// does not do any special log formatting; this is the difference between a 260// "regular" logger and a "standard" logger. 261+ (id)logger; 262 263// Designated initializer. This method returns a GTMLogger initialized with the 264// specified |writer|, |formatter|, and |filter|. See the setter methods below 265// for what values will be used if nil is passed for a parameter. 266- (id)initWithWriter:(id<GTMLogWriter>)writer 267 formatter:(id<GTMLogFormatter>)formatter 268 filter:(id<GTMLogFilter>)filter; 269 270// 271// Logging methods 272// 273 274// Logs a message at the debug level (kGTMLoggerLevelDebug). 275- (void)logDebug:(NSString *)fmt, ... NS_FORMAT_FUNCTION(1, 2); 276// Logs a message at the info level (kGTMLoggerLevelInfo). 277- (void)logInfo:(NSString *)fmt, ... NS_FORMAT_FUNCTION(1, 2); 278// Logs a message at the error level (kGTMLoggerLevelError). 279- (void)logError:(NSString *)fmt, ... NS_FORMAT_FUNCTION(1, 2); 280// Logs a message at the assert level (kGTMLoggerLevelAssert). 281- (void)logAssert:(NSString *)fmt, ... NS_FORMAT_FUNCTION(1, 2); 282 283 284// 285// Accessors 286// 287 288// Accessor methods for the log writer. If the log writer is set to nil, 289// [NSFileHandle fileHandleWithStandardOutput] is used. 290- (id<GTMLogWriter>)writer; 291- (void)setWriter:(id<GTMLogWriter>)writer; 292 293// Accessor methods for the log formatter. If the log formatter is set to nil, 294// GTMLogBasicFormatter is used. This formatter will format log messages in a 295// plain printf style. 296- (id<GTMLogFormatter>)formatter; 297- (void)setFormatter:(id<GTMLogFormatter>)formatter; 298 299// Accessor methods for the log filter. If the log filter is set to nil, 300// GTMLogNoFilter is used, which allows all log messages through. 301- (id<GTMLogFilter>)filter; 302- (void)setFilter:(id<GTMLogFilter>)filter; 303 304@end // GTMLogger 305 306 307// Helper functions that are used by the convenience GTMLogger*() macros that 308// enable the logging of function names. 309@interface GTMLogger (GTMLoggerMacroHelpers) 310- (void)logFuncDebug:(const char *)func msg:(NSString *)fmt, ... 311 NS_FORMAT_FUNCTION(2, 3); 312- (void)logFuncInfo:(const char *)func msg:(NSString *)fmt, ... 313 NS_FORMAT_FUNCTION(2, 3); 314- (void)logFuncError:(const char *)func msg:(NSString *)fmt, ... 315 NS_FORMAT_FUNCTION(2, 3); 316- (void)logFuncAssert:(const char *)func msg:(NSString *)fmt, ... 317 NS_FORMAT_FUNCTION(2, 3); 318@end // GTMLoggerMacroHelpers 319 320 321// The convenience macros are only defined if they haven't already been defined. 322#ifndef GTMLoggerInfo 323 324// Convenience macros that log to the shared GTMLogger instance. These macros 325// are how users should typically log to GTMLogger. Notice that GTMLoggerDebug() 326// calls will be compiled out of non-Debug builds. 327#define GTMLoggerDebug(...) \ 328 [[GTMLogger sharedLogger] logFuncDebug:__func__ msg:__VA_ARGS__] 329#define GTMLoggerInfo(...) \ 330 [[GTMLogger sharedLogger] logFuncInfo:__func__ msg:__VA_ARGS__] 331#define GTMLoggerError(...) \ 332 [[GTMLogger sharedLogger] logFuncError:__func__ msg:__VA_ARGS__] 333#define GTMLoggerAssert(...) \ 334 [[GTMLogger sharedLogger] logFuncAssert:__func__ msg:__VA_ARGS__] 335 336// If we're not in a debug build, remove the GTMLoggerDebug statements. This 337// makes calls to GTMLoggerDebug "compile out" of Release builds 338#ifndef DEBUG 339#undef GTMLoggerDebug 340#define GTMLoggerDebug(...) do {} while(0) 341#endif 342 343#endif // !defined(GTMLoggerInfo) 344 345// Log levels. 346typedef enum { 347 kGTMLoggerLevelUnknown, 348 kGTMLoggerLevelDebug, 349 kGTMLoggerLevelInfo, 350 kGTMLoggerLevelError, 351 kGTMLoggerLevelAssert, 352} GTMLoggerLevel; 353 354 355// 356// Log Writers 357// 358 359// Protocol to be implemented by a GTMLogWriter instance. 360@protocol GTMLogWriter <NSObject> 361// Writes the given log message to where the log writer is configured to write. 362- (void)logMessage:(NSString *)msg level:(GTMLoggerLevel)level; 363@end // GTMLogWriter 364 365 366// Simple category on NSFileHandle that makes NSFileHandles valid log writers. 367// This is convenient because something like, say, +fileHandleWithStandardError 368// now becomes a valid log writer. Log messages are written to the file handle 369// with a newline appended. 370@interface NSFileHandle (GTMFileHandleLogWriter) <GTMLogWriter> 371// Opens the file at |path| in append mode, and creates the file with |mode| 372// if it didn't previously exist. 373+ (id)fileHandleForLoggingAtPath:(NSString *)path mode:(mode_t)mode; 374@end // NSFileHandle 375 376 377// This category makes NSArray a GTMLogWriter that can be composed of other 378// GTMLogWriters. This is the classic Composite GoF design pattern. When the 379// GTMLogWriter -logMessage:level: message is sent to the array, the array 380// forwards the message to all of its elements that implement the GTMLogWriter 381// protocol. 382// 383// This is useful in situations where you would like to send log output to 384// multiple log writers at the same time. Simply create an NSArray of the log 385// writers you wish to use, then set the array as the "writer" for your 386// GTMLogger instance. 387@interface NSArray (GTMArrayCompositeLogWriter) <GTMLogWriter> 388@end // GTMArrayCompositeLogWriter 389 390 391// This category adapts the GTMLogger interface so that it can be used as a log 392// writer; it's an "adapter" in the GoF Adapter pattern sense. 393// 394// This is useful when you want to configure a logger to log to a specific 395// writer with a specific formatter and/or filter. But you want to also compose 396// that with a different log writer that may have its own formatter and/or 397// filter. 398@interface GTMLogger (GTMLoggerLogWriter) <GTMLogWriter> 399@end // GTMLoggerLogWriter 400 401 402// 403// Log Formatters 404// 405 406// Protocol to be implemented by a GTMLogFormatter instance. 407@protocol GTMLogFormatter <NSObject> 408// Returns a formatted string using the format specified in |fmt| and the va 409// args specified in |args|. 410- (NSString *)stringForFunc:(NSString *)func 411 withFormat:(NSString *)fmt 412 valist:(va_list)args 413 level:(GTMLoggerLevel)level NS_FORMAT_FUNCTION(2, 0); 414@end // GTMLogFormatter 415 416 417// A basic log formatter that formats a string the same way that NSLog (or 418// printf) would. It does not do anything fancy, nor does it add any data of its 419// own. 420@interface GTMLogBasicFormatter : NSObject <GTMLogFormatter> 421 422// Helper method for prettying C99 __func__ and GCC __PRETTY_FUNCTION__ 423- (NSString *)prettyNameForFunc:(NSString *)func; 424 425@end // GTMLogBasicFormatter 426 427 428// A log formatter that formats the log string like the basic formatter, but 429// also prepends a timestamp and some basic process info to the message, as 430// shown in the following sample output. 431// 2007-12-30 10:29:24.177 myapp[4588/0xa07d0f60] [lvl=1] log mesage here 432@interface GTMLogStandardFormatter : GTMLogBasicFormatter { 433 @private 434 NSDateFormatter *dateFormatter_; // yyyy-MM-dd HH:mm:ss.SSS 435 NSString *pname_; 436 pid_t pid_; 437} 438@end // GTMLogStandardFormatter 439 440 441// 442// Log Filters 443// 444 445// Protocol to be imlemented by a GTMLogFilter instance. 446@protocol GTMLogFilter <NSObject> 447// Returns YES if |msg| at |level| should be filtered out; NO otherwise. 448- (BOOL)filterAllowsMessage:(NSString *)msg level:(GTMLoggerLevel)level; 449@end // GTMLogFilter 450 451 452// A log filter that filters messages at the kGTMLoggerLevelDebug level out of 453// non-debug builds. Messages at the kGTMLoggerLevelInfo level are also filtered 454// out of non-debug builds unless GTMVerboseLogging is set in the environment or 455// the processes's defaults. Messages at the kGTMLoggerLevelError level are 456// never filtered. 457@interface GTMLogLevelFilter : NSObject <GTMLogFilter> 458@end // GTMLogLevelFilter 459 460// A simple log filter that does NOT filter anything out; 461// -filterAllowsMessage:level will always return YES. This can be a convenient 462// way to enable debug-level logging in release builds (if you so desire). 463@interface GTMLogNoFilter : NSObject <GTMLogFilter> 464@end // GTMLogNoFilter 465 466 467// Base class for custom level filters. Not for direct use, use the minimum 468// or maximum level subclasses below. 469@interface GTMLogAllowedLevelFilter : NSObject <GTMLogFilter> { 470 @private 471 NSIndexSet *allowedLevels_; 472} 473@end 474 475// A log filter that allows you to set a minimum log level. Messages below this 476// level will be filtered. 477@interface GTMLogMininumLevelFilter : GTMLogAllowedLevelFilter 478 479// Designated initializer, logs at levels < |level| will be filtered. 480- (id)initWithMinimumLevel:(GTMLoggerLevel)level; 481 482@end 483 484// A log filter that allows you to set a maximum log level. Messages whose level 485// exceeds this level will be filtered. This is really only useful if you have 486// a composite GTMLogger that is sending the other messages elsewhere. 487@interface GTMLogMaximumLevelFilter : GTMLogAllowedLevelFilter 488 489// Designated initializer, logs at levels > |level| will be filtered. 490- (id)initWithMaximumLevel:(GTMLoggerLevel)level; 491 492@end 493 494 495// For subclasses only 496@interface GTMLogger (PrivateMethods) 497 498- (void)logInternalFunc:(const char *)func 499 format:(NSString *)fmt 500 valist:(va_list)args 501 level:(GTMLoggerLevel)level NS_FORMAT_FUNCTION(2, 0); 502 503@end 504 505