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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MOJO_PUBLIC_C_ENVIRONMENT_LOGGER_H_
      6 #define MOJO_PUBLIC_C_ENVIRONMENT_LOGGER_H_
      7 
      8 #include <stdint.h>
      9 
     10 // |MojoLogLevel|: Used to specify the type of log message. Values are ordered
     11 // by severity (i.e., higher numerical values are more severe).
     12 
     13 typedef int32_t MojoLogLevel;
     14 
     15 #ifdef __cplusplus
     16 const MojoLogLevel MOJO_LOG_LEVEL_VERBOSE = -1;
     17 const MojoLogLevel MOJO_LOG_LEVEL_INFO = 0;
     18 const MojoLogLevel MOJO_LOG_LEVEL_WARNING = 1;
     19 const MojoLogLevel MOJO_LOG_LEVEL_ERROR = 2;
     20 const MojoLogLevel MOJO_LOG_LEVEL_FATAL = 3;
     21 #else
     22 #define MOJO_LOG_LEVEL_VERBOSE ((MojoLogLevel) -1)
     23 #define MOJO_LOG_LEVEL_INFO ((MojoLogLevel) 0)
     24 #define MOJO_LOG_LEVEL_WARNING ((MojoLogLevel) 1)
     25 #define MOJO_LOG_LEVEL_ERROR ((MojoLogLevel) 2)
     26 #define MOJO_LOG_LEVEL_FATAL ((MojoLogLevel) 3)
     27 #endif
     28 
     29 // Structure with basic logging functions (on top of which more friendly logging
     30 // macros may be built). The functions are thread-safe, except for
     31 // |SetMinimumLogLevel()| (see below).
     32 struct MojoLogger {
     33   // Logs |message| at level |log_level| if |log_level| is at least the current
     34   // minimum log level. If |log_level| is |MOJO_LOG_LEVEL_FATAL| (or greater),
     35   // aborts the application/process.
     36   void (*LogMessage)(MojoLogLevel log_level, const char* message);
     37 
     38   // Gets the minimum log level (see above), which will always be at most
     39   // |MOJO_LOG_LEVEL_FATAL|. (Though |LogMessage()| will automatically avoid
     40   // logging messages below the minimum log level, this may be used to avoid
     41   // extra work.)
     42   MojoLogLevel (*GetMinimumLogLevel)(void);
     43 
     44   // Sets the minimum log level (see above) to the lesser of |minimum_log_level|
     45   // and |MOJO_LOG_LEVEL_FATAL|.
     46   //
     47   // Warning: This function may not be thread-safe, and should not be called
     48   // concurrently with other |MojoLogger| functions. (In some environments --
     49   // such as Chromium -- that share a logger across applications, this may mean
     50   // that it is almost never safe to call this.)
     51   void (*SetMinimumLogLevel)(MojoLogLevel minimum_log_level);
     52 };
     53 
     54 #endif  // MOJO_PUBLIC_C_ENVIRONMENT_LOGGER_H_
     55