2 * Copyright 2004-present Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include <folly/Conv.h>
19 #include <folly/CppAttributes.h>
20 #include <folly/Range.h>
21 #include <folly/Synchronized.h>
24 #include <unordered_map>
27 #include <folly/experimental/logging/LogName.h>
32 enum class LogLevel : uint32_t;
35 * LoggerDB stores the set of LogCategory objects.
40 * Get the main LoggerDB singleton.
42 static LoggerDB* get();
45 * Get the LogCategory for the specified name.
47 * This creates the LogCategory for the specified name if it does not exist
50 LogCategory* getCategory(folly::StringPiece name);
53 * Get the LogCategory for the specified name, if it already exists.
55 * This returns nullptr if no LogCategory has been created yet for the
58 LogCategory* FOLLY_NULLABLE getCategoryOrNull(folly::StringPiece name);
61 * Set the log level for the specified category.
63 * Messages logged to a specific log category will be ignored unless the
64 * message log level is greater than the LogCategory's effective log level.
66 * If inherit is true, LogCategory's effective log level is the minimum of
67 * its level and it's parent category's effective log level. If inherit is
68 * false, the LogCategory's effective log level is simply its log level.
69 * (Setting inherit to false is necessary if you want a child LogCategory to
70 * use a less verbose level than its parent categories.)
72 void setLevel(folly::StringPiece name, LogLevel level, bool inherit = true);
73 void setLevel(LogCategory* category, LogLevel level, bool inherit = true);
76 * Apply a configuration string specifying a series a log levels.
78 * The string format is a comma separated list of <name>=<level> sections.
79 * e.g.: "foo=DBG3,log.bar=WARN"
81 * Returns a list of error messages for each error encountered trying to
82 * parse the config string. The return value will be an empty vector if no
83 * errors were encountered.
85 std::vector<std::string> processConfigString(folly::StringPiece config);
88 * Remove all registered LogHandlers on all LogCategory objects.
90 * This is called on the main LoggerDB object during shutdown.
92 void cleanupHandlers();
95 * Initialize the LogCategory* and std::atomic<LogLevel> used by an XLOG()
98 * Returns the current effective LogLevel of the category.
101 folly::StringPiece categoryName,
102 std::atomic<LogLevel>* xlogCategoryLevel,
103 LogCategory** xlogCategory);
104 LogCategory* xlogInitCategory(
105 folly::StringPiece categoryName,
106 LogCategory** xlogCategory,
107 std::atomic<bool>* isInitialized);
109 enum TestConstructorArg { TESTING };
112 * Construct a LoggerDB for testing purposes.
114 * Most callers should not need this function, and should use
115 * LoggerDB::get() to obtain the main LoggerDB singleton. This function
116 * exists mainly to allow testing LoggerDB objects in unit tests.
117 * It requires an explicit argument just to prevent callers from calling it
120 explicit LoggerDB(TestConstructorArg);
123 * internalWarning() is used to report a problem when something goes wrong
124 * internally in the logging library.
126 * We can't log these messages through the normal logging flow since logging
129 * Example scenarios where this is used:
130 * - We fail to write to a log file (for instance, when the disk is full)
131 * - A LogHandler throws an unexpected exception
133 template <typename... Args>
134 static void internalWarning(
135 folly::StringPiece file,
137 Args&&... args) noexcept {
139 file, lineNumber, folly::to<std::string>(std::forward<Args>(args)...));
142 using InternalWarningHandler =
143 void (*)(folly::StringPiece file, int lineNumber, std::string&&);
146 * Set a function to be called when the logging library generates an internal
149 * The supplied handler should never throw exceptions.
151 * If a null handler is supplied, the default built-in handler will be used.
153 * The default handler reports the message with _CrtDbgReport(_CRT_WARN) on
154 * Windows, and prints the message to stderr on other platforms. It also
155 * rate limits messages if they are arriving too quickly.
157 static void setInternalWarningHandler(InternalWarningHandler handler);
160 using LoggerNameMap = std::unordered_map<
162 std::unique_ptr<LogCategory>,
166 // Forbidden copy constructor and assignment operator
167 LoggerDB(LoggerDB const&) = delete;
168 LoggerDB& operator=(LoggerDB const&) = delete;
171 LogCategory* getOrCreateCategoryLocked(
172 LoggerNameMap& loggersByName,
173 folly::StringPiece name);
174 LogCategory* createCategoryLocked(
175 LoggerNameMap& loggersByName,
176 folly::StringPiece name,
177 LogCategory* parent);
179 static void internalWarningImpl(
180 folly::StringPiece filename,
182 std::string&& msg) noexcept;
183 static void defaultInternalWarningImpl(
184 folly::StringPiece filename,
186 std::string&& msg) noexcept;
189 * A map of LogCategory objects by name.
191 * Lookups can be performed using arbitrary StringPiece values that do not
192 * have to be in canonical form.
194 folly::Synchronized<LoggerNameMap> loggersByName_;
196 static std::atomic<InternalWarningHandler> warningHandler_;