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.
16 #include <folly/experimental/logging/LoggerDB.h>
20 #include <folly/Conv.h>
21 #include <folly/FileUtil.h>
22 #include <folly/String.h>
23 #include <folly/experimental/logging/LogCategory.h>
24 #include <folly/experimental/logging/LogConfig.h>
25 #include <folly/experimental/logging/LogHandler.h>
26 #include <folly/experimental/logging/LogHandlerFactory.h>
27 #include <folly/experimental/logging/LogLevel.h>
28 #include <folly/experimental/logging/Logger.h>
29 #include <folly/experimental/logging/RateLimiter.h>
36 class LoggerDBSingleton {
38 explicit LoggerDBSingleton(LoggerDB* db) : db_{db} {}
39 ~LoggerDBSingleton() {
40 // We intentionally leak the LoggerDB object on destruction.
41 // We want Logger objects to remain valid for the entire lifetime of the
42 // program, without having to worry about destruction ordering issues, or
43 // making the Logger perform reference counting on the LoggerDB.
45 // Therefore the main LoggerDB object, and all of the LogCategory objects
46 // it contains, are always intentionally leaked.
48 // However, we do call db_->cleanupHandlers() to destroy any registered
49 // LogHandler objects. The LogHandlers can be user-defined objects and may
50 // hold resources that should be cleaned up. This also ensures that the
51 // LogHandlers flush all outstanding messages before we exit.
52 db_->cleanupHandlers();
55 LoggerDB* getDB() const {
64 LoggerDB* LoggerDB::get() {
65 // Intentionally leaky singleton
66 static LoggerDBSingleton singleton{new LoggerDB()};
67 return singleton.getDB();
70 LoggerDB::LoggerDB() {
71 // Create the root log category, and set the level to ERR by default
72 auto rootUptr = std::make_unique<LogCategory>(this);
73 LogCategory* root = rootUptr.get();
75 loggersByName_.wlock()->emplace(root->getName(), std::move(rootUptr));
78 root->setLevelLocked(LogLevel::ERR, false);
81 LoggerDB::LoggerDB(TestConstructorArg) : LoggerDB() {}
83 LoggerDB::~LoggerDB() {}
85 LogCategory* LoggerDB::getCategory(StringPiece name) {
86 return getOrCreateCategoryLocked(*loggersByName_.wlock(), name);
89 LogCategory* FOLLY_NULLABLE LoggerDB::getCategoryOrNull(StringPiece name) {
90 auto loggersByName = loggersByName_.rlock();
92 auto it = loggersByName->find(name);
93 if (it == loggersByName->end()) {
96 return it->second.get();
99 void LoggerDB::setLevel(folly::StringPiece name, LogLevel level, bool inherit) {
100 auto loggersByName = loggersByName_.wlock();
101 LogCategory* category = getOrCreateCategoryLocked(*loggersByName, name);
102 category->setLevelLocked(level, inherit);
105 void LoggerDB::setLevel(LogCategory* category, LogLevel level, bool inherit) {
106 auto loggersByName = loggersByName_.wlock();
107 category->setLevelLocked(level, inherit);
110 LogConfig LoggerDB::getConfig() const {
111 auto handlerInfo = handlerInfo_.rlock();
113 LogConfig::HandlerConfigMap handlerConfigs;
114 std::unordered_map<std::shared_ptr<LogHandler>, string> handlersToName;
115 for (const auto& entry : handlerInfo->handlers) {
116 auto handler = entry.second.lock();
120 handlersToName.emplace(handler, entry.first);
121 handlerConfigs.emplace(entry.first, handler->getConfig());
124 size_t anonymousNameIndex = 1;
125 auto generateAnonymousHandlerName = [&]() {
126 // Return a unique name of the form "anonymousHandlerN"
127 // Keep incrementing N until we find a name that isn't currently taken.
129 auto name = to<string>("anonymousHandler", anonymousNameIndex);
130 ++anonymousNameIndex;
131 if (handlerInfo->handlers.find(name) == handlerInfo->handlers.end()) {
137 LogConfig::CategoryConfigMap categoryConfigs;
139 auto loggersByName = loggersByName_.rlock();
140 for (const auto& entry : *loggersByName) {
141 auto* category = entry.second.get();
142 auto levelInfo = category->getLevelInfo();
143 auto handlers = category->getHandlers();
145 // Don't report categories that have default settings.
146 if (handlers.empty() && levelInfo.first == LogLevel::MAX_LEVEL &&
151 // Translate the handler pointers to names
152 std::vector<string> handlerNames;
153 for (const auto& handler : handlers) {
154 auto iter = handlersToName.find(handler);
155 if (iter == handlersToName.end()) {
156 // This LogHandler must have been manually attached to the category,
157 // rather than defined with `updateConfig()` or `resetConfig()`.
158 // Generate a unique name to use for reporting it in the config.
159 auto name = generateAnonymousHandlerName();
160 handlersToName.emplace(handler, name);
161 handlerConfigs.emplace(name, handler->getConfig());
162 handlerNames.emplace_back(name);
164 handlerNames.emplace_back(iter->second);
168 LogCategoryConfig categoryConfig(
169 levelInfo.first, levelInfo.second, handlerNames);
170 categoryConfigs.emplace(category->getName(), std::move(categoryConfig));
174 return LogConfig{std::move(handlerConfigs), std::move(categoryConfigs)};
178 * Process handler config information when starting a config update operation.
180 void LoggerDB::startConfigUpdate(
181 const Synchronized<HandlerInfo>::LockedPtr& handlerInfo,
182 const LogConfig& config,
183 NewHandlerMap* handlers,
184 OldToNewHandlerMap* oldToNewHandlerMap) {
185 // Get a map of all currently existing LogHandlers.
186 // This resolves weak_ptrs to shared_ptrs, and ignores expired weak_ptrs.
187 // This prevents any of these LogHandler pointers from expiring during the
189 for (const auto& entry : handlerInfo->handlers) {
190 auto handler = entry.second.lock();
192 handlers->emplace(entry.first, std::move(handler));
196 // Create all of the new LogHandlers needed from this configuration
197 for (const auto& entry : config.getHandlerConfigs()) {
198 // Look up the LogHandlerFactory
199 auto factoryIter = handlerInfo->factories.find(entry.second.type);
200 if (factoryIter == handlerInfo->factories.end()) {
201 throw std::invalid_argument(to<std::string>(
202 "unknown log handler type \"", entry.second.type, "\""));
205 // Check to see if there is an existing LogHandler with this name
206 std::shared_ptr<LogHandler> oldHandler;
207 auto iter = handlers->find(entry.first);
208 if (iter != handlers->end()) {
209 oldHandler = iter->second;
212 // Create the new log handler
213 const auto& factory = factoryIter->second;
214 std::shared_ptr<LogHandler> handler;
217 handler = factory->updateHandler(oldHandler, entry.second.options);
218 if (handler != oldHandler) {
219 oldToNewHandlerMap->emplace(oldHandler, handler);
222 handler = factory->createHandler(entry.second.options);
224 } catch (const std::exception& ex) {
225 // Errors creating or updating the the log handler are generally due to
226 // bad configuration options. It is useful to update the exception
227 // message to include the name of the log handler we were trying to
229 throw std::invalid_argument(to<string>(
231 oldHandler ? "updating" : "creating",
237 handlerInfo->handlers[entry.first] = handler;
238 (*handlers)[entry.first] = handler;
241 // Before we start making any LogCategory changes, confirm that all handlers
242 // named in the category configs are known handlers.
243 for (const auto& entry : config.getCategoryConfigs()) {
244 if (!entry.second.handlers.hasValue()) {
247 for (const auto& handlerName : entry.second.handlers.value()) {
248 auto iter = handlers->find(handlerName);
249 if (iter == handlers->end()) {
250 throw std::invalid_argument(to<std::string>(
251 "unknown log handler \"",
253 "\" configured for log category \"",
262 * Update handlerInfo_ at the end of a config update operation.
264 void LoggerDB::finishConfigUpdate(
265 const Synchronized<HandlerInfo>::LockedPtr& handlerInfo,
266 NewHandlerMap* handlers,
267 OldToNewHandlerMap* oldToNewHandlerMap) {
268 // Build a new map to replace handlerInfo->handlers
269 // This will contain only the LogHandlers that are still in use by the
270 // current LogCategory settings.
271 std::unordered_map<std::string, std::weak_ptr<LogHandler>> newHandlerMap;
272 for (const auto& entry : *handlers) {
273 newHandlerMap.emplace(entry.first, entry.second);
275 // Drop all of our shared_ptr references to LogHandler objects,
276 // and then remove entries in newHandlerMap that are unreferenced.
278 oldToNewHandlerMap->clear();
279 handlerInfo->handlers.clear();
280 for (auto iter = newHandlerMap.begin(); iter != newHandlerMap.end(); /**/) {
281 if (iter->second.expired()) {
282 iter = newHandlerMap.erase(iter);
287 handlerInfo->handlers.swap(newHandlerMap);
290 std::vector<std::shared_ptr<LogHandler>> LoggerDB::buildCategoryHandlerList(
291 const NewHandlerMap& handlerMap,
292 StringPiece categoryName,
293 const std::vector<std::string>& categoryHandlerNames) {
294 std::vector<std::shared_ptr<LogHandler>> catHandlers;
295 for (const auto& handlerName : categoryHandlerNames) {
296 auto iter = handlerMap.find(handlerName);
297 if (iter == handlerMap.end()) {
298 // This really shouldn't be possible; the checks in startConfigUpdate()
299 // should have already bailed out if there was an unknown handler.
300 throw std::invalid_argument(to<std::string>(
301 "bug: unknown log handler \"",
303 "\" configured for log category \"",
307 catHandlers.push_back(iter->second);
313 void LoggerDB::updateConfig(const LogConfig& config) {
314 // Grab the handlerInfo_ lock.
315 // We hold it in write mode for the entire config update operation. This
316 // ensures that only a single config update operation ever runs at once.
317 auto handlerInfo = handlerInfo_.wlock();
319 NewHandlerMap handlers;
320 OldToNewHandlerMap oldToNewHandlerMap;
321 startConfigUpdate(handlerInfo, config, &handlers, &oldToNewHandlerMap);
323 // If an existing LogHandler was replaced with a new one,
324 // walk all current LogCategories and replace this handler.
325 if (!oldToNewHandlerMap.empty()) {
326 auto loggerMap = loggersByName_.rlock();
327 for (const auto& entry : *loggerMap) {
328 entry.second->updateHandlers(oldToNewHandlerMap);
332 // Update log levels and handlers mentioned in the config update
333 auto loggersByName = loggersByName_.wlock();
334 for (const auto& entry : config.getCategoryConfigs()) {
335 LogCategory* category =
336 getOrCreateCategoryLocked(*loggersByName, entry.first);
338 // Update the log handlers
339 if (entry.second.handlers.hasValue()) {
340 auto catHandlers = buildCategoryHandlerList(
341 handlers, entry.first, entry.second.handlers.value());
342 category->replaceHandlers(std::move(catHandlers));
345 // Update the level settings
346 category->setLevelLocked(
347 entry.second.level, entry.second.inheritParentLevel);
350 finishConfigUpdate(handlerInfo, &handlers, &oldToNewHandlerMap);
353 void LoggerDB::resetConfig(const LogConfig& config) {
354 // Grab the handlerInfo_ lock.
355 // We hold it in write mode for the entire config update operation. This
356 // ensures that only a single config update operation ever runs at once.
357 auto handlerInfo = handlerInfo_.wlock();
359 NewHandlerMap handlers;
360 OldToNewHandlerMap oldToNewHandlerMap;
361 startConfigUpdate(handlerInfo, config, &handlers, &oldToNewHandlerMap);
363 // Make sure all log categories mentioned in the new config exist.
364 // This ensures that we will cover them in our walk below.
365 LogCategory* rootCategory;
367 auto loggersByName = loggersByName_.wlock();
368 rootCategory = getOrCreateCategoryLocked(*loggersByName, "");
369 for (const auto& entry : config.getCategoryConfigs()) {
370 getOrCreateCategoryLocked(*loggersByName, entry.first);
375 // Update all log categories
376 auto loggersByName = loggersByName_.rlock();
377 for (const auto& entry : *loggersByName) {
378 auto* category = entry.second.get();
380 auto configIter = config.getCategoryConfigs().find(category->getName());
381 if (configIter == config.getCategoryConfigs().end()) {
382 // This category is not listed in the config settings.
383 // Reset it to the default settings.
384 category->clearHandlers();
386 if (category == rootCategory) {
387 category->setLevelLocked(LogLevel::ERR, false);
389 category->setLevelLocked(LogLevel::MAX_LEVEL, true);
394 const auto& catConfig = configIter->second;
396 // Update the category log level
397 category->setLevelLocked(catConfig.level, catConfig.inheritParentLevel);
399 // Update the category handlers list.
400 // If the handler list is not set in the config, clear out any existing
401 // handlers rather than leaving it as-is.
402 std::vector<std::shared_ptr<LogHandler>> catHandlers;
403 if (catConfig.handlers.hasValue()) {
404 catHandlers = buildCategoryHandlerList(
405 handlers, entry.first, catConfig.handlers.value());
407 category->replaceHandlers(std::move(catHandlers));
411 finishConfigUpdate(handlerInfo, &handlers, &oldToNewHandlerMap);
414 LogCategory* LoggerDB::getOrCreateCategoryLocked(
415 LoggerNameMap& loggersByName,
417 auto it = loggersByName.find(name);
418 if (it != loggersByName.end()) {
419 return it->second.get();
422 StringPiece parentName = LogName::getParent(name);
423 LogCategory* parent = getOrCreateCategoryLocked(loggersByName, parentName);
424 return createCategoryLocked(loggersByName, name, parent);
427 LogCategory* LoggerDB::createCategoryLocked(
428 LoggerNameMap& loggersByName,
430 LogCategory* parent) {
431 auto uptr = std::make_unique<LogCategory>(name, parent);
432 LogCategory* logger = uptr.get();
433 auto ret = loggersByName.emplace(logger->getName(), std::move(uptr));
438 void LoggerDB::cleanupHandlers() {
439 // Get a copy of all categories, so we can call clearHandlers() without
440 // holding the loggersByName_ lock. We don't need to worry about LogCategory
441 // lifetime, since LogCategory objects always live for the lifetime of the
443 std::vector<LogCategory*> categories;
445 auto loggersByName = loggersByName_.wlock();
446 categories.reserve(loggersByName->size());
447 for (const auto& entry : *loggersByName) {
448 categories.push_back(entry.second.get());
452 // Also extract our HandlerFactoryMap and HandlerMap, so we can clear them
453 // later without holding the handlerInfo_ lock.
454 HandlerFactoryMap factories;
457 auto handlerInfo = handlerInfo_.wlock();
458 factories.swap(handlerInfo->factories);
459 handlers.swap(handlerInfo->handlers);
462 // Remove all of the LogHandlers from all log categories,
463 // to drop any shared_ptr references to the LogHandlers
464 for (auto* category : categories) {
465 category->clearHandlers();
469 size_t LoggerDB::flushAllHandlers() {
470 // Build a set of all LogHandlers. We use a set to avoid calling flush()
471 // more than once on the same handler if it is registered on multiple
472 // different categories.
473 std::set<std::shared_ptr<LogHandler>> handlers;
475 auto loggersByName = loggersByName_.wlock();
476 for (const auto& entry : *loggersByName) {
477 for (const auto& handler : entry.second->getHandlers()) {
478 handlers.emplace(handler);
483 // Call flush() on each handler
484 for (const auto& handler : handlers) {
487 return handlers.size();
490 void LoggerDB::registerHandlerFactory(
491 std::unique_ptr<LogHandlerFactory> factory,
492 bool replaceExisting) {
493 auto type = factory->getType();
494 auto handlerInfo = handlerInfo_.wlock();
495 if (replaceExisting) {
496 handlerInfo->factories[type.str()] = std::move(factory);
498 auto ret = handlerInfo->factories.emplace(type.str(), std::move(factory));
500 throw std::range_error(to<std::string>(
501 "a LogHandlerFactory for the type \"", type, "\" already exists"));
506 void LoggerDB::unregisterHandlerFactory(StringPiece type) {
507 auto handlerInfo = handlerInfo_.wlock();
508 auto numRemoved = handlerInfo->factories.erase(type.str());
509 if (numRemoved != 1) {
510 throw std::range_error(
511 to<std::string>("no LogHandlerFactory for type \"", type, "\" found"));
515 LogLevel LoggerDB::xlogInit(
516 StringPiece categoryName,
517 std::atomic<LogLevel>* xlogCategoryLevel,
518 LogCategory** xlogCategory) {
519 // Hold the lock for the duration of the operation
520 // xlogInit() may be called from multiple threads simultaneously.
521 // Only one needs to perform the initialization.
522 auto loggersByName = loggersByName_.wlock();
523 if (xlogCategory != nullptr && *xlogCategory != nullptr) {
524 // The xlogCategory was already initialized before we acquired the lock
525 return (*xlogCategory)->getEffectiveLevel();
528 auto* category = getOrCreateCategoryLocked(*loggersByName, categoryName);
530 // Set *xlogCategory before we update xlogCategoryLevel below.
531 // This is important, since the XLOG() macros check xlogCategoryLevel to
532 // tell if *xlogCategory has been initialized yet.
533 *xlogCategory = category;
535 auto level = category->getEffectiveLevel();
536 xlogCategoryLevel->store(level, std::memory_order_release);
537 category->registerXlogLevel(xlogCategoryLevel);
541 LogCategory* LoggerDB::xlogInitCategory(
542 StringPiece categoryName,
543 LogCategory** xlogCategory,
544 std::atomic<bool>* isInitialized) {
545 // Hold the lock for the duration of the operation
546 // xlogInitCategory() may be called from multiple threads simultaneously.
547 // Only one needs to perform the initialization.
548 auto loggersByName = loggersByName_.wlock();
549 if (isInitialized->load(std::memory_order_acquire)) {
550 // The xlogCategory was already initialized before we acquired the lock
551 return *xlogCategory;
554 auto* category = getOrCreateCategoryLocked(*loggersByName, categoryName);
555 *xlogCategory = category;
556 isInitialized->store(true, std::memory_order_release);
560 std::atomic<LoggerDB::InternalWarningHandler> LoggerDB::warningHandler_;
562 void LoggerDB::internalWarningImpl(
563 folly::StringPiece filename,
565 std::string&& msg) noexcept {
566 auto handler = warningHandler_.load();
568 handler(filename, lineNumber, std::move(msg));
570 defaultInternalWarningImpl(filename, lineNumber, std::move(msg));
574 void LoggerDB::setInternalWarningHandler(InternalWarningHandler handler) {
575 // This API is intentionally pretty basic. It has a number of limitations:
577 // - We only support plain function pointers, and not full std::function
578 // objects. This makes it possible to use std::atomic to access the
579 // handler pointer, and also makes it safe to store in a zero-initialized
580 // file-static pointer.
582 // - We don't support any void* argument to the handler. The caller is
583 // responsible for storing any callback state themselves.
585 // - When replacing or unsetting a handler we don't make any guarantees about
586 // when the old handler will stop being called. It may still be called
587 // from other threads briefly even after setInternalWarningHandler()
588 // returns. This is also a consequence of using std::atomic rather than a
591 // This provides the minimum capabilities needed to customize the handler,
592 // while still keeping the implementation simple and safe to use even before
594 warningHandler_.store(handler);
597 void LoggerDB::defaultInternalWarningImpl(
598 folly::StringPiece filename,
600 std::string&& msg) noexcept {
601 // Rate limit to 10 messages every 5 seconds.
603 // We intentonally use a leaky Meyer's singleton here over folly::Singleton:
604 // - We want this code to work even before main()
605 // - This singleton does not depend on any other singletons.
606 static auto* rateLimiter =
607 new logging::IntervalRateLimiter{10, std::chrono::seconds(5)};
608 if (!rateLimiter->check()) {
612 if (folly::kIsDebug) {
613 // Write directly to file descriptor 2.
615 // It's possible the application has closed fd 2 and is using it for
616 // something other than stderr. However we have no good way to detect
617 // this, which is the main reason we only write to stderr in debug build
618 // modes. assert() also writes directly to stderr on failure, which seems
619 // like a reasonable precedent.
621 // Another option would be to use openlog() and syslog(). However
622 // calling openlog() may inadvertently affect the behavior of other parts
623 // of the program also using syslog().
625 // We don't check for write errors here, since there's not much else we can
627 auto fullMsg = folly::to<std::string>(
628 "logging warning:", filename, ":", lineNumber, ": ", msg, "\n");
629 folly::writeFull(STDERR_FILENO, fullMsg.data(), fullMsg.size());