source/Utility/Log.cpp - llvm-project/lldb - Git at Google

 //===-- Log.cpp -----------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/VASPrintf.h"

 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/iterator.h"

 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/raw_ostream.h"

 #include <chrono>
 #include <cstdarg>
 #include <mutex>
 #include <utility>

 #include <cassert>
 #if defined(_WIN32)
 #include <process.h>
 #else
 #include <unistd.h>
 #endif

 using namespace lldb_private;

 char LogHandler::ID;
 char StreamLogHandler::ID;
 char CallbackLogHandler::ID;
 char RotatingLogHandler::ID;
 char TeeLogHandler::ID;

 llvm::ManagedStatic<Log::ChannelMap> Log::g_channel_map;

 void Log::ForEachCategory(
     const Log::ChannelMap::value_type &entry,
     llvm::function_ref<void(llvm::StringRef, llvm::StringRef)> lambda) {
   lambda("all", "all available logging categories");
   lambda("default", "default set of logging categories");
   for (const auto &category : entry.second.m_channel.categories)
     lambda(category.name, category.description);
 }

 void Log::ListCategories(llvm::raw_ostream &stream,
                          const ChannelMap::value_type &entry) {
   stream << llvm::formatv("Logging categories for '{0}':\n", entry.first());
   ForEachCategory(entry,
                   [&stream](llvm::StringRef name, llvm::StringRef description) {
                     stream << llvm::formatv("  {0} - {1}\n", name, description);
                   });
 }

 Log::MaskType Log::GetFlags(llvm::raw_ostream &stream,
                             const ChannelMap::value_type &entry,
                             llvm::ArrayRef<const char *> categories) {
   bool list_categories = false;
   Log::MaskType flags = 0;
   for (const char *category : categories) {
     if (llvm::StringRef("all").equals_insensitive(category)) {
       flags |= std::numeric_limits<Log::MaskType>::max();
       continue;
     }
     if (llvm::StringRef("default").equals_insensitive(category)) {
       flags |= entry.second.m_channel.default_flags;
       continue;
     }
     auto cat = llvm::find_if(entry.second.m_channel.categories,
                              [&](const Log::Category &c) {
                                return c.name.equals_insensitive(category);
                              });
     if (cat != entry.second.m_channel.categories.end()) {
       flags |= cat->flag;
       continue;
     }
     stream << llvm::formatv("error: unrecognized log category '{0}'\n",
                             category);
     list_categories = true;
   }
   if (list_categories)
     ListCategories(stream, entry);
   return flags;
 }

 void Log::Enable(const std::shared_ptr<LogHandler> &handler_sp,
                  uint32_t options, Log::MaskType flags) {
   llvm::sys::ScopedWriter lock(m_mutex);

   MaskType mask = m_mask.fetch_or(flags, std::memory_order_relaxed);
   if (mask | flags) {
     m_options.store(options, std::memory_order_relaxed);
     m_handler = handler_sp;
     m_channel.log_ptr.store(this, std::memory_order_relaxed);
   }
 }

 void Log::Disable(Log::MaskType flags) {
   llvm::sys::ScopedWriter lock(m_mutex);

   MaskType mask = m_mask.fetch_and(~flags, std::memory_order_relaxed);
   if (!(mask & ~flags)) {
     m_handler.reset();
     m_channel.log_ptr.store(nullptr, std::memory_order_relaxed);
   }
 }

 bool Log::Dump(llvm::raw_ostream &output_stream) {
   llvm::sys::ScopedReader lock(m_mutex);
   if (RotatingLogHandler *handler =
           llvm::dyn_cast_or_null<RotatingLogHandler>(m_handler.get())) {
     handler->Dump(output_stream);
     return true;
   }
   return false;
 }

 const Flags Log::GetOptions() const {
   return m_options.load(std::memory_order_relaxed);
 }

 Log::MaskType Log::GetMask() const {
   return m_mask.load(std::memory_order_relaxed);
 }

 void Log::PutCString(const char *cstr) { PutString(cstr); }

 void Log::PutString(llvm::StringRef str) {
   std::string FinalMessage;
   llvm::raw_string_ostream Stream(FinalMessage);
   WriteHeader(Stream, "", "");
   Stream << str << "\n";
   WriteMessage(FinalMessage);
 }

 // Simple variable argument logging with flags.
 void Log::Printf(const char *format, ...) {
   va_list args;
   va_start(args, format);
   VAPrintf(format, args);
   va_end(args);
 }

 void Log::VAPrintf(const char *format, va_list args) {
   llvm::SmallString<64> Content;
   lldb_private::VASprintf(Content, format, args);
   PutString(Content);
 }

 void Log::Formatf(llvm::StringRef file, llvm::StringRef function,
                   const char *format, ...) {
   va_list args;
   va_start(args, format);
   VAFormatf(file, function, format, args);
   va_end(args);
 }

 void Log::VAFormatf(llvm::StringRef file, llvm::StringRef function,
                     const char *format, va_list args) {
   llvm::SmallString<64> Content;
   lldb_private::VASprintf(Content, format, args);
   Format(file, function, llvm::formatv("{0}", Content));
 }

 // Printing of errors that are not fatal.
 void Log::Error(const char *format, ...) {
   va_list args;
   va_start(args, format);
   VAError(format, args);
   va_end(args);
 }

 void Log::VAError(const char *format, va_list args) {
   llvm::SmallString<64> Content;
   VASprintf(Content, format, args);

   Printf("error: %s", Content.c_str());
 }

 // Printing of warnings that are not fatal only if verbose mode is enabled.
 void Log::Verbose(const char *format, ...) {
   if (!GetVerbose())
     return;

   va_list args;
   va_start(args, format);
   VAPrintf(format, args);
   va_end(args);
 }

 // Printing of warnings that are not fatal.
 void Log::Warning(const char *format, ...) {
   llvm::SmallString<64> Content;
   va_list args;
   va_start(args, format);
   VASprintf(Content, format, args);
   va_end(args);

   Printf("warning: %s", Content.c_str());
 }

 void Log::Register(llvm::StringRef name, Channel &channel) {
   auto iter = g_channel_map->try_emplace(name, channel);
   assert(iter.second == true);
   UNUSED_IF_ASSERT_DISABLED(iter);
 }

 void Log::Unregister(llvm::StringRef name) {
   auto iter = g_channel_map->find(name);
   assert(iter != g_channel_map->end());
   iter->second.Disable(std::numeric_limits<MaskType>::max());
   g_channel_map->erase(iter);
 }

 bool Log::EnableLogChannel(const std::shared_ptr<LogHandler> &log_handler_sp,
                            uint32_t log_options, llvm::StringRef channel,
                            llvm::ArrayRef<const char *> categories,
                            llvm::raw_ostream &error_stream) {
   auto iter = g_channel_map->find(channel);
   if (iter == g_channel_map->end()) {
     error_stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
     return false;
   }
   MaskType flags = categories.empty()
                        ? iter->second.m_channel.default_flags
                        : GetFlags(error_stream, *iter, categories);
   iter->second.Enable(log_handler_sp, log_options, flags);
   return true;
 }

 bool Log::DisableLogChannel(llvm::StringRef channel,
                             llvm::ArrayRef<const char *> categories,
                             llvm::raw_ostream &error_stream) {
   auto iter = g_channel_map->find(channel);
   if (iter == g_channel_map->end()) {
     error_stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
     return false;
   }
   MaskType flags = categories.empty()
                        ? std::numeric_limits<MaskType>::max()
                        : GetFlags(error_stream, *iter, categories);
   iter->second.Disable(flags);
   return true;
 }

 bool Log::DumpLogChannel(llvm::StringRef channel,
                          llvm::raw_ostream &output_stream,
                          llvm::raw_ostream &error_stream) {
   auto iter = g_channel_map->find(channel);
   if (iter == g_channel_map->end()) {
     error_stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
     return false;
   }
   if (!iter->second.Dump(output_stream)) {
     error_stream << llvm::formatv(
         "log channel '{0}' does not support dumping.\n", channel);
     return false;
   }
   return true;
 }

 bool Log::ListChannelCategories(llvm::StringRef channel,
                                 llvm::raw_ostream &stream) {
   auto ch = g_channel_map->find(channel);
   if (ch == g_channel_map->end()) {
     stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
     return false;
   }
   ListCategories(stream, *ch);
   return true;
 }

 void Log::DisableAllLogChannels() {
   for (auto &entry : *g_channel_map)
     entry.second.Disable(std::numeric_limits<MaskType>::max());
 }

 void Log::ForEachChannelCategory(
     llvm::StringRef channel,
     llvm::function_ref<void(llvm::StringRef, llvm::StringRef)> lambda) {
   auto ch = g_channel_map->find(channel);
   if (ch == g_channel_map->end())
     return;

   ForEachCategory(*ch, lambda);
 }

 std::vector<llvm::StringRef> Log::ListChannels() {
   std::vector<llvm::StringRef> result;
   for (const auto &channel : *g_channel_map)
     result.push_back(channel.first());
   return result;
 }

 void Log::ListAllLogChannels(llvm::raw_ostream &stream) {
   if (g_channel_map->empty()) {
     stream << "No logging channels are currently registered.\n";
     return;
   }

   for (const auto &channel : *g_channel_map)
     ListCategories(stream, channel);
 }

 bool Log::GetVerbose() const {
   return m_options.load(std::memory_order_relaxed) & LLDB_LOG_OPTION_VERBOSE;
 }

 void Log::WriteHeader(llvm::raw_ostream &OS, llvm::StringRef file,
                       llvm::StringRef function) {
   Flags options = GetOptions();
   static uint32_t g_sequence_id = 0;
   // Add a sequence ID if requested
   if (options.Test(LLDB_LOG_OPTION_PREPEND_SEQUENCE))
     OS << ++g_sequence_id << " ";

   // Timestamp if requested
   if (options.Test(LLDB_LOG_OPTION_PREPEND_TIMESTAMP)) {
     auto now = std::chrono::duration<double>(
         std::chrono::system_clock::now().time_since_epoch());
     OS << llvm::formatv("{0:f9} ", now.count());
   }

   // Add the process and thread if requested
   if (options.Test(LLDB_LOG_OPTION_PREPEND_PROC_AND_THREAD))
     OS << llvm::formatv("[{0,0+4}/{1,0+4}] ", getpid(),
                         llvm::get_threadid());

   // Add the thread name if requested
   if (options.Test(LLDB_LOG_OPTION_PREPEND_THREAD_NAME)) {
     llvm::SmallString<32> thread_name;
     llvm::get_thread_name(thread_name);

     llvm::SmallString<12> format_str;
     llvm::raw_svector_ostream format_os(format_str);
     format_os << "{0,-" << llvm::alignTo<16>(thread_name.size()) << "} ";
     OS << llvm::formatv(format_str.c_str(), thread_name);
   }

   if (options.Test(LLDB_LOG_OPTION_BACKTRACE))
     llvm::sys::PrintStackTrace(OS);

   if (options.Test(LLDB_LOG_OPTION_PREPEND_FILE_FUNCTION) &&
       (!file.empty() || !function.empty())) {
     file = llvm::sys::path::filename(file).take_front(40);
     function = function.take_front(40);
     OS << llvm::formatv("{0,-60:60} ", (file + ":" + function).str());
   }
 }

 // If we have a callback registered, then we call the logging callback. If we
 // have a valid file handle, we also log to the file.
 void Log::WriteMessage(llvm::StringRef message) {
   // Make a copy of our stream shared pointer in case someone disables our log
   // while we are logging and releases the stream
   auto handler_sp = GetHandler();
   if (!handler_sp)
     return;
   handler_sp->Emit(message);
 }

 void Log::Format(llvm::StringRef file, llvm::StringRef function,
                  const llvm::formatv_object_base &payload) {
   std::string message_string;
   llvm::raw_string_ostream message(message_string);
   WriteHeader(message, file, function);
   message << payload << "\n";
   WriteMessage(message.str());
 }

 StreamLogHandler::StreamLogHandler(int fd, bool should_close,
                                    size_t buffer_size)
     : m_stream(fd, should_close, buffer_size == 0) {
   if (buffer_size > 0)
     m_stream.SetBufferSize(buffer_size);
 }

 StreamLogHandler::~StreamLogHandler() { Flush(); }

 void StreamLogHandler::Flush() {
   std::lock_guard<std::mutex> guard(m_mutex);
   m_stream.flush();
 }

 void StreamLogHandler::Emit(llvm::StringRef message) {
   if (m_stream.GetBufferSize() > 0) {
     std::lock_guard<std::mutex> guard(m_mutex);
     m_stream << message;
   } else {
     m_stream << message;
   }
 }

 CallbackLogHandler::CallbackLogHandler(lldb::LogOutputCallback callback,
                                        void *baton)
     : m_callback(callback), m_baton(baton) {}

 void CallbackLogHandler::Emit(llvm::StringRef message) {
   m_callback(message.data(), m_baton);
 }

 RotatingLogHandler::RotatingLogHandler(size_t size)
     : m_messages(std::make_unique<std::string[]>(size)), m_size(size) {}

 void RotatingLogHandler::Emit(llvm::StringRef message) {
   std::lock_guard<std::mutex> guard(m_mutex);
   ++m_total_count;
   const size_t index = m_next_index;
   m_next_index = NormalizeIndex(index + 1);
   m_messages[index] = message.str();
 }

 size_t RotatingLogHandler::NormalizeIndex(size_t i) const { return i % m_size; }

 size_t RotatingLogHandler::GetNumMessages() const {
   return m_total_count < m_size ? m_total_count : m_size;
 }

 size_t RotatingLogHandler::GetFirstMessageIndex() const {
   return m_total_count < m_size ? 0 : m_next_index;
 }

 void RotatingLogHandler::Dump(llvm::raw_ostream &stream) const {
   std::lock_guard<std::mutex> guard(m_mutex);
   const size_t start_idx = GetFirstMessageIndex();
   const size_t stop_idx = start_idx + GetNumMessages();
   for (size_t i = start_idx; i < stop_idx; ++i) {
     const size_t idx = NormalizeIndex(i);
     stream << m_messages[idx];
   }
   stream.flush();
 }

 TeeLogHandler::TeeLogHandler(std::shared_ptr<LogHandler> first_log_handler,
                              std::shared_ptr<LogHandler> second_log_handler)
     : m_first_log_handler(first_log_handler),
       m_second_log_handler(second_log_handler) {
   assert(m_first_log_handler && "first log handler must be valid");
   assert(m_second_log_handler && "second log handler must be valid");
 }

 void TeeLogHandler::Emit(llvm::StringRef message) {
   m_first_log_handler->Emit(message);
   m_second_log_handler->Emit(message);
 }
	//===-- Log.cpp -----------------------------------------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#include "lldb/Utility/Log.h"
	#include "lldb/Utility/VASPrintf.h"

	#include "llvm/ADT/SmallString.h"
	#include "llvm/ADT/Twine.h"
	#include "llvm/ADT/iterator.h"

	#include "llvm/Support/Casting.h"
	#include "llvm/Support/Chrono.h"
	#include "llvm/Support/ManagedStatic.h"
	#include "llvm/Support/Path.h"
	#include "llvm/Support/Signals.h"
	#include "llvm/Support/Threading.h"
	#include "llvm/Support/raw_ostream.h"

	#include <chrono>
	#include <cstdarg>
	#include <mutex>
	#include <utility>

	#include <cassert>
	#if defined(_WIN32)
	#include <process.h>
	#else
	#include <unistd.h>
	#endif

	using namespace lldb_private;

	char LogHandler::ID;
	char StreamLogHandler::ID;
	char CallbackLogHandler::ID;
	char RotatingLogHandler::ID;
	char TeeLogHandler::ID;

	llvm::ManagedStatic<Log::ChannelMap> Log::g_channel_map;

	void Log::ForEachCategory(
	const Log::ChannelMap::value_type &entry,
	llvm::function_ref<void(llvm::StringRef, llvm::StringRef)> lambda) {
	lambda("all", "all available logging categories");
	lambda("default", "default set of logging categories");
	for (const auto &category : entry.second.m_channel.categories)
	lambda(category.name, category.description);
	}

	void Log::ListCategories(llvm::raw_ostream &stream,
	const ChannelMap::value_type &entry) {
	stream << llvm::formatv("Logging categories for '{0}':\n", entry.first());
	ForEachCategory(entry,
	[&stream](llvm::StringRef name, llvm::StringRef description) {
	stream << llvm::formatv(" {0} - {1}\n", name, description);
	});
	}

	Log::MaskType Log::GetFlags(llvm::raw_ostream &stream,
	const ChannelMap::value_type &entry,
	llvm::ArrayRef<const char *> categories) {
	bool list_categories = false;
	Log::MaskType flags = 0;
	for (const char *category : categories) {
	if (llvm::StringRef("all").equals_insensitive(category)) {
	flags \|= std::numeric_limits<Log::MaskType>::max();
	continue;
	}
	if (llvm::StringRef("default").equals_insensitive(category)) {
	flags \|= entry.second.m_channel.default_flags;
	continue;
	}
	auto cat = llvm::find_if(entry.second.m_channel.categories,
	[&](const Log::Category &c) {
	return c.name.equals_insensitive(category);
	});
	if (cat != entry.second.m_channel.categories.end()) {
	flags \|= cat->flag;
	continue;
	}
	stream << llvm::formatv("error: unrecognized log category '{0}'\n",
	category);
	list_categories = true;
	}
	if (list_categories)
	ListCategories(stream, entry);
	return flags;
	}

	void Log::Enable(const std::shared_ptr<LogHandler> &handler_sp,
	uint32_t options, Log::MaskType flags) {
	llvm::sys::ScopedWriter lock(m_mutex);

	MaskType mask = m_mask.fetch_or(flags, std::memory_order_relaxed);
	if (mask \| flags) {
	m_options.store(options, std::memory_order_relaxed);
	m_handler = handler_sp;
	m_channel.log_ptr.store(this, std::memory_order_relaxed);
	}
	}

	void Log::Disable(Log::MaskType flags) {
	llvm::sys::ScopedWriter lock(m_mutex);

	MaskType mask = m_mask.fetch_and(~flags, std::memory_order_relaxed);
	if (!(mask & ~flags)) {
	m_handler.reset();
	m_channel.log_ptr.store(nullptr, std::memory_order_relaxed);
	}
	}

	bool Log::Dump(llvm::raw_ostream &output_stream) {
	llvm::sys::ScopedReader lock(m_mutex);
	if (RotatingLogHandler *handler =
	llvm::dyn_cast_or_null<RotatingLogHandler>(m_handler.get())) {
	handler->Dump(output_stream);
	return true;
	}
	return false;
	}

	const Flags Log::GetOptions() const {
	return m_options.load(std::memory_order_relaxed);
	}

	Log::MaskType Log::GetMask() const {
	return m_mask.load(std::memory_order_relaxed);
	}

	void Log::PutCString(const char *cstr) { PutString(cstr); }

	void Log::PutString(llvm::StringRef str) {
	std::string FinalMessage;
	llvm::raw_string_ostream Stream(FinalMessage);
	WriteHeader(Stream, "", "");
	Stream << str << "\n";
	WriteMessage(FinalMessage);
	}

	// Simple variable argument logging with flags.
	void Log::Printf(const char *format, ...) {
	va_list args;
	va_start(args, format);
	VAPrintf(format, args);
	va_end(args);
	}

	void Log::VAPrintf(const char *format, va_list args) {
	llvm::SmallString<64> Content;
	lldb_private::VASprintf(Content, format, args);
	PutString(Content);
	}

	void Log::Formatf(llvm::StringRef file, llvm::StringRef function,
	const char *format, ...) {
	va_list args;
	va_start(args, format);
	VAFormatf(file, function, format, args);
	va_end(args);
	}

	void Log::VAFormatf(llvm::StringRef file, llvm::StringRef function,
	const char *format, va_list args) {
	llvm::SmallString<64> Content;
	lldb_private::VASprintf(Content, format, args);
	Format(file, function, llvm::formatv("{0}", Content));
	}

	// Printing of errors that are not fatal.
	void Log::Error(const char *format, ...) {
	va_list args;
	va_start(args, format);
	VAError(format, args);
	va_end(args);
	}

	void Log::VAError(const char *format, va_list args) {
	llvm::SmallString<64> Content;
	VASprintf(Content, format, args);

	Printf("error: %s", Content.c_str());
	}

	// Printing of warnings that are not fatal only if verbose mode is enabled.
	void Log::Verbose(const char *format, ...) {
	if (!GetVerbose())
	return;

	va_list args;
	va_start(args, format);
	VAPrintf(format, args);
	va_end(args);
	}

	// Printing of warnings that are not fatal.
	void Log::Warning(const char *format, ...) {
	llvm::SmallString<64> Content;
	va_list args;
	va_start(args, format);
	VASprintf(Content, format, args);
	va_end(args);

	Printf("warning: %s", Content.c_str());
	}

	void Log::Register(llvm::StringRef name, Channel &channel) {
	auto iter = g_channel_map->try_emplace(name, channel);
	assert(iter.second == true);
	UNUSED_IF_ASSERT_DISABLED(iter);
	}

	void Log::Unregister(llvm::StringRef name) {
	auto iter = g_channel_map->find(name);
	assert(iter != g_channel_map->end());
	iter->second.Disable(std::numeric_limits<MaskType>::max());
	g_channel_map->erase(iter);
	}

	bool Log::EnableLogChannel(const std::shared_ptr<LogHandler> &log_handler_sp,
	uint32_t log_options, llvm::StringRef channel,
	llvm::ArrayRef<const char *> categories,
	llvm::raw_ostream &error_stream) {
	auto iter = g_channel_map->find(channel);
	if (iter == g_channel_map->end()) {
	error_stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
	return false;
	}
	MaskType flags = categories.empty()
	? iter->second.m_channel.default_flags
	: GetFlags(error_stream, *iter, categories);
	iter->second.Enable(log_handler_sp, log_options, flags);
	return true;
	}

	bool Log::DisableLogChannel(llvm::StringRef channel,
	llvm::ArrayRef<const char *> categories,
	llvm::raw_ostream &error_stream) {
	auto iter = g_channel_map->find(channel);
	if (iter == g_channel_map->end()) {
	error_stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
	return false;
	}
	MaskType flags = categories.empty()
	? std::numeric_limits<MaskType>::max()
	: GetFlags(error_stream, *iter, categories);
	iter->second.Disable(flags);
	return true;
	}

	bool Log::DumpLogChannel(llvm::StringRef channel,
	llvm::raw_ostream &output_stream,
	llvm::raw_ostream &error_stream) {
	auto iter = g_channel_map->find(channel);
	if (iter == g_channel_map->end()) {
	error_stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
	return false;
	}
	if (!iter->second.Dump(output_stream)) {
	error_stream << llvm::formatv(
	"log channel '{0}' does not support dumping.\n", channel);
	return false;
	}
	return true;
	}

	bool Log::ListChannelCategories(llvm::StringRef channel,
	llvm::raw_ostream &stream) {
	auto ch = g_channel_map->find(channel);
	if (ch == g_channel_map->end()) {
	stream << llvm::formatv("Invalid log channel '{0}'.\n", channel);
	return false;
	}
	ListCategories(stream, *ch);
	return true;
	}

	void Log::DisableAllLogChannels() {
	for (auto &entry : *g_channel_map)
	entry.second.Disable(std::numeric_limits<MaskType>::max());
	}

	void Log::ForEachChannelCategory(
	llvm::StringRef channel,
	llvm::function_ref<void(llvm::StringRef, llvm::StringRef)> lambda) {
	auto ch = g_channel_map->find(channel);
	if (ch == g_channel_map->end())
	return;

	ForEachCategory(*ch, lambda);
	}

	std::vector<llvm::StringRef> Log::ListChannels() {
	std::vector<llvm::StringRef> result;
	for (const auto &channel : *g_channel_map)
	result.push_back(channel.first());
	return result;
	}

	void Log::ListAllLogChannels(llvm::raw_ostream &stream) {
	if (g_channel_map->empty()) {
	stream << "No logging channels are currently registered.\n";
	return;
	}

	for (const auto &channel : *g_channel_map)
	ListCategories(stream, channel);
	}

	bool Log::GetVerbose() const {
	return m_options.load(std::memory_order_relaxed) & LLDB_LOG_OPTION_VERBOSE;
	}

	void Log::WriteHeader(llvm::raw_ostream &OS, llvm::StringRef file,
	llvm::StringRef function) {
	Flags options = GetOptions();
	static uint32_t g_sequence_id = 0;
	// Add a sequence ID if requested
	if (options.Test(LLDB_LOG_OPTION_PREPEND_SEQUENCE))
	OS << ++g_sequence_id << " ";

	// Timestamp if requested
	if (options.Test(LLDB_LOG_OPTION_PREPEND_TIMESTAMP)) {
	auto now = std::chrono::duration<double>(
	std::chrono::system_clock::now().time_since_epoch());
	OS << llvm::formatv("{0:f9} ", now.count());
	}

	// Add the process and thread if requested
	if (options.Test(LLDB_LOG_OPTION_PREPEND_PROC_AND_THREAD))
	OS << llvm::formatv("[{0,0+4}/{1,0+4}] ", getpid(),
	llvm::get_threadid());

	// Add the thread name if requested
	if (options.Test(LLDB_LOG_OPTION_PREPEND_THREAD_NAME)) {
	llvm::SmallString<32> thread_name;
	llvm::get_thread_name(thread_name);

	llvm::SmallString<12> format_str;
	llvm::raw_svector_ostream format_os(format_str);
	format_os << "{0,-" << llvm::alignTo<16>(thread_name.size()) << "} ";
	OS << llvm::formatv(format_str.c_str(), thread_name);
	}

	if (options.Test(LLDB_LOG_OPTION_BACKTRACE))
	llvm::sys::PrintStackTrace(OS);

	if (options.Test(LLDB_LOG_OPTION_PREPEND_FILE_FUNCTION) &&
	(!file.empty() \|\| !function.empty())) {
	file = llvm::sys::path::filename(file).take_front(40);
	function = function.take_front(40);
	OS << llvm::formatv("{0,-60:60} ", (file + ":" + function).str());
	}
	}

	// If we have a callback registered, then we call the logging callback. If we
	// have a valid file handle, we also log to the file.
	void Log::WriteMessage(llvm::StringRef message) {
	// Make a copy of our stream shared pointer in case someone disables our log
	// while we are logging and releases the stream
	auto handler_sp = GetHandler();
	if (!handler_sp)
	return;
	handler_sp->Emit(message);
	}

	void Log::Format(llvm::StringRef file, llvm::StringRef function,
	const llvm::formatv_object_base &payload) {
	std::string message_string;
	llvm::raw_string_ostream message(message_string);
	WriteHeader(message, file, function);
	message << payload << "\n";
	WriteMessage(message.str());
	}

	StreamLogHandler::StreamLogHandler(int fd, bool should_close,
	size_t buffer_size)
	: m_stream(fd, should_close, buffer_size == 0) {
	if (buffer_size > 0)
	m_stream.SetBufferSize(buffer_size);
	}

	StreamLogHandler::~StreamLogHandler() { Flush(); }

	void StreamLogHandler::Flush() {
	std::lock_guard<std::mutex> guard(m_mutex);
	m_stream.flush();
	}

	void StreamLogHandler::Emit(llvm::StringRef message) {
	if (m_stream.GetBufferSize() > 0) {
	std::lock_guard<std::mutex> guard(m_mutex);
	m_stream << message;
	} else {
	m_stream << message;
	}
	}

	CallbackLogHandler::CallbackLogHandler(lldb::LogOutputCallback callback,
	void *baton)
	: m_callback(callback), m_baton(baton) {}

	void CallbackLogHandler::Emit(llvm::StringRef message) {
	m_callback(message.data(), m_baton);
	}

	RotatingLogHandler::RotatingLogHandler(size_t size)
	: m_messages(std::make_unique<std::string[]>(size)), m_size(size) {}

	void RotatingLogHandler::Emit(llvm::StringRef message) {
	std::lock_guard<std::mutex> guard(m_mutex);
	++m_total_count;
	const size_t index = m_next_index;
	m_next_index = NormalizeIndex(index + 1);
	m_messages[index] = message.str();
	}

	size_t RotatingLogHandler::NormalizeIndex(size_t i) const { return i % m_size; }

	size_t RotatingLogHandler::GetNumMessages() const {
	return m_total_count < m_size ? m_total_count : m_size;
	}

	size_t RotatingLogHandler::GetFirstMessageIndex() const {
	return m_total_count < m_size ? 0 : m_next_index;
	}

	void RotatingLogHandler::Dump(llvm::raw_ostream &stream) const {
	std::lock_guard<std::mutex> guard(m_mutex);
	const size_t start_idx = GetFirstMessageIndex();
	const size_t stop_idx = start_idx + GetNumMessages();
	for (size_t i = start_idx; i < stop_idx; ++i) {
	const size_t idx = NormalizeIndex(i);
	stream << m_messages[idx];
	}
	stream.flush();
	}

	TeeLogHandler::TeeLogHandler(std::shared_ptr<LogHandler> first_log_handler,
	std::shared_ptr<LogHandler> second_log_handler)
	: m_first_log_handler(first_log_handler),
	m_second_log_handler(second_log_handler) {
	assert(m_first_log_handler && "first log handler must be valid");
	assert(m_second_log_handler && "second log handler must be valid");
	}

	void TeeLogHandler::Emit(llvm::StringRef message) {
	m_first_log_handler->Emit(message);
	m_second_log_handler->Emit(message);
	}