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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kControl
#include "mongo/platform/basic.h"
#include "mongo/util/concurrency/thread_name.h"
#if defined(__APPLE__) || defined(__linux__)
#include <pthread.h>
#endif
#if defined(__APPLE__)
#include <TargetConditionals.h>
#if !TARGET_OS_TV && !TARGET_OS_IOS && !TARGET_OS_WATCH
#include <sys/proc_info.h>
#else
#include <mach/thread_info.h>
#endif
#endif
#if defined(__linux__)
#include <sys/syscall.h>
#include <sys/types.h>
#endif
#include <fmt/format.h>
#include "mongo/base/init.h"
#include "mongo/config.h"
#include "mongo/logv2/log.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/util/str.h"
namespace mongo {
using namespace fmt::literals;
namespace {
#ifdef _WIN32
// From https://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx
// Note: The thread name is only set for the thread if the debugger is attached.
const DWORD MS_VC_EXCEPTION = 0x406D1388;
#pragma pack(push, 8)
typedef struct tagTHREADNAME_INFO {
DWORD dwType; // Must be 0x1000.
LPCSTR szName; // Pointer to name (in user addr space).
DWORD dwThreadID; // Thread ID (-1=caller thread).
DWORD dwFlags; // Reserved for future use, must be zero.
} THREADNAME_INFO;
#pragma pack(pop)
void setWindowsThreadName(DWORD dwThreadID, const char* threadName) {
THREADNAME_INFO info;
info.dwType = 0x1000;
info.szName = threadName;
info.dwThreadID = dwThreadID;
info.dwFlags = 0;
#pragma warning(push)
#pragma warning(disable : 6320 6322)
__try {
RaiseException(MS_VC_EXCEPTION, 0, sizeof(info) / sizeof(ULONG_PTR), (ULONG_PTR*)&info);
} __except (EXCEPTION_EXECUTE_HANDLER) {
}
#pragma warning(pop)
}
#endif
constexpr auto kMainId = size_t{0};
auto makeAnonymousThreadName() {
static auto gNextAnonymousId = AtomicWord<size_t>{kMainId};
auto id = gNextAnonymousId.fetchAndAdd(1);
if (id == kMainId) {
// The first thread name should always be "main".
return make_intrusive<ThreadName>("main");
} else {
return make_intrusive<ThreadName>("thread{}"_format(id));
}
}
struct ThreadNameSconce {
ThreadNameSconce() : cachedPtr(makeAnonymousThreadName()) {
// Note that we're not setting the thread name here. It will log differently, but appear the
// same in top and like.
}
// At any given time, either cachedPtr or activePtr can be valid, but not both.
boost::intrusive_ptr<ThreadName> activePtr;
boost::intrusive_ptr<ThreadName> cachedPtr;
};
auto getSconce = ThreadContext::declareDecoration<ThreadNameSconce>();
auto& getThreadName(const boost::intrusive_ptr<ThreadContext>& context) {
auto& sconce = getSconce(context.get());
if (sconce.activePtr) {
return sconce.activePtr;
}
return sconce.cachedPtr;
}
void setOSThreadName(StringData threadName) {
#if defined(_WIN32)
// Naming should not be expensive compared to thread creation and connection set up, but if
// testing shows otherwise we should make this depend on DEBUG again.
setWindowsThreadName(GetCurrentThreadId(), threadName.rawData());
#elif defined(__APPLE__)
// Maximum thread name length on OS X is MAXTHREADNAMESIZE (64 characters). This assumes
// OS X 10.6 or later.
std::string threadNameCopy = threadName.toString();
if (threadNameCopy.size() > MAXTHREADNAMESIZE) {
threadNameCopy.resize(MAXTHREADNAMESIZE - 4);
threadNameCopy += "...";
}
int error = pthread_setname_np(threadNameCopy.c_str());
if (error) {
LOGV2(23102,
"Ignoring error from setting thread name: {error}",
"Ignoring error from setting thread name",
"error"_attr = errnoWithDescription(error));
}
#elif defined(__linux__) && defined(MONGO_CONFIG_HAVE_PTHREAD_SETNAME_NP)
// Do not set thread name on the main() thread. Setting the name on main thread breaks
// pgrep/pkill since these programs base this name on /proc/*/status which displays the thread
// name, not the executable name.
if (getpid() != syscall(SYS_gettid)) {
// Maximum thread name length supported on Linux is 16 including the null terminator.
// Ideally we use short and descriptive thread names that fit: this helps for log
// readability as well. Still, as the limit is so low and a few current names exceed the
// limit, it's best to shorten long names.
int error = 0;
if (threadName.size() > 15) {
std::string shortName = str::stream()
<< threadName.substr(0, 7) << '.' << threadName.substr(threadName.size() - 7);
error = pthread_setname_np(pthread_self(), shortName.c_str());
} else {
error = pthread_setname_np(pthread_self(), threadName.rawData());
}
if (error) {
LOGV2(23103,
"Ignoring error from setting thread name: {error}",
"Ignoring error from setting thread name",
"error"_attr = errnoWithDescription(error));
}
}
#endif
}
} // namespace
ThreadName::Id ThreadName::_nextId() {
static auto gNextId = AtomicWord<Id>{0};
return gNextId.fetchAndAdd(1);
}
StringData ThreadName::getStaticString() {
auto& context = ThreadContext::get();
if (!context) {
// Use a static fallback to avoid allocations. This is the string that will be used before
// initializers run in main a.k.a. pre-init.
static constexpr auto kFallback = "-"_sd;
return kFallback;
}
return getThreadName(context)->toString();
}
boost::intrusive_ptr<ThreadName> ThreadName::get(boost::intrusive_ptr<ThreadContext> context) {
return getThreadName(context);
}
boost::intrusive_ptr<ThreadName> ThreadName::set(boost::intrusive_ptr<ThreadContext> context,
boost::intrusive_ptr<ThreadName> name) {
invariant(name);
auto& sconce = getSconce(context.get());
if (sconce.activePtr) {
invariant(!sconce.cachedPtr);
if (*sconce.activePtr == *name) {
// The name was already set, skip setting it to the OS thread name.
return {};
} else {
// Replace the current active name with the new one, and set the OS thread name.
setOSThreadName(name->toString());
return std::exchange(sconce.activePtr, name);
}
} else if (sconce.cachedPtr) {
if (*sconce.cachedPtr == *name) {
// The name was cached, set it as active and skip setting it to the OS thread name.
sconce.activePtr = std::exchange(sconce.cachedPtr, {});
return {};
} else {
// The new name is different than the cached name, set the active, reset the cached, and
// set the OS thread name.
setOSThreadName(name->toString());
sconce.activePtr = name;
sconce.cachedPtr.reset();
return {};
}
}
MONGO_UNREACHABLE;
}
void ThreadName::release(boost::intrusive_ptr<ThreadContext> context) {
auto& sconce = getSconce(context.get());
if (sconce.activePtr) {
sconce.cachedPtr = std::exchange(sconce.activePtr, {});
}
}
ThreadName::ThreadName(StringData name) : _id(_nextId()), _storage(name.toString()){};
} // namespace mongo
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