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/*
* OXT - OS eXtensions for boosT
* Provides important functionality necessary for writing robust server software.
*
* Copyright (c) 2010 Phusion
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#if !(defined(NDEBUG) || defined(OXT_DISABLE_BACKTRACES))
#include <boost/thread/mutex.hpp>
#include <boost/thread/tss.hpp>
#include <sstream>
#include <cstring>
#include "backtrace.hpp"
namespace oxt {
boost::mutex _thread_registration_mutex;
list<thread_registration *> _registered_threads;
// Register main thread.
static initialize_backtrace_support_for_this_thread main_thread_initialization("Main thread");
namespace {
struct backtrace_data {
vector<trace_point *> list;
spin_lock lock;
backtrace_data() {
list.reserve(50);
}
};
}
/*
* boost::thread_specific_storage is pretty expensive. So we use the __thread
* keyword whenever possible - that's almost free.
* GCC supports the __thread keyword on x86 since version 3.3, but versions earlier
* than 4.1.2 have bugs (http://gcc.gnu.org/ml/gcc-bugs/2006-09/msg02275.html).
*/
#ifndef OXT_GCC_VERSION
#define OXT_GCC_VERSION (__GNUC__ * 10000 \
+ __GNUC_MINOR__ * 100 \
+ __GNUC_PATCHLEVEL__)
#endif
/*
* FreeBSD 5 supports the __thread keyword, and everything works fine in
* micro-tests, but in mod_passenger the thread-local variables are initialized
* to unaligned addresses for some weird reason, thereby causing bus errors.
*
* GCC on OpenBSD supports __thread, but any access to such a variable
* results in a segfault.
*
* Solaris does support __thread, but often it's not compiled into default GCC
* packages (not to mention it's not available for Sparc). Playing it safe...
*
* MacOS X doesn't support __thread at all.
*/
#if OXT_GCC_VERSION >= 40102 && !defined(__FreeBSD__) && \
!defined(__SOLARIS__) && !defined(__OpenBSD__) && !defined(__APPLE__)
static __thread backtrace_data *thread_specific_backtrace_data;
void
_init_backtrace_tls() {
thread_specific_backtrace_data = new backtrace_data();
}
void
_finalize_backtrace_tls() {
delete thread_specific_backtrace_data;
}
bool
_get_backtrace_list_and_its_lock(vector<trace_point *> **backtrace_list, spin_lock **lock) {
if (OXT_LIKELY(thread_specific_backtrace_data != NULL)) {
*backtrace_list = &thread_specific_backtrace_data->list;
*lock = &thread_specific_backtrace_data->lock;
return true;
} else {
return false;
}
}
#else
static thread_specific_ptr<backtrace_data> thread_specific_backtrace_data;
void _init_backtrace_tls() {
/* Not implemented on purpose.
*
* It is not safe to use thread_specific_backtrace_data here
* because this function may be called by
* initialize_backtrace_support_for_this_thread's constructor,
* which in turn may be called by the global static variable
* main_thread_initialization. C++ does not guarantee initialization
* order so thread_specific_backtrace_data may not be usable at
* this time.
*/
}
void _finalize_backtrace_tls() {
// Not implemented either.
}
bool
_get_backtrace_list_and_its_lock(vector<trace_point *> **backtrace_list, spin_lock **lock) {
backtrace_data *data;
data = thread_specific_backtrace_data.get();
if (OXT_UNLIKELY(data == NULL)) {
data = new backtrace_data();
thread_specific_backtrace_data.reset(data);
}
*backtrace_list = &data->list;
*lock = &data->lock;
return true;
}
#endif
template<typename Iterable, typename ReverseIterator> static string
format_backtrace(Iterable backtrace_list) {
if (backtrace_list->empty()) {
return " (empty)";
} else {
stringstream result;
ReverseIterator it;
for (it = backtrace_list->rbegin(); it != backtrace_list->rend(); it++) {
trace_point *p = *it;
result << " in '" << p->function << "'";
if (p->source != NULL) {
const char *source = strrchr(p->source, '/');
if (source != NULL) {
source++;
} else {
source = p->source;
}
result << " (" << source << ":" << p->line << ")";
}
result << endl;
}
return result.str();
}
}
string
_format_backtrace(const list<trace_point *> *backtrace_list) {
return format_backtrace<
const list<trace_point *> *,
list<trace_point *>::const_reverse_iterator
>(backtrace_list);
}
string
_format_backtrace(const vector<trace_point *> *backtrace_list) {
return format_backtrace<
const vector<trace_point *> *,
vector<trace_point *>::const_reverse_iterator
>(backtrace_list);
}
} // namespace oxt
#endif
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