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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "backtrace_helper.h"
#if defined(__linux__)
#include <backtrace/Backtrace.h>
#include <backtrace/BacktraceMap.h>
#include <unistd.h>
#include <sys/types.h>
#include "thread-inl.h"
#else
// For UNUSED
#include "base/macros.h"
#endif
namespace art {
// We only really support libbacktrace on linux which is unfortunate but since this is only for
// gcstress this isn't a huge deal.
#if defined(__linux__)
static const char* kBacktraceCollectorTlsKey = "BacktraceCollectorTlsKey";
struct BacktraceMapHolder : public TLSData {
BacktraceMapHolder() : map_(BacktraceMap::Create(getpid())) {}
std::unique_ptr<BacktraceMap> map_;
};
static BacktraceMap* GetMap(Thread* self) {
BacktraceMapHolder* map_holder =
reinterpret_cast<BacktraceMapHolder*>(self->GetCustomTLS(kBacktraceCollectorTlsKey));
if (map_holder == nullptr) {
map_holder = new BacktraceMapHolder;
// We don't care about the function names. Turning this off makes everything significantly
// faster.
map_holder->map_->SetResolveNames(false);
// Only created and queried on Thread::Current so no sync needed.
self->SetCustomTLS(kBacktraceCollectorTlsKey, map_holder);
}
return map_holder->map_.get();
}
void BacktraceCollector::Collect() {
std::unique_ptr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS,
BACKTRACE_CURRENT_THREAD,
GetMap(Thread::Current())));
backtrace->SetSkipFrames(true);
if (!backtrace->Unwind(skip_count_, nullptr)) {
return;
}
for (Backtrace::const_iterator it = backtrace->begin();
max_depth_ > num_frames_ && it != backtrace->end();
++it) {
out_frames_[num_frames_++] = static_cast<uintptr_t>(it->pc);
}
}
#else
#pragma clang diagnostic push
#pragma clang diagnostic warning "-W#warnings"
#warning "Backtrace collector is not implemented. GCStress cannot be used."
#pragma clang diagnostic pop
// We only have an implementation for linux. On other plaforms just return nothing. This is not
// really correct but we only use this for hashing and gcstress so it's not too big a deal.
void BacktraceCollector::Collect() {
UNUSED(skip_count_);
UNUSED(out_frames_);
UNUSED(max_depth_);
num_frames_ = 0;
}
#endif
} // namespace art
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