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#include "bt.h"
#include <backtrace.h>
#include <backtrace-supported.h>
#include <algorithm>
#include <cstdio>
#include <fstream>
#include <mutex>
#include <sstream>
#include <unordered_map>
#include <queue>
static backtrace_state *State = nullptr;
static int pcinfo_callback(void *data, uintptr_t pc, const char *filename, int lineno, const char *function)
{
std::ostringstream *OS = static_cast<std::ostringstream*>(data);
if (function)
*OS << function << "() @ ";
if (filename)
*OS << filename << ":" << lineno;
else
*OS << pc << " (information not available)";
*OS << "\n";
return 0;
}
static void error_callback(void *data, const char *msg, int errnum)
{
std::ostringstream *OS = static_cast<std::ostringstream*>(data);
*OS << "Backtrace error: " << msg << " (error number " << errnum << ")\n";
}
struct UuidKey
{
const uuid_t *Inner;
bool operator==(const UuidKey& Other) const
{
return uuid_compare(*Inner, *Other.Inner) == 0;
}
};
namespace std
{
template<>
struct hash<UuidKey>
{
size_t operator()(const UuidKey& Key) const
{
return XXH64(*Key.Inner, sizeof(uuid_t), 0);
}
};
}
class StackTrace
{
public:
static const size_t MAX_ITEMS = 128;
uintptr_t PCs[MAX_ITEMS] = { 0 };
size_t Items = 0;
void append(uintptr_t PC)
{
assert(Items < MAX_ITEMS);
PCs[Items++] = PC;
}
bool operator==(const StackTrace& Other) const
{
if (Items != Other.Items)
return false;
for (size_t i = 0; i < Items; i++)
if (PCs[i] != Other.PCs[i])
return false;
return true;
}
void dump(std::ostream &OS) const
{
for (size_t i = 0; i < Items; ++i)
backtrace_pcinfo(State, PCs[i], pcinfo_callback, error_callback, &OS);
OS << std::endl;
}
};
namespace std
{
template<>
struct hash<StackTrace>
{
size_t operator()(const StackTrace& ST) const
{
return XXH64(ST.PCs, ST.Items * sizeof(uintptr_t), 0);
}
};
}
static std::vector<std::pair<uint64_t, StackTrace>> InternedStackTraces;
static size_t stackTraceID(const StackTrace &ST)
{
std::hash<StackTrace> hasher;
uint64_t K = hasher(ST);
auto Pred = [](const std::pair<uint64_t, StackTrace>& a, const std::pair<uint64_t, StackTrace>& b) {
return a.first < b.first;
};
std::pair<uint64_t, StackTrace> P(K, ST);
auto It = std::lower_bound(InternedStackTraces.begin(), InternedStackTraces.end(), P, Pred);
if (It != InternedStackTraces.end() && It->first == K)
return K;
InternedStackTraces.insert(It, {K, ST});
return K;
}
static const StackTrace &lookupStackTrace(uint64_t ID)
{
auto Pred = [](const std::pair<uint64_t, StackTrace>& element, uint64_t value) {
return element.first < value;
};
auto It = std::lower_bound(InternedStackTraces.begin(), InternedStackTraces.end(), ID, Pred);
return It->second;
}
static std::unordered_map<UuidKey, std::queue<uint64_t>> USTs;
static std::mutex Mutex;
static int simple_callback(void *data, uintptr_t pc)
{
StackTrace *ST = static_cast<StackTrace*>(data);
if (ST->Items == StackTrace::MAX_ITEMS)
fatal("StackTrace too big...");
ST->append(pc);
return 0;
}
const char *bt_path = NULL;
void bt_init(const char *exepath, const char *cache_dir)
{
State = backtrace_create_state(exepath, 1, nullptr, nullptr);
char buf[FILENAME_MAX + 1];
snprintfz(buf, FILENAME_MAX, "%s/%s", cache_dir, "bt.log");
bt_path = strdupz(buf);
}
void bt_collect(const uuid_t *uuid)
{
// Enable collection on 1/16th of UUIDs to save on CPU and RAM consumption
if (*uuid[0] != 0x0A)
return;
{
std::lock_guard<std::mutex> lock(Mutex);
UuidKey UK = { uuid };
auto& Q = USTs[UK];
if (Q.size() == 128)
Q.pop();
StackTrace ST;
backtrace_simple(State, 1, simple_callback, error_callback, &ST);
Q.push(stackTraceID(ST));
}
}
void bt_dump(const uuid_t *uuid)
{
std::lock_guard<std::mutex> lock(Mutex);
UuidKey UK = { uuid };
auto It = USTs.find(UK);
if (It == USTs.end())
return;
std::queue<uint64_t> Q = It->second;
std::ostringstream OS;
size_t Idx = 0;
while (!Q.empty())
{
OS << "Stack trace " << ++Idx << "/" << It->second.size() << ":\n";
const StackTrace& ST = lookupStackTrace(Q.front());
ST.dump(OS);
Q.pop();
}
std::ofstream OF{bt_path};
if (OF.is_open())
{
OF << OS.str();
OF.close();
}
}
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