dash/src/sync.cpp
2023-01-02 14:19:33 -06:00

285 lines
8.9 KiB
C++

// Copyright (c) 2011-2015 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#if defined(HAVE_CONFIG_H)
#include <config/bitcoin-config.h>
#endif
#include <sync.h>
#include <logging.h>
#include <tinyformat.h>
#include <util/strencodings.h>
#include <util/threadnames.h>
#include <map>
#include <set>
#include <system_error>
#include <thread>
#include <unordered_map>
#include <utility>
#include <vector>
#ifdef DEBUG_LOCKCONTENTION
#if !defined(HAVE_THREAD_LOCAL)
static_assert(false, "thread_local is not supported");
#endif
void PrintLockContention(const char* pszName, const char* pszFile, int nLine)
{
LogPrintf("LOCKCONTENTION: %s Locker: %s:%d\n", pszName, pszFile, nLine);
}
#endif /* DEBUG_LOCKCONTENTION */
#ifdef DEBUG_LOCKORDER
//
// Early deadlock detection.
// Problem being solved:
// Thread 1 locks A, then B, then C
// Thread 2 locks D, then C, then A
// --> may result in deadlock between the two threads, depending on when they run.
// Solution implemented here:
// Keep track of pairs of locks: (A before B), (A before C), etc.
// Complain if any thread tries to lock in a different order.
//
struct CLockLocation {
CLockLocation(
const char* pszName,
const char* pszFile,
int nLine,
bool fTryIn,
const std::string& thread_name)
: fTry(fTryIn),
mutexName(pszName),
sourceFile(pszFile),
m_thread_name(thread_name),
sourceLine(nLine) {}
std::string ToString() const
{
return strprintf(
"'%s' in %s:%s%s (in thread '%s')",
mutexName, sourceFile, sourceLine, (fTry ? " (TRY)" : ""), m_thread_name);
}
std::string Name() const
{
return mutexName;
}
private:
bool fTry;
std::string mutexName;
std::string sourceFile;
const std::string& m_thread_name;
int sourceLine;
};
using LockStackItem = std::pair<void*, CLockLocation>;
using LockStack = std::vector<LockStackItem>;
using LockStacks = std::unordered_map<std::thread::id, LockStack>;
using LockPair = std::pair<void*, void*>;
using LockOrders = std::map<LockPair, LockStack>;
using InvLockOrders = std::set<LockPair>;
struct LockData {
LockStacks m_lock_stacks;
LockOrders lockorders;
InvLockOrders invlockorders;
std::mutex dd_mutex;
};
LockData& GetLockData() {
// This approach guarantees that the object is not destroyed until after its last use.
// The operating system automatically reclaims all the memory in a program's heap when that program exits.
// Since the ~LockData() destructor is never called, the LockData class and all
// its subclasses must have implicitly-defined destructors.
static LockData& lock_data = *new LockData();
return lock_data;
}
static void potential_deadlock_detected(const LockPair& mismatch, const LockStack& s1, const LockStack& s2)
{
std::string strOutput = "";
strOutput += "POTENTIAL DEADLOCK DETECTED\n";
strOutput += "Previous lock order was:\n";
for (const LockStackItem& i : s1) {
if (i.first == mismatch.first) {
strOutput += " (1)";
}
if (i.first == mismatch.second) {
strOutput += " (2)";
}
strOutput += strprintf(" %s\n", i.second.ToString());
}
std::string mutex_a, mutex_b;
strOutput += "Current lock order is:\n";
for (const LockStackItem& i : s2) {
if (i.first == mismatch.first) {
strOutput += " (1)";
mutex_a = i.second.Name();
}
if (i.first == mismatch.second) {
strOutput += " (2)";
mutex_b = i.second.Name();
}
strOutput += strprintf(" %s\n", i.second.ToString());
}
LogPrintf("%s\n", strOutput);
if (g_debug_lockorder_abort) {
tfm::format(std::cerr, "Assertion failed: detected inconsistent lock order for %s, details in debug log.\n", s2.back().second.ToString());
abort();
}
throw std::logic_error(strprintf("potential deadlock detected: %s -> %s -> %s", mutex_b, mutex_a, mutex_b));
}
static void push_lock(void* c, const CLockLocation& locklocation)
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
LockStack& lock_stack = lockdata.m_lock_stacks[std::this_thread::get_id()];
lock_stack.emplace_back(c, locklocation);
for (const LockStackItem& i : lock_stack) {
if (i.first == c)
break;
const LockPair p1 = std::make_pair(i.first, c);
if (lockdata.lockorders.count(p1))
continue;
const LockPair p2 = std::make_pair(c, i.first);
if (lockdata.lockorders.count(p2)) {
auto lock_stack_copy = lock_stack;
lock_stack.pop_back();
potential_deadlock_detected(p1, lockdata.lockorders[p2], lock_stack_copy);
// potential_deadlock_detected() does not return.
}
lockdata.lockorders.emplace(p1, lock_stack);
lockdata.invlockorders.insert(p2);
}
}
static void pop_lock()
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
LockStack& lock_stack = lockdata.m_lock_stacks[std::this_thread::get_id()];
lock_stack.pop_back();
if (lock_stack.empty()) {
lockdata.m_lock_stacks.erase(std::this_thread::get_id());
}
}
void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry)
{
push_lock(cs, CLockLocation(pszName, pszFile, nLine, fTry, util::ThreadGetInternalName()));
}
void CheckLastCritical(void* cs, std::string& lockname, const char* guardname, const char* file, int line)
{
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
const LockStack& lock_stack = lockdata.m_lock_stacks[std::this_thread::get_id()];
if (!lock_stack.empty()) {
const auto& lastlock = lock_stack.back();
if (lastlock.first == cs) {
lockname = lastlock.second.Name();
return;
}
}
}
throw std::system_error(EPERM, std::generic_category(), strprintf("%s:%s %s was not most recent critical section locked", file, line, guardname));
}
void LeaveCritical()
{
pop_lock();
}
std::string LocksHeld()
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
const LockStack& lock_stack = lockdata.m_lock_stacks[std::this_thread::get_id()];
std::string result;
for (const LockStackItem& i : lock_stack)
result += i.second.ToString() + std::string("\n");
return result;
}
static bool LockHeld(void* mutex)
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
const LockStack& lock_stack = lockdata.m_lock_stacks[std::this_thread::get_id()];
for (const LockStackItem& i : lock_stack) {
if (i.first == mutex) return true;
}
return false;
}
template <typename MutexType>
void AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, MutexType* cs)
{
if (LockHeld(cs)) return;
tfm::format(std::cerr, "Assertion failed: lock %s not held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld());
abort();
}
template void AssertLockHeldInternal(const char*, const char*, int, Mutex*);
template void AssertLockHeldInternal(const char*, const char*, int, CCriticalSection*);
void AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs)
{
if (!LockHeld(cs)) return;
tfm::format(std::cerr, "Assertion failed: lock %s held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld());
abort();
}
void DeleteLock(void* cs)
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
const LockPair item = std::make_pair(cs, nullptr);
LockOrders::iterator it = lockdata.lockorders.lower_bound(item);
while (it != lockdata.lockorders.end() && it->first.first == cs) {
const LockPair invitem = std::make_pair(it->first.second, it->first.first);
lockdata.invlockorders.erase(invitem);
lockdata.lockorders.erase(it++);
}
InvLockOrders::iterator invit = lockdata.invlockorders.lower_bound(item);
while (invit != lockdata.invlockorders.end() && invit->first == cs) {
const LockPair invinvitem = std::make_pair(invit->second, invit->first);
lockdata.lockorders.erase(invinvitem);
lockdata.invlockorders.erase(invit++);
}
}
bool LockStackEmpty()
{
LockData& lockdata = GetLockData();
std::lock_guard<std::mutex> lock(lockdata.dd_mutex);
const auto it = lockdata.m_lock_stacks.find(std::this_thread::get_id());
if (it == lockdata.m_lock_stacks.end()) {
return true;
}
return it->second.empty();
}
bool g_debug_lockorder_abort = true;
#endif /* DEBUG_LOCKORDER */