LBRYCommunity/lbrycrd
1
0
Fork 0
Code Issues 29 Pull requests 1 Projects Releases 32 Packages Wiki Activity

Locking system overhaul, add condition variables

Browse source 
This commit simplifies the locking system: CCriticalSection becomes a
simple typedef for boost::interprocess::interprocess_recursive_mutex,
and CCriticalBlock and CTryCriticalBlock are replaced by a templated
CMutexLock, which wraps boost::interprocess::scoped_lock.

By making the lock type a template parameter, some critical sections
can now be changed to non-recursive locks, which support waiting via
condition variables. These are implemented in CWaitableCriticalSection
and WAITABLE_CRITICAL_BLOCK.

CWaitableCriticalSection is a wrapper for a different Boost mutex,
which supports waiting/notification via condition variables. This
should enable us to remove much of the used polling code. Important
is that this mutex is not recursive, so functions that perform the
locking must not call eachother.

Because boost::interprocess::scoped_lock does not support assigning
and copying, I had to revert to the older CRITICAL_BLOCK macros that
use a nested for loop instead of a simple if.
This commit is contained in:
Pieter Wuille 2012-04-02 02:40:41 +02:00
parent b0a7e05a45
commit 712fd182b7
2 changed files with 124 additions and 117 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

56
src/util.cpp
View file

@ -1193,62 +1193,14 @@ static void pop_lock()
dd_mutex.unlock();
}
void CCriticalSection::Enter(const char* pszName, const char* pszFile, int nLine)
void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs)
{
push_lock(this, CLockLocation(pszName, pszFile, nLine));
#ifdef DEBUG_LOCKCONTENTION
bool result = mutex.try_lock();
if (!result)
{
printf("LOCKCONTENTION: %s\n", pszName);
printf("Locker: %s:%d\n", pszFile, nLine);
mutex.lock();
printf("Locked\n");
}
#else
mutex.lock();
#endif
push_lock(cs, CLockLocation(pszName, pszFile, nLine));
}
void CCriticalSection::Leave()
void LeaveCritical()
{
mutex.unlock();
pop_lock();
}
bool CCriticalSection::TryEnter(const char* pszName, const char* pszFile, int nLine)
{
push_lock(this, CLockLocation(pszName, pszFile, nLine));
bool result = mutex.try_lock();
if (!result) pop_lock();
return result;
}
#else
void CCriticalSection::Enter(const char* pszName, const char* pszFile, int nLine)
{
#ifdef DEBUG_LOCKCONTENTION
bool result = mutex.try_lock();
if (!result)
{
printf("LOCKCONTENTION: %s\n", pszName);
printf("Locker: %s:%d\n", pszFile, nLine);
mutex.lock();
}
#else
mutex.lock();
#endif
}
void CCriticalSection::Leave()
{
mutex.unlock();
}
bool CCriticalSection::TryEnter(const char*, const char*, int)
{
bool result = mutex.try_lock();
return result;
}
#endif /* DEBUG_LOCKORDER */

185
src/util.h
View file

@ -20,6 +20,9 @@ typedef int pid_t; /* define for windows compatiblity */
#include <boost/thread.hpp>
#include <boost/interprocess/sync/interprocess_recursive_mutex.hpp>
#include <boost/interprocess/sync/scoped_lock.hpp>
#include <boost/interprocess/sync/interprocess_condition.hpp>
#include <boost/interprocess/sync/lock_options.hpp>
#include <boost/date_time/gregorian/gregorian_types.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>
@ -180,82 +183,134 @@ void AddTimeData(const CNetAddr& ip, int64 nTime);
/** Wrapped boost mutex: supports recursive locking, but no waiting */
typedef boost::interprocess::interprocess_recursive_mutex CCriticalSection;
/** Wrapper to automatically initialize mutex. */
class CCriticalSection
/** Wrapped boost mutex: supports waiting but not recursive locking */
typedef boost::interprocess::interprocess_mutex CWaitableCriticalSection;
#ifdef DEBUG_LOCKORDER
void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs);
void LeaveCritical();
#else
void static inline EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs) {}
void static inline LeaveCritical() {}
#endif
/** Wrapper around boost::interprocess::scoped_lock */
template<typename Mutex>
class CMutexLock
{
protected:
boost::interprocess::interprocess_recursive_mutex mutex;
private:
boost::interprocess::scoped_lock<Mutex> lock;
public:
explicit CCriticalSection() { }
~CCriticalSection() { }
void Enter(const char* pszName, const char* pszFile, int nLine);
void Leave();
bool TryEnter(const char* pszName, const char* pszFile, int nLine);
};
/** RAII object that acquires mutex. Needed for exception safety. */
class CCriticalBlock
{
protected:
CCriticalSection* pcs;
public:
CCriticalBlock(CCriticalSection& csIn, const char* pszName, const char* pszFile, int nLine)
void Enter(const char* pszName, const char* pszFile, int nLine)
{
pcs = &csIn;
pcs->Enter(pszName, pszFile, nLine);
}
operator bool() const
{
return true;
}
~CCriticalBlock()
{
pcs->Leave();
}
};
#define CRITICAL_BLOCK(cs) \
if (CCriticalBlock criticalblock = CCriticalBlock(cs, #cs, __FILE__, __LINE__))
#define ENTER_CRITICAL_SECTION(cs) \
(cs).Enter(#cs, __FILE__, __LINE__)
#define LEAVE_CRITICAL_SECTION(cs) \
(cs).Leave()
/** RAII object that tries to acquire mutex. Needed for exception safety. */
class CTryCriticalBlock
{
protected:
CCriticalSection* pcs;
public:
CTryCriticalBlock(CCriticalSection& csIn, const char* pszName, const char* pszFile, int nLine)
{
pcs = (csIn.TryEnter(pszName, pszFile, nLine) ? &csIn : NULL);
}
operator bool() const
{
return Entered();
}
~CTryCriticalBlock()
{
if (pcs)
if (!lock.owns())
{
pcs->Leave();
EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
#ifdef DEBUG_LOCKCONTENTION
if (!lock.try_lock())
{
printf("LOCKCONTENTION: %s\n", pszName);
printf("Locker: %s:%d\n", pszFile, nLine);
}
#endif
lock.lock();
}
}
bool Entered() const { return pcs != NULL; }
void Leave()
{
if (lock.owns())
{
lock.unlock();
LeaveCritical();
}
}
bool TryEnter(const char* pszName, const char* pszFile, int nLine)
{
if (!lock.owns())
{
EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
lock.try_lock();
if (!lock.owns())
LeaveCritical();
}
return lock.owns();
}
CMutexLock(Mutex& mutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) : lock(mutexIn, boost::interprocess::defer_lock)
{
if (fTry)
TryEnter(pszName, pszFile, nLine);
else
Enter(pszName, pszFile, nLine);
}
~CMutexLock()
{
if (lock.owns())
LeaveCritical();
}
operator bool()
{
return lock.owns();
}
boost::interprocess::scoped_lock<Mutex> &GetLock()
{
return lock;
}
};
typedef CMutexLock<CCriticalSection> CCriticalBlock;
typedef CMutexLock<CWaitableCriticalSection> CWaitableCriticalBlock;
typedef boost::interprocess::interprocess_condition CConditionVariable;
/** Wait for a given condition inside a WAITABLE_CRITICAL_BLOCK */
#define WAIT(name,condition) \
do { while(!(condition)) { (name).wait(waitablecriticalblock.GetLock()); } } while(0)
/** Notify waiting threads that a condition may hold now */
#define NOTIFY(name) \
do { (name).notify_one(); } while(0)
#define NOTIFY_ALL(name) \
do { (name).notify_all(); } while(0)
#define CRITICAL_BLOCK(cs) \
for (bool fcriticalblockonce=true; fcriticalblockonce; assert(("break caught by CRITICAL_BLOCK!" && !fcriticalblockonce)), fcriticalblockonce=false) \
for (CCriticalBlock criticalblock(cs, #cs, __FILE__, __LINE__); fcriticalblockonce; fcriticalblockonce=false)
#define WAITABLE_CRITICAL_BLOCK(cs) \
for (bool fcriticalblockonce=true; fcriticalblockonce; assert(("break caught by WAITABLE_CRITICAL_BLOCK!" && !fcriticalblockonce)), fcriticalblockonce=false) \
for (CWaitableCriticalBlock waitablecriticalblock(cs, #cs, __FILE__, __LINE__); fcriticalblockonce; fcriticalblockonce=false)
#define ENTER_CRITICAL_SECTION(cs) \
{ \
EnterCritical(#cs, __FILE__, __LINE__, (void*)(&cs)); \
(cs).lock(); \
}
#define LEAVE_CRITICAL_SECTION(cs) \
{ \
(cs).unlock(); \
LeaveCritical(); \
}
#define TRY_CRITICAL_BLOCK(cs) \
if (CTryCriticalBlock criticalblock = CTryCriticalBlock(cs, #cs, __FILE__, __LINE__))
for (bool fcriticalblockonce=true; fcriticalblockonce; assert(("break caught by TRY_CRITICAL_BLOCK!" && !fcriticalblockonce)), fcriticalblockonce=false) \
for (CCriticalBlock criticalblock(cs, #cs, __FILE__, __LINE__, true); fcriticalblockonce && (fcriticalblockonce = criticalblock); fcriticalblockonce=false)
// This is exactly like std::string, but with a custom allocator.
// (secure_allocator<> is defined in serialize.h)
typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;