Locking system overhaul, add condition variables

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.
12 years ago · 712fd182b7
2 changed files with 110 additions and 103 deletions
--- a/src/util.cpp
+++ b/src/util.cpp
@ -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
-}
-void CCriticalSection::Leave()
-{
-    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;
+    push_lock(cs, CLockLocation(pszName, pszFile, nLine));
 }

-#else
-
-void CCriticalSection::Enter(const char* pszName, const char* pszFile, int nLine)
+void LeaveCritical()
 {
-#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;
+    pop_lock();
 }

 #endif /* DEBUG_LOCKORDER */
-
--- a/src/util.h
+++ b/src/util.h
@ -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
-{
-protected:
-    boost::interprocess::interprocess_recursive_mutex mutex;
-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);
-};
+/** Wrapped boost mutex: supports waiting but not recursive locking */
+typedef boost::interprocess::interprocess_mutex CWaitableCriticalSection;

-/** RAII object that acquires mutex. Needed for exception safety. */
-class CCriticalBlock
-{
-protected:
-    CCriticalSection* pcs;
+#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
+{
+private:
+    boost::interprocess::scoped_lock<Mutex> lock;
 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);
+        if (!lock.owns())
+        {
+            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();
+        }
    }

-    operator bool() const
+    void Leave()
    {
-        return true;
+        if (lock.owns())
+        {
+            lock.unlock();
+            LeaveCritical();
+        }
    }

-    ~CCriticalBlock()
+    bool TryEnter(const char* pszName, const char* pszFile, int nLine)
    {
-        pcs->Leave();
+        if (!lock.owns())
+        {
+            EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
+            lock.try_lock();
+            if (!lock.owns())
+                LeaveCritical();
+        }
+        return lock.owns();
    }
-};
-
-#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;
+    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);
+    }

-public:
-    CTryCriticalBlock(CCriticalSection& csIn, const char* pszName, const char* pszFile, int nLine)
+    ~CMutexLock()
    {
-        pcs = (csIn.TryEnter(pszName, pszFile, nLine) ? &csIn : NULL);
+        if (lock.owns())
+            LeaveCritical();
    }

-    operator bool() const
+    operator bool()
    {
-        return Entered();
+        return lock.owns();
    }

-    ~CTryCriticalBlock()
+    boost::interprocess::scoped_lock<Mutex> &GetLock()
    {
-        if (pcs)
-        {
-            pcs->Leave();
-        }
+        return lock;
    }
-    bool Entered() const { return pcs != NULL; }
 };

+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;
+