From fa7f1a3ca99de67a0f094be3418af91ff8a270d2 Mon Sep 17 00:00:00 2001
From: dwight <dwight@10gen.com>
Date: Wed, 5 Jan 2011 00:43:04 -0500
Subject: [PATCH] merge

---
 dbtests/threadedtests.cpp             |   4 +-
 util/concurrency/rwlock.h             |  19 +-
 util/concurrency/shared_mutex_win.hpp | 573 ++++++++++++++++++++++++++
 3 files changed, 590 insertions(+), 6 deletions(-)
 create mode 100755 util/concurrency/shared_mutex_win.hpp

diff --git a/dbtests/threadedtests.cpp b/dbtests/threadedtests.cpp
index bf0c96f199a..0cffe2a2afa 100644
--- a/dbtests/threadedtests.cpp
+++ b/dbtests/threadedtests.cpp
@@ -57,8 +57,8 @@ namespace ThreadedTests {
         }
     };
 
-    class MongoMutexTest : public ThreadedTest<135> {
-        enum { N = 100000 };
+    class MongoMutexTest : public ThreadedTest<135> { 
+        enum { N = 80000 };
         MongoMutex *mm;
         virtual void setup() {
             mm = new MongoMutex("MongoMutexTest");
diff --git a/util/concurrency/rwlock.h b/util/concurrency/rwlock.h
index 81d8cab242d..ca81a9ffa03 100644
--- a/util/concurrency/rwlock.h
+++ b/util/concurrency/rwlock.h
@@ -21,7 +21,11 @@
 #include "mutex.h"
 #include "../time_support.h"
 
-#if !defined(_WIN32)
+// this requires Vista+ to work
+// it works better than sharable_mutex under high contention
+//#define MONGO_USE_SRW_ON_WINDOWS 1
+
+#if !defined(MONGO_USE_SRW_ON_WINDOWS)
 
 #if BOOST_VERSION >= 103500
 # define BOOST_RWLOCK
@@ -32,7 +36,14 @@
 # include <pthread.h>
 #endif
 
-#ifdef BOOST_RWLOCK
+#if defined(_WIN32)
+# include "shared_mutex_win.hpp"
+namespace mongo {
+    typedef boost::modified_shared_mutex shared_mutex;
+}
+# undef assert
+# define assert MONGO_assert
+#elif defined(BOOST_RWLOCK)
 # include <boost/thread/shared_mutex.hpp>
 # undef assert
 # define assert MONGO_assert
@@ -42,7 +53,7 @@
 
 namespace mongo {
 
-#if defined(_WIN32)
+#if defined(MONGO_USE_SRW_ON_WINDOWS) && defined(_WIN32)
 
     class RWLock {
     public:
@@ -80,7 +91,7 @@ namespace mongo {
 
 #elif defined(BOOST_RWLOCK)
     class RWLock {
-        boost::shared_mutex _m;
+        shared_mutex _m;
     public:
 #if defined(_DEBUG)
         const char *_name;
diff --git a/util/concurrency/shared_mutex_win.hpp b/util/concurrency/shared_mutex_win.hpp
new file mode 100755
index 00000000000..5356cf2af11
--- /dev/null
+++ b/util/concurrency/shared_mutex_win.hpp
@@ -0,0 +1,573 @@
+#ifndef BOOST_THREAD_WIN32_SHARED_MUTEX_HPP_MODIFIED
+#define BOOST_THREAD_WIN32_SHARED_MUTEX_HPP_MODIFIED
+
+//  (C) Copyright 2006-8 Anthony Williams
+//
+//  Distributed under the Boost Software License, Version 1.0. (See
+//  accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+
+// MongoDB : 
+//
+// Slightly modified boost file to not die above 127 pending writes
+// 
+
+#include <boost/assert.hpp>
+#include <boost/detail/interlocked.hpp>
+#include <boost/thread/win32/thread_primitives.hpp>
+#include <boost/static_assert.hpp>
+#include <limits.h>
+#include <boost/utility.hpp>
+#include <boost/thread/thread_time.hpp>
+
+#include <boost/config/abi_prefix.hpp>
+
+namespace boost
+{
+    class modified_shared_mutex:
+        private boost::noncopyable
+    {
+    private:
+        struct state_data
+        {
+            unsigned shared_count:11,
+                shared_waiting:11,
+                exclusive:1,
+                upgrade:1,
+                exclusive_waiting:7,
+                exclusive_waiting_blocked:1;
+
+            friend bool operator==(state_data const& lhs,state_data const& rhs)
+            {
+                return *reinterpret_cast<unsigned const*>(&lhs)==*reinterpret_cast<unsigned const*>(&rhs);
+            }
+        };
+        
+
+        template<typename T>
+        T interlocked_compare_exchange(T* target,T new_value,T comparand)
+        {
+            BOOST_STATIC_ASSERT(sizeof(T)==sizeof(long));
+            long const res=BOOST_INTERLOCKED_COMPARE_EXCHANGE(reinterpret_cast<long*>(target),
+                                                              *reinterpret_cast<long*>(&new_value),
+                                                              *reinterpret_cast<long*>(&comparand));
+            return *reinterpret_cast<T const*>(&res);
+        }
+
+        state_data state;
+        detail::win32::handle semaphores[2];
+        detail::win32::handle &unlock_sem;
+        detail::win32::handle &exclusive_sem;
+        detail::win32::handle upgrade_sem;
+
+        void release_waiters(state_data old_state)
+        {
+            if(old_state.exclusive_waiting)
+            {
+                BOOST_VERIFY(detail::win32::ReleaseSemaphore(exclusive_sem,1,0)!=0);
+            }
+                        
+            if(old_state.shared_waiting || old_state.exclusive_waiting)
+            {
+                BOOST_VERIFY(detail::win32::ReleaseSemaphore(unlock_sem,old_state.shared_waiting + (old_state.exclusive_waiting?1:0),0)!=0);
+            }
+        }
+        
+
+    public:
+        modified_shared_mutex():
+            unlock_sem(semaphores[0]),
+            exclusive_sem(semaphores[1]) 
+        {
+            unlock_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX);
+            exclusive_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX);
+            upgrade_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX);
+            state_data state_={0};
+            state=state_;
+        }
+
+        ~modified_shared_mutex()
+        {
+            detail::win32::CloseHandle(upgrade_sem);
+            detail::win32::CloseHandle(unlock_sem);
+            detail::win32::CloseHandle(exclusive_sem);
+        }
+
+        bool try_lock_shared()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                if(!new_state.exclusive && !new_state.exclusive_waiting_blocked)
+                {
+                    ++new_state.shared_count;
+                }
+                
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            return !(old_state.exclusive| old_state.exclusive_waiting_blocked);
+        }
+
+        void lock_shared()
+        {
+            BOOST_VERIFY(timed_lock_shared(::boost::detail::get_system_time_sentinel()));
+        }
+
+        template<typename TimeDuration>
+        bool timed_lock_shared(TimeDuration const & relative_time)
+        {
+            return timed_lock_shared(get_system_time()+relative_time);
+        }
+
+        bool timed_lock_shared(boost::system_time const& wait_until)
+        {
+            for(;;)
+            {
+                state_data old_state=state;
+                for(;;)
+                {
+                    state_data new_state=old_state;
+                    if(new_state.exclusive || new_state.exclusive_waiting_blocked)
+                    {
+                        ++new_state.shared_waiting;
+                    }
+                    else
+                    {
+                        ++new_state.shared_count;
+                    }
+
+                    state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                    if(current_state==old_state)
+                    {
+                        break;
+                    }
+                    old_state=current_state;
+                }
+
+                if(!(old_state.exclusive| old_state.exclusive_waiting_blocked))
+                {
+                    return true;
+                }
+                    
+                unsigned long const res=detail::win32::WaitForSingleObject(unlock_sem,::boost::detail::get_milliseconds_until(wait_until));
+                if(res==detail::win32::timeout)
+                {
+                    for(;;)
+                    {
+                        state_data new_state=old_state;
+                        if(new_state.exclusive || new_state.exclusive_waiting_blocked)
+                        {
+                            if(new_state.shared_waiting)
+                            {
+                                --new_state.shared_waiting;
+                            }
+                        }
+                        else
+                        {
+                            ++new_state.shared_count;
+                        }
+
+                        state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                        if(current_state==old_state)
+                        {
+                            break;
+                        }
+                        old_state=current_state;
+                    }
+
+                    if(!(old_state.exclusive| old_state.exclusive_waiting_blocked))
+                    {
+                        return true;
+                    }
+                    return false;
+                }
+                
+                BOOST_ASSERT(res==0);
+            }
+        }
+
+        void unlock_shared()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                bool const last_reader=!--new_state.shared_count;
+                
+                if(last_reader)
+                {
+                    if(new_state.upgrade)
+                    {
+                        new_state.upgrade=false;
+                        new_state.exclusive=true;
+                    }
+                    else
+                    {
+                        if(new_state.exclusive_waiting)
+                        {
+                            --new_state.exclusive_waiting;
+                            new_state.exclusive_waiting_blocked=false;
+                        }
+                        new_state.shared_waiting=0;
+                    }
+                }
+                
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    if(last_reader)
+                    {
+                        if(old_state.upgrade)
+                        {
+                            BOOST_VERIFY(detail::win32::ReleaseSemaphore(upgrade_sem,1,0)!=0);
+                        }
+                        else
+                        {
+                            release_waiters(old_state);
+                        }
+                    }
+                    break;
+                }
+                old_state=current_state;
+            }
+        }
+
+        void lock()
+        {
+            BOOST_VERIFY(timed_lock(::boost::detail::get_system_time_sentinel()));
+        }
+
+        template<typename TimeDuration>
+        bool timed_lock(TimeDuration const & relative_time)
+        {
+            return timed_lock(get_system_time()+relative_time);
+        }
+
+        bool try_lock()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                if(new_state.shared_count || new_state.exclusive)
+                {
+                    return false;
+                }
+                else
+                {
+                    new_state.exclusive=true;
+                }
+                
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            return true;
+        }
+
+
+        bool timed_lock(boost::system_time const& wait_until)
+        {
+            for(;;)
+            {
+                state_data old_state=state;
+
+                for(;;)
+                {
+                    state_data new_state=old_state;
+                    if(new_state.shared_count || new_state.exclusive)
+                    {
+                        if( new_state.exclusive_waiting == 127 ) // the maximum already!
+                            break;
+                        ++new_state.exclusive_waiting;
+                        new_state.exclusive_waiting_blocked=true;
+                    }
+                    else
+                    {
+                        new_state.exclusive=true;
+                    }
+
+                    state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                    if(current_state==old_state)
+                    {
+                        break;
+                    }
+                    old_state=current_state;
+                }
+
+                if(!old_state.shared_count && !old_state.exclusive)
+                {
+                    return true;
+                }
+                unsigned long const wait_res=detail::win32::WaitForMultipleObjects(2,semaphores,true,::boost::detail::get_milliseconds_until(wait_until));
+                if(wait_res==detail::win32::timeout)
+                {
+                    for(;;)
+                    {
+                        state_data new_state=old_state;
+                        if(new_state.shared_count || new_state.exclusive)
+                        {
+                            if(new_state.exclusive_waiting)
+                            {
+                                if(!--new_state.exclusive_waiting)
+                                {
+                                    new_state.exclusive_waiting_blocked=false;
+                                }
+                            }
+                        }
+                        else
+                        {
+                            new_state.exclusive=true;
+                        }
+
+                        state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                        if(current_state==old_state)
+                        {
+                            break;
+                        }
+                        old_state=current_state;
+                    }
+                    if(!old_state.shared_count && !old_state.exclusive)
+                    {
+                        return true;
+                    }
+                    return false;
+                }
+                BOOST_ASSERT(wait_res<2);
+            }
+        }
+
+        void unlock()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                new_state.exclusive=false;
+                if(new_state.exclusive_waiting)
+                {
+                    --new_state.exclusive_waiting;
+                    new_state.exclusive_waiting_blocked=false;
+                }
+                new_state.shared_waiting=0;
+
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            release_waiters(old_state);
+        }
+
+        void lock_upgrade()
+        {
+            for(;;)
+            {
+                state_data old_state=state;
+                for(;;)
+                {
+                    state_data new_state=old_state;
+                    if(new_state.exclusive || new_state.exclusive_waiting_blocked || new_state.upgrade)
+                    {
+                        ++new_state.shared_waiting;
+                    }
+                    else
+                    {
+                        ++new_state.shared_count;
+                        new_state.upgrade=true;
+                    }
+
+                    state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                    if(current_state==old_state)
+                    {
+                        break;
+                    }
+                    old_state=current_state;
+                }
+
+                if(!(old_state.exclusive|| old_state.exclusive_waiting_blocked|| old_state.upgrade))
+                {
+                    return;
+                }
+                    
+                BOOST_VERIFY(!detail::win32::WaitForSingleObject(unlock_sem,detail::win32::infinite));
+            }
+        }
+
+        bool try_lock_upgrade()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                if(new_state.exclusive || new_state.exclusive_waiting_blocked || new_state.upgrade)
+                {
+                    return false;
+                }
+                else
+                {
+                    ++new_state.shared_count;
+                    new_state.upgrade=true;
+                }
+                
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            return true;
+        }
+
+        void unlock_upgrade()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                new_state.upgrade=false;
+                bool const last_reader=!--new_state.shared_count;
+                
+                if(last_reader)
+                {
+                    if(new_state.exclusive_waiting)
+                    {
+                        --new_state.exclusive_waiting;
+                        new_state.exclusive_waiting_blocked=false;
+                    }
+                    new_state.shared_waiting=0;
+                }
+                
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    if(last_reader)
+                    {
+                        release_waiters(old_state);
+                    }
+                    break;
+                }
+                old_state=current_state;
+            }
+        }
+
+        void unlock_upgrade_and_lock()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                bool const last_reader=!--new_state.shared_count;
+                
+                if(last_reader)
+                {
+                    new_state.upgrade=false;
+                    new_state.exclusive=true;
+                }
+                
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    if(!last_reader)
+                    {
+                        BOOST_VERIFY(!detail::win32::WaitForSingleObject(upgrade_sem,detail::win32::infinite));
+                    }
+                    break;
+                }
+                old_state=current_state;
+            }
+        }
+
+        void unlock_and_lock_upgrade()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                new_state.exclusive=false;
+                new_state.upgrade=true;
+                ++new_state.shared_count;
+                if(new_state.exclusive_waiting)
+                {
+                    --new_state.exclusive_waiting;
+                    new_state.exclusive_waiting_blocked=false;
+                }
+                new_state.shared_waiting=0;
+
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            release_waiters(old_state);
+        }
+        
+        void unlock_and_lock_shared()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                new_state.exclusive=false;
+                ++new_state.shared_count;
+                if(new_state.exclusive_waiting)
+                {
+                    --new_state.exclusive_waiting;
+                    new_state.exclusive_waiting_blocked=false;
+                }
+                new_state.shared_waiting=0;
+
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            release_waiters(old_state);
+        }
+        
+        void unlock_upgrade_and_lock_shared()
+        {
+            state_data old_state=state;
+            for(;;)
+            {
+                state_data new_state=old_state;
+                new_state.upgrade=false;
+                if(new_state.exclusive_waiting)
+                {
+                    --new_state.exclusive_waiting;
+                    new_state.exclusive_waiting_blocked=false;
+                }
+                new_state.shared_waiting=0;
+
+                state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
+                if(current_state==old_state)
+                {
+                    break;
+                }
+                old_state=current_state;
+            }
+            release_waiters(old_state);
+        }
+        
+    };
+}
+
+#include <boost/config/abi_suffix.hpp>
+
+#endif