Merge downstream code

10 files changed, 1371 insertions, 3 deletions

diff --git a/indra/llcommon/CMakeLists.txt b/indra/llcommon/CMakeLists.txt
index 8eb0c6249d..8767616a70 100755
--- a/indra/llcommon/CMakeLists.txt
+++ b/indra/llcommon/CMakeLists.txt
@@ -43,6 +43,7 @@ set(llcommon_SOURCE_FILES
     llcriticaldamp.cpp
     llcursortypes.cpp
     lldate.cpp
+    lldeadmantimer.cpp
     lldependencies.cpp
     lldictionary.cpp
     llerror.cpp
@@ -79,6 +80,7 @@ set(llcommon_SOURCE_FILES
     llptrto.cpp 
     llprocess.cpp
     llprocessor.cpp
+    llprocinfo.cpp
     llqueuedthread.cpp
     llrand.cpp
     llrefcount.cpp
@@ -146,6 +148,7 @@ set(llcommon_HEADER_FILES
     lldarray.h
     lldarrayptr.h
     lldate.h
+    lldeadmantimer.h
     lldefs.h
     lldependencies.h
     lldeleteutils.h
@@ -207,6 +210,7 @@ set(llcommon_HEADER_FILES
     llpriqueuemap.h
     llprocess.h
     llprocessor.h
+    llprocinfo.h
     llptrskiplist.h
     llptrskipmap.h
     llptrto.h
@@ -324,12 +328,14 @@ if (LL_TESTS)
   LL_ADD_INTEGRATION_TEST(bitpack "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llbase64 "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(lldate "" "${test_libs}")
+  LL_ADD_INTEGRATION_TEST(lldeadmantimer "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(lldependencies "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llerror "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llframetimer "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llinstancetracker "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(lllazy "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llprocessor "" "${test_libs}")
+  LL_ADD_INTEGRATION_TEST(llprocinfo "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llrand "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llsdserialize "" "${test_libs}")
   LL_ADD_INTEGRATION_TEST(llsingleton "" "${test_libs}")                          
diff --git a/indra/llcommon/lldeadmantimer.cpp b/indra/llcommon/lldeadmantimer.cpp
new file mode 100644
index 0000000000..7d9097e344
--- /dev/null
+++ b/indra/llcommon/lldeadmantimer.cpp
@@ -0,0 +1,188 @@
+/** 
+* @file lldeadmantimer.cpp
+* @brief Simple deadman-switch timer.
+* @author monty@lindenlab.com
+*
+* $LicenseInfo:firstyear=2013&license=viewerlgpl$
+* Second Life Viewer Source Code
+* Copyright (C) 2013, Linden Research, Inc.
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation;
+* version 2.1 of the License only.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public
+* License along with this library; if not, write to the Free Software
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*
+* Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+* $/LicenseInfo$
+*/
+
+
+#include "lldeadmantimer.h"
+
+
+// *TODO:  Currently, this uses lltimer functions for its time
+// aspects and this leaks into the apis in the U64s/F64s.  Would
+// like to perhaps switch this over to TSC register-based timers
+// sometime and drop the overhead some more.
+
+
+//  Flag states and their meaning:
+//  mActive  mDone   Meaning
+//   false   false   Nothing running, no result available
+//    true   false   Timer running, no result available
+//   false    true   Timer finished, result can be read once
+//    true    true   Not allowed
+//
+LLDeadmanTimer::LLDeadmanTimer(F64 horizon, bool inc_cpu)
+	: mHorizon(time_type(llmax(horizon, F64(0.0)) * gClockFrequency)),
+	  mActive(false),			// If true, a timer is running.
+	  mDone(false),				// If true, timer has completed and can be read (once)
+	  mStarted(U64L(0)),
+	  mExpires(U64L(0)),
+	  mStopped(U64L(0)),
+	  mCount(U64L(0)),
+	  mIncCPU(inc_cpu),
+	  mUStartCPU(LLProcInfo::time_type(U64L(0))),
+	  mUEndCPU(LLProcInfo::time_type(U64L(0))),
+	  mSStartCPU(LLProcInfo::time_type(U64L(0))),
+	  mSEndCPU(LLProcInfo::time_type(U64L(0)))
+{}
+
+
+// static
+LLDeadmanTimer::time_type LLDeadmanTimer::getNow()
+{
+	return LLTimer::getCurrentClockCount();
+}
+
+
+void LLDeadmanTimer::start(time_type now)
+{
+	// *TODO:  If active, let's complete an existing timer and save
+	// the result to the side.  I think this will be useful later.
+	// For now, wipe out anything in progress, start fresh.
+	
+	if (! now)
+	{
+		now = LLTimer::getCurrentClockCount();
+	}
+	mActive = true;
+	mDone = false;
+	mStarted = now;
+	mExpires = now + mHorizon;
+	mStopped = now;
+	mCount = U64L(0);
+	if (mIncCPU)
+	{
+		LLProcInfo::getCPUUsage(mUStartCPU, mSStartCPU);
+	}
+}
+
+
+void LLDeadmanTimer::stop(time_type now)
+{
+	if (! mActive)
+	{
+		return;
+	}
+
+	if (! now)
+	{
+		now = getNow();
+	}
+	mStopped = now;
+	mActive = false;
+	mDone = true;
+	if (mIncCPU)
+	{
+		LLProcInfo::getCPUUsage(mUEndCPU, mSEndCPU);
+	}
+}
+
+
+bool LLDeadmanTimer::isExpired(time_type now, F64 & started, F64 & stopped, U64 & count,
+							   U64 & user_cpu, U64 & sys_cpu)
+{
+	const bool status(isExpired(now, started, stopped, count));
+	if (status)
+	{
+		user_cpu = U64(mUEndCPU - mUStartCPU);
+		sys_cpu = U64(mSEndCPU - mSStartCPU);
+	}
+	return status;
+}
+
+		
+bool LLDeadmanTimer::isExpired(time_type now, F64 & started, F64 & stopped, U64 & count)
+{
+	if (mActive && ! mDone)
+	{
+		if (! now)
+		{
+			now = getNow();
+		}
+
+		if (now >= mExpires)
+		{
+			// mStopped from ringBell() is the value we want
+			mActive = false;
+			mDone = true;
+		}
+	}
+
+	if (! mDone)
+	{
+		return false;
+	}
+	
+	started = mStarted * gClockFrequencyInv;
+	stopped = mStopped * gClockFrequencyInv;
+	count = mCount;
+	mDone = false;
+
+	return true;
+}
+
+	
+void LLDeadmanTimer::ringBell(time_type now, unsigned int count)
+{
+	if (! mActive)
+	{
+		return;
+	}
+	
+	if (! now)
+	{
+		now = getNow();
+	}
+
+	if (now >= mExpires)
+	{
+		// Timer has expired, this event will be dropped
+		mActive = false;
+		mDone = true;
+	}
+	else
+	{
+		// Timer renewed, keep going
+		mStopped = now;
+		mExpires = now + mHorizon;
+		mCount += count;
+		if (mIncCPU)
+		{
+			LLProcInfo::getCPUUsage(mUEndCPU, mSEndCPU);
+		}
+	}
+	
+	return;
+}
+
diff --git a/indra/llcommon/lldeadmantimer.h b/indra/llcommon/lldeadmantimer.h
new file mode 100644
index 0000000000..980976e176
--- /dev/null
+++ b/indra/llcommon/lldeadmantimer.h
@@ -0,0 +1,214 @@
+/** 
+* @file   lldeadmantimer.h
+* @brief  Interface to a simple event timer with a deadman's switch
+* @author monty@lindenlab.com
+*
+* $LicenseInfo:firstyear=2013&license=viewerlgpl$
+* Second Life Viewer Source Code
+* Copyright (C) 2013, Linden Research, Inc.
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation;
+* version 2.1 of the License only.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public
+* License along with this library; if not, write to the Free Software
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*
+* Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+* $/LicenseInfo$
+*/
+
+#ifndef	LL_DEADMANTIMER_H
+#define	LL_DEADMANTIMER_H
+
+
+#include "linden_common.h"
+
+#include "lltimer.h"
+#include "llprocinfo.h"
+
+
+/// @file lldeadmantimer.h
+///
+/// There are interesting user-experienced events in the viewer that
+/// would seem to have well-defined start and stop points but which
+/// actually lack such milestones in the code.  Such events (like
+/// time to load meshes after logging in, initial inventory load,
+/// display name fetch) can be defined somewhat after-the-fact by
+/// noticing when we no longer perform operations towards their
+/// completion.  This class is intended to help in such applications.
+///
+/// What it implements is a deadman's switch (also known as a
+/// keepalive switch and a doorbell switch).  The basic operation is
+/// as follows:
+///
+/// * LLDeadmanTimer is instantiated with a horizon value in seconds,
+///   one for each event of interest.
+/// * When an event starts, @see start() is invoked to begin a
+///   timing operation.
+/// * As operations are performed in service of the event (issuing
+///   HTTP requests, receiving responses), @see ringBell() is invoked
+///   to inform the timer that the operation is still active.
+/// * If the operation is canceled or otherwise terminated, @see
+///   stop() can be called to end the timing operation.
+/// * Concurrent with the ringBell() calls, the program makes
+///   periodic (shorter than the horizon but not too short) calls
+///   to @see isExpired() to see if the event has expired due to
+///   either a stop() call or lack of activity (defined as a ringBell()
+///   call in the previous 'horizon' seconds).  If it has expired,
+///   the caller also receives start, stop and count values for the
+///   event which the application can then report in whatever manner
+///   it sees fit.
+/// * The timer becomes passive after an isExpired() call that returns
+///   true.  It can then be restarted with a new start() call.
+///
+/// Threading:  Instances are not thread-safe.  They also use
+/// timing code from lltimer.h which is also unsafe.
+///
+/// Allocation:  Not refcounted, may be stack or heap allocated.
+///
+
+class LL_COMMON_API LLDeadmanTimer
+{
+public:
+	/// Public types
+
+	/// Low-level time type chosen for compatibility with
+	/// LLTimer::getCurrentClockCount() which is the basis
+	/// of time operations in this class.  This is likely
+	/// to change in a future version in a move to TSC-based
+	/// timing.
+	typedef U64 time_type;
+	
+public:
+	/// Construct and initialize an LLDeadmanTimer
+	///
+	/// @param horizon	Time, in seconds, after the last @see ringBell()
+	///                 call at which point the timer will consider itself
+	///					expired.
+	///
+	/// @param inc_cpu	If true, gather system and user cpu stats while
+	///					running the timer.  This does require more syscalls
+	///					during updates.  If false, cpu usage data isn't
+	///					collected and will be zero if queried.
+	LLDeadmanTimer(F64 horizon, bool inc_cpu);
+
+	~LLDeadmanTimer() 
+		{}
+	
+private:
+	LLDeadmanTimer(const LLDeadmanTimer &);				// Not defined
+	void operator=(const LLDeadmanTimer &);				// Not defined
+
+public:
+	/// Get the current time.  Zero-basis for this time
+	/// representation is not defined and is different on
+	/// different platforms.  Do not attempt to compute
+	/// negative times relative to the first value returned,
+	/// there may not be enough 'front porch' on the range
+	/// to prevent wraparound.
+	///
+	/// Note:  Implementation is expected to change in a
+	/// future release as well.
+	///
+	static time_type getNow();
+
+	/// Begin timing.  If the timer is already active, it is reset
+	///	and timing begins now.
+	///
+	/// @param now		Current time as returned by @see
+	///					LLTimer::getCurrentClockCount().  If zero,
+	///					method will lookup current time.
+	///
+	void start(time_type now);
+
+	/// End timing.  Actively declare the end of the event independent
+	/// of the deadman's switch operation.  @see isExpired() will return
+	/// true and appropriate values will be returned.
+	///
+	/// @param now		Current time as returned by @see
+	///					LLTimer::getCurrentClockCount().  If zero,
+	///					method will lookup current time.
+	///
+	void stop(time_type now);
+
+	/// Declare that something interesting happened.  This has two
+	/// effects on an unexpired-timer.  1)  The expiration time
+	/// is extended for 'horizon' seconds after the 'now' value.
+	/// 2)  An internal counter associated with the event is incremented
+	/// by the @ref count parameter.  This count is returned via the
+	/// @see isExpired() method.
+	///
+	/// @param now		Current time as returned by @see
+	///					LLTimer::getCurrentClockCount().  If zero,
+	///					method will lookup current time.
+	///
+	/// @param count	Count of events to be associated with
+	///					this bell ringing.
+	///
+	void ringBell(time_type now, unsigned int count);
+	
+	/// Checks the status of the timer.  If the timer has expired,
+	/// also returns various timer-related stats.  Unlike ringBell(),
+	/// does not extend the horizon, it only checks for expiration.
+	///
+	/// @param now		Current time as returned by @see
+	///					LLTimer::getCurrentClockCount().  If zero,
+	///					method will lookup current time.
+	///
+	/// @param started	If expired, the starting time of the event is
+	///					returned to the caller via this reference.
+	///
+	/// @param stopped	If expired, the ending time of the event is
+	///					returned to the caller via this reference.
+	///					Ending time will be that provided in the
+	///					stop() method or the last ringBell() call
+	///					leading to expiration, whichever (stop() call
+	///					or notice of expiration) happened first.
+	///
+	/// @param count	If expired, the number of ringBell() calls
+	///					made prior to expiration.
+	///
+	/// @param user_cpu	Amount of CPU spent in user mode by the process
+	///					during the event.  Value in microseconds and will
+	///					read zero if not enabled by the constructor.
+	///
+	/// @param sys_cpu	Amount of CPU spent in system mode by the process.
+	///
+	/// @return			true if the timer has expired, false otherwise.
+	///					If true, it also returns the started,
+	///					stopped and count values otherwise these are
+	///					left unchanged.
+	///
+	bool isExpired(time_type now, F64 & started, F64 & stopped, U64 & count,
+				   U64 & user_cpu, U64 & sys_cpu);
+
+	/// Identical to the six-arugment form except it does without the
+	/// CPU time return if the caller isn't interested in it.
+	bool isExpired(time_type now, F64 & started, F64 & stopped, U64 & count);
+
+protected:
+	time_type					mHorizon;
+	bool						mActive;
+	bool						mDone;
+	time_type					mStarted;
+	time_type					mExpires;
+	time_type					mStopped;
+	time_type					mCount;
+
+	const bool					mIncCPU;		// Include CPU metrics in timer
+	LLProcInfo::time_type		mUStartCPU;
+	LLProcInfo::time_type		mUEndCPU;
+	LLProcInfo::time_type		mSStartCPU;
+	LLProcInfo::time_type		mSEndCPU;
+};
+	
+
+#endif	// LL_DEADMANTIMER_H
diff --git a/indra/llcommon/llprocinfo.cpp b/indra/llcommon/llprocinfo.cpp
new file mode 100644
index 0000000000..c00f979b0b
--- /dev/null
+++ b/indra/llcommon/llprocinfo.cpp
@@ -0,0 +1,94 @@
+/** 
+* @file llprocinfo.cpp
+* @brief Process, cpu and resource usage information APIs.
+* @author monty@lindenlab.com
+*
+* $LicenseInfo:firstyear=2013&license=viewerlgpl$
+* Second Life Viewer Source Code
+* Copyright (C) 2013, Linden Research, Inc.
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation;
+* version 2.1 of the License only.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public
+* License along with this library; if not, write to the Free Software
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*
+* Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+* $/LicenseInfo$
+*/
+
+
+#include "llprocinfo.h"
+
+#if LL_WINDOWS
+
+#define	PSAPI_VERSION	1
+#include "windows.h"
+#include "psapi.h"
+
+#elif LL_DARWIN
+
+#include <sys/resource.h>
+#include <mach/mach.h>
+	
+#else
+
+#include <sys/time.h>
+#include <sys/resource.h>
+
+#endif // LL_WINDOWS/LL_DARWIN
+
+
+// static
+void LLProcInfo::getCPUUsage(time_type & user_time, time_type & system_time)
+{
+#if LL_WINDOWS
+
+	HANDLE self(GetCurrentProcess());			// Does not have to be closed
+	FILETIME ft_dummy, ft_system, ft_user;
+
+	GetProcessTimes(self, &ft_dummy, &ft_dummy, &ft_system, &ft_user);
+	ULARGE_INTEGER uli;
+	uli.u.LowPart = ft_system.dwLowDateTime;
+	uli.u.HighPart = ft_system.dwHighDateTime;
+	system_time = uli.QuadPart / U64L(10);		// Convert to uS
+	uli.u.LowPart = ft_user.dwLowDateTime;
+	uli.u.HighPart = ft_user.dwHighDateTime;
+	user_time = uli.QuadPart / U64L(10);
+	
+#elif LL_DARWIN
+
+	struct rusage usage;
+
+	if (getrusage(RUSAGE_SELF, &usage))
+	{
+		user_time = system_time = time_type(0U);
+		return;
+	}
+	user_time = U64(usage.ru_utime.tv_sec) * U64L(1000000) + usage.ru_utime.tv_usec;
+	system_time = U64(usage.ru_stime.tv_sec) * U64L(1000000) + usage.ru_stime.tv_usec;
+
+#else // Linux
+
+	struct rusage usage;
+
+	if (getrusage(RUSAGE_SELF, &usage))
+	{
+		user_time = system_time = time_type(0U);
+		return;
+	}
+	user_time = U64(usage.ru_utime.tv_sec) * U64L(1000000) + usage.ru_utime.tv_usec;
+	system_time = U64(usage.ru_stime.tv_sec) * U64L(1000000) + usage.ru_stime.tv_usec;
+	
+#endif // LL_WINDOWS/LL_DARWIN/Linux
+}
+
+
diff --git a/indra/llcommon/llprocinfo.h b/indra/llcommon/llprocinfo.h
new file mode 100644
index 0000000000..e78bcf490a
--- /dev/null
+++ b/indra/llcommon/llprocinfo.h
@@ -0,0 +1,68 @@
+/** 
+* @file   llprocinfo.h
+* @brief  Interface to process/cpu/resource information services.
+* @author monty@lindenlab.com
+*
+* $LicenseInfo:firstyear=2013&license=viewerlgpl$
+* Second Life Viewer Source Code
+* Copyright (C) 2013, Linden Research, Inc.
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation;
+* version 2.1 of the License only.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public
+* License along with this library; if not, write to the Free Software
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*
+* Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+* $/LicenseInfo$
+*/
+
+#ifndef	LL_PROCINFO_H
+#define	LL_PROCINFO_H
+
+
+#include "linden_common.h"
+
+/// @file llprocinfo.h
+///
+/// Right now, this is really a namespace disguised as a class.
+/// It wraps some types and functions to return information about
+/// process resource consumption in a non-OS-specific manner.
+///
+/// Threading:  No instances so that's thread-safe.  Implementations
+/// of static functions should be thread-safe, they mostly involve
+/// direct syscall invocations.
+///
+/// Allocation:  Not instantiatable.
+
+class LL_COMMON_API LLProcInfo
+{
+public:
+	/// Public types
+
+	typedef U64 time_type;								/// Relative microseconds
+	
+private:
+	LLProcInfo();										// Not defined
+	~LLProcInfo();										// Not defined
+	LLProcInfo(const LLProcInfo &);						// Not defined
+	void operator=(const LLProcInfo &);					// Not defined
+
+public:
+	/// Get accumulated system and user CPU time in
+	/// microseconds.  Syscalls involved in every invocation.
+	///
+	/// Threading:  expected to be safe.
+	static void getCPUUsage(time_type & user_time, time_type & system_time);
+};
+	
+
+#endif	// LL_PROCINFO_H
diff --git a/indra/llcommon/llthread.cpp b/indra/llcommon/llthread.cpp
index 60adeeaeb7..e67d1bc57b 100755
--- a/indra/llcommon/llthread.cpp
+++ b/indra/llcommon/llthread.cpp
@@ -3,7 +3,7 @@
  *
  * $LicenseInfo:firstyear=2004&license=viewerlgpl$
  * Second Life Viewer Source Code
- * Copyright (C) 2010, Linden Research, Inc.
+ * Copyright (C) 2010-2013, Linden Research, Inc.
  * 
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -373,6 +373,36 @@ void LLMutex::lock()
 #endif
 }
 
+bool LLMutex::trylock()
+{
+	if(isSelfLocked())
+	{ //redundant lock
+		mCount++;
+		return true;
+	}
+	
+	apr_status_t status(apr_thread_mutex_trylock(mAPRMutexp));
+	if (APR_STATUS_IS_EBUSY(status))
+	{
+		return false;
+	}
+	
+#if MUTEX_DEBUG
+	// Have to have the lock before we can access the debug info
+	U32 id = LLThread::currentID();
+	if (mIsLocked[id] != FALSE)
+		llerrs << "Already locked in Thread: " << id << llendl;
+	mIsLocked[id] = TRUE;
+#endif
+
+#if LL_DARWIN
+	mLockingThread = LLThread::currentID();
+#else
+	mLockingThread = sThreadID;
+#endif
+	return true;
+}
+
 void LLMutex::unlock()
 {
 	if (mCount > 0)
diff --git a/indra/llcommon/llthread.h b/indra/llcommon/llthread.h
index f51d985b5f..8c7143304f 100755
--- a/indra/llcommon/llthread.h
+++ b/indra/llcommon/llthread.h
@@ -4,7 +4,7 @@
  *
  * $LicenseInfo:firstyear=2004&license=viewerlgpl$
  * Second Life Viewer Source Code
- * Copyright (C) 2010, Linden Research, Inc.
+ * Copyright (C) 2010-2013, Linden Research, Inc.
  * 
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -156,7 +156,8 @@ public:
 	virtual ~LLMutex();
 	
 	void lock();		// blocks
-	void unlock();
+	bool trylock();		// non-blocking, returns true if lock held.
+	void unlock();		// undefined behavior when called on mutex not being held
 	bool isLocked(); 	// non-blocking, but does do a lock/unlock so not free
 	bool isSelfLocked(); //return true if locked in a same thread
 	U32 lockingThread() const; //get ID of locking thread
@@ -174,6 +175,8 @@ protected:
 #endif
 };
 
+//============================================================================
+
 // Actually a condition/mutex pair (since each condition needs to be associated with a mutex).
 class LL_COMMON_API LLCondition : public LLMutex
 {
@@ -189,6 +192,8 @@ protected:
 	apr_thread_cond_t *mAPRCondp;
 };
 
+//============================================================================
+
 class LLMutexLock
 {
 public:
@@ -210,6 +215,43 @@ private:
 
 //============================================================================
 
+// Scoped locking class similar in function to LLMutexLock but uses
+// the trylock() method to conditionally acquire lock without
+// blocking.  Caller resolves the resulting condition by calling
+// the isLocked() method and either punts or continues as indicated.
+//
+// Mostly of interest to callers needing to avoid stalls who can
+// guarantee another attempt at a later time.
+
+class LLMutexTrylock
+{
+public:
+	LLMutexTrylock(LLMutex* mutex)
+		: mMutex(mutex),
+		  mLocked(false)
+	{
+		if (mMutex)
+			mLocked = mMutex->trylock();
+	}
+
+	~LLMutexTrylock()
+	{
+		if (mMutex && mLocked)
+			mMutex->unlock();
+	}
+
+	bool isLocked() const
+	{
+		return mLocked;
+	}
+	
+private:
+	LLMutex*	mMutex;
+	bool		mLocked;
+};
+
+//============================================================================
+
 void LLThread::lockData()
 {
 	mDataLock->lock();
diff --git a/indra/llcommon/lltimer.h b/indra/llcommon/lltimer.h
index 513de0605d..e73741217c 100755
--- a/indra/llcommon/lltimer.h
+++ b/indra/llcommon/lltimer.h
@@ -146,6 +146,13 @@ static inline time_t time_max()
 	}
 }
 
+// These are really statics but they've been global for awhile
+// and they're material to other timing classes.  If you are
+// not implementing a timer class, do not use these directly.
+extern LL_COMMON_API F64 gClockFrequency;
+extern LL_COMMON_API F64 gClockFrequencyInv;
+extern LL_COMMON_API F64 gClocksToMicroseconds;
+
 // Correction factor used by time_corrected() above.
 extern LL_COMMON_API S32 gUTCOffset;
 
diff --git a/indra/llcommon/tests/lldeadmantimer_test.cpp b/indra/llcommon/tests/lldeadmantimer_test.cpp
new file mode 100644
index 0000000000..7fd2dde6e0
--- /dev/null
+++ b/indra/llcommon/tests/lldeadmantimer_test.cpp
@@ -0,0 +1,628 @@
+/** 
+ * @file lldeadmantimer_test.cpp
+ * @brief Tests for the LLDeadmanTimer class.
+ *
+ * $LicenseInfo:firstyear=2013&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2013, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+
+#include "../lldeadmantimer.h"
+#include "../llsd.h"
+#include "../lltimer.h"
+
+#include "../test/lltut.h"
+
+// Convert between floating point time deltas and U64 time deltas.
+// Reflects an implementation detail inside lldeadmantimer.cpp
+
+static LLDeadmanTimer::time_type float_time_to_u64(F64 delta)
+{
+	return LLDeadmanTimer::time_type(delta * gClockFrequency);
+}
+
+static F64 u64_time_to_float(LLDeadmanTimer::time_type delta)
+{
+	return delta * gClockFrequencyInv;
+}
+
+
+namespace tut
+{
+
+struct deadmantimer_test
+{
+	deadmantimer_test()
+		{
+			// LLTimer internals updating
+			update_clock_frequencies();
+		}
+};
+
+typedef test_group<deadmantimer_test> deadmantimer_group_t;
+typedef deadmantimer_group_t::object deadmantimer_object_t;
+tut::deadmantimer_group_t deadmantimer_instance("LLDeadmanTimer");
+
+// Basic construction test and isExpired() call
+template<> template<>
+void deadmantimer_object_t::test<1>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(10.0, false);
+
+		ensure_equals("WOCM isExpired() returns false after ctor()", timer.isExpired(0, started, stopped, count), false);
+		ensure_approximately_equals("WOCM t1 - isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WOCM t1 - isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WOCM t1 - isExpired() does not modify count", count, U64L(8));
+	}
+
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(10.0, true);
+
+		ensure_equals("WCM isExpired() returns false after ctor()", timer.isExpired(0, started, stopped, count, user_cpu, sys_cpu), false);
+		ensure_approximately_equals("WCM t1 - isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WCM t1 - isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WCM t1 - isExpired() does not modify count", count, U64L(8));
+		ensure_equals("WCM t1 - isExpired() does not modify user_cpu", user_cpu, U64L(29000));
+		ensure_equals("WCM t1 - isExpired() does not modify sys_cpu", sys_cpu, U64L(57000));
+	}
+}
+
+
+// Construct with zero horizon - not useful generally but will be useful in testing
+template<> template<>
+void deadmantimer_object_t::test<2>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(0.0, false);			// Zero is pre-expired
+		
+		ensure_equals("WOCM isExpired() still returns false with 0.0 time ctor()",
+					  timer.isExpired(0, started, stopped, count), false);
+	}
+
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(0.0, true);			// Zero is pre-expired
+		
+		ensure_equals("WCM isExpired() still returns false with 0.0 time ctor()",
+					  timer.isExpired(0, started, stopped, count, user_cpu, sys_cpu), false);
+	}
+}
+
+
+// "pre-expired" timer - starting a timer with a 0.0 horizon will result in
+// expiration on first test.
+template<> template<>
+void deadmantimer_object_t::test<3>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(0.0, false);
+
+		timer.start(0);
+		ensure_equals("WOCM isExpired() returns true with 0.0 horizon time",
+					  timer.isExpired(0, started, stopped, count), true);
+ 		ensure_approximately_equals("WOCM expired timer with no bell ringing has stopped == started", started, stopped, 8);
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(0.0, true);
+
+		timer.start(0);
+		ensure_equals("WCM isExpired() returns true with 0.0 horizon time",
+					  timer.isExpired(0, started, stopped, count, user_cpu, sys_cpu), true);
+		ensure_approximately_equals("WCM expired timer with no bell ringing has stopped == started", started, stopped, 8);
+	}
+}
+
+
+// "pre-expired" timer - bell rings are ignored as we're already expired.
+template<> template<>
+void deadmantimer_object_t::test<4>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(0.0, false);
+	
+		timer.start(0);
+		timer.ringBell(LLDeadmanTimer::getNow() + float_time_to_u64(1000.0), 1);
+		ensure_equals("WOCM isExpired() returns true with 0.0 horizon time after bell ring",
+					  timer.isExpired(0, started, stopped, count), true);
+		ensure_approximately_equals("WOCM ringBell has no impact on expired timer leaving stopped == started", started, stopped, 8);
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(0.0, true);
+	
+		timer.start(0);
+		timer.ringBell(LLDeadmanTimer::getNow() + float_time_to_u64(1000.0), 1);
+		ensure_equals("WCM isExpired() returns true with 0.0 horizon time after bell ring",
+					  timer.isExpired(0, started, stopped, count, user_cpu, sys_cpu), true);
+		ensure_approximately_equals("WCM ringBell has no impact on expired timer leaving stopped == started", started, stopped, 8);
+	}
+}
+
+
+// start(0) test - unexpired timer reports unexpired
+template<> template<>
+void deadmantimer_object_t::test<5>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(10.0, false);
+	
+		timer.start(0);
+		ensure_equals("WOCM isExpired() returns false after starting with 10.0 horizon time",
+					  timer.isExpired(0, started, stopped, count), false);
+		ensure_approximately_equals("WOCM t5 - isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WOCM t5 - isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WOCM t5 - isExpired() does not modify count", count, U64L(8));
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(10.0, true);
+	
+		timer.start(0);
+		ensure_equals("WCM isExpired() returns false after starting with 10.0 horizon time",
+					  timer.isExpired(0, started, stopped, count, user_cpu, sys_cpu), false);
+		ensure_approximately_equals("WCM t5 - isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WCM t5 - isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WCM t5 - isExpired() does not modify count", count, U64L(8));
+		ensure_equals("WCM t5 - isExpired() does not modify user_cpu", user_cpu, U64L(29000));
+		ensure_equals("WCM t5 - isExpired() does not modify sys_cpu", sys_cpu, U64L(57000));
+	}
+}
+
+
+// start() test - start in the past but not beyond 1 horizon
+template<> template<>
+void deadmantimer_object_t::test<6>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(10.0, false);
+
+		// Would like to do subtraction on current time but can't because
+		// the implementation on Windows is zero-based.  We wrap around
+		// the backside resulting in a large U64 number.
+	
+		LLDeadmanTimer::time_type the_past(LLDeadmanTimer::getNow());
+		LLDeadmanTimer::time_type now(the_past + float_time_to_u64(5.0));
+		timer.start(the_past);
+		ensure_equals("WOCM t6 - isExpired() returns false with 10.0 horizon time starting 5.0 in past",
+					  timer.isExpired(now, started, stopped, count), false);
+		ensure_approximately_equals("WOCM t6 - isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WOCM t6 - isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WOCM t6 - isExpired() does not modify count", count, U64L(8));
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(10.0, true);
+
+		// Would like to do subtraction on current time but can't because
+		// the implementation on Windows is zero-based.  We wrap around
+		// the backside resulting in a large U64 number.
+	
+		LLDeadmanTimer::time_type the_past(LLDeadmanTimer::getNow());
+		LLDeadmanTimer::time_type now(the_past + float_time_to_u64(5.0));
+		timer.start(the_past);
+		ensure_equals("WCM t6 - isExpired() returns false with 10.0 horizon time starting 5.0 in past",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+		ensure_approximately_equals("WCM t6 - isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WCM t6 - isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("t6 - isExpired() does not modify count", count, U64L(8));
+		ensure_equals("WCM t6 - isExpired() does not modify user_cpu", user_cpu, U64L(29000));
+		ensure_equals("WCM t6 - isExpired() does not modify sys_cpu", sys_cpu, U64L(57000));
+	}
+}
+
+
+// start() test - start in the past but well beyond 1 horizon
+template<> template<>
+void deadmantimer_object_t::test<7>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(10.0, false);
+		
+		// Would like to do subtraction on current time but can't because
+		// the implementation on Windows is zero-based.  We wrap around
+		// the backside resulting in a large U64 number.
+	
+		LLDeadmanTimer::time_type the_past(LLDeadmanTimer::getNow());
+		LLDeadmanTimer::time_type now(the_past + float_time_to_u64(20.0));
+		timer.start(the_past);
+		ensure_equals("WOCM t7 - isExpired() returns true with 10.0 horizon time starting 20.0 in past",
+					  timer.isExpired(now,started, stopped, count), true);
+		ensure_approximately_equals("WOCM t7 - starting before horizon still gives equal started / stopped", started, stopped, 8);
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(10.0, true);
+		
+		// Would like to do subtraction on current time but can't because
+		// the implementation on Windows is zero-based.  We wrap around
+		// the backside resulting in a large U64 number.
+	
+		LLDeadmanTimer::time_type the_past(LLDeadmanTimer::getNow());
+		LLDeadmanTimer::time_type now(the_past + float_time_to_u64(20.0));
+		timer.start(the_past);
+		ensure_equals("WCM t7 - isExpired() returns true with 10.0 horizon time starting 20.0 in past",
+					  timer.isExpired(now,started, stopped, count, user_cpu, sys_cpu), true);
+		ensure_approximately_equals("WOCM t7 - starting before horizon still gives equal started / stopped", started, stopped, 8);
+	}
+}
+
+
+// isExpired() test - results are read-once.  Probes after first true are false.
+template<> template<>
+void deadmantimer_object_t::test<8>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(10.0, false);
+
+		// Would like to do subtraction on current time but can't because
+		// the implementation on Windows is zero-based.  We wrap around
+		// the backside resulting in a large U64 number.
+	
+		LLDeadmanTimer::time_type the_past(LLDeadmanTimer::getNow());
+		LLDeadmanTimer::time_type now(the_past + float_time_to_u64(20.0));
+		timer.start(the_past);
+		ensure_equals("WOCM t8 - isExpired() returns true with 10.0 horizon time starting 20.0 in past",
+					  timer.isExpired(now, started, stopped, count), true);
+		
+		started = 42.0;
+		stopped = 97.0;
+		count = U64L(8);
+		ensure_equals("WOCM t8 - second isExpired() returns false after true",
+					  timer.isExpired(now, started, stopped, count), false);
+		ensure_approximately_equals("WOCM t8 - 2nd isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WOCM t8 - 2nd isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WOCM t8 - 2nd isExpired() does not modify count", count, U64L(8));
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(10.0, true);
+
+		// Would like to do subtraction on current time but can't because
+		// the implementation on Windows is zero-based.  We wrap around
+		// the backside resulting in a large U64 number.
+	
+		LLDeadmanTimer::time_type the_past(LLDeadmanTimer::getNow());
+		LLDeadmanTimer::time_type now(the_past + float_time_to_u64(20.0));
+		timer.start(the_past);
+		ensure_equals("WCM t8 - isExpired() returns true with 10.0 horizon time starting 20.0 in past",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), true);
+		
+		started = 42.0;
+		stopped = 97.0;
+		count = U64L(8);
+		user_cpu = 29000;
+		sys_cpu = 57000;
+		ensure_equals("WCM t8 - second isExpired() returns false after true",
+					  timer.isExpired(now, started, stopped, count), false);
+		ensure_approximately_equals("WCM t8 - 2nd isExpired() does not modify started", started, F64(42.0), 2);
+		ensure_approximately_equals("WCM t8 - 2nd isExpired() does not modify stopped", stopped, F64(97.0), 2);
+		ensure_equals("WCM t8 - 2nd isExpired() does not modify count", count, U64L(8));
+		ensure_equals("WCM t8 - 2nd isExpired() does not modify user_cpu", user_cpu, U64L(29000));
+		ensure_equals("WCM t8 - 2nd isExpired() does not modify sys_cpu", sys_cpu, U64L(57000));
+	}
+}
+
+
+// ringBell() test - see that we can keep a timer from expiring
+template<> template<>
+void deadmantimer_object_t::test<9>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(5.0, false);
+
+		LLDeadmanTimer::time_type now(LLDeadmanTimer::getNow());
+		F64 real_start(u64_time_to_float(now));
+		timer.start(0);
+
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		ensure_equals("WOCM t9 - 5.0 horizon timer has not timed out after 10 1-second bell rings",
+					  timer.isExpired(now, started, stopped, count), false);
+		F64 last_good_ring(u64_time_to_float(now));
+
+		// Jump forward and expire
+		now += float_time_to_u64(10.0);
+		ensure_equals("WOCM t9 - 5.0 horizon timer expires on 10-second jump",
+					  timer.isExpired(now, started, stopped, count), true);
+		ensure_approximately_equals("WOCM t9 - started matches start() time", started, real_start, 4);
+		ensure_approximately_equals("WOCM t9 - stopped matches last ringBell() time", stopped, last_good_ring, 4);
+		ensure_equals("WOCM t9 - 10 good ringBell()s", count, U64L(10));
+		ensure_equals("WOCM t9 - single read only", timer.isExpired(now, started, stopped, count), false);
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+		LLDeadmanTimer timer(5.0, true);
+
+		LLDeadmanTimer::time_type now(LLDeadmanTimer::getNow());
+		F64 real_start(u64_time_to_float(now));
+		timer.start(0);
+
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		ensure_equals("WCM t9 - 5.0 horizon timer has not timed out after 10 1-second bell rings",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+		F64 last_good_ring(u64_time_to_float(now));
+
+		// Jump forward and expire
+		now += float_time_to_u64(10.0);
+		ensure_equals("WCM t9 - 5.0 horizon timer expires on 10-second jump",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), true);
+		ensure_approximately_equals("WCM t9 - started matches start() time", started, real_start, 4);
+		ensure_approximately_equals("WCM t9 - stopped matches last ringBell() time", stopped, last_good_ring, 4);
+		ensure_equals("WCM t9 - 10 good ringBell()s", count, U64L(10));
+		ensure_equals("WCM t9 - single read only", timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+	}
+}
+
+
+// restart after expiration test - verify that restarts behave well
+template<> template<>
+void deadmantimer_object_t::test<10>()
+{
+	{
+		// Without cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8));
+		LLDeadmanTimer timer(5.0, false);
+
+		LLDeadmanTimer::time_type now(LLDeadmanTimer::getNow());
+		F64 real_start(u64_time_to_float(now));
+		timer.start(0);
+
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		ensure_equals("WOCM t10 - 5.0 horizon timer has not timed out after 10 1-second bell rings",
+					  timer.isExpired(now, started, stopped, count), false);
+		F64 last_good_ring(u64_time_to_float(now));
+
+		// Jump forward and expire
+		now += float_time_to_u64(10.0);
+		ensure_equals("WOCM t10 - 5.0 horizon timer expires on 10-second jump",
+					  timer.isExpired(now, started, stopped, count), true);
+		ensure_approximately_equals("WOCM t10 - started matches start() time", started, real_start, 4);
+		ensure_approximately_equals("WOCM t10 - stopped matches last ringBell() time", stopped, last_good_ring, 4);
+		ensure_equals("WOCM t10 - 10 good ringBell()s", count, U64L(10));
+		ensure_equals("WOCM t10 - single read only", timer.isExpired(now, started, stopped, count), false);
+		
+		// Jump forward and restart
+		now += float_time_to_u64(1.0);
+		real_start = u64_time_to_float(now);
+		timer.start(now);
+		
+		// Run a modified bell ring sequence
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		ensure_equals("WOCM t10 - 5.0 horizon timer has not timed out after 8 1-second bell rings",
+					  timer.isExpired(now, started, stopped, count), false);
+		last_good_ring = u64_time_to_float(now);
+
+		// Jump forward and expire
+		now += float_time_to_u64(10.0);
+		ensure_equals("WOCM t10 - 5.0 horizon timer expires on 8-second jump",
+					  timer.isExpired(now, started, stopped, count), true);
+		ensure_approximately_equals("WOCM t10 - 2nd started matches start() time", started, real_start, 4);
+		ensure_approximately_equals("WOCM t10 - 2nd stopped matches last ringBell() time", stopped, last_good_ring, 4);
+		ensure_equals("WOCM t10 - 8 good ringBell()s", count, U64L(8));
+		ensure_equals("WOCM t10 - single read only - 2nd start",
+					  timer.isExpired(now, started, stopped, count), false);
+	}
+	{
+		// With cpu metrics
+		F64 started(42.0), stopped(97.0);
+		U64 count(U64L(8)), user_cpu(29000), sys_cpu(57000);
+
+		LLDeadmanTimer timer(5.0, true);
+
+		LLDeadmanTimer::time_type now(LLDeadmanTimer::getNow());
+		F64 real_start(u64_time_to_float(now));
+		timer.start(0);
+
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		ensure_equals("WCM t10 - 5.0 horizon timer has not timed out after 10 1-second bell rings",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+		F64 last_good_ring(u64_time_to_float(now));
+
+		// Jump forward and expire
+		now += float_time_to_u64(10.0);
+		ensure_equals("WCM t10 - 5.0 horizon timer expires on 10-second jump",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), true);
+		ensure_approximately_equals("WCM t10 - started matches start() time", started, real_start, 4);
+		ensure_approximately_equals("WCM t10 - stopped matches last ringBell() time", stopped, last_good_ring, 4);
+		ensure_equals("WCM t10 - 10 good ringBell()s", count, U64L(10));
+		ensure_equals("WCM t10 - single read only", timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+		
+		// Jump forward and restart
+		now += float_time_to_u64(1.0);
+		real_start = u64_time_to_float(now);
+		timer.start(now);
+		
+		// Run a modified bell ring sequence
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		now += float_time_to_u64(1.0);
+		timer.ringBell(now, 1);
+		ensure_equals("WCM t10 - 5.0 horizon timer has not timed out after 8 1-second bell rings",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+		last_good_ring = u64_time_to_float(now);
+
+		// Jump forward and expire
+		now += float_time_to_u64(10.0);
+		ensure_equals("WCM t10 - 5.0 horizon timer expires on 8-second jump",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), true);
+		ensure_approximately_equals("WCM t10 - 2nd started matches start() time", started, real_start, 4);
+		ensure_approximately_equals("WCM t10 - 2nd stopped matches last ringBell() time", stopped, last_good_ring, 4);
+		ensure_equals("WCM t10 - 8 good ringBell()s", count, U64L(8));
+		ensure_equals("WCM t10 - single read only - 2nd start",
+					  timer.isExpired(now, started, stopped, count, user_cpu, sys_cpu), false);
+	}
+}
+
+
+
+} // end namespace tut
diff --git a/indra/llcommon/tests/llprocinfo_test.cpp b/indra/llcommon/tests/llprocinfo_test.cpp
new file mode 100644
index 0000000000..12d5a695ee
--- /dev/null
+++ b/indra/llcommon/tests/llprocinfo_test.cpp
@@ -0,0 +1,91 @@
+/** 
+ * @file llprocinfo_test.cpp
+ * @brief Tests for the LLProcInfo class.
+ *
+ * $LicenseInfo:firstyear=2013&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2013, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+
+#include "../llprocinfo.h"
+
+#include "../test/lltut.h"
+#include "../lltimer.h"
+
+
+static const LLProcInfo::time_type bad_user(289375U), bad_system(275U);
+
+
+namespace tut
+{
+
+struct procinfo_test
+{
+	procinfo_test()
+		{
+		}
+};
+
+typedef test_group<procinfo_test> procinfo_group_t;
+typedef procinfo_group_t::object procinfo_object_t;
+tut::procinfo_group_t procinfo_instance("LLProcInfo");
+
+
+// Basic invocation works
+template<> template<>
+void procinfo_object_t::test<1>()
+{
+	LLProcInfo::time_type user(bad_user), system(bad_system);
+
+	set_test_name("getCPUUsage() basic function");
+
+	LLProcInfo::getCPUUsage(user, system);
+	
+	ensure_not_equals("getCPUUsage() writes to its user argument", user, bad_user);
+	ensure_not_equals("getCPUUsage() writes to its system argument", system, bad_system);
+}
+
+
+// Time increases
+template<> template<>
+void procinfo_object_t::test<2>()
+{
+	LLProcInfo::time_type user(bad_user), system(bad_system);
+	LLProcInfo::time_type user2(bad_user), system2(bad_system);
+
+	set_test_name("getCPUUsage() increases over time");
+
+	LLProcInfo::getCPUUsage(user, system);
+	
+	for (int i(0); i < 100000; ++i)
+	{
+		ms_sleep(0);
+	}
+	
+	LLProcInfo::getCPUUsage(user2, system2);
+
+	ensure_equals("getCPUUsage() user value doesn't decrease over time", user2 >= user, true);
+	ensure_equals("getCPUUsage() system value doesn't decrease over time", system2 >= system, true);
+}
+
+
+} // end namespace tut