SL-15200: Add LLApp::sleep(duration) methods.

Two sleep() methods: one accepting F32Milliseconds, or in general any LLUnits
time class; the other accepting any std::chrono::duration.

The significant thing about each of these sleep() methods, as opposed to any
freestanding sleep() function, is that it only sleeps until the app starts
shutdown. Moreover, it returns true if it slept for the whole specified
duration, false if it woke for app shutdown.

This is accomplished by making LLApp::sStatus be an LLScalarCond<EAppStatus>
instead of a plain EAppStatus enum, and by making setStatus() call set_all()
each time the value changes. Then each new sleep() method can call
wait_for_unequal(duration, APP_STATUS_RUNNING).

Introducing llcond.h into llapp.h triggered an #include circularity because
llthread.h #included llapp.h even though it didn't reference anything from it.
Removed. This, in turn, necessitated adding #include "llapp.h" to several .cpp
files that reference LLApp but had been depending on other header files to
drag in llapp.h.

indra/llcommon/llapp.cpp

@@ -113,7 +113,8 @@ BOOL LLApp::sDisableCrashlogger = FALSE;
 BOOL LLApp::sLogInSignal = FALSE;
 
 // static
-LLApp::EAppStatus LLApp::sStatus = LLApp::APP_STATUS_STOPPED; // Keeps track of application status
+// Keeps track of application status
+LLScalarCond<LLApp::EAppStatus> LLApp::sStatus{LLApp::APP_STATUS_STOPPED};
 LLAppErrorHandler LLApp::sErrorHandler = NULL;
 BOOL LLApp::sErrorThreadRunning = FALSE;
 
@@ -579,7 +580,8 @@ static std::map<LLApp::EAppStatus, const char*> statusDesc
 // static
 void LLApp::setStatus(EAppStatus status)
 {
-    sStatus = status;
+    // notify everyone waiting on sStatus any time its value changes
+    sStatus.set_all(status);
 
     // This can also happen very late in the application lifecycle -- don't
     // resurrect a deleted LLSingleton
@@ -609,6 +611,12 @@ void LLApp::setError()
 	setStatus(APP_STATUS_ERROR);
 }
 
+// static
+bool LLApp::sleep(F32Milliseconds duration)
+{
+    return ! sStatus.wait_for_unequal(duration, APP_STATUS_RUNNING);
+}
+
 void LLApp::setMiniDumpDir(const std::string &path)
 {
 	if (path.empty())
@@ -668,28 +676,28 @@ void LLApp::setStopped()
 // static
 bool LLApp::isStopped()
 {
-	return (APP_STATUS_STOPPED == sStatus);
+	return (APP_STATUS_STOPPED == sStatus.get());
 }
 
 
 // static
 bool LLApp::isRunning()
 {
-	return (APP_STATUS_RUNNING == sStatus);
+	return (APP_STATUS_RUNNING == sStatus.get());
 }
 
 
 // static
 bool LLApp::isError()
 {
-	return (APP_STATUS_ERROR == sStatus);
+	return (APP_STATUS_ERROR == sStatus.get());
 }
 
 
 // static
 bool LLApp::isQuitting()
 {
-	return (APP_STATUS_QUITTING == sStatus);
+	return (APP_STATUS_QUITTING == sStatus.get());
 }
 
 // static

indra/llcommon/llapp.h

@@ -28,9 +28,11 @@
 #define LL_LLAPP_H
 
 #include <map>
+#include "llcond.h"
 #include "llrun.h"
 #include "llsd.h"
 #include <atomic>
+#include <chrono>
 // Forward declarations
 class LLErrorThread;
 class LLLiveFile;
@@ -211,6 +213,36 @@ public:
 	static bool isExiting(); // Either quitting or error (app is exiting, cleanly or not)
 	static int getPid();
 
+	//
+	// Sleep for specified time while still running
+	//
+	// For use by a coroutine or thread that performs some maintenance on a
+	// periodic basis. (See also LLEventTimer.) This method supports the
+	// pattern of an "infinite" loop that sleeps for some time, performs some
+	// action, then sleeps again. The trouble with literally sleeping a worker
+	// thread is that it could potentially sleep right through attempted
+	// application shutdown. This method avoids that by returning false as
+	// soon as the application status changes away from APP_STATUS_RUNNING
+	// (isRunning()).
+	//
+	// sleep() returns true if it sleeps undisturbed for the entire specified
+	// duration. The idea is that you can code 'while sleep(duration) ...',
+	// which will break the loop once shutdown begins.
+	//
+	// Since any time-based LLUnit should be implicitly convertible to
+	// F32Milliseconds, accept that specific type as a proxy.
+	static bool sleep(F32Milliseconds duration);
+	// Allow any duration defined in terms of <chrono>.
+	// One can imagine a wonderfully general bidirectional conversion system
+	// between any type derived from LLUnits::LLUnit<T, LLUnits::Seconds> and
+	// any std::chrono::duration -- but that doesn't yet exist.
+	template <typename Rep, typename Period>
+	bool sleep(const std::chrono::duration<Rep, Period>& duration)
+	{
+		// wait_for_unequal() has the opposite bool return convention
+		return ! sStatus.wait_for_unequal(duration, APP_STATUS_RUNNING);
+	}
+
 	/** @name Error handling methods */
 	//@{
 	/**
@@ -241,8 +273,8 @@ public:
 
 	// Return the Google Breakpad minidump filename after a crash.
 	char *getMiniDumpFilename() { return mMinidumpPath; }
-    std::string* getStaticDebugFile() { return &mStaticDebugFileName; }
-    std::string* getDynamicDebugFile() { return &mDynamicDebugFileName; }
+	std::string* getStaticDebugFile() { return &mStaticDebugFileName; }
+	std::string* getDynamicDebugFile() { return &mDynamicDebugFileName; }
 
 	// Write out a Google Breakpad minidump file.
 	void writeMiniDump();
@@ -266,7 +298,7 @@ public:
 protected:
 
 	static void setStatus(EAppStatus status);		// Use this to change the application status.
-	static EAppStatus sStatus; // Reflects current application status
+	static LLScalarCond<EAppStatus> sStatus; // Reflects current application status
 	static BOOL sErrorThreadRunning; // Set while the error thread is running
 	static BOOL sDisableCrashlogger; // Let the OS handle crashes for us.
 	std::wstring mCrashReportPipeStr;  //Name of pipe to use for crash reporting.

indra/llcommon/llthread.h

@@ -27,7 +27,6 @@
 #ifndef LL_LLTHREAD_H
 #define LL_LLTHREAD_H
 
-#include "llapp.h"
 #include "llapr.h"
 #include "boost/intrusive_ptr.hpp"
 #include "llrefcount.h"

indra/llcommon/lluuid.cpp

@@ -33,6 +33,7 @@
 #include <iphlpapi.h>
 #endif
 
+#include "llapp.h"
 #include "lldefs.h"
 #include "llerror.h"
 

indra/llcrashlogger/llcrashlogger.cpp

@@ -595,7 +595,7 @@ bool LLCrashLogger::init()
 #if LL_WINDOWS
 		Sleep(1000);
 #else
-        sleep(1);
+        ::sleep(1);
 #endif 
         locked = mKeyMaster.checkMaster();
     }

indra/llmessage/message.cpp

@@ -46,6 +46,7 @@
 #include "apr_poll.h"
 
 // linden library headers
+#include "llapp.h"
 #include "indra_constants.h"
 #include "lldir.h"
 #include "llerror.h"

indra/llplugin/llpluginprocessparent.cpp

@@ -28,6 +28,7 @@
 
 #include "linden_common.h"
 
+#include "llapp.h"
 #include "llpluginprocessparent.h"
 #include "llpluginmessagepipe.h"
 #include "llpluginmessageclasses.h"