DRTVWR-494: Use std::thread::id for LLThread::currentID().

LLThread::currentID() used to return a U32, a distinct unsigned value
incremented by explicitly constructing LLThread or by calling LLThread::
registerThreadID() early in a thread launched by other means. The latter
imposed an unobvious requirement on new code based on std::thread. Using
std::thread::id instead delegates to the compiler/library the problem of
distinguishing threads launched by any means.

Change lots of explicit U32 declarations. Introduce LLThread::id_t typedef to
avoid having to run around fixing uses again if we later revisit this decision.

LLMutex, which stores an LLThread::id_t, wants a distinguished value meaning
NO_THREAD, and had an enum with that name. But as std::thread::id promises
that the default-constructed value is distinct from every valid value,
NO_THREAD becomes unnecessary and goes away.

Because LLMutex now stores LLThread::id_t instead of U32, make llmutex.h
#include "llthread.h" instead of the other way around. This makes LLMutex an
incomplete type within llthread.h, so move LLThread::lockData() and
unlockData() to the .cpp file. Similarly, remove llrefcount.h's #include
"llmutex.h" to break circularity; instead forward-declare LLMutex.

It turns out that a number of source files assumed that #include "llthread.h"
would get the definition for LLMutex. Sprinkle #include "llmutex.h" as needed.

In the SAFE_SSL code in llcorehttp/httpcommon.cpp, there's an ssl_thread_id()
callback that returns an unsigned long to the SSL library. When LLThread::
currentID() was U32, we could simply return that. But std::thread::id is very
deliberately opaque, and can't be reinterpret_cast to unsigned long.
Fortunately it can be hashed because std::hash is specialized with that type.

1 files changed, 19 insertions, 17 deletions

diff --git a/indra/llcommon/llthread.cpp b/indra/llcommon/llthread.cpp
index f875e4e0dc..0b9dec969c 100644
--- a/indra/llcommon/llthread.cpp
+++ b/indra/llcommon/llthread.cpp
@@ -92,21 +92,16 @@ void set_thread_name( DWORD dwThreadID, const char* threadName)
 // }
 // 
 //----------------------------------------------------------------------------
-
-U32 LL_THREAD_LOCAL sThreadID = 0;
-
-U32 LLThread::sIDIter = 0;
-
 namespace
 {
 
-    U32 main_thread()
+    LLThread::id_t main_thread()
     {
         // Using a function-static variable to identify the main thread
         // requires that control reach here from the main thread before it
         // reaches here from any other thread. We simply trust that whichever
         // thread gets here first is the main thread.
-        static U32 s_thread_id = LLThread::currentID();
+        static LLThread::id_t s_thread_id = LLThread::currentID();
         return s_thread_id;
     }
 
@@ -128,10 +123,8 @@ LL_COMMON_API void assert_main_thread()
     }
 }
 
-void LLThread::registerThreadID()
-{
-    sThreadID = ++sIDIter;
-}
+// this function has become moot
+void LLThread::registerThreadID() {}
 
 //
 // Handed to the APR thread creation function
@@ -142,11 +135,12 @@ void LLThread::threadRun()
     set_thread_name(-1, mName.c_str());
 #endif
 
+    // this is the first point at which we're actually running in the new thread
+    mID = currentID();
+
     // for now, hard code all LLThreads to report to single master thread recorder, which is known to be running on main thread
     mRecorder = new LLTrace::ThreadRecorder(*LLTrace::get_master_thread_recorder());
 
-    sThreadID = mID;
-
     // Run the user supplied function
     do 
     {
@@ -188,8 +182,6 @@ LLThread::LLThread(const std::string& name, apr_pool_t *poolp) :
     mStatus(STOPPED),
     mRecorder(NULL)
 {
-
-    mID = ++sIDIter;
     mRunCondition = new LLCondition();
     mDataLock = new LLMutex();
     mLocalAPRFilePoolp = NULL ;
@@ -367,9 +359,9 @@ void LLThread::setQuitting()
 }
 
 // static
-U32 LLThread::currentID()
+LLThread::id_t LLThread::currentID()
 {
-    return sThreadID;
+    return std::this_thread::get_id();
 }
 
 // static
@@ -396,6 +388,16 @@ void LLThread::wakeLocked()
     }
 }
 
+void LLThread::lockData()
+{
+    mDataLock->lock();
+}
+
+void LLThread::unlockData()
+{
+    mDataLock->unlock();
+}
+
 //============================================================================
 
 //----------------------------------------------------------------------------