From 699f700162f410519e5510c667aebc9940d4e91e Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Fri, 6 Apr 2012 12:39:07 +0200
Subject: [PATCH] Introduce thread local storage

Use thread local storage to store a pointer to the thread we
are running on. This will allow to remove thread info from
Position class.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---
 src/platform.h | 10 ++++++++++
 src/thread.cpp | 10 ++++++++--
 src/thread.h   |  5 ++++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/platform.h b/src/platform.h
index e002d218..a925d5f7 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -54,6 +54,7 @@ inline uint64_t time_to_msec(const sys_time_t& t) { return t.tv_sec * 1000LL + t
 typedef pthread_mutex_t Lock;
 typedef pthread_cond_t WaitCondition;
 typedef pthread_t NativeHandle;
+typedef pthread_key_t ThreadLocalStorageKey;
 typedef void*(*pt_start_fn)(void*);
 
 #  define lock_init(x) pthread_mutex_init(&(x), NULL)
@@ -67,6 +68,10 @@ typedef void*(*pt_start_fn)(void*);
 #  define cond_timedwait(x,y,z) pthread_cond_timedwait(&(x),&(y),z)
 #  define thread_create(x,f,t) !pthread_create(&(x),NULL,(pt_start_fn)f,t)
 #  define thread_join(x) pthread_join(x, NULL)
+#  define tls_init(k) pthread_key_create(&k,NULL)
+#  define tls_get(k) pthread_getspecific(k)
+#  define tls_set(k,x) pthread_setspecific(k,x)
+#  define tls_destroy(k) pthread_key_delete(k)
 
 #else // Windows and MinGW
 
@@ -91,6 +96,7 @@ inline uint64_t time_to_msec(const sys_time_t& t) { return t.time * 1000LL + t.m
 typedef CRITICAL_SECTION Lock;
 typedef HANDLE WaitCondition;
 typedef HANDLE NativeHandle;
+typedef DWORD ThreadLocalStorageKey;
 
 #  define lock_init(x) InitializeCriticalSection(&(x))
 #  define lock_grab(x) EnterCriticalSection(&(x))
@@ -103,6 +109,10 @@ typedef HANDLE NativeHandle;
 #  define cond_timedwait(x,y,z) { lock_release(y); WaitForSingleObject(x,z); lock_grab(y); }
 #  define thread_create(x,f,t) (x = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)f,t,0,NULL), x != NULL)
 #  define thread_join(x) { WaitForSingleObject(x, INFINITE); CloseHandle(x); }
+#  define tls_init(k) do { k = TlsAlloc(); } while(0)
+#  define tls_get(k) TlsGetValue(k)
+#  define tls_set(k,x) TlsSetValue(k,x)
+#  define tls_destroy(k) TlsFree(k)
 
 #endif
 
diff --git a/src/thread.cpp b/src/thread.cpp
index 54b42d46..b8686f4c 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -34,10 +34,14 @@ namespace { extern "C" {
  // start_routine() is the C function which is called when a new thread
  // is launched. It is a wrapper to member function pointed by start_fn.
 
- long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
+ long start_routine(Thread* th) {
 
-} }
+   Threads.set_this_thread(th); // Save pointer into thread local storage
+   (th->*(th->start_fn))();
+   return 0;
+ }
 
+} }
 
 // Thread c'tor starts a newly-created thread of execution that will call
 // the idle loop function pointed by start_fn going immediately to sleep.
@@ -201,6 +205,7 @@ bool Thread::is_available_to(const Thread& master) const {
 
 void ThreadsManager::init() {
 
+  tls_init(tlsKey);
   cond_init(sleepCond);
   lock_init(splitLock);
   timer = new Thread(&Thread::timer_loop);
@@ -219,6 +224,7 @@ ThreadsManager::~ThreadsManager() {
   delete timer;
   lock_destroy(splitLock);
   cond_destroy(sleepCond);
+  tls_destroy(tlsKey);
 }
 
 
diff --git a/src/thread.h b/src/thread.h
index 12fc4f23..3f3c8c4c 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -119,7 +119,9 @@ public:
   bool use_sleeping_threads() const { return useSleepingThreads; }
   int min_split_depth() const { return minimumSplitDepth; }
   int size() const { return (int)threads.size(); }
-  Thread* main_thread() { return threads[0]; }
+  Thread* main_thread() const { return threads[0]; }
+  Thread* this_thread() const { return (Thread*)tls_get(tlsKey); }
+  void set_this_thread(Thread* th) const { tls_set(tlsKey, th); }
 
   void wake_up() const;
   void sleep() const;
@@ -138,6 +140,7 @@ private:
 
   std::vector<Thread*> threads;
   Thread* timer;
+  ThreadLocalStorageKey tlsKey;
   Lock splitLock;
   WaitCondition sleepCond;
   Depth minimumSplitDepth;
-- 
2.39.2