From: Marco Costalba <mcostalba@gmail.com>
Date: Fri, 20 Feb 2015 11:13:09 +0000 (+0100)
Subject: Improve comments in SMP code
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=7ff965eebfbc17d2bb4be9c64d56fecf68615010;hp=a6f873cd8d05dda3638a7ea624ccbac90ecb98af

Improve comments in SMP code

No functional change.
---

diff --git a/src/search.cpp b/src/search.cpp
index bc41978f..67693a38 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1517,9 +1517,9 @@ void Thread::idle_loop() {
 
   // Pointer 'this_sp' is not null only if we are called from split(), and not
   // at the thread creation. This means we are the split point's master.
-  SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : nullptr;
+  SplitPoint* this_sp = activeSplitPoint;
 
-  assert(!this_sp || (this_sp->masterThread == this && searching));
+  assert(!this_sp || (this_sp->master == this && searching));
 
   while (!exit)
   {
@@ -1529,6 +1529,7 @@ void Thread::idle_loop() {
           Threads.mutex.lock();
 
           assert(activeSplitPoint);
+
           SplitPoint* sp = activeSplitPoint;
 
           Threads.mutex.unlock();
@@ -1567,11 +1568,11 @@ void Thread::idle_loop() {
 
           // Wake up the master thread so to allow it to return from the idle
           // loop in case we are the last slave of the split point.
-          if (    this != sp->masterThread
-              &&  sp->slavesMask.none())
+          if (this != sp->master && sp->slavesMask.none())
           {
-              assert(!sp->masterThread->searching);
-              sp->masterThread->notify_one();
+              assert(!sp->master->searching);
+
+              sp->master->notify_one();
           }
 
           // After releasing the lock we can't access any SplitPoint related data
@@ -1638,7 +1639,7 @@ void Thread::idle_loop() {
           }
       }
 
-      // Grab the lock to avoid races with Thread::notify_one()
+      // Avoid races with notify_one() fired from last slave of the split point
       std::unique_lock<std::mutex> lk(mutex);
 
       // If we are master and all slaves have finished then exit idle_loop
diff --git a/src/thread.cpp b/src/thread.cpp
index 279d9cfe..a466df87 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -145,7 +145,7 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
   // Pick and init the next available split point
   SplitPoint& sp = splitPoints[splitPointsSize];
 
-  sp.masterThread = this;
+  sp.master = this;
   sp.parentSplitPoint = activeSplitPoint;
   sp.slavesMask = 0, sp.slavesMask.set(idx);
   sp.depth = depth;
diff --git a/src/thread.h b/src/thread.h
index 54083d2e..606f9626 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -46,7 +46,7 @@ struct SplitPoint {
   // Const data after split point has been setup
   const Position* pos;
   Search::Stack* ss;
-  Thread* masterThread;
+  Thread* master;
   Depth depth;
   Value beta;
   int nodeType;