From c483ffc773c012b49f4ea2f5bd1d788c1f0dc4ac Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Sun, 25 Mar 2012 12:01:56 +0100
Subject: [PATCH] Try to mimic std::thread API

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---
 src/platform.h |  4 ++--
 src/thread.cpp | 40 +++++++++++++++-------------------------
 src/thread.h   |  8 ++++++--
 3 files changed, 23 insertions(+), 29 deletions(-)

diff --git a/src/platform.h b/src/platform.h
index f9739c69..64122618 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -53,7 +53,7 @@ inline uint64_t time_to_msec(const sys_time_t& t) { return t.tv_sec * 1000LL + t
 #  include <pthread.h>
 typedef pthread_mutex_t Lock;
 typedef pthread_cond_t WaitCondition;
-typedef pthread_t ThreadHandle;
+typedef pthread_t NativeHandle;
 typedef void*(*start_fn)(void*);
 
 #  define lock_init(x) pthread_mutex_init(&(x), NULL)
@@ -90,7 +90,7 @@ inline uint64_t time_to_msec(const sys_time_t& t) { return t.time * 1000LL + t.m
 // but apart from this they have the same speed performance of SRW locks.
 typedef CRITICAL_SECTION Lock;
 typedef HANDLE WaitCondition;
-typedef HANDLE ThreadHandle;
+typedef HANDLE NativeHandle;
 
 #  define lock_init(x) InitializeCriticalSection(&(x))
 #  define lock_grab(x) EnterCriticalSection(&(x))
diff --git a/src/thread.cpp b/src/thread.cpp
index 031ee848..d67b9fcd 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -32,37 +32,24 @@ ThreadsManager Threads; // Global object
 namespace { extern "C" {
 
  // start_routine() is the C function which is called when a new thread
- // is launched. It simply calls idle_loop() of the supplied thread. The first
- // and last thread are special. First one is the main search thread while the
- // last one mimics a timer, they run in main_loop() and timer_loop().
+ // is launched. It is a wrapper to member function pointed by start_fn
 
-  long start_routine(Thread* th) {
-
-    if (th->threadID == 0)
-        th->main_loop();
-
-    else if (th->threadID == MAX_THREADS)
-        th->timer_loop();
-
-    else
-        th->idle_loop(NULL);
-
-    return 0;
-  }
+ long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
 
 } }
 
 
-// Thread c'tor creates and launches the OS thread, that will go immediately to
-// sleep.
+// 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.
 
-Thread::Thread(int id) {
+Thread::Thread(Fn fn) {
 
   is_searching = do_exit = false;
   maxPly = splitPointsCnt = 0;
   curSplitPoint = NULL;
-  threadID = id;
-  do_sleep = (id != 0); // Avoid a race with start_thinking()
+  start_fn = fn;
+  threadID = Threads.size();
+  do_sleep = (threadID != 0); // Avoid a race with start_thinking()
 
   lock_init(sleepLock);
   cond_init(sleepCond);
@@ -72,7 +59,7 @@ Thread::Thread(int id) {
 
   if (!thread_create(handle, start_routine, this))
   {
-      std::cerr << "Failed to create thread number " << id << std::endl;
+      std::cerr << "Failed to create thread number " << threadID << std::endl;
       ::exit(EXIT_FAILURE);
   }
 }
@@ -221,8 +208,10 @@ void ThreadsManager::read_uci_options() {
   useSleepingThreads      = Options["Use Sleeping Threads"];
   int requested           = Options["Threads"];
 
+  assert(requested > 0);
+
   while (size() < requested)
-      threads.push_back(new Thread(size()));
+      threads.push_back(new Thread(&Thread::idle_loop));
 
   while (size() > requested)
   {
@@ -264,8 +253,9 @@ void ThreadsManager::init() {
 
     cond_init(sleepCond);
     lock_init(splitLock);
-    timer = new Thread(MAX_THREADS);
-    read_uci_options(); // Creates at least the main thread
+    timer = new Thread(&Thread::timer_loop);
+    threads.push_back(new Thread(&Thread::main_loop));
+    read_uci_options();
 }
 
 
diff --git a/src/thread.h b/src/thread.h
index 6744ef31..4b712076 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -70,14 +70,17 @@ class Thread {
   Thread(const Thread&);            // Only declared to disable the default ones
   Thread& operator=(const Thread&); // that are not suitable in this case.
 
+  typedef void (Thread::* Fn) ();
+
 public:
-  Thread(int id);
+  Thread(Fn fn);
   ~Thread();
 
   void wake_up();
   bool cutoff_occurred() const;
   bool is_available_to(int master) const;
   void idle_loop(SplitPoint* sp_master);
+  void idle_loop() { idle_loop(NULL); } // Hack to allow storing in start_fn
   void main_loop();
   void timer_loop();
   void wait_for_stop_or_ponderhit();
@@ -89,7 +92,8 @@ public:
   int maxPly;
   Lock sleepLock;
   WaitCondition sleepCond;
-  ThreadHandle handle;
+  NativeHandle handle;
+  Fn start_fn;
   SplitPoint* volatile curSplitPoint;
   volatile int splitPointsCnt;
   volatile bool is_searching;
-- 
2.39.2