X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=df76dcca7a2e1fe990c4859bd23219afcc8188f8;hp=002819de566ce71a2c91e2566ca481bf1376445c;hb=d58176bfead421088bb3543b3cb6d1c359a3c91b;hpb=339e1b49f619ceffa75019e196adf4de74b32cce

diff --git a/src/thread.cpp b/src/thread.cpp
index 002819de..df76dcca 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -19,36 +19,85 @@
 
 #include <iostream>
 
+#include "search.h"
 #include "thread.h"
 #include "ucioption.h"
 
-ThreadsManager ThreadsMgr; // Global object definition
+ThreadsManager Threads; // Global object definition
 
-namespace {
+namespace { extern "C" {
 
- // init_thread() is the function which is called when a new thread is
- // launched. It simply calls the idle_loop() function with the supplied
- // threadID. There are two versions of this function; one for POSIX
- // threads and one for Windows threads.
+ // 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
+ // last two threads are dedicated to read input from GUI and to mimic a
+ // timer, so they run in listener_loop() and timer_loop() respectively.
 
-#if !defined(_MSC_VER)
+#if defined(_MSC_VER)
+  DWORD WINAPI start_routine(LPVOID thread) {
+#else
+  void* start_routine(void* thread) {
+#endif
+
+    if (((Thread*)thread)->threadID == MAX_THREADS)
+        ((Thread*)thread)->listener_loop();
 
-  void* init_thread(void* threadID) {
+    else if (((Thread*)thread)->threadID == MAX_THREADS + 1)
+        ((Thread*)thread)->timer_loop();
+    else
+        ((Thread*)thread)->idle_loop(NULL);
 
-    ThreadsMgr.idle_loop(*(int*)threadID, NULL);
-    return NULL;
+    return 0;
   }
 
-#else
+} }
 
-  DWORD WINAPI init_thread(LPVOID threadID) {
 
-    ThreadsMgr.idle_loop(*(int*)threadID, NULL);
-    return 0;
-  }
+// wake_up() wakes up the thread, normally at the beginning of the search or,
+// if "sleeping threads" is used, when there is some work to do.
 
-#endif
+void Thread::wake_up() {
+
+  lock_grab(&sleepLock);
+  cond_signal(&sleepCond);
+  lock_release(&sleepLock);
+}
+
+
+// cutoff_occurred() checks whether a beta cutoff has occurred in the current
+// active split point, or in some ancestor of the split point.
+
+bool Thread::cutoff_occurred() const {
+
+  for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
+      if (sp->is_betaCutoff)
+          return true;
+  return false;
+}
+
+
+// is_available_to() checks whether the thread is available to help the thread with
+// threadID "master" at a split point. An obvious requirement is that thread must be
+// idle. With more than two threads, this is not by itself sufficient: If the thread
+// is the master of some active split point, it is only available as a slave to the
+// threads which are busy searching the split point at the top of "slave"'s split
+// point stack (the "helpful master concept" in YBWC terminology).
 
+bool Thread::is_available_to(int master) const {
+
+  if (is_searching)
+      return false;
+
+  // Make a local copy to be sure doesn't become zero under our feet while
+  // testing next condition and so leading to an out of bound access.
+  int localActiveSplitPoints = activeSplitPoints;
+
+  // No active split points means that the thread is available as a slave for any
+  // other thread otherwise apply the "helpful master" concept if possible.
+  if (   !localActiveSplitPoints
+      || splitPoints[localActiveSplitPoints - 1].is_slave[master])
+      return true;
+
+  return false;
 }
 
 
@@ -61,31 +110,51 @@ void ThreadsManager::read_uci_options() {
   maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value<int>();
   minimumSplitDepth       = Options["Minimum Split Depth"].value<int>() * ONE_PLY;
   useSleepingThreads      = Options["Use Sleeping Threads"].value<bool>();
-  activeThreads           = Options["Threads"].value<int>();
+
+  set_size(Options["Threads"].value<int>());
 }
 
 
-// init_threads() is called during startup. Initializes locks and condition
-// variables and launches all threads sending them immediately to sleep.
+// set_size() changes the number of active threads and raises do_sleep flag for
+// all the unused threads that will go immediately to sleep.
 
-void ThreadsManager::init_threads() {
+void ThreadsManager::set_size(int cnt) {
 
-  int arg[MAX_THREADS];
+  assert(cnt > 0 && cnt <= MAX_THREADS);
 
-  // This flag is needed to properly end the threads when program exits
-  allThreadsShouldExit = false;
+  activeThreads = cnt;
 
-  // Threads will sent to sleep as soon as created, only main thread is kept alive
-  activeThreads = 1;
-  threads[0].state = THREAD_SEARCHING;
+  for (int i = 0; i < MAX_THREADS; i++)
+      if (i < activeThreads)
+      {
+          // Dynamically allocate pawn and material hash tables according to the
+          // number of active threads. This avoids preallocating memory for all
+          // possible threads if only few are used as, for instance, on mobile
+          // devices where memory is scarce and allocating for MAX_THREADS could
+          // even result in a crash.
+          threads[i].pawnTable.init();
+          threads[i].materialTable.init();
+
+          threads[i].do_sleep = false;
+      }
+      else
+          threads[i].do_sleep = true;
+}
 
-  // Allocate pawn and material hash tables for main thread
-  init_hash_tables();
 
-  lock_init(&mpLock);
+// init() is called during startup. Initializes locks and condition variables
+// and launches all threads sending them immediately to sleep.
 
-  // Initialize thread and split point locks
-  for (int i = 0; i < MAX_THREADS; i++)
+void ThreadsManager::init() {
+
+  // Initialize sleep condition used to block waiting for GUI input
+  cond_init(&sleepCond);
+
+  // Initialize threads lock, used when allocating slaves during splitting
+  lock_init(&threadsLock);
+
+  // Initialize sleep and split point locks
+  for (int i = 0; i < MAX_THREADS + 2; i++)
   {
       lock_init(&threads[i].sleepLock);
       cond_init(&threads[i].sleepCond);
@@ -94,49 +163,55 @@ void ThreadsManager::init_threads() {
           lock_init(&(threads[i].splitPoints[j].lock));
   }
 
-  // Create and startup all the threads but the main that is already running
-  for (int i = 1; i < MAX_THREADS; i++)
+  // Initialize main thread's associated data
+  threads[0].is_searching = true;
+  threads[0].threadID = 0;
+  set_size(1); // This makes all the threads but the main to go to sleep
+
+  // Create and launch all the threads but the main that is already running,
+  // threads will go immediately to sleep.
+  for (int i = 1; i < MAX_THREADS + 2; i++)
   {
-      threads[i].state = THREAD_INITIALIZING;
-      arg[i] = i;
+      threads[i].is_searching = false;
+      threads[i].threadID = i;
 
-#if !defined(_MSC_VER)
-      pthread_t pthread[1];
-      bool ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0);
-      pthread_detach(pthread[0]);
+#if defined(_MSC_VER)
+      threads[i].handle = CreateThread(NULL, 0, start_routine, (LPVOID)&threads[i], 0, NULL);
+      bool ok = (threads[i].handle != NULL);
 #else
-      bool ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL);
+      bool ok = (pthread_create(&threads[i].handle, NULL, start_routine, (void*)&threads[i]) == 0);
 #endif
+
       if (!ok)
       {
-          std::cout << "Failed to create thread number " << i << std::endl;
-          exit(EXIT_FAILURE);
+          std::cerr << "Failed to create thread number " << i << std::endl;
+          ::exit(EXIT_FAILURE);
       }
-
-      // Wait until the thread has finished launching and is gone to sleep
-      while (threads[i].state == THREAD_INITIALIZING) {}
   }
 }
 
 
-// exit_threads() is called when the program exits. It makes all the
-// helper threads exit cleanly.
+// exit() is called to cleanly terminate the threads when the program finishes
 
-void ThreadsManager::exit_threads() {
+void ThreadsManager::exit() {
 
-  // Force the woken up threads to exit idle_loop() and hence terminate
-  allThreadsShouldExit = true;
-
-  for (int i = 0; i < MAX_THREADS; i++)
+  for (int i = 0; i < MAX_THREADS + 2; i++)
   {
-      // Wake up all the threads and waits for termination
       if (i != 0)
       {
+          threads[i].do_terminate = true;
           threads[i].wake_up();
-          while (threads[i].state != THREAD_TERMINATED) {}
+
+          // Wait for slave termination
+#if defined(_MSC_VER)
+          WaitForSingleObject(threads[i].handle, 0);
+          CloseHandle(threads[i].handle);
+#else
+          pthread_join(threads[i].handle, NULL);
+#endif
       }
 
-      // Now we can safely destroy the locks and wait conditions
+      // Now we can safely destroy locks and wait conditions
       lock_destroy(&threads[i].sleepLock);
       cond_destroy(&threads[i].sleepCond);
 
@@ -144,86 +219,20 @@ void ThreadsManager::exit_threads() {
           lock_destroy(&(threads[i].splitPoints[j].lock));
   }
 
-  lock_destroy(&mpLock);
+  lock_destroy(&threadsLock);
+  cond_destroy(&sleepCond);
 }
 
 
-// init_hash_tables() dynamically allocates pawn and material hash tables
-// according to the number of active threads. This avoids preallocating
-// memory for all possible threads if only few are used as, for instance,
-// on mobile devices where memory is scarce and allocating for MAX_THREADS
-// threads could even result in a crash.
-
-void ThreadsManager::init_hash_tables() {
-
-  for (int i = 0; i < activeThreads; i++)
-  {
-      threads[i].pawnTable.init();
-      threads[i].materialTable.init();
-  }
-}
-
-
-// cutoff_at_splitpoint() checks whether a beta cutoff has occurred in
-// the thread's currently active split point, or in some ancestor of
-// the current split point.
-
-bool ThreadsManager::cutoff_at_splitpoint(int threadID) const {
-
-  assert(threadID >= 0 && threadID < activeThreads);
-
-  SplitPoint* sp = threads[threadID].splitPoint;
-
-  for ( ; sp && !sp->betaCutoff; sp = sp->parent) {}
-  return sp != NULL;
-}
-
-
-// thread_is_available() checks whether the thread with threadID "slave" is
-// available to help the thread with threadID "master" at a split point. An
-// obvious requirement is that "slave" must be idle. With more than two
-// threads, this is not by itself sufficient:  If "slave" is the master of
-// some active split point, it is only available as a slave to the other
-// threads which are busy searching the split point at the top of "slave"'s
-// split point stack (the "helpful master concept" in YBWC terminology).
-
-bool ThreadsManager::thread_is_available(int slave, int master) const {
-
-  assert(slave >= 0 && slave < activeThreads);
-  assert(master >= 0 && master < activeThreads);
-  assert(activeThreads > 1);
-
-  if (threads[slave].state != THREAD_AVAILABLE || slave == master)
-      return false;
-
-  // Make a local copy to be sure doesn't change under our feet
-  int localActiveSplitPoints = threads[slave].activeSplitPoints;
-
-  // No active split points means that the thread is available as
-  // a slave for any other thread.
-  if (localActiveSplitPoints == 0 || activeThreads == 2)
-      return true;
-
-  // Apply the "helpful master" concept if possible. Use localActiveSplitPoints
-  // that is known to be > 0, instead of threads[slave].activeSplitPoints that
-  // could have been set to 0 by another thread leading to an out of bound access.
-  if (threads[slave].splitPoints[localActiveSplitPoints - 1].slaves[master])
-      return true;
-
-  return false;
-}
-
-
-// available_thread_exists() tries to find an idle thread which is available as
+// available_slave_exists() tries to find an idle thread which is available as
 // a slave for the thread with threadID "master".
 
-bool ThreadsManager::available_thread_exists(int master) const {
+bool ThreadsManager::available_slave_exists(int master) const {
 
   assert(master >= 0 && master < activeThreads);
-  assert(activeThreads > 1);
 
   for (int i = 0; i < activeThreads; i++)
-      if (thread_is_available(i, master))
+      if (i != master && threads[i].is_available_to(master))
           return true;
 
   return false;
@@ -240,13 +249,13 @@ bool ThreadsManager::available_thread_exists(int master) const {
 // call search().When all threads have returned from search() then split() returns.
 
 template <bool Fake>
-void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta,
-                           Value* bestValue, Depth depth, Move threatMove,
-                           int moveCount, MovePicker* mp, bool pvNode) {
-  assert(pos.is_ok());
-  assert(*bestValue >= -VALUE_INFINITE);
-  assert(*bestValue <= *alpha);
-  assert(*alpha < beta);
+Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value beta,
+                            Value bestValue, Depth depth, Move threatMove,
+                            int moveCount, MovePicker* mp, int nodeType) {
+  assert(pos.pos_is_ok());
+  assert(bestValue >= -VALUE_INFINITE);
+  assert(bestValue <= alpha);
+  assert(alpha < beta);
   assert(beta <= VALUE_INFINITE);
   assert(depth > DEPTH_ZERO);
   assert(pos.thread() >= 0 && pos.thread() < activeThreads);
@@ -255,93 +264,230 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V
   int i, master = pos.thread();
   Thread& masterThread = threads[master];
 
-  lock_grab(&mpLock);
-
-  // If no other thread is available to help us, or if we have too many
-  // active split points, don't split.
-  if (   !available_thread_exists(master)
-      || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
-  {
-      lock_release(&mpLock);
-      return;
-  }
+  // If we already have too many active split points, don't split
+  if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
+      return bestValue;
 
   // Pick the next available split point object from the split point stack
-  SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++];
+  SplitPoint* sp = masterThread.splitPoints + masterThread.activeSplitPoints;
 
   // Initialize the split point object
-  splitPoint.parent = masterThread.splitPoint;
-  splitPoint.master = master;
-  splitPoint.betaCutoff = false;
-  splitPoint.depth = depth;
-  splitPoint.threatMove = threatMove;
-  splitPoint.alpha = *alpha;
-  splitPoint.beta = beta;
-  splitPoint.pvNode = pvNode;
-  splitPoint.bestValue = *bestValue;
-  splitPoint.mp = mp;
-  splitPoint.moveCount = moveCount;
-  splitPoint.pos = &pos;
-  splitPoint.nodes = 0;
-  splitPoint.ss = ss;
+  sp->parent = masterThread.splitPoint;
+  sp->master = master;
+  sp->is_betaCutoff = false;
+  sp->depth = depth;
+  sp->threatMove = threatMove;
+  sp->alpha = alpha;
+  sp->beta = beta;
+  sp->nodeType = nodeType;
+  sp->bestValue = bestValue;
+  sp->mp = mp;
+  sp->moveCount = moveCount;
+  sp->pos = &pos;
+  sp->nodes = 0;
+  sp->ss = ss;
   for (i = 0; i < activeThreads; i++)
-      splitPoint.slaves[i] = 0;
-
-  masterThread.splitPoint = &splitPoint;
+      sp->is_slave[i] = false;
 
   // If we are here it means we are not available
-  assert(masterThread.state != THREAD_AVAILABLE);
+  assert(masterThread.is_searching);
 
   int workersCnt = 1; // At least the master is included
 
-  // Allocate available threads setting state to THREAD_BOOKED
+  // Try to allocate available threads and ask them to start searching setting
+  // the state to Thread::WORKISWAITING, this must be done under lock protection
+  // to avoid concurrent allocation of the same slave by another master.
+  lock_grab(&threadsLock);
+
   for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
-      if (thread_is_available(i, master))
+      if (i != master && threads[i].is_available_to(master))
       {
-          threads[i].state = THREAD_BOOKED;
-          threads[i].splitPoint = &splitPoint;
-          splitPoint.slaves[i] = 1;
           workersCnt++;
-      }
+          sp->is_slave[i] = true;
+          threads[i].splitPoint = sp;
 
-  assert(Fake || workersCnt > 1);
+          // This makes the slave to exit from idle_loop()
+          threads[i].is_searching = true;
 
-  // We can release the lock because slave threads are already booked and master is not available
-  lock_release(&mpLock);
+          if (useSleepingThreads)
+              threads[i].wake_up();
+      }
 
-  // Tell the threads that they have work to do. This will make them leave
-  // their idle loop.
-  for (i = 0; i < activeThreads; i++)
-      if (i == master || splitPoint.slaves[i])
-      {
-          assert(i == master || threads[i].state == THREAD_BOOKED);
+  lock_release(&threadsLock);
 
-          threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop()
+  // We failed to allocate even one slave, return
+  if (!Fake && workersCnt == 1)
+      return bestValue;
 
-          if (useSleepingThreads && i != master)
-              threads[i].wake_up();
-      }
+  masterThread.splitPoint = sp;
+  masterThread.activeSplitPoints++;
+
+  // Everything is set up. The master thread enters the idle loop, from which
+  // it will instantly launch a search, because its is_searching flag is set.
+  // We pass the split point as a parameter to the idle loop, which means that
+  // the thread will return from the idle loop when all slaves have finished
+  // their work at this split point.
+  masterThread.idle_loop(sp);
 
-  // Everything is set up. The master thread enters the idle loop, from
-  // which it will instantly launch a search, because its state is
-  // THREAD_WORKISWAITING.  We send the split point as a second parameter to the
-  // idle loop, which means that the main thread will return from the idle
-  // loop when all threads have finished their work at this split point.
-  idle_loop(master, &splitPoint);
+  // In helpful master concept a master can help only a sub-tree, and
+  // because here is all finished is not possible master is booked.
+  assert(!masterThread.is_searching);
 
   // We have returned from the idle loop, which means that all threads are
-  // finished. Update alpha and bestValue, and return.
-  lock_grab(&mpLock);
+  // finished. Note that changing state and decreasing activeSplitPoints is done
+  // under lock protection to avoid a race with Thread::is_available_to().
+  lock_grab(&threadsLock);
 
-  *alpha = splitPoint.alpha;
-  *bestValue = splitPoint.bestValue;
+  masterThread.is_searching = true;
   masterThread.activeSplitPoints--;
-  masterThread.splitPoint = splitPoint.parent;
-  pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
 
-  lock_release(&mpLock);
+  lock_release(&threadsLock);
+
+  masterThread.splitPoint = sp->parent;
+  pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
+
+  return sp->bestValue;
 }
 
 // Explicit template instantiations
-template void ThreadsManager::split<0>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
-template void ThreadsManager::split<1>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
+template Value ThreadsManager::split<false>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+template Value ThreadsManager::split<true>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+
+
+// Thread::timer_loop() is where the timer thread waits maxPly milliseconds
+// and then calls do_timer_event().
+
+void Thread::timer_loop() {
+
+  while (!do_terminate)
+  {
+      lock_grab(&sleepLock);
+      timed_wait(&sleepCond, &sleepLock, maxPly ? maxPly : INT_MAX);
+      lock_release(&sleepLock);
+      do_timer_event();
+  }
+}
+
+
+// ThreadsManager::set_timer() is used to set the timer to trigger after msec
+// milliseconds. If msec is 0 then timer is stopped.
+
+void ThreadsManager::set_timer(int msec) {
+
+  Thread& timer = threads[MAX_THREADS + 1];
+
+  lock_grab(&timer.sleepLock);
+  timer.maxPly = msec;
+  cond_signal(&timer.sleepCond); // Wake up and restart the timer
+  lock_release(&timer.sleepLock);
+}
+
+
+// Thread::listener_loop() is where the listener thread, used for I/O, waits for
+// input. When is_searching is false then input is read in sync with main thread
+// (that blocks), otherwise the listener thread reads any input asynchronously
+// and processes the input line calling do_uci_async_cmd().
+
+void Thread::listener_loop() {
+
+  std::string cmd;
+
+  while (true)
+  {
+      lock_grab(&sleepLock);
+
+      Threads.inputLine = cmd;
+      do_sleep = !is_searching;
+
+      // Here the thread is parked in sync mode after a line has been read
+      while (do_sleep && !do_terminate) // Catches spurious wake ups
+      {
+          cond_signal(&Threads.sleepCond);   // Wake up main thread
+          cond_wait(&sleepCond, &sleepLock); // Sleep here
+      }
+
+      lock_release(&sleepLock);
+
+      if (do_terminate)
+          return;
+
+      if (!std::getline(std::cin, cmd)) // Block waiting for input
+          cmd = "quit";
+
+      lock_grab(&sleepLock);
+
+      // If we are in async mode then process the command now
+      if (is_searching)
+      {
+          // Command "quit" is the last one received by the GUI, so park the
+          // thread waiting for exiting.
+          if (cmd == "quit")
+              is_searching = false;
+
+          do_uci_async_cmd(cmd);
+          cmd = ""; // Input has been consumed
+      }
+
+      lock_release(&sleepLock);
+  }
+}
+
+
+// ThreadsManager::getline() is used by main thread to block and wait for input,
+// the behaviour mimics std::getline().
+
+void ThreadsManager::getline(std::string& cmd) {
+
+  Thread& listener = threads[MAX_THREADS];
+
+  lock_grab(&listener.sleepLock);
+
+  listener.is_searching = false; // Set sync mode
+
+  // If there is already some input to grab then skip without to wake up the
+  // listener. This can happen if after we send the "bestmove", the GUI sends
+  // a command that the listener buffers in inputLine before going to sleep.
+  if (inputLine.empty())
+  {
+      listener.do_sleep = false;
+      cond_signal(&listener.sleepCond); // Wake up listener thread
+
+      while (!listener.do_sleep)
+          cond_wait(&sleepCond, &listener.sleepLock); // Wait for input
+  }
+
+  cmd = inputLine;
+  inputLine = ""; // Input has been consumed
+
+  lock_release(&listener.sleepLock);
+}
+
+
+// ThreadsManager::start_listener() is called at the beginning of the search to
+// swith from sync behaviour (default) to async and so be able to read from UCI
+// while other threads are searching. This avoids main thread polling for input.
+
+void ThreadsManager::start_listener() {
+
+  Thread& listener = threads[MAX_THREADS];
+
+  lock_grab(&listener.sleepLock);
+  listener.is_searching = true;
+  listener.do_sleep = false;
+  cond_signal(&listener.sleepCond); // Wake up listener thread
+  lock_release(&listener.sleepLock);
+}
+
+
+// ThreadsManager::stop_listener() is called before to send "bestmove" to GUI to
+// return to in-sync behaviour. This is needed because while in async mode any
+// command is discarded without being processed (except for a very few ones).
+
+void ThreadsManager::stop_listener() {
+
+  Thread& listener = threads[MAX_THREADS];
+
+  lock_grab(&listener.sleepLock);
+  listener.is_searching = false;
+  lock_release(&listener.sleepLock);
+}