Merge remote-tracking branch 'suokko/main_thread_ownership_for_df_ai' into develop

library/Core.cpp

@@ -97,13 +97,36 @@ using df::global::world;
 static bool parseKeySpec(std::string keyspec, int *psym, int *pmod, std::string *pfocus = NULL);
 size_t loadScriptFiles(Core* core, color_ostream& out, const vector<std::string>& prefix, const std::string& folder);
 
-//! mainThreadSuspend keeps the main DF thread suspended from Core::Init to
+namespace DFHack {
+struct MainThread {
+    //! MainThread::suspend keeps the main DF thread suspended from Core::Init to
     //! thread exit.
-template<typename M>
+    static CoreSuspenderBase& suspend() {
-static std::unique_lock<M>& mainThreadSuspend(M& mutex) {
+        static thread_local CoreSuspenderBase lock(std::defer_lock);
-    static thread_local std::unique_lock<M> lock(mutex, std::defer_lock);
         return lock;
     }
+};
+}
+
+CoreSuspendReleaseMain::CoreSuspendReleaseMain()
+{
+    MainThread::suspend().unlock();
+}
+
+CoreSuspendReleaseMain::~CoreSuspendReleaseMain()
+{
+    MainThread::suspend().lock();
+}
+
+CoreSuspendClaimMain::CoreSuspendClaimMain()
+{
+    MainThread::suspend().lock();
+}
+
+CoreSuspendClaimMain::~CoreSuspendClaimMain()
+{
+    MainThread::suspend().unlock();
+}
 
 struct Core::Private
 {
@@ -1456,8 +1479,8 @@ void fIOthread(void * iodata)
 
 Core::~Core()
 {
-    if (mainThreadSuspend(CoreSuspendMutex).owns_lock())
+    if (MainThread::suspend().owns_lock())
-        mainThreadSuspend(CoreSuspendMutex).unlock();
+        MainThread::suspend().unlock();
 
     if (d->hotkeythread.joinable()) {
         std::lock_guard<std::mutex> lock(HotkeyMutex);
@@ -1546,7 +1569,7 @@ bool Core::Init()
 
     // Lock the CoreSuspendMutex until the thread exits or call Core::Shutdown
     // Core::Update will temporary unlock when there is any commands queued
-    mainThreadSuspend(CoreSuspendMutex).lock();
+    MainThread::suspend().lock();
 
     // Re-route stdout and stderr again - DF seems to set up stdout and
     // stderr.txt on Windows as of 0.43.05. Also, log before switching files to
@@ -2007,8 +2030,6 @@ int Core::Update()
     // Pretend this thread has suspended the core in the usual way,
     // and run various processing hooks.
     {
-        CoreSuspendClaimer suspend(true);
-
         // Initialize the core
         bool first_update = false;
 
@@ -2025,7 +2046,7 @@ int Core::Update()
     }
 
     // Let all commands run that require CoreSuspender
-    CoreWakeup.wait(mainThreadSuspend(CoreSuspendMutex),
+    CoreWakeup.wait(MainThread::suspend(),
             [this]() -> bool {return this->toolCount.load() == 0;});
 
     return 0;
@@ -2247,8 +2268,8 @@ int Core::Shutdown ( void )
     errorstate = 1;
 
     // Make sure we release main thread if this is called from main thread
-    if (mainThreadSuspend(CoreSuspendMutex).owns_lock())
+    if (MainThread::suspend().owns_lock())
-        mainThreadSuspend(CoreSuspendMutex).unlock();
+        MainThread::suspend().unlock();
 
     // Make sure the console thread shutdowns before clean up to avoid any
     // unlikely data races.

library/include/Core.h

@@ -299,14 +299,54 @@ namespace DFHack
         friend class CoreService;
         friend class ServerConnection;
         friend class CoreSuspender;
+        friend class CoreSuspenderBase;
+        friend struct CoreSuspendClaimMain;
+        friend struct CoreSuspendReleaseMain;
         ServerMain *server;
     };
 
-    template<typename Derived>
+    class CoreSuspenderBase  : protected std::unique_lock<std::recursive_mutex> {
-    struct ToolIncrement {
+    protected:
-        ToolIncrement(std::atomic<size_t>& toolCount) {
+        using parent_t = std::unique_lock<std::recursive_mutex>;
-            toolCount += 1;
+        std::thread::id tid;
+
+        CoreSuspenderBase(std::defer_lock_t d) : CoreSuspenderBase{&Core::getInstance(), d} {}
+
+        CoreSuspenderBase(Core* core, std::defer_lock_t) :
+            /* Lock the core */
+            parent_t{core->CoreSuspendMutex,std::defer_lock},
+            /* Mark this thread to be the core owner */
+            tid{}
+        {}
+    public:
+        void lock()
+        {
+            auto& core = Core::getInstance();
+            parent_t::lock();
+            tid = core.ownerThread.exchange(std::this_thread::get_id(),
+                    std::memory_order_acquire);
+        }
+
+        void unlock()
+        {
+            auto& core = Core::getInstance();
+            /* Restore core owner to previous value */
+            core.ownerThread.store(tid, std::memory_order_release);
+            if (tid == std::thread::id{})
+                Lua::Core::Reset(core.getConsole(), "suspend");
+            parent_t::unlock();
+        }
+
+        bool owns_lock() const noexcept
+        {
+            return parent_t::owns_lock();
         }
+
+        ~CoreSuspenderBase() {
+            if (owns_lock())
+                unlock();
+        }
+        friend class MainThread;
     };
 
     /*!
@@ -332,37 +372,66 @@ namespace DFHack
      *   no more tools are queued trying to acquire the
      *   Core::CoreSuspenderMutex.
      */
-    class CoreSuspender : protected ToolIncrement<CoreSuspender>,
+    class CoreSuspender : public CoreSuspenderBase {
-                          public std::unique_lock<std::recursive_mutex> {
+        using parent_t = CoreSuspenderBase;
-        using parent_t = std::unique_lock<std::recursive_mutex>;
-        Core *core;
-        std::thread::id tid;
     public:
-        CoreSuspender() : CoreSuspender(&Core::getInstance()) { }
+        CoreSuspender() : CoreSuspender{&Core::getInstance()} { }
-        CoreSuspender(bool) : CoreSuspender(&Core::getInstance()) { }
+        CoreSuspender(std::defer_lock_t d) : CoreSuspender{&Core::getInstance(),d} { }
-        CoreSuspender(Core* core, bool) : CoreSuspender(core) { }
+        CoreSuspender(bool) : CoreSuspender{&Core::getInstance()} { }
+        CoreSuspender(Core* core, bool) : CoreSuspender{core} { }
         CoreSuspender(Core* core) :
-            /* Increment the wait count */
+            CoreSuspenderBase{core, std::defer_lock}
-            ToolIncrement{core->toolCount},
+        {
-            /* Lock the core */
+            lock();
-            parent_t{core->CoreSuspendMutex},
+        }
-            core{core},
+        CoreSuspender(Core* core, std::defer_lock_t) :
-            /* Mark this thread to be the core owner */
+            CoreSuspenderBase{core, std::defer_lock}
-            tid{core->ownerThread.exchange(std::this_thread::get_id())}
         {}
-        ~CoreSuspender() {
+
-            /* Restore core owner to previous value */
+        void lock()
-            core->ownerThread.store(tid);
+        {
-            if (tid == std::thread::id{})
+            auto& core = Core::getInstance();
-                Lua::Core::Reset(core->getConsole(), "suspend");
+            core.toolCount.fetch_add(1, std::memory_order_relaxed);
+            parent_t::lock();
+        }
+
+        void unlock()
+        {
+            auto& core = Core::getInstance();
+            parent_t::unlock();
             /* Notify core to continue when all queued tools have completed
              * 0 = None wants to own the core
              * 1+ = There are tools waiting core access
              * fetch_add returns old value before subtraction
              */
-            if (core->toolCount.fetch_add(-1) == 1)
+            if (core.toolCount.fetch_add(-1, std::memory_order_relaxed) == 1)
-                core->CoreWakeup.notify_one();
+                core.CoreWakeup.notify_one();
         }
+
+        ~CoreSuspender() {
+            if (owns_lock())
+                unlock();
+        }
+    };
+
+    /*!
+     * Temporary release main thread ownership to allow alternative thread
+     * implement DF logic thread loop
+     */
+    struct DFHACK_EXPORT CoreSuspendReleaseMain {
+        CoreSuspendReleaseMain();
+        ~CoreSuspendReleaseMain();
+    };
+
+    /*!
+     * Temporary claim main thread ownership. This allows caller to call
+     * Core::Update from a different thread than original DF logic thread if
+     * logic thread has released main thread ownership with
+     * CoreSuspendReleaseMain
+     */
+    struct DFHACK_EXPORT CoreSuspendClaimMain {
+        CoreSuspendClaimMain();
+        ~CoreSuspendClaimMain();
     };
 
     using CoreSuspendClaimer = CoreSuspender;