1 files changed, 242 insertions, 21 deletions

diff --git a/indra/llcommon/llcallbacklist.h b/indra/llcommon/llcallbacklist.h
index d6c415f7c5..b245b3db94 100644
--- a/indra/llcommon/llcallbacklist.h
+++ b/indra/llcommon/llcallbacklist.h
@@ -27,53 +27,274 @@
 #ifndef LL_LLCALLBACKLIST_H
 #define LL_LLCALLBACKLIST_H
 
+#include "lldate.h"
+#include "llsingleton.h"
 #include "llstl.h"
-#include <boost/function.hpp>
-#include <list>
+#include <boost/container_hash/hash.hpp>
+#include <boost/heap/fibonacci_heap.hpp>
+#include <boost/signals2.hpp>
+#include <functional>
+#include <unordered_map>
 
-class LLCallbackList
+/*****************************************************************************
+*   LLCallbackList: callbacks every idle tick (every callFunctions() call)
+*****************************************************************************/
+class LLCallbackList: public LLSingleton<LLCallbackList>
 {
+    LLSINGLETON(LLCallbackList);
 public:
     typedef void (*callback_t)(void*);
 
-    typedef std::pair< callback_t,void* >   callback_pair_t;
-    // NOTE: It is confirmed that we DEPEND on the order provided by using a list :(
-    //
-    typedef std::list< callback_pair_t >    callback_list_t;
+    typedef boost::signals2::signal<void()> callback_list_t;
+    typedef callback_list_t::slot_type callable_t;
+    typedef boost::signals2::connection handle_t;
+    typedef boost::signals2::scoped_connection temp_handle_t;
+    typedef std::function<bool ()> bool_func_t;
 
-    LLCallbackList();
     ~LLCallbackList();
 
-    void addFunction( callback_t func, void *data = NULL );         // register a callback, which will be called as func(data)
+    handle_t addFunction( callback_t func, void *data = NULL );     // register a callback, which will be called as func(data)
+    handle_t addFunction( const callable_t& func );
     bool containsFunction( callback_t func, void *data = NULL );    // true if list already contains the function/data pair
     bool deleteFunction( callback_t func, void *data = NULL );      // removes the first instance of this function/data pair from the list, false if not found
-    void callFunctions();                                                       // calls all functions
+    void deleteFunction( const handle_t& handle );
+    void callFunctions();                                           // calls all functions
     void deleteAllFunctions();
 
+    handle_t doOnIdleOneTime( const callable_t& func );
+    handle_t doOnIdleRepeating( const bool_func_t& func );
+    bool isRunning(const handle_t& handle) const { return handle.connected(); };
+
     static void test();
 
 protected:
-
-    inline callback_list_t::iterator find(callback_t func, void *data);
-
     callback_list_t mCallbackList;
+
+    // "Additional specializations for std::pair and the standard container
+    // types, as well as utility functions to compose hashes are available in
+    // boost::hash."
+    // https://en.cppreference.com/w/cpp/utility/hash
+    typedef std::pair< callback_t,void* >   callback_pair_t;
+    typedef std::unordered_map<callback_pair_t, handle_t,
+        boost::hash<callback_pair_t>> lookup_table;
+    lookup_table mLookup;
 };
 
-typedef boost::function<void ()> nullary_func_t;
-typedef boost::function<bool ()> bool_func_t;
+/*-------------------- legacy names in global namespace --------------------*/
+#define gIdleCallbacks (LLCallbackList::instance())
+
+using nullary_func_t = LLCallbackList::callable_t;
+using bool_func_t    = LLCallbackList::bool_func_t;
 
 // Call a given callable once in idle loop.
-void doOnIdleOneTime(nullary_func_t callable);
+inline
+LLCallbackList::handle_t doOnIdleOneTime(nullary_func_t callable)
+{
+    return gIdleCallbacks.doOnIdleOneTime(callable);
+}
 
 // Repeatedly call a callable in idle loop until it returns true.
-void doOnIdleRepeating(bool_func_t callable);
+inline
+LLCallbackList::handle_t doOnIdleRepeating(bool_func_t callable)
+{
+    return gIdleCallbacks.doOnIdleRepeating(callable);
+}
+
+/*****************************************************************************
+*   LL::Timers: callbacks at some future time
+*****************************************************************************/
+namespace LL
+{
+
+class Timers: public LLSingleton<Timers>
+{
+    LLSINGLETON(Timers);
+
+    using token_t = U32;
+
+    // Define a struct for our priority queue entries, instead of using
+    // a tuple, because we need to define the comparison operator.
+    struct func_at
+    {
+        // callback to run when this timer fires
+        bool_func_t mFunc;
+        // key to look up metadata in mHandles
+        token_t mToken;
+        // time at which this timer is supposed to fire
+        LLDate::timestamp mTime;
+
+        func_at(const bool_func_t& func, token_t token, LLDate::timestamp tm):
+            mFunc(func),
+            mToken(token),
+            mTime(tm)
+        {}
+
+        friend bool operator<(const func_at& lhs, const func_at& rhs)
+        {
+            // use greater-than because we want fibonacci_heap to select the
+            // EARLIEST time as the top()
+            return lhs.mTime > rhs.mTime;
+        }
+    };
+
+    // Accept default stable<false>: when two funcs have the same timestamp,
+    // we don't care in what order they're called.
+    // Specify constant_time_size<false>: we don't need to optimize the size()
+    // method, iow we don't need to store and maintain a count of entries.
+    typedef boost::heap::fibonacci_heap<func_at, boost::heap::constant_time_size<false>>
+        queue_t;
+
+public:
+    // If tasks that come ready during a given tick() take longer than this,
+    // defer any subsequent ready tasks to a future tick() call.
+    static constexpr F32 TIMESLICE{ 0.005f };
+
+    class handle_t
+    {
+    private:
+        friend class Timers;
+        token_t token;
+    public:
+        handle_t(token_t token=0): token(token) {}
+        bool operator==(const handle_t& rhs) const { return this->token == rhs.token; }
+        explicit operator bool() const { return bool(token); }
+        bool operator!() const { return ! bool(*this); }
+    };
 
+    // Call a given callable once at specified timestamp.
+    handle_t scheduleAt(nullary_func_t callable, LLDate::timestamp time);
+
+    // Call a given callable once after specified interval.
+    handle_t scheduleAfter(nullary_func_t callable, F32 seconds);
+
+    // Call a given callable every specified number of seconds, until it returns true.
+    handle_t scheduleEvery(bool_func_t callable, F32 seconds);
+
+    // test whether specified handle is still live
+    bool isRunning(handle_t timer) const;
+    // check remaining time
+    F32 timeUntilCall(handle_t timer) const;
+
+    // Cancel a future timer set by scheduleAt(), scheduleAfter(), scheduleEvery().
+    // Return true if and only if the handle corresponds to a live timer.
+    bool cancel(const handle_t& timer);
+    // If we're canceling a non-const handle_t, also clear it so we need not
+    // cancel again.
+    bool cancel(handle_t& timer);
+
+    // Store a handle_t returned by scheduleAt(), scheduleAfter() or
+    // scheduleEvery() in a temp_handle_t to cancel() automatically on
+    // destruction of the temp_handle_t.
+    class temp_handle_t
+    {
+    public:
+        temp_handle_t() = default;
+        temp_handle_t(const handle_t& hdl): mHandle(hdl) {}
+        temp_handle_t(const temp_handle_t&) = delete;
+        temp_handle_t(temp_handle_t&&) = default;
+        temp_handle_t& operator=(const handle_t& hdl)
+        {
+            // initializing a new temp_handle_t, then swapping it into *this,
+            // takes care of destroying any previous mHandle
+            temp_handle_t replacement(hdl);
+            swap(replacement);
+            return *this;
+        }
+        temp_handle_t& operator=(const temp_handle_t&) = delete;
+        temp_handle_t& operator=(temp_handle_t&&) = default;
+        ~temp_handle_t()
+        {
+            cancel();
+        }
+
+        // temp_handle_t should be usable wherever handle_t is
+        operator handle_t() const { return mHandle; }
+        // If we're dealing with a non-const temp_handle_t, pass a reference
+        // to our handle_t member (e.g. to Timers::cancel()).
+        operator handle_t&() { return mHandle; }
+
+        // For those in the know, provide a cancel() method of our own that
+        // avoids Timers::instance() lookup when mHandle isn't live.
+        bool cancel()
+        {
+            if (! mHandle)
+            {
+                return false;
+            }
+            else
+            {
+                return Timers::instance().cancel(mHandle);
+            }
+        }
+
+        void swap(temp_handle_t& other) noexcept
+        {
+            std::swap(this->mHandle, other.mHandle);
+        }
+
+    private:
+        handle_t mHandle;
+    };
+
+private:
+    handle_t scheduleAtEvery(bool_func_t callable, LLDate::timestamp time, F32 interval);
+    LLDate::timestamp now() const { return LLDate::now().secondsSinceEpoch(); }
+    // wrap a nullary_func_t with a bool_func_t that will only execute once
+    bool_func_t once(nullary_func_t callable)
+    {
+        return [callable]
+        {
+            callable();
+            return true;
+        };
+    }
+    bool tick();
+
+    // NOTE: We don't lock our data members because it doesn't make sense to
+    // register cross-thread callbacks. If we start wanting to use Timers on
+    // threads other than the main thread, it would make more sense to make
+    // our data members thread_local than to lock them.
+
+    // the heap aka priority queue
+    queue_t mQueue;
+
+    // metadata about a given task
+    struct Metadata
+    {
+        // handle to mQueue entry
+        queue_t::handle_type mHandle;
+        // time at which this timer is supposed to fire
+        LLDate::timestamp mTime;
+        // interval at which this timer is supposed to fire repeatedly
+        F32 mInterval{ 0 };
+        // mFunc is currently running: don't delete this entry
+        bool mRunning{ false };
+        // cancel() was called while mFunc was running: deferred cancel
+        bool mCancel{ false };
+    };
+
+    using MetaMap = std::unordered_map<token_t, Metadata>;
+    MetaMap mMeta;
+    token_t mToken{ 0 };
+    // While mQueue is non-empty, register for regular callbacks.
+    LLCallbackList::temp_handle_t mLive;
+};
+
+} // namespace LL
+
+/*-------------------- legacy names in global namespace --------------------*/
 // Call a given callable once after specified interval.
-void doAfterInterval(nullary_func_t callable, F32 seconds);
+inline
+LL::Timers::handle_t doAfterInterval(nullary_func_t callable, F32 seconds)
+{
+    return LL::Timers::instance().scheduleAfter(callable, seconds);
+}
 
 // Call a given callable every specified number of seconds, until it returns true.
-void doPeriodically(bool_func_t callable, F32 seconds);
-
-extern LLCallbackList gIdleCallbacks;
+inline
+LL::Timers::handle_t doPeriodically(bool_func_t callable, F32 seconds)
+{
+    return LL::Timers::instance().scheduleEvery(callable, seconds);
+}
 
 #endif