Add AICurlTimer - timer support for the curl thread.

Not used yet. Deliberately not threadsafe.
Usage the same as AIFrameTimer, upon which is was based.

indra/llmessage/aicurltimer.cpp

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+/**
+ * @file aicurltimer.cpp
+ *
+ * Copyright (c) 2013, Aleric Inglewood.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * There are special exceptions to the terms and conditions of the GPL as
+ * it is applied to this Source Code. View the full text of the exception
+ * in the file doc/FLOSS-exception.txt in this software distribution.
+ *
+ * CHANGELOG
+ *   and additional copyright holders.
+ *
+ *   29/06/2013
+ *   - Initial version, written by Aleric Inglewood @ SL
+ */
+
+// An AICurlTimer object provides a callback API for timer events
+// by and from the curl thread. It is NOT threadsafe. Everything
+// has to be called from the curl thread.
+//
+// Typical usage:
+//
+// AICurlTimer timer;
+// ...
+// // In curl thread (after successful construction is guaranteed).
+// timer.create(5.5, boost::bind(&the_callback, <optional params>));	// Call the_callback(<optional params>) in 5.5 seconds.
+//
+// The callback function is always called by the curl thread.
+//
+// If timer.cancel() is called before the timer expires, then the callback
+// function isn't called. Calling cancel() multiple times is not a problem.
+// Note: It is not allowed to call cancel() is from the callback function
+// (and rather pointless).
+//
+// The timer object can be reused (by calling create() again), but
+// only after either the callback function was called, or after cancel()
+// returned. Most notably, you can call create() again from inside the
+// callback function to "restart" the timer.
+//
+
+#include "aicurltimer.h"
+#include "lltimer.h"
+
+static U64 const NEVER = ((U64)1) << 60;	// The year 36,560,871.
+
+//static
+F64 const AICurlTimer::sClockWidth_1ms = 1000.0 / calc_clock_frequency();       // Time between two clock ticks, in 1ms units.
+U64 AICurlTimer::sTime_1ms;														// Time in 1ms units, set once per select() entry.
+U64 AICurlTimer::sNextExpiration;
+AICurlTimer::timer_list_type AICurlTimer::sTimerList;
+
+void AICurlTimer::create(deltams_type expiration, signal_type::slot_type const& slot)
+{
+	AIRunningCurlTimer new_timer(expiration, this);
+	llassert(mHandle.mRunningTimer == sTimerList.end());	// Create may only be called when the timer isn't already running.
+	mHandle.init(sTimerList.insert(new_timer), slot);
+	sNextExpiration = sTimerList.begin()->expiration();
+}
+
+void AICurlTimer::cancel(void)
+{
+    if (mHandle.mRunningTimer != sTimerList.end())
+	{
+		sTimerList.erase(mHandle.mRunningTimer);
+		mHandle.mRunningTimer = sTimerList.end();
+		sNextExpiration = sTimerList.empty() ? NEVER : sTimerList.begin()->expiration();
+	}
+}
+
+void AICurlTimer::handleExpiration(void)
+{
+	for(;;)
+	{
+		if (sTimerList.empty())
+		{
+			// No running timers left.
+			sNextExpiration = NEVER;
+			break;
+		}
+		timer_list_type::iterator running_timer = sTimerList.begin();
+		sNextExpiration = running_timer->expiration();
+		if (sNextExpiration > sTime_1ms)
+		{
+			// Didn't expire yet.
+			break;
+		}
+
+		Handle& handle(running_timer->getTimer()->mHandle);
+		llassert_always(running_timer == handle.mRunningTimer);
+		handle.mRunningTimer = sTimerList.end();
+		running_timer->do_callback();		// May not throw exceptions.
+
+		// Erase the timer from the running list.
+		sTimerList.erase(running_timer);
+	}
+}
+