cannam@49: // Copyright (c) 2014 Google Inc. (contributed by Remy Blank <rblank@google.com>)
cannam@49: // Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
cannam@49: // Licensed under the MIT License:
cannam@49: //
cannam@49: // Permission is hereby granted, free of charge, to any person obtaining a copy
cannam@49: // of this software and associated documentation files (the "Software"), to deal
cannam@49: // in the Software without restriction, including without limitation the rights
cannam@49: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
cannam@49: // copies of the Software, and to permit persons to whom the Software is
cannam@49: // furnished to do so, subject to the following conditions:
cannam@49: //
cannam@49: // The above copyright notice and this permission notice shall be included in
cannam@49: // all copies or substantial portions of the Software.
cannam@49: //
cannam@49: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
cannam@49: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
cannam@49: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
cannam@49: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
cannam@49: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
cannam@49: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
cannam@49: // THE SOFTWARE.
cannam@49: 
cannam@49: #ifndef KJ_TIME_H_
cannam@49: #define KJ_TIME_H_
cannam@49: 
cannam@49: #if defined(__GNUC__) && !KJ_HEADER_WARNINGS
cannam@49: #pragma GCC system_header
cannam@49: #endif
cannam@49: 
cannam@49: #include "async.h"
cannam@49: #include "units.h"
cannam@49: #include <inttypes.h>
cannam@49: 
cannam@49: namespace kj {
cannam@49: namespace _ {  // private
cannam@49: 
cannam@49: class NanosecondLabel;
cannam@49: class TimeLabel;
cannam@49: class DateLabel;
cannam@49: 
cannam@49: }  // namespace _ (private)
cannam@49: 
cannam@49: using Duration = Quantity<int64_t, _::NanosecondLabel>;
cannam@49: // A time value, in microseconds.
cannam@49: 
cannam@49: constexpr Duration NANOSECONDS = unit<Duration>();
cannam@49: constexpr Duration MICROSECONDS = 1000 * NANOSECONDS;
cannam@49: constexpr Duration MILLISECONDS = 1000 * MICROSECONDS;
cannam@49: constexpr Duration SECONDS = 1000 * MILLISECONDS;
cannam@49: constexpr Duration MINUTES = 60 * SECONDS;
cannam@49: constexpr Duration HOURS = 60 * MINUTES;
cannam@49: constexpr Duration DAYS = 24 * HOURS;
cannam@49: 
cannam@49: using TimePoint = Absolute<Duration, _::TimeLabel>;
cannam@49: // An absolute time measured by some particular instance of `Timer`.  `Time`s from two different
cannam@49: // `Timer`s may be measured from different origins and so are not necessarily compatible.
cannam@49: 
cannam@49: using Date = Absolute<Duration, _::DateLabel>;
cannam@49: // A point in real-world time, measured relative to the Unix epoch (Jan 1, 1970 00:00:00 UTC).
cannam@49: 
cannam@49: constexpr Date UNIX_EPOCH = origin<Date>();
cannam@49: // The `Date` representing Jan 1, 1970 00:00:00 UTC.
cannam@49: 
cannam@49: class Timer {
cannam@49:   // Interface to time and timer functionality.
cannam@49:   //
cannam@49:   // Each `Timer` may have a different origin, and some `Timer`s may in fact tick at a different
cannam@49:   // rate than real time (e.g. a `Timer` could represent CPU time consumed by a thread).  However,
cannam@49:   // all `Timer`s are monotonic: time will never appear to move backwards, even if the calendar
cannam@49:   // date as tracked by the system is manually modified.
cannam@49: 
cannam@49: public:
cannam@49:   virtual TimePoint now() = 0;
cannam@49:   // Returns the current value of a clock that moves steadily forward, independent of any
cannam@49:   // changes in the wall clock. The value is updated every time the event loop waits,
cannam@49:   // and is constant in-between waits.
cannam@49: 
cannam@49:   virtual Promise<void> atTime(TimePoint time) = 0;
cannam@49:   // Returns a promise that returns as soon as now() >= time.
cannam@49: 
cannam@49:   virtual Promise<void> afterDelay(Duration delay) = 0;
cannam@49:   // Equivalent to atTime(now() + delay).
cannam@49: 
cannam@49:   template <typename T>
cannam@49:   Promise<T> timeoutAt(TimePoint time, Promise<T>&& promise) KJ_WARN_UNUSED_RESULT;
cannam@49:   // Return a promise equivalent to `promise` but which throws an exception (and cancels the
cannam@49:   // original promise) if it hasn't completed by `time`. The thrown exception is of type
cannam@49:   // "OVERLOADED".
cannam@49: 
cannam@49:   template <typename T>
cannam@49:   Promise<T> timeoutAfter(Duration delay, Promise<T>&& promise) KJ_WARN_UNUSED_RESULT;
cannam@49:   // Return a promise equivalent to `promise` but which throws an exception (and cancels the
cannam@49:   // original promise) if it hasn't completed after `delay` from now. The thrown exception is of
cannam@49:   // type "OVERLOADED".
cannam@49: 
cannam@49: private:
cannam@49:   static kj::Exception makeTimeoutException();
cannam@49: };
cannam@49: 
cannam@49: // =======================================================================================
cannam@49: // inline implementation details
cannam@49: 
cannam@49: template <typename T>
cannam@49: Promise<T> Timer::timeoutAt(TimePoint time, Promise<T>&& promise) {
cannam@49:   return promise.exclusiveJoin(atTime(time).then([]() -> kj::Promise<T> {
cannam@49:     return makeTimeoutException();
cannam@49:   }));
cannam@49: }
cannam@49: 
cannam@49: template <typename T>
cannam@49: Promise<T> Timer::timeoutAfter(Duration delay, Promise<T>&& promise) {
cannam@49:   return promise.exclusiveJoin(afterDelay(delay).then([]() -> kj::Promise<T> {
cannam@49:     return makeTimeoutException();
cannam@49:   }));
cannam@49: }
cannam@49: 
cannam@49: }  // namespace kj
cannam@49: 
cannam@49: #endif  // KJ_TIME_H_