Adding support for pre-sent messages

components/copresence/timed_map.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_COPRESENCE_TIMED_MAP_H_
 #define COMPONENTS_COPRESENCE_TIMED_MAP_H_
 
 #include <map>
 #include <queue>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 
 namespace copresence {
 
 // TimedMap is a map with the added functionality of clearing any
 // key/value pair after its specified lifetime is over.
+// TODO(ckehoe): Why is this interface so different from std::map?
 template <typename KeyType, typename ValueType>
 class TimedMap {
  public:
   TimedMap(const base::TimeDelta& lifetime, size_t max_elements)
       : kEmptyValue(ValueType()),
         clock_(new base::DefaultTickClock()),
         lifetime_(lifetime),
         max_elements_(max_elements) {
     timer_.Start(FROM_HERE, lifetime_, this, &TimedMap::ClearExpiredTokens);
   }
@@ skipping 11 matching lines @@
     ClearExpiredTokens();
     return map_.find(key) != map_.end();
   }
 
   const ValueType& GetValue(const KeyType& key) {
     ClearExpiredTokens();
     auto elt = map_.find(key);
     return elt == map_.end() ? kEmptyValue : elt->second;
   }
 
+  ValueType* GetMutableValue(const KeyType& key) {
+    ClearExpiredTokens();
+    auto elt = map_.find(key);
+    return elt == map_.end() ? nullptr : &(elt->second);
+  }
+
+  // TODO(ckehoe): Add a unit test for this.
+  size_t Erase(const KeyType& key) {
+    return map_.erase(key);
+  }
+
   void set_clock_for_testing(scoped_ptr<base::TickClock> clock) {
     clock_ = clock.Pass();
   }
 
  private:
   void ClearExpiredTokens() {
     while (!expiry_queue_.empty() &&
            expiry_queue_.top().second <= clock_->NowTicks())
       ClearOldestToken();
   }
@@ skipping 26 matching lines @@
   // Priority queue with our element keys ordered by the earliest expiring keys
   // first.
   ExpiryQueue expiry_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(TimedMap);
 };
 
 }  // namespace copresence
 
 #endif  // COMPONENTS_COPRESENCE_TIMED_MAP_H_