Issue #1652, #3456 - Replace 's_asyncWebBrowser2' with thread-safe facilities

src/plugin/Instances.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus 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 Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #ifndef _INSTANCES_H_
 #define _INSTANCES_H_
 
+#include <map>
 #include <mutex>
-#include <map>
+#include <set>
 
 /**
  * A base class for a synchronized map from threads to BHO instances.
  *
  * This is a base class for 'CurrentThreadMap', defined in PluginClass.cpp.
  * It's separated out here for testability.
  * This class should not be used as polymorphic base class, as it has no virtual base class.
  *
  * The member functions here not simply forwarded versions of the container functions.
  * Rather, they are specialized for tracking BHO calls to SetSite().
@@ skipping 56 matching lines @@
    * Returns nullValue otherwise.
    */
   T Locate(Key id) const
   {
     SentryType sentry(mutex);
     auto it = idMap.find(id);
     return (it != idMap.end()) ? it->second : nullValue;
   }
 };
 
+/**
+ * Template class for a synchronized set of BHO instances
+ */
+template<class T, T nullValue>
+class SyncSet
+{
+  typedef std::lock_guard<std::mutex> SentryType;
+
+  /**
+   * Underlying set container
+   */
+  std::set<T> set;
+
+  /**
+   * Synchronization primitive
+   */
+  mutable std::mutex mutex;
+
+public:
+  /**
+   * \return
+   *   true if (as expected) the argument was not already a member of the set
+   *   false otherwise
+   *
+   * \par Postcondition
+   *   - argument is a member of the set
+   */
+  bool InsertIfAbsent(T p)
+  {
+    SentryType sentry(mutex);
+    auto it = set.find(p);
+    if (it != set.end())
+    {
+      return false;
+    }
+    set.insert(p);
+    return true;
+  }
+
+  /**
+   * \return
+   *   true if (as expected) the argument was already a member of the set
+   *   false otherwise
+   *
+   * \par Postcondition
+   *   - argument is not a member of the set
+   */
+  bool EraseWithCheck(T p)
+  {
+    SentryType sentry(mutex);
+    auto it = set.find(p);
+    if (it == set.end())
+    {
+      return false;
+    }
+    set.erase(it);
+    return true;
+  }
+
+  /**
+   * \param f
+   *   Search criterion is a simple predicate function 
+   *
+   * \return
+   *   - If no member of the set meets the search criterion, the null value
+   *   - Otherwise some member of the set that meets the search criterion
+   */
+  T LinearSearch(std::function<bool(T)> f)
+  {
+    SentryType sentry(mutex);
+    for (auto member : set)
+    {
+      bool b = f(member);
+      if (b)
+      {
+        return member;
+      }
+    }
+    return nullValue;
+  }
+
+  bool Empty() const
+  {
+    SentryType sentry(mutex);
+    return set.empty();
+  }
+};
+
 #endif