--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Resources/ImplementationNotes/JobsEngineStates.dot	Thu May 03 15:24:33 2018 +0200
@@ -0,0 +1,23 @@
+// dot -Tpdf JobsEngineStates.dot -o JobsEngineStates.pdf
+
+digraph G
+{
+  rankdir="LR";
+  init [shape=point];
+  failure, success [shape=doublecircle];
+
+  // Internal transitions
+  init -> pending;
+  pending -> running;
+  running -> success;
+  running -> failure;
+  running -> retry;
+  retry -> pending [label="timeout"];
+
+  // External actions
+  failure -> pending  [label="Resubmit()" fontcolor="red"];
+  paused -> pending  [label="Resume()" fontcolor="red"];
+  pending -> paused  [label="Pause()" fontcolor="red"];
+  retry -> paused  [label="Pause()" fontcolor="red"];
+  running -> paused  [label="Pause()" fontcolor="red"];
+ }

--- a/UnitTestsSources/MultiThreadingTests.cpp	Thu May 03 13:45:31 2018 +0200
+++ b/UnitTestsSources/MultiThreadingTests.cpp	Thu May 03 15:24:33 2018 +0200
@@ -481,13 +481,13 @@
       }
       else
       {
-        return retryTime_ >= now;
+        return retryTime_ <= now;
       }
     }
   };
 
 
-  class JobsMonitor : public boost::noncopyable
+  class JobsRegistry : public boost::noncopyable
   {
   private:
     struct PriorityComparator
@@ -506,641 +506,661 @@
                                 std::vector<JobHandler*>,   // Could be a "std::deque"
                                 PriorityComparator>         PendingJobs;
 
-    boost::mutex               mutex_;
-    JobsIndex                  jobsIndex_;
-    PendingJobs                pendingJobs_;
-    CompletedJobs              completedJobs_;
-    RetryJobs                  retryJobs_;
+  boost::mutex               mutex_;
+  JobsIndex                  jobsIndex_;
+  PendingJobs                pendingJobs_;
+  CompletedJobs              completedJobs_;
+  RetryJobs                  retryJobs_;
 
-    boost::condition_variable  pendingJobAvailable_;
-    size_t                     maxCompletedJobs_;
+  boost::condition_variable  pendingJobAvailable_;
+  size_t                     maxCompletedJobs_;
 
 
 #ifndef NDEBUG
-    bool IsPendingJob(const JobHandler& job) const
+  bool IsPendingJob(const JobHandler& job) const
+  {
+    PendingJobs copy = pendingJobs_;
+    while (!copy.empty())
+    {
+      if (copy.top() == &job)
+      {
+        return true;
+      }
+
+      copy.pop();
+    }
+
+    return false;
+  }
+
+  bool IsCompletedJob(const JobHandler& job) const
+  {
+    for (CompletedJobs::const_iterator it = completedJobs_.begin();
+         it != completedJobs_.end(); ++it)
+    {
+      if (*it == &job)
+      {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  bool IsRetryJob(JobHandler& job) const
+  {
+    return retryJobs_.find(&job) != retryJobs_.end();
+  }
+#endif
+
+
+  void CheckInvariants()
+  {
+#ifndef NDEBUG
     {
       PendingJobs copy = pendingJobs_;
       while (!copy.empty())
       {
-        if (copy.top() == &job)
-        {
-          return true;
-        }
-
+        assert(copy.top()->GetState() == JobState_Pending);
         copy.pop();
       }
+    }
 
-      return false;
+    assert(completedJobs_.size() <= maxCompletedJobs_);
+
+    for (CompletedJobs::const_iterator it = completedJobs_.begin();
+         it != completedJobs_.end(); ++it)
+    {
+      assert((*it)->GetState() == JobState_Success ||
+             (*it)->GetState() == JobState_Failure);
+    }
+
+    for (RetryJobs::const_iterator it = retryJobs_.begin();
+         it != retryJobs_.end(); ++it)
+    {
+      assert((*it)->GetState() == JobState_Retry);
     }
 
-    bool IsCompletedJob(const JobHandler& job) const
+    for (JobsIndex::iterator it = jobsIndex_.begin();
+         it != jobsIndex_.end(); ++it)
     {
-      for (CompletedJobs::const_iterator it = completedJobs_.begin();
-           it != completedJobs_.end(); ++it)
+      JobHandler& job = *it->second;
+
+      assert(job.GetId() == it->first);
+
+      switch (job.GetState())
       {
-        if (*it == &job)
-        {
-          return true;
-        }
-      }
+        case JobState_Pending:
+          assert(!IsRetryJob(job) && IsPendingJob(job) && !IsCompletedJob(job));
+          break;
+            
+        case JobState_Success:
+        case JobState_Failure:
+          assert(!IsRetryJob(job) && !IsPendingJob(job) && IsCompletedJob(job));
+          break;
+            
+        case JobState_Retry:
+          assert(IsRetryJob(job) && !IsPendingJob(job) && !IsCompletedJob(job));
+          break;
+            
+        case JobState_Running:
+        case JobState_Paused:
+          assert(!IsRetryJob(job) && !IsPendingJob(job) && !IsCompletedJob(job));
+          break;
 
-      return false;
-    }
-
-    bool IsRetryJob(JobHandler& job) const
-    {
-      return retryJobs_.find(&job) != retryJobs_.end();
+        default:
+          throw OrthancException(ErrorCode_InternalError);
+      }
     }
 #endif
+  }
 
 
-    void CheckInvariants()
+  void ForgetOldCompletedJobs()
+  {
+    if (maxCompletedJobs_ != 0)
     {
-#ifndef NDEBUG
-      {
-        PendingJobs copy = pendingJobs_;
-        while (!copy.empty())
-        {
-          assert(copy.top()->GetState() == JobState_Pending);
-          copy.pop();
-        }
-      }
-
-      assert(completedJobs_.size() <= maxCompletedJobs_);
-
-      for (CompletedJobs::const_iterator it = completedJobs_.begin();
-           it != completedJobs_.end(); ++it)
-      {
-        assert((*it)->GetState() == JobState_Success ||
-               (*it)->GetState() == JobState_Failure);
-      }
-
-      for (RetryJobs::const_iterator it = retryJobs_.begin();
-           it != retryJobs_.end(); ++it)
-      {
-        assert((*it)->GetState() == JobState_Retry);
-      }
-
-      for (JobsIndex::iterator it = jobsIndex_.begin();
-           it != jobsIndex_.end(); ++it)
+      while (completedJobs_.size() > maxCompletedJobs_)
       {
-        JobHandler& job = *it->second;
+        assert(completedJobs_.front() != NULL);
+
+        std::string id = completedJobs_.front()->GetId();
+        assert(jobsIndex_.find(id) != jobsIndex_.end());
 
-        assert(job.GetId() == it->first);
+        jobsIndex_.erase(id);
+        delete(completedJobs_.front());
+        completedJobs_.pop_front();
+      }
+    }
+  }
+
 
-        switch (job.GetState())
-        {
-          case JobState_Pending:
-            assert(!IsRetryJob(job) && IsPendingJob(job) && !IsCompletedJob(job));
-            break;
-            
-          case JobState_Success:
-          case JobState_Failure:
-            assert(!IsRetryJob(job) && !IsPendingJob(job) && IsCompletedJob(job));
-            break;
-            
-          case JobState_Retry:
-            assert(IsRetryJob(job) && !IsPendingJob(job) && !IsCompletedJob(job));
-            break;
-            
-          case JobState_Running:
-          case JobState_Paused:
-            assert(!IsRetryJob(job) && !IsPendingJob(job) && !IsCompletedJob(job));
-            break;
+  void MarkRunningAsCompleted(JobHandler& job,
+                              bool success)
+  {
+    LOG(INFO) << "Job has completed with " << (success ? "success" : "failure")
+              << ": " << job.GetId();
 
-          default:
-            throw OrthancException(ErrorCode_InternalError);
-        }
-      }
-#endif
-    }
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+    assert(job.GetState() == JobState_Running);
+
+    job.SetState(success ? JobState_Success : JobState_Failure);
+
+    completedJobs_.push_back(&job);
+    ForgetOldCompletedJobs();
+
+    CheckInvariants();
+  }
 
 
-    void ForgetOldCompletedJobs()
-    {
-      if (maxCompletedJobs_ != 0)
-      {
-        while (completedJobs_.size() > maxCompletedJobs_)
-        {
-          assert(completedJobs_.front() != NULL);
+  void MarkRunningAsRetry(JobHandler& job,
+                          unsigned int timeout)
+  {
+    LOG(INFO) << "Job scheduled for retry in " << timeout << "ms: " << job.GetId();
+
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+
+    assert(job.GetState() == JobState_Running &&
+           retryJobs_.find(&job) == retryJobs_.end());
+
+    retryJobs_.insert(&job);
+    job.SetRetryState(timeout);
+
+    CheckInvariants();
+  }
+
+
+  void MarkRunningAsPaused(JobHandler& job)
+  {
+    LOG(INFO) << "Job paused: " << job.GetId();
 
-          std::string id = completedJobs_.front()->GetId();
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+    assert(job.GetState() == JobState_Running);
+
+    job.SetState(JobState_Paused);
 
-          assert(jobsIndex_.find(id) != jobsIndex_.end());
+    CheckInvariants();
+  }
+
+
+  JobHandler* WaitPendingJob(unsigned int timeout)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
 
-          jobsIndex_.erase(id);
-          delete(completedJobs_.front());
-          completedJobs_.pop_front();
+    while (pendingJobs_.empty())
+    {
+      if (timeout == 0)
+      {
+        pendingJobAvailable_.wait(lock);
+      }
+      else
+      {
+        bool success = pendingJobAvailable_.timed_wait
+          (lock, boost::posix_time::milliseconds(timeout));
+        if (!success)
+        {
+          return NULL;
         }
       }
     }
 
-
-    void MarkRunningAsCompleted(JobHandler& job,
-                                bool success)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-      assert(job.GetState() == JobState_Running);
+    JobHandler* job = pendingJobs_.top();
+    pendingJobs_.pop();
+      
+    job->SetState(JobState_Running);
+    return job;
+  }
 
-      job.SetState(success ? JobState_Success : JobState_Failure);
 
-      completedJobs_.push_back(&job);
-      ForgetOldCompletedJobs();
-
-      CheckInvariants();
-    }
+public:
+  JobsRegistry() :
+    maxCompletedJobs_(10)
+  {
+  }
 
 
-    void MarkRunningAsRetry(JobHandler& job,
-                            unsigned int timeout)
+  ~JobsRegistry()
+  {
+    for (JobsIndex::iterator it = jobsIndex_.begin(); it != jobsIndex_.end(); ++it)
     {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
+      assert(it->second != NULL);
+      delete it->second;
+    }
+  }
+
+
+  void SetMaxCompletedJobs(size_t i)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
 
-      assert(job.GetState() == JobState_Running &&
-             retryJobs_.find(&job) == retryJobs_.end());
+    maxCompletedJobs_ = i;
+    ForgetOldCompletedJobs();
+
+    CheckInvariants();
+  }
+
 
-      retryJobs_.insert(&job);
-      job.SetRetryState(timeout);
+  void ListJobs(std::set<std::string>& target)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
 
-      CheckInvariants();
+    for (JobsIndex::const_iterator it = jobsIndex_.begin();
+         it != jobsIndex_.end(); ++it)
+    {
+      target.insert(it->first);
     }
+  }
 
 
-    void MarkRunningAsPaused(JobHandler& job)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-      assert(job.GetState() == JobState_Running);
+  void Submit(std::string& id,
+              IJob* job,        // Takes ownership
+              int priority)
+  {
+    std::auto_ptr<JobHandler>  handler(new JobHandler(job, priority));
+
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+      
+    id = handler->GetId();
+
+    pendingJobs_.push(handler.get());
+    pendingJobAvailable_.notify_one();
 
-      job.SetState(JobState_Paused);
+    jobsIndex_.insert(std::make_pair(id, handler.release()));
+
+    LOG(INFO) << "New job submitted: " << id;
+
+    CheckInvariants();
+  }
 
-      CheckInvariants();
-    }
+
+  void Submit(IJob* job,        // Takes ownership
+              int priority)
+  {
+    std::string id;
+    Submit(id, job, priority);
+  }
 
 
-    JobHandler* WaitPendingJob(unsigned int timeout)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
+  void SetPriority(const std::string& id,
+                   int priority)
+  {
+    LOG(INFO) << "Changing priority to " << priority << " for job: " << id;
 
-      while (pendingJobs_.empty())
-      {
-        if (timeout == 0)
-        {
-          pendingJobAvailable_.wait(lock);
-        }
-        else
-        {
-          bool success = pendingJobAvailable_.timed_wait
-            (lock, boost::posix_time::milliseconds(timeout));
-          if (!success)
-          {
-            return NULL;
-          }
-        }
-      }
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+
+    JobsIndex::iterator found = jobsIndex_.find(id);
 
-      JobHandler* job = pendingJobs_.top();
-      pendingJobs_.pop();
-      
-      job->SetState(JobState_Running);
-      return job;
+    if (found == jobsIndex_.end())
+    {
+      LOG(WARNING) << "Unknown job: " << id;
     }
-
+    else
+    {
+      found->second->SetPriority(priority);
 
-  public:
-    JobsMonitor() :
-      maxCompletedJobs_(10)
-    {
-    }
-
+      if (found->second->GetState() == JobState_Pending)
+      {
+        // If the job is pending, we need to reconstruct the
+        // priority queue, as the heap condition has changed
 
-    ~JobsMonitor()
-    {
-      for (JobsIndex::iterator it = jobsIndex_.begin(); it != jobsIndex_.end(); ++it)
-      {
-        assert(it->second != NULL);
-        delete it->second;
+        PendingJobs copy;
+        std::swap(copy, pendingJobs_);
+
+        assert(pendingJobs_.empty());
+        while (!copy.empty())
+        {
+          pendingJobs_.push(copy.top());
+          copy.pop();
+        }
       }
     }
 
-
-    void SetMaxCompletedJobs(size_t i)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      maxCompletedJobs_ = i;
-      ForgetOldCompletedJobs();
-
-      CheckInvariants();
-    }
-
-
-    void ListJobs(std::set<std::string>& target)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      for (JobsIndex::const_iterator it = jobsIndex_.begin();
-           it != jobsIndex_.end(); ++it)
-      {
-        target.insert(it->first);
-      }
-    }
+    CheckInvariants();
+  }
 
 
-    void Submit(std::string& id,
-                IJob* job,        // Takes ownership
-                int priority)
-    {
-      std::auto_ptr<JobHandler>  handler(new JobHandler(job, priority));
+  void Pause(const std::string& id)
+  {
+    LOG(INFO) << "Pausing job: " << id;
 
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-      
-      id = handler->GetId();
-      pendingJobs_.push(handler.get());
-      jobsIndex_.insert(std::make_pair(id, handler.release()));
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
 
-      pendingJobAvailable_.notify_one();
+    JobsIndex::iterator found = jobsIndex_.find(id);
 
-      CheckInvariants();
-    }
-
-
-    void Submit(IJob* job,        // Takes ownership
-                int priority)
+    if (found == jobsIndex_.end())
     {
-      std::string id;
-      Submit(id, job, priority);
+      LOG(WARNING) << "Unknown job: " << id;
     }
-
-
-    void SetPriority(const std::string& id,
-                     int priority)
+    else
     {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      JobsIndex::iterator found = jobsIndex_.find(id);
-
-      if (found == jobsIndex_.end())
+      switch (found->second->GetState())
       {
-        LOG(WARNING) << "Unknown job: " << id;
-      }
-      else
-      {
-        found->second->SetPriority(priority);
-
-        if (found->second->GetState() == JobState_Pending)
+        case JobState_Pending:
         {
           // If the job is pending, we need to reconstruct the
-          // priority queue, as the heap condition has changed
-
+          // priority queue to remove it
           PendingJobs copy;
           std::swap(copy, pendingJobs_);
 
           assert(pendingJobs_.empty());
           while (!copy.empty())
           {
-            pendingJobs_.push(copy.top());
+            if (copy.top()->GetId() != id)
+            {
+              pendingJobs_.push(copy.top());
+            }
+
             copy.pop();
           }
+
+          found->second->SetState(JobState_Paused);
+
+          break;
         }
+
+        case JobState_Retry:
+        {
+          RetryJobs::iterator item = retryJobs_.find(found->second);
+          assert(item != retryJobs_.end());            
+          retryJobs_.erase(item);
+
+          found->second->SetState(JobState_Paused);
+
+          break;
+        }
+
+        case JobState_Paused:
+        case JobState_Success:
+        case JobState_Failure:
+          // Nothing to be done
+          break;
+
+        case JobState_Running:
+          found->second->SchedulePause();
+          break;
+
+        default:
+          throw OrthancException(ErrorCode_InternalError);
       }
-
-      CheckInvariants();
     }
 
-
-    void Pause(const std::string& id)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      JobsIndex::iterator found = jobsIndex_.find(id);
-
-      if (found == jobsIndex_.end())
-      {
-        LOG(WARNING) << "Unknown job: " << id;
-      }
-      else
-      {
-        switch (found->second->GetState())
-        {
-          case JobState_Pending:
-          {
-            // If the job is pending, we need to reconstruct the
-            // priority queue to remove it
-            PendingJobs copy;
-            std::swap(copy, pendingJobs_);
-
-            assert(pendingJobs_.empty());
-            while (!copy.empty())
-            {
-              if (copy.top()->GetId() != id)
-              {
-                pendingJobs_.push(copy.top());
-              }
-
-              copy.pop();
-            }
-
-            found->second->SetState(JobState_Paused);
-
-            break;
-          }
-
-          case JobState_Retry:
-          {
-            RetryJobs::iterator item = retryJobs_.find(found->second);
-            assert(item != retryJobs_.end());            
-            retryJobs_.erase(item);
-
-            found->second->SetState(JobState_Paused);
-
-            break;
-          }
-
-          case JobState_Paused:
-          case JobState_Success:
-          case JobState_Failure:
-            // Nothing to be done
-            break;
-
-          case JobState_Running:
-            found->second->SchedulePause();
-            break;
-
-          default:
-            throw OrthancException(ErrorCode_InternalError);
-        }
-      }
-
-      CheckInvariants();
-    }
+    CheckInvariants();
+  }
 
 
-    void Resume(const std::string& id)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
+  void Resume(const std::string& id)
+  {
+    LOG(INFO) << "Resuming job: " << id;
 
-      JobsIndex::iterator found = jobsIndex_.find(id);
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+
+    JobsIndex::iterator found = jobsIndex_.find(id);
 
-      if (found == jobsIndex_.end())
-      {
-        LOG(WARNING) << "Unknown job: " << id;
-      }
-      else if (found->second->GetState() != JobState_Paused)
-      {
-        LOG(WARNING) << "Cannot resume a job that is not paused: " << id;
-      }
-      else
-      {
-        found->second->SetState(JobState_Pending);
-        pendingJobs_.push(found->second);
-        pendingJobAvailable_.notify_one();
-      }
+    if (found == jobsIndex_.end())
+    {
+      LOG(WARNING) << "Unknown job: " << id;
+    }
+    else if (found->second->GetState() != JobState_Paused)
+    {
+      LOG(WARNING) << "Cannot resume a job that is not paused: " << id;
+    }
+    else
+    {
+      found->second->SetState(JobState_Pending);
+      pendingJobs_.push(found->second);
+      pendingJobAvailable_.notify_one();
+    }
 
-      CheckInvariants();
-    }
+    CheckInvariants();
+  }
 
 
-    void Resubmit(const std::string& id)
-    {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      JobsIndex::iterator found = jobsIndex_.find(id);
+  void Resubmit(const std::string& id)
+  {
+    LOG(INFO) << "Resubmitting failed job: " << id;
 
-      if (found == jobsIndex_.end())
-      {
-        LOG(WARNING) << "Unknown job: " << id;
-      }
-      else if (found->second->GetState() != JobState_Failure)
-      {
-        LOG(WARNING) << "Cannot resubmit a job that has not failed: " << id;
-      }
-      else
-      {
-        bool ok = false;
-        for (CompletedJobs::iterator it = completedJobs_.begin(); 
-             it != completedJobs_.end(); ++it)
-        {
-          if (*it == found->second)
-          {
-            ok = true;
-            completedJobs_.erase(it);
-            break;
-          }
-        }
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+
+    JobsIndex::iterator found = jobsIndex_.find(id);
 
-        assert(ok);
-
-        found->second->SetState(JobState_Pending);
-        pendingJobs_.push(found->second);
-        pendingJobAvailable_.notify_one();
-      }
-
-      CheckInvariants();
+    if (found == jobsIndex_.end())
+    {
+      LOG(WARNING) << "Unknown job: " << id;
     }
-
-
-    void ScheduleRetries()
+    else if (found->second->GetState() != JobState_Failure)
+    {
+      LOG(WARNING) << "Cannot resubmit a job that has not failed: " << id;
+    }
+    else
     {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      RetryJobs copy;
-      std::swap(copy, retryJobs_);
-
-      const boost::posix_time::ptime now = boost::posix_time::microsec_clock::universal_time();
-
-      assert(retryJobs_.empty());
-      for (RetryJobs::iterator it = copy.begin(); it != copy.end(); ++it)
+      bool ok = false;
+      for (CompletedJobs::iterator it = completedJobs_.begin(); 
+           it != completedJobs_.end(); ++it)
       {
-        if ((*it)->IsRetryReady(now))
+        if (*it == found->second)
         {
-          (*it)->SetState(JobState_Pending);
-        }
-        else
-        {
-          retryJobs_.insert(*it);
+          ok = true;
+          completedJobs_.erase(it);
+          break;
         }
       }
 
-      CheckInvariants();
+      assert(ok);
+
+      found->second->SetState(JobState_Pending);
+      pendingJobs_.push(found->second);
+      pendingJobAvailable_.notify_one();
     }
 
+    CheckInvariants();
+  }
+
 
-    bool GetState(JobState& state,
-                  const std::string& id)
+  void ScheduleRetries()
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+
+    RetryJobs copy;
+    std::swap(copy, retryJobs_);
+
+    const boost::posix_time::ptime now = boost::posix_time::microsec_clock::universal_time();
+
+    assert(retryJobs_.empty());
+    for (RetryJobs::iterator it = copy.begin(); it != copy.end(); ++it)
     {
-      boost::mutex::scoped_lock lock(mutex_);
-      CheckInvariants();
-
-      JobsIndex::const_iterator it = jobsIndex_.find(id);
-      if (it == jobsIndex_.end())
+      if ((*it)->IsRetryReady(now))
       {
-        return false;
+        LOG(INFO) << "Retrying job: " << (*it)->GetId();
+        (*it)->SetState(JobState_Pending);
+        pendingJobs_.push(*it);
+        pendingJobAvailable_.notify_one();
       }
       else
       {
-        state = it->second->GetState();
-        return true;
+        retryJobs_.insert(*it);
       }
     }
 
+    CheckInvariants();
+  }
 
-    class RunningJob : public boost::noncopyable
+
+  bool GetState(JobState& state,
+                const std::string& id)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+    CheckInvariants();
+
+    JobsIndex::const_iterator it = jobsIndex_.find(id);
+    if (it == jobsIndex_.end())
     {
-    private:
-      JobsMonitor&  that_;
-      JobHandler*   handler_;
-      JobState      targetState_;
-      unsigned int  retryTimeout_;
+      return false;
+    }
+    else
+    {
+      state = it->second->GetState();
+      return true;
+    }
+  }
+
+
+  class RunningJob : public boost::noncopyable
+  {
+  private:
+    JobsRegistry&  that_;
+    JobHandler*   handler_;
+    JobState      targetState_;
+    unsigned int  retryTimeout_;
       
-    public:
-      RunningJob(JobsMonitor& that,
-                 unsigned int timeout) :
-        that_(that),
-        handler_(NULL),
-        targetState_(JobState_Failure),
-        retryTimeout_(0)
-      {
-        handler_ = that_.WaitPendingJob(timeout);
-      }
+  public:
+    RunningJob(JobsRegistry& that,
+               unsigned int timeout) :
+      that_(that),
+      handler_(NULL),
+      targetState_(JobState_Failure),
+      retryTimeout_(0)
+    {
+      handler_ = that_.WaitPendingJob(timeout);
+    }
 
-      ~RunningJob()
+    ~RunningJob()
+    {
+      if (IsValid())
       {
-        if (IsValid())
+        switch (targetState_)
         {
-          switch (targetState_)
-          {
-            case JobState_Failure:
-              that_.MarkRunningAsCompleted(*handler_, false);
-              break;
+          case JobState_Failure:
+            that_.MarkRunningAsCompleted(*handler_, false);
+            break;
 
-            case JobState_Success:
-              that_.MarkRunningAsCompleted(*handler_, true);
-              break;
+          case JobState_Success:
+            that_.MarkRunningAsCompleted(*handler_, true);
+            break;
 
-            case JobState_Paused:
-              that_.MarkRunningAsPaused(*handler_);
-              break;            
+          case JobState_Paused:
+            that_.MarkRunningAsPaused(*handler_);
+            break;            
 
-            case JobState_Retry:
-              that_.MarkRunningAsRetry(*handler_, retryTimeout_);
-              break;
+          case JobState_Retry:
+            that_.MarkRunningAsRetry(*handler_, retryTimeout_);
+            break;
             
-            default:
-              assert(0);
-          }
+          default:
+            assert(0);
         }
       }
+    }
 
-      bool IsValid() const
+    bool IsValid() const
+    {
+      return handler_ != NULL;
+    }
+
+    const std::string& GetId() const
+    {
+      if (IsValid())
       {
-        return handler_ != NULL;
+        return handler_->GetId();
       }
-
-      const std::string& GetId() const
+      else
       {
-        if (IsValid())
-        {
-          return handler_->GetId();
-        }
-        else
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }      
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
+      }      
+    }
+
+    int GetPriority() const
+    {
+      if (IsValid())
+      {
+        return handler_->GetPriority();
+      }
+      else
+      {
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
+      }      
+    }
+
+    bool IsPauseScheduled()
+    {
+      if (!IsValid())
+      {
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
       }
 
-      int GetPriority() const
+      boost::mutex::scoped_lock lock(that_.mutex_);
+      that_.CheckInvariants();
+      assert(handler_->GetState() == JobState_Running);
+
+      return handler_->IsPauseScheduled();
+    }
+
+    IJob& GetJob()
+    {
+      if (!IsValid())
       {
-        if (IsValid())
-        {
-          return handler_->GetPriority();
-        }
-        else
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }      
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
       }
 
-      bool IsPauseScheduled()
-      {
-        if (!IsValid())
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }
-
-        boost::mutex::scoped_lock lock(that_.mutex_);
-        that_.CheckInvariants();
-        assert(handler_->GetState() == JobState_Running);
+      boost::mutex::scoped_lock lock(that_.mutex_);
+      that_.CheckInvariants();
+      assert(handler_->GetState() == JobState_Running);
 
-        return handler_->IsPauseScheduled();
-      }
+      return handler_->GetJob();
+    }
 
-      IJob& GetJob()
+    void MarkSuccess()
+    {
+      if (!IsValid())
       {
-        if (!IsValid())
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }
-
-        boost::mutex::scoped_lock lock(that_.mutex_);
-        that_.CheckInvariants();
-        assert(handler_->GetState() == JobState_Running);
-
-        return handler_->GetJob();
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
       }
 
-      void MarkSuccess()
-      {
-        if (!IsValid())
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }
+      targetState_ = JobState_Success;
+    }
 
-        targetState_ = JobState_Success;
-      }
-
-      void MarkFailure()
+    void MarkFailure()
+    {
+      if (!IsValid())
       {
-        if (!IsValid())
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }
-
-        targetState_ = JobState_Failure;
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
       }
 
-      void MarkPause()
+      targetState_ = JobState_Failure;
+    }
+
+    void SchedulePause()
+    {
+      if (!IsValid())
       {
-        if (!IsValid())
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }
-
-        targetState_ = JobState_Paused;
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
       }
 
-      void MarkRetry(unsigned int timeout)
+      targetState_ = JobState_Paused;
+    }
+
+    void MarkRetry(unsigned int timeout)
+    {
+      if (!IsValid())
       {
-        if (!IsValid())
-        {
-          throw OrthancException(ErrorCode_BadSequenceOfCalls);
-        }
+        throw OrthancException(ErrorCode_BadSequenceOfCalls);
+      }
 
-        targetState_ = JobState_Retry;
-        retryTimeout_ = timeout;
-      }
-    };
+      targetState_ = JobState_Retry;
+      retryTimeout_ = timeout;
+    }
   };
+};
 }
 
 
@@ -1181,12 +1201,12 @@
 };
 
 
-static bool CheckState(Orthanc::JobsMonitor& monitor,
+static bool CheckState(Orthanc::JobsRegistry& registry,
                        const std::string& id,
                        Orthanc::JobState state)
 {
   Orthanc::JobState s;
-  if (monitor.GetState(s, id))
+  if (registry.GetState(s, id))
   {
     return state == s;
   }
@@ -1197,20 +1217,20 @@
 }
 
 
-TEST(JobsMonitor, Priority)
+TEST(JobsRegistry, Priority)
 {
-  JobsMonitor monitor;
+  JobsRegistry registry;
 
   std::string i1, i2, i3, i4;
-  monitor.Submit(i1, new DummyJob(), 10);
-  monitor.Submit(i2, new DummyJob(), 30);
-  monitor.Submit(i3, new DummyJob(), 20);
-  monitor.Submit(i4, new DummyJob(), 5);  
+  registry.Submit(i1, new DummyJob(), 10);
+  registry.Submit(i2, new DummyJob(), 30);
+  registry.Submit(i3, new DummyJob(), 20);
+  registry.Submit(i4, new DummyJob(), 5);  
 
-  monitor.SetMaxCompletedJobs(2);
+  registry.SetMaxCompletedJobs(2);
 
   std::set<std::string> id;
-  monitor.ListJobs(id);
+  registry.ListJobs(id);
 
   ASSERT_EQ(4u, id.size());
   ASSERT_TRUE(id.find(i1) != id.end());
@@ -1218,100 +1238,268 @@
   ASSERT_TRUE(id.find(i3) != id.end());
   ASSERT_TRUE(id.find(i4) != id.end());
 
-  ASSERT_TRUE(CheckState(monitor, i2, Orthanc::JobState_Pending));
+  ASSERT_TRUE(CheckState(registry, i2, Orthanc::JobState_Pending));
 
   {
-    JobsMonitor::RunningJob job(monitor, 0);
+    JobsRegistry::RunningJob job(registry, 0);
     ASSERT_TRUE(job.IsValid());
     ASSERT_EQ(30, job.GetPriority());
     ASSERT_EQ(i2, job.GetId());
 
-    ASSERT_TRUE(CheckState(monitor, i2, Orthanc::JobState_Running));
+    ASSERT_TRUE(CheckState(registry, i2, Orthanc::JobState_Running));
   }
 
-  ASSERT_TRUE(CheckState(monitor, i2, Orthanc::JobState_Failure));
-  ASSERT_TRUE(CheckState(monitor, i3, Orthanc::JobState_Pending));
+  ASSERT_TRUE(CheckState(registry, i2, Orthanc::JobState_Failure));
+  ASSERT_TRUE(CheckState(registry, i3, Orthanc::JobState_Pending));
 
   {
-    JobsMonitor::RunningJob job(monitor, 0);
+    JobsRegistry::RunningJob job(registry, 0);
     ASSERT_TRUE(job.IsValid());
     ASSERT_EQ(20, job.GetPriority());
     ASSERT_EQ(i3, job.GetId());
 
     job.MarkSuccess();
 
-    ASSERT_TRUE(CheckState(monitor, i3, Orthanc::JobState_Running));
+    ASSERT_TRUE(CheckState(registry, i3, Orthanc::JobState_Running));
   }
 
-  ASSERT_TRUE(CheckState(monitor, i3, Orthanc::JobState_Success));
+  ASSERT_TRUE(CheckState(registry, i3, Orthanc::JobState_Success));
 
   {
-    JobsMonitor::RunningJob job(monitor, 0);
+    JobsRegistry::RunningJob job(registry, 0);
     ASSERT_TRUE(job.IsValid());
     ASSERT_EQ(10, job.GetPriority());
     ASSERT_EQ(i1, job.GetId());
   }
 
   {
-    JobsMonitor::RunningJob job(monitor, 0);
+    JobsRegistry::RunningJob job(registry, 0);
     ASSERT_TRUE(job.IsValid());
     ASSERT_EQ(5, job.GetPriority());
     ASSERT_EQ(i4, job.GetId());
   }
 
   {
-    JobsMonitor::RunningJob job(monitor, 1);
+    JobsRegistry::RunningJob job(registry, 1);
     ASSERT_FALSE(job.IsValid());
   }
 
   Orthanc::JobState s;
-  ASSERT_TRUE(monitor.GetState(s, i1));
-  ASSERT_FALSE(monitor.GetState(s, i2));  // Removed because oldest
-  ASSERT_FALSE(monitor.GetState(s, i3));  // Removed because second oldest
-  ASSERT_TRUE(monitor.GetState(s, i4));
+  ASSERT_TRUE(registry.GetState(s, i1));
+  ASSERT_FALSE(registry.GetState(s, i2));  // Removed because oldest
+  ASSERT_FALSE(registry.GetState(s, i3));  // Removed because second oldest
+  ASSERT_TRUE(registry.GetState(s, i4));
 
-  monitor.SetMaxCompletedJobs(1);  // (*)
-  ASSERT_FALSE(monitor.GetState(s, i1));  // Just discarded by (*)
-  ASSERT_TRUE(monitor.GetState(s, i4));
+  registry.SetMaxCompletedJobs(1);  // (*)
+  ASSERT_FALSE(registry.GetState(s, i1));  // Just discarded by (*)
+  ASSERT_TRUE(registry.GetState(s, i4));
 }
 
 
-TEST(JobsMonitor, Resubmit)
+TEST(JobsRegistry, Simultaneous)
 {
-  JobsMonitor monitor;
+  JobsRegistry registry;
+
+  std::string i1, i2;
+  registry.Submit(i1, new DummyJob(), 20);
+  registry.Submit(i2, new DummyJob(), 10);
+
+  ASSERT_TRUE(CheckState(registry, i1, Orthanc::JobState_Pending));
+  ASSERT_TRUE(CheckState(registry, i2, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job1(registry, 0);
+    JobsRegistry::RunningJob job2(registry, 0);
+
+    ASSERT_TRUE(job1.IsValid());
+    ASSERT_TRUE(job2.IsValid());
+
+    job1.MarkFailure();
+    job2.MarkSuccess();
+
+    ASSERT_TRUE(CheckState(registry, i1, Orthanc::JobState_Running));
+    ASSERT_TRUE(CheckState(registry, i2, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, i1, Orthanc::JobState_Failure));
+  ASSERT_TRUE(CheckState(registry, i2, Orthanc::JobState_Success));
+}
+
+
+TEST(JobsRegistry, Resubmit)
+{
+  JobsRegistry registry;
 
   std::string id;
-  monitor.Submit(id, new DummyJob(), 10);
+  registry.Submit(id, new DummyJob(), 10);
 
-  ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Pending));
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
 
-  monitor.Resubmit(id);
-  ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Pending));
+  registry.Resubmit(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
 
   {
-    JobsMonitor::RunningJob job(monitor, 0);
+    JobsRegistry::RunningJob job(registry, 0);
     ASSERT_TRUE(job.IsValid());
     job.MarkFailure();
 
-    ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Running));
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
 
-    monitor.Resubmit(id);
-    ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Running));
+    registry.Resubmit(id);
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
   }
 
-  ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Failure));
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Failure));
 
-  monitor.Resubmit(id);
-  ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Pending));
+  registry.Resubmit(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
 
   {
-    JobsMonitor::RunningJob job(monitor, 0);
+    JobsRegistry::RunningJob job(registry, 0);
     ASSERT_TRUE(job.IsValid());
     ASSERT_EQ(id, job.GetId());
 
     job.MarkSuccess();
-    ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Running));
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Success));
+
+  registry.Resubmit(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Success));
+}
+
+
+TEST(JobsRegistry, Retry)
+{
+  JobsRegistry registry;
+
+  std::string id;
+  registry.Submit(id, new DummyJob(), 10);
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job(registry, 0);
+    ASSERT_TRUE(job.IsValid());
+    job.MarkRetry(0);
+
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Retry));
+
+  registry.Resubmit(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Retry));
+  
+  registry.ScheduleRetries();
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job(registry, 0);
+    ASSERT_TRUE(job.IsValid());
+    job.MarkSuccess();
+
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
   }
 
-  ASSERT_TRUE(CheckState(monitor, id, Orthanc::JobState_Success));
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Success));
+}
+
+
+TEST(JobsRegistry, PausePending)
+{
+  JobsRegistry registry;
+
+  std::string id;
+  registry.Submit(id, new DummyJob(), 10);
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  registry.Pause(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Paused));
+
+  registry.Pause(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Paused));
+
+  registry.Resubmit(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Paused));
+
+  registry.Resume(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
 }
+
+
+TEST(JobsRegistry, PauseRunning)
+{
+  JobsRegistry registry;
+
+  std::string id;
+  registry.Submit(id, new DummyJob(), 10);
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job(registry, 0);
+    ASSERT_TRUE(job.IsValid());
+
+    registry.Resubmit(id);
+    job.SchedulePause();
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Paused));
+
+  registry.Resubmit(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Paused));
+
+  registry.Resume(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job(registry, 0);
+    ASSERT_TRUE(job.IsValid());
+
+    job.MarkSuccess();
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Success));
+}
+
+
+TEST(JobsRegistry, PauseRetry)
+{
+  JobsRegistry registry;
+
+  std::string id;
+  registry.Submit(id, new DummyJob(), 10);
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job(registry, 0);
+    ASSERT_TRUE(job.IsValid());
+
+    job.MarkRetry(0);
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Retry));
+
+  registry.Pause(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Paused));
+
+  registry.Resume(id);
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Pending));
+
+  {
+    JobsRegistry::RunningJob job(registry, 0);
+    ASSERT_TRUE(job.IsValid());
+
+    job.MarkSuccess();
+    ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Running));
+  }
+
+  ASSERT_TRUE(CheckState(registry, id, Orthanc::JobState_Success));
+}