Queue.cpp

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#include <sstream>

#include "Queue.h"
#include "madara/knowledge/ContextGuard.h"

bool
madara::knowledge::containers::Queue::enqueue (
  const knowledge::KnowledgeRecord & record)
{
  bool result (false);

  if (context_)
  {
    ContextGuard context_guard (*context_);
    MADARA_GUARD_TYPE guard (mutex_);

    if (count_ < 0)
      count_ = 0;
    
    // avoid double retrieval of count_ during check
    knowledge::KnowledgeRecord::Integer count = *count_;

    if (context_ && name_ != "" && queue_.size () > 0 && 
        count < (KnowledgeRecord::Integer)queue_.size ())
    {
      // there's no point in signaling inside of a locked context
      if (!settings_.signal_changes)
        settings_.signal_changes = false;
      
      knowledge::KnowledgeRecord::Integer tail = *tail_;

      context_->set (queue_.vector_[tail], record, settings_);
      tail_ = increment (tail, 1);
      ++count_;
    }
  }

  // now that we no longer have a lock on context, signal
  if (context_)
    context_->signal ();

  return result;
}

madara::knowledge::KnowledgeRecord
madara::knowledge::containers::Queue::dequeue (bool wait)
{
  madara::knowledge::KnowledgeRecord result;
  
  if (context_ && name_ != "")
  {
    ContextGuard context_guard (*context_);
    MADARA_GUARD_TYPE guard (mutex_);
    
    if (wait)
    {
      while (count_ <= 0)
        context_->wait_for_change (true);
    }

    if (count_ > 0)
    {
      knowledge::KnowledgeRecord::Integer head = *head_;

      result = context_->get (queue_.vector_[head], settings_);
    
      head_ = increment (head, 1);
      --count_;
    }
  }
  
  // now that we no longer have a lock on context, signal
  if (context_)
    context_->signal ();

  return result;
}

void
madara::knowledge::containers::Queue::set_name (
  const std::string & var_name,
  KnowledgeBase & knowledge)
{
  KnowledgeUpdateSettings keep_local (true);
  context_ = &(knowledge.get_context ());

  ContextGuard context_guard (*context_);
  MADARA_GUARD_TYPE guard (mutex_);

  name_ = var_name;
  
  this->count_.set_name (var_name + ".count", knowledge);
  this->head_.set_name (var_name + ".head", knowledge);
  this->tail_.set_name (var_name + ".tail", knowledge);
  this->queue_.set_name (var_name, knowledge);
}

void
madara::knowledge::containers::Queue::set_name (
  const std::string & var_name,
  Variables & knowledge)
{
  KnowledgeUpdateSettings keep_local (true);
  context_ = knowledge.get_context ();

  ContextGuard context_guard (*context_);
  MADARA_GUARD_TYPE guard (mutex_);

  name_ = var_name;
  
  this->count_.set_name (var_name + ".count", knowledge);
  this->head_.set_name (var_name + ".head", knowledge);
  this->tail_.set_name (var_name + ".tail", knowledge);
  this->queue_.set_name (var_name, knowledge);
}