Initial commit

Lts/Services/AudioVideoManagement/avs_command_queue.cpp

@@ -0,0 +1,133 @@
+/**
+  * @RDE_HEADER@
+  * AvsCommandQueue
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Christian Fröbel, NLSE, 2018-02-23
+  */
+
+#include "avs_command_queue.h"
+#include "icommand.h"
+#include <LtsUtilsCore/connection.h>
+
+
+namespace AudioVideoManagement
+{
+
+AvsCommandQueue::AvsCommandQueue(std::chrono::milliseconds timeout)
+  : m_logger(getLogger("AvsCommandQueue"))
+{
+  if (timeout.count())
+  {
+    m_timer.setSingleShot(true);
+    m_timer.setInterval(timeout.count());
+    connect(&m_timer, &QTimer::timeout, this, &AvsCommandQueue::timeout); // signal -> signal
+  }
+}
+
+AvsCommandQueue::~AvsCommandQueue()
+{
+  flush();
+}
+
+void AvsCommandQueue::queue(std::unique_ptr<ICommand> cmd, std::unique_ptr<LtsUtils::IConnection> connection)
+{
+  Q_ASSERT(cmd);
+
+  bool   noPendingCommand = m_queue.empty();
+  m_queue.push_back(CommandWithConn{std::move(cmd), std::move(connection)});
+  DEBUG_LOG(m_logger) << "queueing command, queue size: " << m_queue.size();
+  tryReduce();
+  if (noPendingCommand)
+    nextCommand();
+}
+
+void AvsCommandQueue::done()
+{
+  Q_ASSERT(!m_queue.empty());
+  m_timer.stop();
+  m_queue.pop_front();
+  DEBUG_LOG(m_logger) << "command finished, queue size: " << m_queue.size();
+  if (m_queue.empty())
+    emit queueEmpty();
+  else
+    nextCommand();
+}
+
+ICommand *AvsCommandQueue::currentCommand() const
+{
+  Q_ASSERT(!m_queue.empty());
+  return m_queue.front().cmd.get();
+}
+
+bool AvsCommandQueue::currentHasConnection() const
+{
+  Q_ASSERT(!m_queue.empty());
+  return m_queue.front().connection != nullptr;
+}
+
+LtsUtils::IConnection *AvsCommandQueue::currentConnection() const
+{
+  Q_ASSERT(!m_queue.empty());
+  Q_ASSERT(m_queue.front().connection);
+  return m_queue.front().connection.get();
+}
+
+void AvsCommandQueue::flush()
+{
+  if (m_queue.empty())
+    return;
+
+  DEBUG_LOG(m_logger) << "flushing " << m_queue.size() << " commands";
+  m_timer.stop();
+  m_queue.clear();
+  emit queueEmpty();
+}
+
+void AvsCommandQueue::alive()
+{
+  Q_ASSERT(!m_queue.empty());
+  m_timer.start();
+}
+
+void AvsCommandQueue::nextCommand()
+{
+  Q_ASSERT(!m_queue.empty());
+
+  DEBUG_LOG(m_logger) << "sending next command";
+  ICommand   *cmd = currentCommand();
+  m_timer.start();
+  cmd->send();
+}
+
+/**
+ * Given the last queued command in the queue this method
+ * tries to find commands queued earlier where the effect
+ * of the earlier command will be nullified by the new command.
+ * If such a command is found, it will be dropped.
+ * For example when there was a SetVolume(x) followed by
+ * a SetVolume(y), we can simply drop the first one.
+ */
+void AvsCommandQueue::tryReduce()
+{
+  if (m_queue.size() <= 2)
+    return;
+
+  const CommandWithConn   &lastCommand = m_queue.back();
+
+  // Do not check against the first command as it is beeing executed right now.
+  for (size_t i = 1; i < m_queue.size() - 1; ++i)
+  {
+    const CommandWithConn   &current = m_queue[i];
+
+    if (!lastCommand.cmd->nullifies(current.cmd.get()))
+      continue;
+
+    DEBUG_LOG(m_logger) << "dropping command due to override";
+    m_queue.erase(m_queue.begin() + i);
+    return;
+  }
+}
+
+} // namespace AudioVideoManagement