utils: Add a class to cache service lookups
Currently we are doing interface + path -> service lookups for each ipmi
command sent to the daemon. For many types of commands this is not ideal
as the daemon is unlikely to change often at runtime. Implement a basic
cache with the ability to invalidate the service name at any time. This
is used by code in a future commit.
Change-Id: I85b04dd17ac19e31d49070f289704b429bd1e577
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/utils.hpp b/utils.hpp
index b4f090f..878b05a 100644
--- a/utils.hpp
+++ b/utils.hpp
@@ -1,7 +1,8 @@
#pragma once
+#include <experimental/optional>
+#include <sdbusplus/server.hpp>
#include "types.hpp"
-#include <sdbusplus/server.hpp>
namespace ipmi
{
@@ -20,6 +21,64 @@
constexpr auto METHOD_GET_ALL = "GetAll";
constexpr auto METHOD_SET = "Set";
+/** @class ServiceCache
+ * @brief Caches lookups of service names from the object mapper.
+ * @details Most ipmi commands need to talk to other dbus daemons to perform
+ * their intended actions on the BMC. This usually means they will
+ * first look up the service name providing the interface they
+ * require. This class reduces the number of such calls by caching
+ * the lookup for a specific service.
+ */
+class ServiceCache {
+ public:
+ /** @brief Creates a new service cache for the given interface
+ * and path.
+ *
+ * @param[in] intf - The interface used for each lookup
+ * @param[in] path - The path used for each lookup
+ */
+ ServiceCache(const std::string& intf, const std::string& path);
+ ServiceCache(std::string&& intf, std::string&& path);
+
+ /** @brief Gets the service name from the cache or does in a
+ * lookup when invalid.
+ *
+ * @param[in] bus - The bus associated with and used for looking
+ * up the service.
+ */
+ const std::string& getService(sdbusplus::bus::bus& bus);
+
+ /** @brief Invalidates the current service name */
+ void invalidate();
+
+ /** @brief A wrapper around sdbusplus bus.new_method_call
+ *
+ * @param[in] bus - The bus used for calling the method
+ * @param[in] intf - The interface containing the method
+ * @param[in] method - The method name
+ * @return The message containing the method call.
+ */
+ sdbusplus::message::message newMethodCall(sdbusplus::bus::bus& bus,
+ const char *intf,
+ const char *method);
+ private:
+ /** @brief DBUS interface provided by the service */
+ const std::string intf;
+ /** @brief DBUS path provided by the service */
+ const std::string path;
+ /** @brief The name of the service if valid */
+ std::experimental::optional<std::string> cachedService;
+ /** @brief The name of the bus used in the service lookup */
+ std::experimental::optional<std::string> cachedBusName;
+
+ /** @brief Check to see if the current cache is valid
+ *
+ * @param[in] bus - The bus used for the service lookup
+ * @return True if the cache is valid false otherwise.
+ */
+ bool isValid(sdbusplus::bus::bus& bus) const;
+};
+
/**
* @brief Get the DBUS Service name for the input dbus path
*