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- // Copyright (C) 2013 Internet Systems Consortium, Inc. ("ISC")
- //
- // Permission to use, copy, modify, and/or distribute this software for any
- // purpose with or without fee is hereby granted, provided that the above
- // copyright notice and this permission notice appear in all copies.
- //
- // THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
- // REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- // AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
- // INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- // LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
- // OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- // PERFORMANCE OF THIS SOFTWARE.
- #ifndef LIBRARY_HANDLE_H
- #define LIBRARY_HANDLE_H
- #include <map>
- #include <string>
- #include <boost/any.hpp>
- #include <boost/shared_ptr.hpp>
- #include <exceptions/exceptions.h>
- #include <util/hooks/server_hooks.h>
- namespace isc {
- namespace util {
- /// @brief No such hook
- ///
- /// Thrown if an attempt is made to use an invalid hook name or hook index.
- class NoSuchHook : public Exception {
- public:
- NoSuchHook(const char* file, size_t line, const char* what) :
- isc::Exception(file, line, what) {}
- };
- /// @brief No Such Context
- ///
- /// Thrown if an attempt is made to obtain context that has not been previously
- /// set.
- class NoSuchContext : public Exception {
- public:
- NoSuchContext(const char* file, size_t line, const char* what) :
- isc::Exception(file, line, what) {}
- };
- // Forward declaration for CalloutHandle
- class CalloutHandle;
- /// Typedef for a callout pointer
- extern "C" {
- typedef int (*CalloutPtr)(CalloutHandle&);
- };
- /// @brief Library handle
- ///
- /// This class is used to manage a loaded library. It is used by the user
- /// library to register callouts and by the HookManager to call them. The
- /// class also contains storage for library-specific context.
- ///
- /// Although there is a persuasive argument for the class to load unload the
- /// user library, that is handled by the HookManager to prevent the user library
- /// from accessing those functions.
- class LibraryHandle {
- private:
- /// Typedef to allow abbreviation of iterator specification in methods
- typedef std::map<std::string, boost::any> ContextCollection;
- public:
- /// @brief Constructor
- ///
- /// This is passed the ServerHooks object and an index number: the former
- /// allows for the sizing of the internal hook vector, and the latter
- /// is used by the CalloutHandle object to access appropriate context
- ///
- /// @param hooks Pointer to the hooks registered by the server.
- /// @param index Index of this library in the list of loaded libraries.
- LibraryHandle(boost::shared_ptr<ServerHooks> hooks, int index)
- : context_(), hooks_(hooks), hook_vector_(hooks->getCount()),
- index_(index)
- {}
- /// @brief Set context
- ///
- /// Sets an element in the library context. If an element of the name
- /// is already present, it is replaced.
- ///
- /// @param name Name of the element in the context to set
- /// @param value Value to set
- template <typename T>
- void setContext(const std::string& name, T value) {
- context_[name] = value;
- }
- /// @brief Get context
- ///
- /// Sets an element in the library context. If the name does not exist,
- /// a "NoSuchContext" exception is thrown.
- ///
- /// @param name Name of the element in the context to set.
- /// @param value [out] Value to set. The type of "value" is important:
- /// it must match the type of the value set.
- ///
- /// @throw NoSuchContext Thrown if no context element with the name
- /// "name" is present.
- /// @throw boost::bad_any_cast Thrown if the context element is present,
- /// but the type of the element is not that expected
- template <typename T>
- void getContext(const std::string& name, T& value) const {
- ContextCollection::const_iterator element_ptr = context_.find(name);
- if (element_ptr == context_.end()) {
- isc_throw(NoSuchContext, "unable to find library context datum " <<
- name << " in library at index " << index_);
- }
- value = boost::any_cast<T>(element_ptr->second);
- }
- /// @brief Register a callout
- ///
- /// Registers a callout function with a given hook. The callout is added
- /// to the end of the callouts associated with the hook.
- ///
- /// @param name Name of the hook to which the callout is added.
- /// @param callout Pointer to the callout function to be registered.
- ///
- /// @throw NoSuchHook Thrown if the hook name is unrecognised.
- /// @throw Unexpected Hooks name is valid but internal data structure is
- /// of the wrong size.
- void registerCallout(const std::string& name, CalloutPtr callout);
- /// @brief De-Register a callout
- ///
- /// Searches through the functions associated with the named hook and
- /// removes all entries matching the callout. If there are no matching
- /// callouts, the result is a no-op.
- ///
- /// @param name Name of the hook from which the callout is removed.
- /// @param callout Pointer to the callout function to be removed.
- ///
- /// @throw NoSuchHook Thrown if the hook name is unrecognised.
- /// @throw Unexpected Hooks name is valid but internal data structure is
- /// of the wrong size.
- void deregisterCallout(const std::string& name, CalloutPtr callout);
- /// @brief Removes all callouts
- ///
- /// Removes all callouts associated with a given hook. This is a no-op
- /// if there are no callouts associated with the hook.
- ///
- /// @param name Name of the hook from which the callouts are removed.
- ///
- /// @throw NoSuchHook Thrown if the hook name is unrecognised.
- void deregisterAll(const std::string& name);
- /// @brief Checks if callouts are present
- ///
- /// @param index Hook index for which callouts are checked.
- ///
- /// @return true if callouts are present, false if not.
- ///
- /// @throw NoSuchHook Thrown if the index is not valid.
- bool calloutsPresent(int index) const;
- /// @brief Calls the callouts for a given hook
- ///
- /// Calls the callouts associated with the given hook index.
- ///
- /// @param index Index of the hook to call.
- /// @param handle Reference to the CalloutHandle object for the current
- /// object being processed.
- ///
- /// @return Status return.
- ///
- int callCallouts(int index, CalloutHandle& handle);
- private:
- /// @brief Check hook index
- ///
- /// Checks that the hook index is valid for the hook vector. If not,
- /// an exception is thrown.
- ///
- /// @param index Hooks index to check.
- ///
- /// @throw NoSuchHook Thrown if the index is not valid for the hook vector.
- void checkHookIndex(int index) const;
- /// @brief Get hook index
- ///
- /// Utility function to return the index associated with a hook name. It
- /// also checks for validity of the index: if the name is valid, the
- /// index should be valid. However, as the class only keeps a pointer to
- /// a shared ServerHooks object, it is possible that the object was modified
- /// after the hook_vector_ was sized. This function performs some checks
- /// on the name and throws an exception if the checks fail.
- ///
- /// @param name Name of the hook to check
- ///
- /// @return Index of the hook in the hook_vector_
- ///
- /// @throw NoSuchHook Thrown if the hook name is unrecognised.
- /// @throw Unexpected Index not valid for the hook vector.
- int getHookIndex(const std::string& name) const;
- /// @brief Callout pointers equal
- ///
- /// Unary predicate to
- // Member variables
- /// Context - mapping of names variables that can be of different types.
- ContextCollection context_;
- /// Pointer to the list of hooks registered by the server
- boost::shared_ptr<ServerHooks> hooks_; ///< Pointer to hooks
- /// Each element in the following vector corresponds to a single hook and
- /// is an ordered list of callouts for that hook.
- std::vector<std::vector<CalloutPtr> > hook_vector_;
- /// Index of this library in the list of libraries
- int index_;
- };
- } // namespace util
- } // namespace isc
- #endif // LIBRARY_HANDLE_H
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