Adding upstream version 2.4.1.upstream/2.4.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 248 insertions, 0 deletions

diff --git a/src/bin/d2/d2_update_mgr.h b/src/bin/d2/d2_update_mgr.h
new file mode 100644
index 0000000..593cfd1
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+++ b/src/bin/d2/d2_update_mgr.h
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+// Copyright (C) 2013-2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef D2_UPDATE_MGR_H
+#define D2_UPDATE_MGR_H
+
+/// @file d2_update_mgr.h This file defines the class D2UpdateMgr.
+
+#include <asiolink/io_service.h>
+#include <d2/d2_queue_mgr.h>
+#include <d2srv/nc_trans.h>
+#include <d2srv/d2_cfg_mgr.h>
+#include <d2srv/d2_log.h>
+#include <exceptions/exceptions.h>
+
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <map>
+
+namespace isc {
+namespace d2 {
+
+/// @brief Thrown if the update manager encounters a general error.
+class D2UpdateMgrError : public isc::Exception {
+public:
+    D2UpdateMgrError(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) { };
+};
+
+/// @brief Defines a list of transactions.
+typedef std::map<TransactionKey, NameChangeTransactionPtr> TransactionList;
+
+/// @brief D2UpdateMgr creates and manages update transactions.
+///
+/// D2UpdateMgr is the DHCP_DDNS task master, instantiating and then supervising
+/// transactions that execute the DNS updates needed to fulfill the requests
+/// (NameChangeRequests) received from DHCP_DDNS clients (e.g. DHCP servers).
+///
+/// D2UpdateMgr uses the services of D2QueueMgr to monitor the queue of
+/// NameChangeRequests and select and dequeue requests for processing.
+/// When a request is dequeued for processing it is removed from the queue and
+/// wrapped in NameChangeTransaction and added to the D2UpdateMgr's list of
+/// transactions.
+///
+/// As part of the process of forming transactions, D2UpdateMgr matches each
+/// request with the appropriate list of DNS servers.  This matching is  based
+/// upon request attributes, primarily the FQDN and update direction (forward
+/// or reverse).  D2UpdateMgr uses the services of D2CfgMgr to match requests
+/// to DNS server lists.
+///
+/// Once created, each transaction is responsible for carrying out the steps
+/// required to fulfill its specific request.  These steps typically consist of
+/// one or more DNS packet exchanges with the appropriate DNS server.  As
+/// transactions complete,  D2UpdateMgr removes them from the transaction list,
+/// replacing them with new transactions.
+///
+/// D2UpdateMgr carries out each of the above steps, with a method called
+/// sweep().  This method is intended to be called as IO events complete.
+/// The upper layer(s) are responsible for calling sweep in a timely and cyclic
+/// manner.
+///
+class D2UpdateMgr : public boost::noncopyable {
+public:
+    /// @brief Maximum number of concurrent transactions
+    /// NOTE that 32 is an arbitrary choice picked for the initial
+    /// implementation.
+    static const size_t MAX_TRANSACTIONS_DEFAULT = 32;
+
+    /// @brief Constructor
+    ///
+    /// @param queue_mgr reference to the queue manager receiving requests
+    /// @param cfg_mgr reference to the configuration manager
+    /// @param io_service IO service used by the upper layer(s) to manage
+    /// IO events
+    /// @param max_transactions the maximum number of concurrent transactions
+    ///
+    /// @throw D2UpdateMgrError if either the queue manager or configuration
+    /// managers are NULL, or max transactions is less than one.
+    D2UpdateMgr(D2QueueMgrPtr& queue_mgr, D2CfgMgrPtr& cfg_mgr,
+                asiolink::IOServicePtr& io_service,
+                const size_t max_transactions = MAX_TRANSACTIONS_DEFAULT);
+
+    /// @brief Destructor
+    virtual ~D2UpdateMgr();
+
+    /// @brief Check current transactions; start transactions for new requests.
+    ///
+    /// This method is the primary public interface used by the upper layer. It
+    /// should be called as IO events complete.  During each invocation it does
+    /// the following:
+    ///
+    /// - Removes all completed transactions from the transaction list.
+    ///
+    /// - If the request queue is not empty and the number of transactions
+    /// in the transaction list has not reached maximum allowed, then select
+    /// a request from the queue.
+    ///
+    /// - If a request was selected, start a new transaction for it and
+    /// add the transaction to the list of transactions.
+    void sweep();
+
+protected:
+    /// @brief Performs post-completion cleanup on completed transactions.
+    ///
+    /// Iterates through the list of transactions and removes any that have
+    /// reached completion.  This method may expand in complexity or even
+    /// disappear altogether as the implementation matures.
+    void checkFinishedTransactions();
+
+    /// @brief Starts a transaction for the next eligible request in the queue.
+    ///
+    /// This method will scan the request queue for the next request to
+    /// dequeue.  The current implementation starts at the front of the queue
+    /// and looks for the first request for whose DHCID there is no current
+    /// transaction in progress.
+    ///
+    /// If a request is selected, it is removed from the queue and transaction
+    /// is constructed for it.
+    ///
+    /// It is possible that no such request exists, though this is likely to be
+    /// rather rare unless a system is frequently seeing requests for the same
+    /// clients in quick succession.
+    void pickNextJob();
+
+    /// @brief Create a new transaction for the given request.
+    ///
+    /// This method will attempt to match the request to suitable DNS servers.
+    /// If matching servers are found, it will instantiate a transaction for
+    /// the requests, add the transaction to the transaction list, and start
+    /// the transaction.
+    ///
+    /// If updates in a given direction are disabled requests for updates in
+    /// that direction will be ignored.  For example: If a request is received
+    /// which asks for updates in both directions but only forward updates are
+    /// enabled; only the forward update will be attempted.  Effectively, the
+    /// request will be treated as if it only asked for forward updates.
+    ///
+    /// If updates in a given direction are enabled, and a request asks for
+    /// updates in that direction, failing to match the request to a list
+    /// of servers is an error which will be logged and the request will be
+    /// discarded.
+    ///
+    /// Finally, If conflict resolution is enabled, it will instantiate either
+    /// a NameAddTransaction or a NameRemoveTransaction. If disabled it will
+    /// instantiate either a SimpleAddTransaction or a SimpleRemoveTransaction.
+    ///
+    /// @param ncr the NameChangeRequest for which to create a transaction.
+    ///
+    /// @throw D2UpdateMgrError if a transaction for this DHCID already
+    /// exists. Note this would be programmatic error.
+    void makeTransaction(isc::dhcp_ddns::NameChangeRequestPtr& ncr);
+
+public:
+    /// @brief Gets the D2UpdateMgr's IOService.
+    ///
+    /// @return returns a reference to the IOService
+    const asiolink::IOServicePtr& getIOService() {
+        return (io_service_);
+    }
+
+    /// @brief Returns the maximum number of concurrent transactions.
+    size_t getMaxTransactions() const {
+        return (max_transactions_);
+    }
+
+    /// @brief Sets the maximum number of entries allowed in the queue.
+    ///
+    /// @param max_transactions is the new maximum number of transactions
+    ///
+    /// @throw Throws D2QueueMgrError if the new value is less than one or if
+    /// the new value is less than the number of entries currently in the
+    /// queue.
+    void setMaxTransactions(const size_t max_transactions);
+
+    /// @brief Search the transaction list for the given key.
+    ///
+    /// @param key the transaction key value for which to search.
+    ///
+    /// @return Iterator pointing to the entry found.  If no entry is
+    /// it will point to the list end position.
+    TransactionList::iterator findTransaction(const TransactionKey& key);
+
+    /// @brief Returns the transaction list end position.
+    TransactionList::iterator transactionListEnd();
+
+    /// @brief Returns the transaction list beg position.
+    TransactionList::iterator transactionListBegin();
+
+    /// @brief Convenience method that checks transaction list for the given key
+    ///
+    /// @param key the transaction key value for which to search.
+    ///
+    /// @return Returns true if the key is found within the list, false
+    /// otherwise.
+    bool hasTransaction(const TransactionKey& key);
+
+    /// @brief Removes the entry pointed to by key from the transaction list.
+    ///
+    /// Removes the entry referred to by key if it exists.  It has no effect
+    /// if the entry is not found.
+    ///
+    /// @param key of the transaction to remove
+    void removeTransaction(const TransactionKey& key);
+
+    /// @brief Immediately discards all entries in the transaction list.
+    ///
+    /// @todo For now this just wipes them out. We might need something
+    /// more elegant, that allows a cancel first.
+    void clearTransactionList();
+
+    /// @brief Convenience method that returns the number of requests queued.
+    size_t getQueueCount() const;
+
+    /// @brief Returns the current number of transactions.
+    size_t getTransactionCount() const;
+
+private:
+    /// @brief Pointer to the queue manager.
+    D2QueueMgrPtr queue_mgr_;
+
+    /// @brief Pointer to the configuration manager.
+    D2CfgMgrPtr cfg_mgr_;
+
+    /// @brief Primary IOService instance.
+    /// This is the IOService that the upper layer(s) use for IO events, such
+    /// as shutdown and configuration commands.  It is the IOService that is
+    /// passed into transactions to manager their IO events.
+    /// (For future reference, multi-threaded transactions would each use their
+    /// own IOService instance.)
+    asiolink::IOServicePtr io_service_;
+
+    /// @brief Maximum number of concurrent transactions.
+    size_t max_transactions_;
+
+    /// @brief List of transactions.
+    TransactionList transaction_list_;
+};
+
+/// @brief Defines a pointer to a D2UpdateMgr instance.
+typedef boost::shared_ptr<D2UpdateMgr> D2UpdateMgrPtr;
+
+
+} // namespace isc::d2
+} // namespace isc
+#endif