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dbcon/execplan/objectidmanager.h

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+/* Copyright (C) 2014 InfiniDB, Inc.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; version 2 of
+   the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA. */
+
+/******************************************************************************
+ * $Id: objectidmanager.h 9744 2013-08-07 03:32:19Z bwilkinson $
+ *
+ *****************************************************************************/
+
+/** @file 
+ * class ObjectIDManager interface. 
+ */
+
+#ifndef OBJECTIDMANAGER_H_
+#define OBJECTIDMANAGER_H_
+
+#include <string>
+#include <stdint.h>
+#include "dbrm.h"
+
+namespace execplan {
+
+/** @brief The class that manages the Object ID space
+ *
+ * The class that manages the allocation and deallocation of IDs
+ * for objects in the database.
+ */
+class ObjectIDManager
+{
+
+public:
+	/** @brief Default constructor
+	 *
+	 * @note Throws ios::failure on a file IO error
+	 */
+	ObjectIDManager();
+	virtual ~ObjectIDManager();
+
+	/** @brief Allocate one Object ID
+	 *
+	 * @return The allocated OID (>= 0) on success, -1 on error.
+	 */
+	int allocOID();
+
+	/** @brief Allocate a contiguous range of Object IDs
+	 *
+	 * @param num The number of contiguous Object IDs to allocate
+	 * @return The first OID allocated on success, -1 on failure
+	 */
+	int allocOIDs(int num);
+
+	/** @brief Allocates a new oid for a version buffer file, associates it
+	 * with dbroot.
+	 *
+	 * @return Returns -1 on all errors.
+	 */
+	int allocVBOID(uint32_t dbroot);
+
+	/** @brief Returns the DBRoot of the given version buffer OID, or -1 on error. */
+	int getDBRootOfVBOID(uint32_t vboid);
+
+	/** @brief Returns the VB OID -> DB Root mapping.  ret[0] = dbroot of VB OID 0
+	 *
+	 * @return vector where index n = dbroot of VBOID n.
+	 * @throw runtime_exception on error
+	 */
+	std::vector<uint16_t> getVBOIDToDBRootMap();
+	/** @brief Return an OID to the pool
+	 *
+	 * @param oid The OID to return
+	 */
+	void returnOID(int oid);
+
+	/** @brief Return a list of OIDs to the pool
+	 *
+	 * @param start The first OID to return
+	 * @param end The last OID to return
+	 */
+	void returnOIDs(int start, int end);
+
+	/** @brief Counts the number of allocated OIDs
+	 *
+	 * @note This currently assumes the bitmap length is a multiple of 4096
+	 * @return The number of allocated OIDs
+	 */
+	int size();
+
+	/** @brief Get the OID bitmap filename
+	 */
+	const std::string getFilename() const;
+
+private:
+	std::string fFilename;
+	BRM::DBRM dbrm;
+
+#if 0
+
+	static const int FreeListEntries = 256;
+	static const int HeaderSize = FreeListEntries * sizeof(FEntry);
+	static const int FileSize = HeaderSize + 2097152;  // (2^24/8)
+	static const int MaxRetries = 10;   /// max number of retries on file operations
+	int fFd;  /// file descriptor referencing the bitmap file
+
+	/** @brief Grab the file lock
+	 *
+	 * Grab the file lock.
+	 * @note Throws ios::failure after MaxRetries hard errors
+	 */
+	void lockFile() const;
+
+	/** @brief Reliably reads data from the bitmap file
+	 *
+	 * Reliably reads data from the bitmap file.
+	 * @note Throws ios::failure after MaxRetries hard errors
+	 * @note Caller is responsible for locking & unlocking
+	 * @param buf the buffer to read into
+	 * @param offset the offset to start reading at
+	 * @param size the number of bytes to read into buf
+	 */
+	void readData(uint8_t* buf, off64_t offset, int size) const;
+
+	/** @brief Reliably writes data to the bitmap file
+	 *
+	 * Reliably write data to the bitmap file.
+	 * @note Throws ios::failure after MaxRetries hard errors
+	 * @note Caller is responsible for locking & unlocking
+	 * @param buf the data to write
+	 * @param offset the offset to start writing at
+	 * @param size the number of bytes to write
+	 */
+	void writeData(uint8_t* buf, off64_t offset, int size) const;
+
+	/** @brief If there is no bitmap file yet, this is used to make one
+	 * 
+	 * If there is no bitmap file yet, this is used to make one.
+	 * @note It assumes no OIDs are allocated, we may want
+	 *       to fully rebuild it from actual DB contents instead.
+	 */
+	void initializeBitmap() const;
+
+	/** @brief Allocates OIDs using a designated freelist entry
+	 *
+	 * Allocates OIDs using a designated freelist entry
+	 * @param fe The freelist entry to use.
+	 * @param num The number of OIDs to allocate from that block
+	 */
+	void useFreeListEntry(struct FEntry& fe, int num);
+
+	/** @brief This allocates or deallocates a block of OIDs
+	 *
+	 * This allocates or deallocates a block of OIDs
+	 * @param start The first OID to alloc/dealloc
+	 * @param end The number of OIDs to flip
+	 * @param mode mode = 0 means 'allocate', mode = 1 means 'deallocate'
+	 */
+	void flipOIDBlock(int start, int num, int mode) const;
+
+	/** @brief This scans the whole bitmap for a block of free OIDs
+	 *
+	 * This scans the whole bitmap for a block of free OIDs
+	 * @param num the size of the block to locate
+	 * @param freelist the freelist
+	 * @return The first OID of the block allocated, or -1 if there is no match
+	 */
+	int fullScan(int num, struct FEntry* freelist) const;
+
+	/** @brief This is used by allocOIDs to fix the freelist after a full scan
+	 *
+	 * This is used by fullScan to fix the freelist before an allocation
+	 * @param freelist The freelist
+	 * @param start The first OID of the block allocated by fullScan
+	 * @param num The number of OIDs allocated
+	 * @note At the moment it throws logic_error if it detects a specific error in
+	 * fullscan
+	 */
+	void patchFreelist(struct FEntry* freelist, int start, int num) const;
+#endif
+
+
+};
+
+}	// namespace
+
+#endif