Imported Upstream version 1.8.2upstream/1.8.2

1 files changed, 123 insertions, 0 deletions

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+/******************************************************************************
+ *
+ * $Id: $
+ *
+ * Copyright (C) 1997-2012 by Dimitri van Heesch.
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation under the terms of the GNU General Public License is hereby 
+ * granted. No representations are made about the suitability of this software 
+ * for any purpose. It is provided "as is" without express or implied warranty.
+ * See the GNU General Public License for more details.
+ *
+ * Documents produced by Doxygen are derivative works derived from the
+ * input used in their production; they are not affected by this license.
+ *
+ */
+
+#ifndef STORE_H
+#define STORE_H
+
+#include <qglobal.h>
+#include <stdio.h>
+
+#include "portable.h"
+
+/*! @brief Abstract interface for file based memory storage operations */
+class StorageIntf
+{
+  public:
+    /*! Required by gcc */
+    virtual ~StorageIntf() {}
+    /*! Read \a size bytes from the store into \a buf. */
+    virtual int read(char *buf,uint size) = 0;
+    /*! Write \a size bytes from \a buf into the store. */
+    virtual int write(const char *buf,uint size) = 0;
+};
+
+/*! @brief The Store is a file based memory manager.
+ *
+ *  You can open the store using open(). Then obtain a handle via alloc()
+ *  followed by a sequence of write() commands to store information,
+ *  and finalize it using end(). 
+ *  
+ *  Later on you locate the information
+ *  with seek() using the handle obtained with alloc(), and then use a
+ *  sequence of read() calls to read the information back. 
+ *
+ *  If no longer needed the storage space can be freed using release().
+ *  
+ *  The store will dynamically grow the file on disk if needed.
+ */
+class Store : public StorageIntf
+{
+  public:
+    /*! Creates a store. */
+    Store();
+
+    /*! Releases the store object. Will close the underlying file if opened. */
+   ~Store();
+
+    /*! Opens the file underlying the store using \a name as the file name. 
+     *  Returns 0 upon success, or -1 otherwise.
+     */
+    int open(const char *name);
+
+    /*! Allocates a handle to write to and read from. */
+    portable_off_t alloc();
+
+    /*! Writes \a size bytes in array \a buf to the store. 
+     *  First alloc() has to be called.
+     *  \note The information can only be read after end() has been called.
+     */
+    int write(const char *buf,uint size);
+
+    /*! Ends the sequence of writes. 
+     *  \note After this call, first alloc() has to be called
+     *  before new writes can be done.
+     */
+    void end();
+
+    /*! Releases the memory corresponding to the handle returned with alloc() */
+    void release(portable_off_t handle);
+
+    /*! Closes the store */
+    void close();
+
+    /*! Goes to the start of information corresponding to handle \a pos */
+    void seek(portable_off_t handle);
+
+    /*! Reads \a size bytes from the store into the array pointed to be \a buf.
+     *  \note Before reading seek() has to be called to set the right start of the store.
+     */
+    int read(char *buf,uint size);
+
+    void printStats();
+
+    portable_off_t pos() const { return m_cur; }
+
+    void dumpBlock(portable_off_t start,portable_off_t end);
+
+  private:
+    enum State
+    {
+      Init,
+      Reading,
+      Writing
+    };
+    struct Node
+    {
+      portable_off_t pos;
+      struct Node *next;
+    };
+    void printFreeList();
+    FILE *m_file;
+    portable_off_t m_front;
+    portable_off_t m_cur;
+    Node *m_head;
+    State m_state;
+    int m_reads;
+    int m_writes;
+};
+
+#endif