BitMap Class Reference

#include <BitMap.h>

Public Member Functions
	BitMap ()
	~BitMap ()
int	Initialize (char *BitMapFileName, unsigned int nBits, ostream *LogStream)
int	Format ()
int	Load ()
int	Reset ()
int	Confirm ()
int	Close ()
int	AllocSeq (unsigned int Startbit, unsigned int *Bit)
void	Free (unsigned int Bit)
unsigned int	nFree ()
Private Member Functions
void	ifreestg ()
int	iclose ()
unsigned int	CountnFree ()
bool	TestBit (const unsigned int Bit)
void	SetBit (const unsigned int Bit)
void	ClearBit (const unsigned int Bit)
unsigned int	CountFreeBits (const int Byte)
Private Attributes
char *	m_FileName
unsigned int	m_nBits
unsigned int	m_nFree
unsigned int	m_nFreeConfirmed
unsigned int	m_nBytes
unsigned char *	m_BitMap
int	m_handle
ostream *	m_log
bool	m_changed

---

Detailed Description

Definition at line 29 of file BitMap.h.

---

Constructor & Destructor Documentation

BitMap::BitMap

(

)

Definition at line 50 of file BitMap.cpp.

{
    m_FileName       = NULL;
    m_nBits          = 0;
    m_nFree          = 0;
    m_nFreeConfirmed = 0;
    m_nBytes         = 0;
    m_BitMap         = NULL;
    m_handle         = -1;
    m_log            = NULL;
    m_changed        = false;
}

BitMap::~BitMap

(

)

Definition at line 63 of file BitMap.cpp.

{
    iclose();
    ifreestg();
}

---

Member Function Documentation

int BitMap::AllocSeq	(	unsigned int	Startbit,
		unsigned int *	Bit
	)

Definition at line 311 of file BitMap.cpp.

{
    if( m_nFree <= 0 )
    {
        return ERROR_BITMAP + 1;
    }

    if( Startbit >= m_nBits )
    {
        abort();    // caller logic error, Startbit out of range
    }

    unsigned int x = Startbit;
    int off;
    unsigned int BitCount = 0;

    while( 1 )
    {
        // Check if been all the way around (Give 8 extra bits
        // to account for possible unused bits at end of BitMap)
        if( BitCount > ( m_nBits + 8 ) )
            break;
        if( x >= m_nBits )      // wrap bit table
            x = 0;
        off = x >> 3;

        // optimization: skip to next byte if all bits are used
        // in current byte
        if( m_BitMap[off] == 0xff )
        {
            x = ( off + 1 ) << 3;
            BitCount += 8;
        }
        else
        {
            if( !TestBit( x ) )
            {
                SetBit( x );
                *Bit = x;
                m_changed = true;
                m_nFree--;
                return 0;
            }
            x++;
            BitCount++;
        }
    }

    // no free bits found
    // This should not happen, as m_nFree above claimed some were
    // available
    *m_log  << "BitMap::AllocSeq(): no free bits found for "
            << m_FileName << " (UNEXPECTED ERROR)" << endl;
    return ERROR_BITMAP + 2;
}

void BitMap::ClearBit

(

const unsigned int

Bit

)

[private]

Definition at line 415 of file BitMap.cpp.

{
    int mask = 0x80 >> ( Bit & 7 );
    int off  = Bit >> 3;
    m_BitMap[off] &= ~mask;
}

int BitMap::Close

(

)

int BitMap::Confirm

(

)

Definition at line 284 of file BitMap.cpp.

{
    // If there was any change in bit map, update file
    if( m_changed )
    {
        // Start writing from file begining
        lseek( m_handle, 0, SEEK_SET );
        unsigned int nBytes;
        // Write bit map to file
        nBytes = write( m_handle, m_BitMap, m_nBytes );
        if( ( nBytes != ( unsigned int ) m_nBytes ) )
        {
            (*m_log) << "BitMap::Flush(): Error writing bitmap file "
                     << m_FileName << "\n  SYSTEM ERROR: " << strerror(errno) 
                     << endl;
            return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
        }
        // Flush OS file buffers to disk
        fsync( m_handle );
        m_nFreeConfirmed = m_nFree;
        m_changed = false;
    }
    return 0;
}

unsigned int BitMap::CountFreeBits

(

const int

Byte

)

[private]

Definition at line 423 of file BitMap.cpp.

{
    unsigned int count = 0;
    int mask = 0x80;
    for( int i = 0; i < 8; i++ )
    {
        if( ( mask & byte ) == 0 )
            count++;
        mask = mask >> 1;
    }
    return count;
}

unsigned int BitMap::CountnFree

(

)

[private]

Definition at line 386 of file BitMap.cpp.

{
    // Count number of free bits in bitmap
    unsigned int count = 0;
    for( unsigned int i = 0;i < m_nBytes; i++ )
    {
        count += CountFreeBits( m_BitMap[i] );
    }

    return count;
}

int BitMap::Format

(

)

Definition at line 146 of file BitMap.cpp.

{
    // set all bits to not allocated (zero)
    memset( m_BitMap, 0, m_nBytes );

    // set extra bits at end of bitmap so they won't be allocated
    unsigned int x;
    for( x = m_nBits; x < ( m_nBytes << 3 ); x++ )
    {
        SetBit( x );
    }

    // create file to store bitmap
    m_handle = open( m_FileName, O_RDWR | O_TRUNC | O_CREAT, 0700 );
    if( m_handle == -1 )
    {
        (*m_log) << "BitMap::Format(): "
                 << " open create for " << m_FileName << " failed "
                 << strerror(errno) << endl;
        return ERROR_OBJECTMANAGER + ERROR_SYSTEM_CONFIGURATION;
    }

    // init free bit count
    m_nFree = CountnFree();

    // force write of metadata to disk
    m_changed = true;
    return Confirm();
}

void BitMap::Free

(

unsigned int

Bit

)

Definition at line 368 of file BitMap.cpp.

{
    if( TestBit( Bit ) )
    {
        ClearBit(Bit);
        m_changed = true;
        m_nFree++;
        return;
    }

    // terrible error -- freeing bit already free
    *m_log << "BitMap::Free(): Attempt to free bit already free for "
           << m_FileName << " bit " << Bit << endl;
    RioErr << "BitMap::Free(): Attempt to free bit already free for "
           << m_FileName << " bit " << Bit << endl;
}

int BitMap::iclose

(

)

[private]

Definition at line 89 of file BitMap.cpp.

{
    if( m_handle != -1 )
    {
        if( close( m_handle ) == -1 )
        {
            *m_log << "BitMap::Close(): Error closing bitmap file "
                   << m_FileName << "\n  SYSTEM ERROR: " << strerror( errno ) 
                   << endl;
            return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
        }
        m_handle = -1;
    }
    return 0;
}

void BitMap::ifreestg

(

)

[private]

Definition at line 71 of file BitMap.cpp.

{
    if( m_BitMap != 0 )
    {
        delete[] m_BitMap;
        m_BitMap = 0;
    }

    if( m_FileName != 0 )
    {
        delete[] m_FileName;
        m_FileName = 0;
    }
    m_nBits = m_nBytes = 0;
}

int BitMap::Initialize	(	char *	BitMapFileName,
		unsigned int	nBits,
		ostream *	LogStream
	)

Definition at line 106 of file BitMap.cpp.

{
    m_log = Logstream;

    if( nBits < 1 )
    {
        (*m_log) << "BitMap::Initialize(): Unexpected error. "
                 << " Number of Bits specified is less than one"
                 << endl;
        return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
    }

    ifreestg();

    m_nBits = nBits;
    m_nBytes = ( m_nBits + 7 ) >> 3;
    m_BitMap = new unsigned char[m_nBytes];
    if( m_BitMap == NULL )
    {
        ifreestg();
        return ERROR_OBJECTMANAGER + ERROR_MEMORY;
    }

    // Allocate file name string
    m_FileName = new char [strlen( BitMapFileName ) + 1];
    // Check if memory was allocated successfully
    if( m_FileName == NULL )
    {
        ifreestg();
        return ERROR_OBJECTMANAGER + ERROR_MEMORY;
    }
    // Update name of file with bit map
    strcpy( m_FileName, BitMapFileName );

    return 0;
}

int BitMap::Load

(

)

Definition at line 177 of file BitMap.cpp.

{
    // Load bitmap from  file
    m_handle = open( m_FileName, O_RDWR, 0 );
    if( m_handle == -1 )
    {
        RioErr << "BitMap::Load(): Could not open bitmap file "
               << m_FileName << " with RDWR permissions, trying to open with "
               << "RDONLY permission" << endl;

        m_handle = open( m_FileName, O_RDONLY, 0 );
        if( m_handle == -1 )
        {
            // to insert new devices without
            // removing everything and copying it again.
            char answer[128] = "";

            do {
                //cout << "Would you like to insert this new device"
                //     << " and format it? [y/n]\n";
                //fgets( answer, 128, stdin );
                //if( ( answer[0] == 'n' ) || ( answer[0] == 'N' ) )
                RioErr << "BitMap::Load() You have to format the new disk "
                       << " before start server. Exiting..." << endl;
                    return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
            }while(( answer[0] != 'Y' ) && ( answer[0] != 'y' ));

            //Format the new device
            RioErr <<  " Trying to format ... " << endl;
            int rc2 = Format();
            // preallocate block 0, 1
            unsigned int junk;
            if( !rc2 )
            {
                rc2 = AllocSeq( 0, &junk );
            }
            if( !rc2 )
            {
                rc2 = AllocSeq( 1, &junk );
            }
            if( rc2 )
            {
                    RioErr <<  " Error! " << endl;
                    return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
            }
            RioErr <<  " New device formatted. " << endl;
            Confirm();
            close( m_handle );
            RioErr <<  " Trying to open the new device." << endl;
            m_handle = open( m_FileName, O_RDWR, 0 );
            if( m_handle == -1 )
            {
                RioErr << "BitMap::Load(): Could not open bitmap file "
                       << m_FileName << endl
                        << "  SYSTEM ERROR: " << strerror(errno) << endl;
                return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
            }
            RioErr <<  " OK. " << endl;
            // --------------------------------------------------------------------
        }
    }

    unsigned int nBytes;
    nBytes = read( m_handle, m_BitMap, m_nBytes );
    if( ( nBytes != ( unsigned int )m_nBytes ) )
    {
        RioErr << "BitMap::Load(): Error reading bitmap file "
               << m_FileName << endl
                 << "  SYSTEM ERROR: " << strerror(errno) << endl;
        close( m_handle );
        return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
    }

    // init free bit count
    m_nFree = CountnFree();
    m_nFreeConfirmed = m_nFree;

    m_changed = false;
    return 0;
}

unsigned int BitMap::nFree

(

)

[inline]

Definition at line 64 of file BitMap.h.

{ return m_nFree; };

int BitMap::Reset

(

void

)

Definition at line 260 of file BitMap.cpp.

{
    unsigned int nBytes;
    // Reload bitmap from  file (erasing previous updates not flushed to disk)
    lseek( m_handle, 0, SEEK_SET );
    nBytes = read( m_handle, m_BitMap, m_nBytes );
    if( ( nBytes != ( unsigned int ) m_nBytes ) )
    {
        (*m_log) << "BitMap::Reset(): Error reading bitmap file "
                 << m_FileName << " - " << strerror(errno) << endl;
        //### I'm not really sure what to do at this point
        //### the bitmap is probably lost...
        iclose();
        return ERROR_OBJECTMANAGER + ERROR_UNEXPECTED;
    }

    m_nFree = m_nFreeConfirmed;
    m_changed = false;
    return 0;
}

void BitMap::SetBit

(

const unsigned int

Bit

)

[private]

Definition at line 407 of file BitMap.cpp.

{
    int mask = 0x80 >> ( Bit & 7 );
    int off  = Bit >> 3;
    m_BitMap[off] |= mask;
}

bool BitMap::TestBit

(

const unsigned int

Bit

)

[private]

Definition at line 399 of file BitMap.cpp.

{
    int mask = 0x80 >> ( Bit & 7 );
    int off  = Bit >> 3;
    return (( m_BitMap[off] & mask ) != 0);
}

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Field Documentation

unsigned char* BitMap::m_BitMap [private]

Definition at line 37 of file BitMap.h.

bool BitMap::m_changed [private]

Definition at line 41 of file BitMap.h.

char* BitMap::m_FileName [private]

Definition at line 32 of file BitMap.h.

int BitMap::m_handle [private]

Definition at line 39 of file BitMap.h.

ostream* BitMap::m_log [private]

Definition at line 40 of file BitMap.h.

unsigned int BitMap::m_nBits [private]

Definition at line 33 of file BitMap.h.

unsigned int BitMap::m_nBytes [private]

Definition at line 36 of file BitMap.h.

unsigned int BitMap::m_nFree [private]

Definition at line 34 of file BitMap.h.

unsigned int BitMap::m_nFreeConfirmed [private]

Definition at line 35 of file BitMap.h.

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The documentation for this class was generated from the following files:

• BitMap.h
• BitMap.cpp