MirrorBufferSet Class Reference

#include <MirrorBufferSet.h>

Collaboration diagram for MirrorBufferSet:

Public Types
enum	{ eNotSupported =0, eSupportedPosixShm, eSupportedTmpFile }
typedef unsigned long	ulong

Public Member Functions
	MirrorBufferSet (ulong bufferSz, ulong mirrorSz, int nBuffers=1)
	~MirrorBufferSet (void)
ulong	BufferSize (void) const
ulong	MirrorSize (void) const
ulong	NumBuffers (void) const
	operator void * (void) const

Static Public Member Functions
static int	Supported (void)
static ulong	PageSize (void)

Protected Member Functions
int	GetFileDescriptor (void)

Protected Attributes
void *	bufferBase
ulong	bufferSize
ulong	mirrorSize
int	numBuffers
char	fileName [112]

Detailed Description

Definition at line 27 of file MirrorBufferSet.h.

Member Typedef Documentation

typedef unsigned long MirrorBufferSet::ulong

Definition at line 29 of file MirrorBufferSet.h.

Member Enumeration Documentation

anonymous enum

Enumerator
eNotSupported
eSupportedPosixShm
eSupportedTmpFile

Definition at line 38 of file MirrorBufferSet.h.

{ eNotSupported=0, eSupportedPosixShm, eSupportedTmpFile };

Constructor & Destructor Documentation

MirrorBufferSet::MirrorBufferSet	(	ulong	bufferSz,
		ulong	mirrorSz,
		int	nBuffers = 1
	)

Definition at line 140 of file MirrorBufferSet.cc.

References bufferBase, bufferSize, fileName, fprintf1, fprintf2, GetFileDescriptor(), MAP_FAILED, MAP_NORESERVE, mirrorSize, numBuffers, PageSize(), and StrError().

:   bufferBase(0),
    bufferSize(bufferSz),
    mirrorSize(mirrorSz),
    numBuffers(nBuffers)
{
    fileName[0] = 0;
    ulong pageSize = PageSize();

    // if bufferSize or mirrorSize are not a multiple of pageSize, round them up
    if (bufferSize % pageSize) {
        bufferSize += pageSize - (bufferSize % pageSize);
    }
    if (mirrorSize % pageSize) {
        mirrorSize += pageSize - (mirrorSize % pageSize);
    }

#if 1
    // do a sanity check for our math
    if ( bufferSize % pageSize)
        fprintf(stderr, "### Error: bufferSize = %lu is not a multiple of pageSize = %lu\n",
            bufferSize, pageSize);
    if ( mirrorSize % pageSize)
        fprintf(stderr, "### Error: mirrorSize = %lu is not a multiple of pageSize = %lu\n",
            mirrorSize, pageSize);
#endif

    int fd = GetFileDescriptor();

    // make the file large enough
    ulong numBytes = (bufferSize+mirrorSize) * numBuffers;
    if ( ftruncate(fd, numBytes) ) {
        perror("ftruncate");
        close(fd);
        throw std::runtime_error(StrError(errno));
    }

    // map the entire buffer space, so there will be enough space reserved
    fprintf1((stderr,"MirrorBufferSet: reserving %lu bytes for mapping ", numBytes));
    caddr_t baseAddr = (caddr_t) mmap(0, numBytes, PROT_READ|PROT_WRITE, 
            MAP_SHARED|MAP_NORESERVE, fd, (off_t)0);
    if (baseAddr == MAP_FAILED) {
        fprintf1((stderr,"failed\n"));
        perror("mmap");
        close(fd);
        throw std::runtime_error(StrError(errno));
    }
    bufferBase = baseAddr;
    fprintf1((stderr,"[%p - %p)\n", (void*)baseAddr, (void*)(baseAddr+numBytes)));
    fprintf1((stderr,"MirrorBufferSet: file \"%s\" is %d bytes\n",
        fileName, (int)(bufferSize*numBuffers)));

    // now map each of the individual buffers twice
    for (int buf=0; buf<numBuffers; buf++) {
        // once for the buffer
        caddr_t theAddr     = baseAddr+buf*(bufferSize+mirrorSize);
        size_t  theSize     = bufferSize;
        off_t  theOffset   = buf*bufferSize;
        fprintf2((stderr,"mapping 0x%06lX bytes @ offset 0x%06lX ", (long unsigned)theSize, (long unsigned)theOffset));
        caddr_t addr = (caddr_t) mmap(theAddr, theSize, PROT_READ|PROT_WRITE,
            MAP_SHARED|MAP_FIXED|MAP_NORESERVE, fd, theOffset);
        if (addr == MAP_FAILED) {
            fprintf2((stderr,"failed\n"));
            perror("mmap");
            close(fd);
            throw std::runtime_error(StrError(errno));
        }
        fprintf2((stderr,"to [%p - %p)\n", (void*)theAddr, (void*)(theAddr+theSize)));
        if (addr!=theAddr) {
            fprintf(stderr, "### Error: mapped to 0x%p instead of 0x%p\n",
                addr, theAddr );
            close(fd);
            throw std::runtime_error(StrError(errno));
        }

        // and again for the mirror
        theAddr     +=bufferSize;
        theSize     = mirrorSize;
        fprintf2((stderr,"mapping 0x%06lX bytes @ offset 0x%06lX ", (long unsigned)theSize, (long unsigned)theOffset));
        addr = (caddr_t) mmap(theAddr, theSize, PROT_READ|PROT_WRITE,
            MAP_SHARED|MAP_FIXED|MAP_NORESERVE, fd, theOffset);
        if (addr == MAP_FAILED) {
            fprintf2((stderr,"failed\n"));
            perror("mmap");
            close(fd);
            throw std::runtime_error(StrError(errno));
        }
        fprintf2((stderr,"to [%p - %p)\n", (void*)theAddr, (void*)(theAddr+theSize)));
        if (addr!=theAddr) {
            fprintf(stderr, "### Error: mapped to 0x%p instead of 0x%p\n", addr, theAddr );
            close(fd);
            throw std::runtime_error(StrError(errno));
        }
    }

    // close the file
    if ( close(fd) ) {
        perror("close");
    }
}

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MirrorBufferSet::~MirrorBufferSet

(

void

)

Definition at line 290 of file MirrorBufferSet.cc.

References bufferBase, bufferSize, fileName, fprintf2, mirrorSize, and numBuffers.

{
    if (!bufferBase) return;

    // unmap the file
    if ( munmap((caddr_t)bufferBase, (bufferSize+mirrorSize)*numBuffers) ) {
        perror("munmap");
    }
    fprintf2((stderr,"unmapped- \"%s\" [%p - %p), %lu bytes\n",
        fileName, bufferBase,
        (void*)((char*)bufferBase+((bufferSize+mirrorSize)*numBuffers)),
        ((bufferSize+mirrorSize)*numBuffers)));
}

Member Function Documentation

ulong MirrorBufferSet::BufferSize ( void  ) const

inline

Definition at line 34 of file MirrorBufferSet.h.

References bufferSize.

Referenced by ThresholdQueueBase::AllocateBuf().

{ return bufferSize; }

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int MirrorBufferSet::GetFileDescriptor ( void  )

protected

Definition at line 244 of file MirrorBufferSet.cc.

References fileName, and fprintf2.

Referenced by MirrorBufferSet().

{
    // get a temporary file name
#if MBS_USE_POSIX_SHM
    unsigned i = 0;
    while (true) {
        sprintf(fileName, "/MirrorBufferSet-%u", i);
        #if defined(OS_IRIX) || defined(OS_HPUX)
        // these platforms don't do shm_open as defined in the spec 
        tmpnam(fileName);
        fprintf2((stderr,"tmpnam returned \"%s\"\n",fileName));
        #endif
        fprintf2((stderr,"calling shm_open with \"%s\"\n",fileName));
        int fd = shm_open(fileName,O_RDWR|O_CREAT|O_EXCL,0600);
        if (fd < 0) {
            if (errno == EEXIST) {
                ++i;
            } else{
                fprintf(stderr, "shm_open \"%s\": ", fileName);
                perror(0);
                return -1;
            }
        } else {
            // remove the shared memory object
            if ( shm_unlink(fileName) ) {
                fprintf(stderr, "### shm_unlink(\"%s\") failed: ", fileName);
                perror(0);
            }
            return fd;
        }
    }
#else
    sprintf(fileName, "/tmp/MirrorBufferSet-XXXXXX");
    int fd = mkstemp(fileName);
    // remove the temporary file
    if ( unlink(fileName) ) {
        fprintf(stderr, "### unlink(\"%s\") failed: ", fileName);
        perror(0);
    }
    return fd;
#endif
}

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ulong MirrorBufferSet::MirrorSize ( void  ) const

inline

Definition at line 35 of file MirrorBufferSet.h.

References mirrorSize.

Referenced by ThresholdQueueBase::AllocateBuf().

{ return mirrorSize; }

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ulong MirrorBufferSet::NumBuffers ( void  ) const

inline

Definition at line 36 of file MirrorBufferSet.h.

References numBuffers.

{ return numBuffers; }

MirrorBufferSet::operator void * ( void  ) const

inline

Definition at line 43 of file MirrorBufferSet.h.

References bufferBase.

{ return bufferBase; }

unsigned long MirrorBufferSet::PageSize ( void  )

static

Definition at line 307 of file MirrorBufferSet.cc.

Referenced by MirrorBufferSet(), and ThresholdQueueBase::ThresholdQueueBase().

{
#ifdef __APPLE__
    return getpagesize();
#else
    return sysconf(_SC_PAGESIZE);
#endif
}

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int MirrorBufferSet::Supported ( void  )

static

Definition at line 27 of file MirrorBufferSet.cc.

References eNotSupported, eSupportedPosixShm, and eSupportedTmpFile.

Referenced by ThresholdQueueBase::AllocateBuf().

{
    #if !MirrorBufferSet_SUPPORTED
        return eNotSupported;
    #endif

    #if MBS_USE_POSIX_SHM
        return eSupportedPosixShm;
    #else
        return eSupportedTmpFile;
    #endif
}

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Member Data Documentation

void* MirrorBufferSet::bufferBase

protected

Definition at line 48 of file MirrorBufferSet.h.

Referenced by MirrorBufferSet(), operator void *(), and ~MirrorBufferSet().

ulong MirrorBufferSet::bufferSize

protected

Definition at line 49 of file MirrorBufferSet.h.

Referenced by BufferSize(), MirrorBufferSet(), and ~MirrorBufferSet().

char MirrorBufferSet::fileName[112]

protected

Definition at line 52 of file MirrorBufferSet.h.

Referenced by GetFileDescriptor(), MirrorBufferSet(), and ~MirrorBufferSet().

ulong MirrorBufferSet::mirrorSize

protected

Definition at line 50 of file MirrorBufferSet.h.

Referenced by MirrorBufferSet(), MirrorSize(), and ~MirrorBufferSet().

int MirrorBufferSet::numBuffers

protected

Definition at line 51 of file MirrorBufferSet.h.

Referenced by MirrorBufferSet(), NumBuffers(), and ~MirrorBufferSet().

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

• lib/MirrorBufferSet.h
• lib/MirrorBufferSet.cc