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Diffstat (limited to 'src/backend/storage/file/buffile.c')
| -rw-r--r-- | src/backend/storage/file/buffile.c | 576 |
1 files changed, 0 insertions, 576 deletions
diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c deleted file mode 100644 index e518897b348..00000000000 --- a/src/backend/storage/file/buffile.c +++ /dev/null @@ -1,576 +0,0 @@ -/*------------------------------------------------------------------------- - * - * buffile.c - * Management of large buffered files, primarily temporary files. - * - * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/file/buffile.c,v 1.13 2002/06/20 20:29:34 momjian Exp $ - * - * NOTES: - * - * BufFiles provide a very incomplete emulation of stdio atop virtual Files - * (as managed by fd.c). Currently, we only support the buffered-I/O - * aspect of stdio: a read or write of the low-level File occurs only - * when the buffer is filled or emptied. This is an even bigger win - * for virtual Files than for ordinary kernel files, since reducing the - * frequency with which a virtual File is touched reduces "thrashing" - * of opening/closing file descriptors. - * - * Note that BufFile structs are allocated with palloc(), and therefore - * will go away automatically at transaction end. If the underlying - * virtual File is made with OpenTemporaryFile, then all resources for - * the file are certain to be cleaned up even if processing is aborted - * by elog(ERROR). To avoid confusion, the caller should take care that - * all calls for a single BufFile are made in the same palloc context. - * - * BufFile also supports temporary files that exceed the OS file size limit - * (by opening multiple fd.c temporary files). This is an essential feature - * for sorts and hashjoins on large amounts of data. - *------------------------------------------------------------------------- - */ - -#include <errno.h> - -#include "postgres.h" - -#include "storage/fd.h" -#include "storage/buffile.h" - -/* - * The maximum safe file size is presumed to be RELSEG_SIZE * BLCKSZ. - * Note we adhere to this limit whether or not LET_OS_MANAGE_FILESIZE - * is defined, although md.c ignores it when that symbol is defined. - */ -#define MAX_PHYSICAL_FILESIZE (RELSEG_SIZE * BLCKSZ) - -/* - * This data structure represents a buffered file that consists of one or - * more physical files (each accessed through a virtual file descriptor - * managed by fd.c). - */ -struct BufFile -{ - int numFiles; /* number of physical files in set */ - /* all files except the last have length exactly MAX_PHYSICAL_FILESIZE */ - File *files; /* palloc'd array with numFiles entries */ - long *offsets; /* palloc'd array with numFiles entries */ - - /* - * offsets[i] is the current seek position of files[i]. We use this - * to avoid making redundant FileSeek calls. - */ - - bool isTemp; /* can only add files if this is TRUE */ - bool dirty; /* does buffer need to be written? */ - - /* - * "current pos" is position of start of buffer within the logical - * file. Position as seen by user of BufFile is (curFile, curOffset + - * pos). - */ - int curFile; /* file index (0..n) part of current pos */ - int curOffset; /* offset part of current pos */ - int pos; /* next read/write position in buffer */ - int nbytes; /* total # of valid bytes in buffer */ - char buffer[BLCKSZ]; -}; - -static BufFile *makeBufFile(File firstfile); -static void extendBufFile(BufFile *file); -static void BufFileLoadBuffer(BufFile *file); -static void BufFileDumpBuffer(BufFile *file); -static int BufFileFlush(BufFile *file); - - -/* - * Create a BufFile given the first underlying physical file. - * NOTE: caller must set isTemp true if appropriate. - */ -static BufFile * -makeBufFile(File firstfile) -{ - BufFile *file = (BufFile *) palloc(sizeof(BufFile)); - - file->numFiles = 1; - file->files = (File *) palloc(sizeof(File)); - file->files[0] = firstfile; - file->offsets = (long *) palloc(sizeof(long)); - file->offsets[0] = 0L; - file->isTemp = false; - file->dirty = false; - file->curFile = 0; - file->curOffset = 0L; - file->pos = 0; - file->nbytes = 0; - - return file; -} - -/* - * Add another component temp file. - */ -static void -extendBufFile(BufFile *file) -{ - File pfile; - - Assert(file->isTemp); - pfile = OpenTemporaryFile(); - Assert(pfile >= 0); - - file->files = (File *) repalloc(file->files, - (file->numFiles + 1) * sizeof(File)); - file->offsets = (long *) repalloc(file->offsets, - (file->numFiles + 1) * sizeof(long)); - file->files[file->numFiles] = pfile; - file->offsets[file->numFiles] = 0L; - file->numFiles++; -} - -/* - * Create a BufFile for a new temporary file (which will expand to become - * multiple temporary files if more than MAX_PHYSICAL_FILESIZE bytes are - * written to it). - */ -BufFile * -BufFileCreateTemp(void) -{ - BufFile *file; - File pfile; - - pfile = OpenTemporaryFile(); - Assert(pfile >= 0); - - file = makeBufFile(pfile); - file->isTemp = true; - - return file; -} - -#ifdef NOT_USED -/* - * Create a BufFile and attach it to an already-opened virtual File. - * - * This is comparable to fdopen() in stdio. This is the only way at present - * to attach a BufFile to a non-temporary file. Note that BufFiles created - * in this way CANNOT be expanded into multiple files. - */ -BufFile * -BufFileCreate(File file) -{ - return makeBufFile(file); -} -#endif - -/* - * Close a BufFile - * - * Like fclose(), this also implicitly FileCloses the underlying File. - */ -void -BufFileClose(BufFile *file) -{ - int i; - - /* flush any unwritten data */ - BufFileFlush(file); - /* close the underlying file(s) (with delete if it's a temp file) */ - for (i = 0; i < file->numFiles; i++) - FileClose(file->files[i]); - /* release the buffer space */ - pfree(file->files); - pfree(file->offsets); - pfree(file); -} - -/* - * BufFileLoadBuffer - * - * Load some data into buffer, if possible, starting from curOffset. - * At call, must have dirty = false, pos and nbytes = 0. - * On exit, nbytes is number of bytes loaded. - */ -static void -BufFileLoadBuffer(BufFile *file) -{ - File thisfile; - - /* - * Advance to next component file if necessary and possible. - * - * This path can only be taken if there is more than one component, so it - * won't interfere with reading a non-temp file that is over - * MAX_PHYSICAL_FILESIZE. - */ - if (file->curOffset >= MAX_PHYSICAL_FILESIZE && - file->curFile + 1 < file->numFiles) - { - file->curFile++; - file->curOffset = 0L; - } - - /* - * May need to reposition physical file. - */ - thisfile = file->files[file->curFile]; - if (file->curOffset != file->offsets[file->curFile]) - { - if (FileSeek(thisfile, file->curOffset, SEEK_SET) != file->curOffset) - return; /* seek failed, read nothing */ - file->offsets[file->curFile] = file->curOffset; - } - - /* - * Read whatever we can get, up to a full bufferload. - */ - file->nbytes = FileRead(thisfile, file->buffer, sizeof(file->buffer)); - if (file->nbytes < 0) - file->nbytes = 0; - file->offsets[file->curFile] += file->nbytes; - /* we choose not to advance curOffset here */ -} - -/* - * BufFileDumpBuffer - * - * Dump buffer contents starting at curOffset. - * At call, should have dirty = true, nbytes > 0. - * On exit, dirty is cleared if successful write, and curOffset is advanced. - */ -static void -BufFileDumpBuffer(BufFile *file) -{ - int wpos = 0; - int bytestowrite; - File thisfile; - - /* - * Unlike BufFileLoadBuffer, we must dump the whole buffer even if it - * crosses a component-file boundary; so we need a loop. - */ - while (wpos < file->nbytes) - { - /* - * Advance to next component file if necessary and possible. - */ - if (file->curOffset >= MAX_PHYSICAL_FILESIZE && file->isTemp) - { - while (file->curFile + 1 >= file->numFiles) - extendBufFile(file); - file->curFile++; - file->curOffset = 0L; - } - - /* - * Enforce per-file size limit only for temp files, else just try - * to write as much as asked... - */ - bytestowrite = file->nbytes - wpos; - if (file->isTemp) - { - long availbytes = MAX_PHYSICAL_FILESIZE - file->curOffset; - - if ((long) bytestowrite > availbytes) - bytestowrite = (int) availbytes; - } - - /* - * May need to reposition physical file. - */ - thisfile = file->files[file->curFile]; - if (file->curOffset != file->offsets[file->curFile]) - { - if (FileSeek(thisfile, file->curOffset, SEEK_SET) != file->curOffset) - return; /* seek failed, give up */ - file->offsets[file->curFile] = file->curOffset; - } - bytestowrite = FileWrite(thisfile, file->buffer, bytestowrite); - if (bytestowrite <= 0) - return; /* failed to write */ - file->offsets[file->curFile] += bytestowrite; - file->curOffset += bytestowrite; - wpos += bytestowrite; - } - file->dirty = false; - - /* - * At this point, curOffset has been advanced to the end of the - * buffer, ie, its original value + nbytes. We need to make it point - * to the logical file position, ie, original value + pos, in case - * that is less (as could happen due to a small backwards seek in a - * dirty buffer!) - */ - file->curOffset -= (file->nbytes - file->pos); - if (file->curOffset < 0) /* handle possible segment crossing */ - { - file->curFile--; - Assert(file->curFile >= 0); - file->curOffset += MAX_PHYSICAL_FILESIZE; - } - - /* - * Now we can set the buffer empty without changing the logical - * position - */ - file->pos = 0; - file->nbytes = 0; -} - -/* - * BufFileRead - * - * Like fread() except we assume 1-byte element size. - */ -size_t -BufFileRead(BufFile *file, void *ptr, size_t size) -{ - size_t nread = 0; - size_t nthistime; - - if (file->dirty) - { - if (BufFileFlush(file) != 0) - return 0; /* could not flush... */ - Assert(!file->dirty); - } - - while (size > 0) - { - if (file->pos >= file->nbytes) - { - /* Try to load more data into buffer. */ - file->curOffset += file->pos; - file->pos = 0; - file->nbytes = 0; - BufFileLoadBuffer(file); - if (file->nbytes <= 0) - break; /* no more data available */ - } - - nthistime = file->nbytes - file->pos; - if (nthistime > size) - nthistime = size; - Assert(nthistime > 0); - - memcpy(ptr, file->buffer + file->pos, nthistime); - - file->pos += nthistime; - ptr = (void *) ((char *) ptr + nthistime); - size -= nthistime; - nread += nthistime; - } - - return nread; -} - -/* - * BufFileWrite - * - * Like fwrite() except we assume 1-byte element size. - */ -size_t -BufFileWrite(BufFile *file, void *ptr, size_t size) -{ - size_t nwritten = 0; - size_t nthistime; - - while (size > 0) - { - if (file->pos >= BLCKSZ) - { - /* Buffer full, dump it out */ - if (file->dirty) - { - BufFileDumpBuffer(file); - if (file->dirty) - break; /* I/O error */ - } - else - { - /* Hmm, went directly from reading to writing? */ - file->curOffset += file->pos; - file->pos = 0; - file->nbytes = 0; - } - } - - nthistime = BLCKSZ - file->pos; - if (nthistime > size) - nthistime = size; - Assert(nthistime > 0); - - memcpy(file->buffer + file->pos, ptr, nthistime); - - file->dirty = true; - file->pos += nthistime; - if (file->nbytes < file->pos) - file->nbytes = file->pos; - ptr = (void *) ((char *) ptr + nthistime); - size -= nthistime; - nwritten += nthistime; - } - - return nwritten; -} - -/* - * BufFileFlush - * - * Like fflush() - */ -static int -BufFileFlush(BufFile *file) -{ - if (file->dirty) - { - BufFileDumpBuffer(file); - if (file->dirty) - return EOF; - } - - return 0; -} - -/* - * BufFileSeek - * - * Like fseek(), except that target position needs two values in order to - * work when logical filesize exceeds maximum value representable by long. - * We do not support relative seeks across more than LONG_MAX, however. - * - * Result is 0 if OK, EOF if not. Logical position is not moved if an - * impossible seek is attempted. - */ -int -BufFileSeek(BufFile *file, int fileno, long offset, int whence) -{ - int newFile; - long newOffset; - - switch (whence) - { - case SEEK_SET: - if (fileno < 0) - return EOF; - newFile = fileno; - newOffset = offset; - break; - case SEEK_CUR: - - /* - * Relative seek considers only the signed offset, ignoring - * fileno. Note that large offsets (> 1 gig) risk overflow in - * this add... - */ - newFile = file->curFile; - newOffset = (file->curOffset + file->pos) + offset; - break; -#ifdef NOT_USED - case SEEK_END: - /* could be implemented, not needed currently */ - break; -#endif - default: - elog(ERROR, "BufFileSeek: invalid whence: %d", whence); - return EOF; - } - while (newOffset < 0) - { - if (--newFile < 0) - return EOF; - newOffset += MAX_PHYSICAL_FILESIZE; - } - if (newFile == file->curFile && - newOffset >= file->curOffset && - newOffset <= file->curOffset + file->nbytes) - { - /* - * Seek is to a point within existing buffer; we can just adjust - * pos-within-buffer, without flushing buffer. Note this is OK - * whether reading or writing, but buffer remains dirty if we were - * writing. - */ - file->pos = (int) (newOffset - file->curOffset); - return 0; - } - /* Otherwise, must reposition buffer, so flush any dirty data */ - if (BufFileFlush(file) != 0) - return EOF; - - /* - * At this point and no sooner, check for seek past last segment. The - * above flush could have created a new segment, so checking sooner - * would not work (at least not with this code). - */ - if (file->isTemp) - { - /* convert seek to "start of next seg" to "end of last seg" */ - if (newFile == file->numFiles && newOffset == 0) - { - newFile--; - newOffset = MAX_PHYSICAL_FILESIZE; - } - while (newOffset > MAX_PHYSICAL_FILESIZE) - { - if (++newFile >= file->numFiles) - return EOF; - newOffset -= MAX_PHYSICAL_FILESIZE; - } - } - if (newFile >= file->numFiles) - return EOF; - /* Seek is OK! */ - file->curFile = newFile; - file->curOffset = newOffset; - file->pos = 0; - file->nbytes = 0; - return 0; -} - -void -BufFileTell(BufFile *file, int *fileno, long *offset) -{ - *fileno = file->curFile; - *offset = file->curOffset + file->pos; -} - -/* - * BufFileSeekBlock --- block-oriented seek - * - * Performs absolute seek to the start of the n'th BLCKSZ-sized block of - * the file. Note that users of this interface will fail if their files - * exceed BLCKSZ * LONG_MAX bytes, but that is quite a lot; we don't work - * with tables bigger than that, either... - * - * Result is 0 if OK, EOF if not. Logical position is not moved if an - * impossible seek is attempted. - */ -int -BufFileSeekBlock(BufFile *file, long blknum) -{ - return BufFileSeek(file, - (int) (blknum / RELSEG_SIZE), - (blknum % RELSEG_SIZE) * BLCKSZ, - SEEK_SET); -} - -#ifdef NOT_USED -/* - * BufFileTellBlock --- block-oriented tell - * - * Any fractional part of a block in the current seek position is ignored. - */ -long -BufFileTellBlock(BufFile *file) -{ - long blknum; - - blknum = (file->curOffset + file->pos) / BLCKSZ; - blknum += file->curFile * RELSEG_SIZE; - return blknum; -} - -#endif |