747 lines
16 KiB
Plaintext
747 lines
16 KiB
Plaintext
/******************************************************************************
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VERSION $Id: buf.c,v 1.26 92/01/09 09:15:26 margo Exp $
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PACKAGE: User Level Shared Memory Manager
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DESCRIPTION:
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This package provides a buffer pool interface implemented as
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a collection of file pages mapped into shared memory.
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Based on Mark's buffer manager
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ROUTINES:
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External
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buf_alloc
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buf_flags
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buf_get
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buf_init
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buf_last
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buf_open
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buf_pin
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buf_sync
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buf_unpin
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Internal
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bf_assign_buf
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bf_fid_to_fd
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bf_newbuf
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bf_put_page
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******************************************************************************/
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#include <sys/types.h>
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#include <assert.h>
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <stdio.h>
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#include <errno.h>
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#include "list.h"
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#include "user.h"
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#include "txn_sys.h"
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#include "buf.h"
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#include "semkeys.h"
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#include "error.h"
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/*
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we need to translate between some type of file id that the user
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process passes and a file descriptor. For now, it's a nop.
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*/
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#define GET_MASTER get_sem ( buf_spinlock )
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#define RELEASE_MASTER release_sem ( buf_spinlock )
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#define LRUID *buf_lru
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#define LRUP (bufhdr_table+*buf_lru)
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#define MRU bufhdr_table[*buf_lru].lru.prev
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/* Global indicator that you have started reusing buffers */
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int do_statistics = 0;
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/*
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Process Statics (pointers into shared memory)
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*/
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static BUF_T *buf_table = 0;
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static BUFHDR_T *bufhdr_table;
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static int *buf_hash_table;
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static int *buf_lru; /* LRU is the free list */
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static int buf_spinlock;
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static FINFO_T *buf_fids;
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static int *buf_sp; /* Pointer to string free space */
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static char *buf_strings;
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/* Process Local FID->FD table */
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static int fds[NUM_FILE_ENTRIES];
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/* Static routines */
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static BUFHDR_T *bf_assign_buf();
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static int bf_fid_to_fd();
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static BUFHDR_T *bf_newbuf();
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static int bf_put_page();
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/*
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Return 0 on success
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1 on failure
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*/
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extern int
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buf_init ( )
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{
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ADDR_T buf_region;
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BUFHDR_T *bhp;
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int i;
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int ref_count;
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int *spinlockp;
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/*
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Initialize Process local structures
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*/
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for ( i = 0; i < NUM_FILE_ENTRIES; i++ ) {
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fds[i] = -1;
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}
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buf_region = attach_region ( BUF_REGION_NAME, BUF_REGION_NUM,
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BUF_REGION_SIZE, &ref_count );
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if ( !buf_region ) {
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return (1);
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}
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error_log3 ( "Buf Region: ADDR: %d ID: %d SIZE: %d\n", buf_region,
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BUF_REGION_NUM, BUF_REGION_SIZE );
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buf_table = (BUF_T *)buf_region;
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bufhdr_table = (BUFHDR_T *)(buf_table + NUM_BUFS);
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buf_hash_table = (int *)(bufhdr_table + NUM_BUFS);
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buf_lru = buf_hash_table + NUMTABLE_ENTRIES;
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spinlockp = buf_lru + 1;
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buf_fids = (FINFO_T *)(spinlockp+1);
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buf_sp = (int *)(buf_fids + NUM_FILE_ENTRIES);
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buf_strings = (char *)(buf_sp + 1);
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/* Create locking spinlock (gets creating holding the lock) */
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buf_spinlock = create_sem ( BUF_SPIN_NAME, BUF_SPIN_NUM, ref_count <= 1 );
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if ( buf_spinlock < 0 ) {
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return(1);
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}
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if ( ref_count <= 1 ) {
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*spinlockp = buf_spinlock;
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/* Now initialize the buffer manager */
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/* 1. Free list */
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*buf_lru = 0;
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/* 2. Buffer headers */
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for ( i = 0, bhp = bufhdr_table; i < NUM_BUFS; bhp++, i++ ) {
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bhp->lru.next = i+1;
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bhp->lru.prev = i-1;
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bhp->flags = 0; /* All Flags off */
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bhp->refcount = 0;
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bhp->wait_proc = -1; /* No sleepers */
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LISTPE_INIT ( hash, bhp, i ); /* Hash chains */
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}
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bufhdr_table[0].lru.prev = NUM_BUFS-1;
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bufhdr_table[NUM_BUFS-1].lru.next = 0;
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/* 3. Hash Table */
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for ( i = 0; i < NUMTABLE_ENTRIES; i++ ) {
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buf_hash_table[i] = NUM_BUFS;
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}
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/* 4. File ID Table */
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for ( i = 0; i < NUM_FILE_ENTRIES; i++ ) {
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buf_fids[i].offset = -1;
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buf_fids[i].npages = -1;
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buf_fids[i].refcount = 0;
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}
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/* 5. Free String Pointer */
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*buf_sp = (FILE_NAME_LEN*NUM_FILE_ENTRIES);
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if (RELEASE_MASTER) {
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return(1);
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}
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error_log0 ( "Initialized buffer region\n" );
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}
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return (0);
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}
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extern void
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buf_exit()
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{
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int ref;
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int i;
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/* Flush Buffer Pool on Exit */
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for ( i = 0; i < NUM_FILE_ENTRIES; i++ ) {
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if ( fds[i] != -1 ) {
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close ( fds[i] );
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}
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}
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if ( buf_table ) {
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detach_region ( buf_table, BUF_REGION_NUM, BUF_REGION_SIZE, &ref );
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}
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return;
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}
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/*
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We need an empty buffer. Find the LRU unpinned NON-Dirty page.
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*/
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static BUFHDR_T *
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bf_newbuf()
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{
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int fd;
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int lruid;
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int nbytes;
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int ndx;
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BUFHDR_T *bhp;
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lruid = LRUID;
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for ( bhp = LRUP;
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bhp->flags & (BUF_PINNED|BUF_IO_IN_PROGRESS);
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bhp = LISTP_NEXTP (bufhdr_table, lru, bhp ) ) {
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if ( bhp->lru.next == lruid ) {
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/* OUT OF BUFFERS */
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error_log1 ( "All buffers are pinned. %s\n",
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"Unable to grant buffer request" );
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return(NULL);
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}
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}
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/* BHP can be used */
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if ( bhp->flags & BUF_DIRTY ) {
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do_statistics = 1;
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/*
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MIS Check for log flushed appropriately
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*/
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fd = bf_fid_to_fd(bhp->id.file_id);
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if ( fd == -1 ) {
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error_log1 ("Invalid fid %d\n", bhp->id.file_id);
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return(NULL);
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}
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if ( bf_put_page(fd, bhp) < 0 ) {
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return(NULL);
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}
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}
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/* Update Hash Pointers */
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ndx = BUF_HASH ( bhp->id.file_id, bhp->id.obj_id );
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LISTP_REMOVE(bufhdr_table, hash, bhp);
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if ( buf_hash_table[ndx] == (bhp-bufhdr_table) ) {
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if ( bhp->hash.next != (bhp-bufhdr_table) ) {
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buf_hash_table[ndx] = bhp->hash.next;
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} else {
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buf_hash_table[ndx] = NUM_BUFS;
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}
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}
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INIT_BUF(bhp);
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return(bhp);
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}
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/*
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buf_alloc
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Add a page to a file and return a buffer for it.
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*/
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ADDR_T
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buf_alloc ( fid, new_pageno )
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int fid;
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int *new_pageno;
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{
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BUFHDR_T *bhp;
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int fd;
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int len;
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int ndx;
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OBJ_T fobj;
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if (GET_MASTER) {
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return(NULL);
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}
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if ( buf_fids[fid].npages == -1 ) {
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/* initialize npages field */
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fd = bf_fid_to_fd ( fid );
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}
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assert (fid < NUM_FILE_ENTRIES);
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*new_pageno = buf_fids[fid].npages;
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if ( *new_pageno == -1 ) {
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RELEASE_MASTER;
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return ( NULL );
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}
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buf_fids[fid].npages++;
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ndx = BUF_HASH ( fid, *new_pageno );
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fobj.file_id = fid;
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fobj.obj_id = *new_pageno;
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bhp = bf_assign_buf ( ndx, &fobj, BF_PIN|BF_DIRTY|BF_EMPTY, &len );
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if ( RELEASE_MASTER ) {
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/* Memory leak */
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return(NULL);
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}
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if ( bhp ) {
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return ((ADDR_T)(buf_table+(bhp-bufhdr_table)));
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} else {
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return ( NULL );
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}
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}
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/*
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Buffer Flags
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BF_DIRTY Mark page as dirty
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BF_EMPTY Don't initialize page, just get buffer
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BF_PIN Retrieve with pin
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MIS
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Might want to add a flag that sets an LSN for this buffer is the
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DIRTY flag is set
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Eventually, you may want a flag that indicates the I/O and lock
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request should be shipped off together, but not for now.
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*/
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extern ADDR_T
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buf_get ( file_id, page_id, flags, len )
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int file_id;
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int page_id;
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u_long flags;
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int *len; /* Number of bytes read into buffer */
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{
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BUFHDR_T *bhp;
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int bufid;
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int fd;
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int ndx;
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int next_bufid;
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int stat;
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OBJ_T fobj;
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ndx = BUF_HASH ( file_id, page_id );
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fobj.file_id = (long) file_id;
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fobj.obj_id = (long) page_id;
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if ( GET_MASTER ) {
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return(NULL);
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}
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/*
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This could be a for loop, but we lose speed
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by making all the cases general purpose so we
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optimize for the no-collision case.
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*/
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bufid = buf_hash_table[ndx];
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if ( bufid < NUM_BUFS ) {
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for ( bhp = bufhdr_table+bufid;
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!OBJ_EQ (bhp->id, fobj) || !(bhp->flags & BUF_VALID);
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bhp = LISTP_NEXTP ( bufhdr_table, hash, bhp ) ) {
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if ( bhp->hash.next == bufid ) {
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goto not_found;
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}
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}
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/* found */
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if ( flags & BF_PIN ) {
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bhp->flags |= BUF_PINNED;
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bhp->refcount++;
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#ifdef PIN_DEBUG
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fprintf(stderr, "buf_get: %X PINNED (%d)\n",
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buf_table + (bhp-bufhdr_table), bhp->refcount);
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#endif
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}
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if ( flags & BF_DIRTY ) {
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bhp->flags |= BUF_DIRTY;
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}
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while ( bhp->flags & BUF_IO_IN_PROGRESS ) {
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/* MIS -- eventually err check here */
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#ifdef DEBUG
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printf("About to sleep on %d (me: %d\n)\n", bhp->wait_proc,
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my_txnp - txn_table);
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#endif
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#ifdef WAIT_STATS
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buf_waits++;
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#endif
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stat = proc_sleep_on ( &(bhp->wait_proc), buf_spinlock );
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if ( stat ) {
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/* Memory leak */
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return(NULL);
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}
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if (!( bhp->flags & BUF_IO_IN_PROGRESS) &&
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(!OBJ_EQ (bhp->id, fobj) || !(bhp->flags & BUF_VALID))) {
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if (RELEASE_MASTER)
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return(NULL);
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return(buf_get ( file_id, page_id, flags, len ));
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}
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}
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MAKE_MRU( bhp );
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*len = BUFSIZE;
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} else {
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not_found:
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/* If you get here, the page isn't in the hash table */
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bhp = bf_assign_buf ( ndx, &fobj, flags, len );
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}
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/* Common code between found and not found */
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if ( bhp && bhp->flags & BUF_NEWPAGE ) {
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*len = 0;
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}
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if (RELEASE_MASTER){
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/* Memory leak */
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return(NULL);
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}
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if ( bhp ) {
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return ((ADDR_T)(buf_table+(bhp-bufhdr_table)));
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} else {
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return ( NULL );
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}
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}
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/*
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MIS - do I want to add file links to buffer pool?
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*/
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extern int
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buf_sync ( fid, close )
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int fid;
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int close; /* should we dec refcount and possibly
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invalidate all the buffers */
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{
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int i;
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int fd;
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int invalidate;
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BUFHDR_T *bhp;
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if ( (fd = bf_fid_to_fd ( fid )) < 0 ) {
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return(1);
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}
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if (GET_MASTER) {
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return(1);
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}
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invalidate = (buf_fids[fid].refcount == 1 && close);
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if ( invalidate )
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for ( bhp = bufhdr_table, i = 0; i < NUM_BUFS; bhp++, i++ ) {
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if (bhp->id.file_id == fid) {
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if ((bhp->flags & BF_DIRTY) && (bf_put_page( fd, bhp ) < 0)) {
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return(1);
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}
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bhp->id.file_id = -1;
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}
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}
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if (invalidate || close)
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buf_fids[fid].refcount--;
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if (RELEASE_MASTER) {
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return(1);
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}
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return(0);
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}
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extern int
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buf_flags ( addr, set_flags, unset_flags )
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ADDR_T addr;
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u_long set_flags;
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u_long unset_flags;
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{
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int bufid;
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BUFHDR_T *bhp;
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#ifdef PIN_DEBUG
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fprintf(stderr, "buf_flags: %X setting %s%s%s%s%s releasing %s%s%s%s%s\n",
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addr,
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set_flags&BUF_DIRTY ? "DIRTY " : "",
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set_flags&BUF_VALID ? "VALID " : "",
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set_flags&BUF_PINNED ? "PINNED " : "",
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set_flags&BUF_IO_ERROR ? "IO_ERROR " : "",
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set_flags&BUF_IO_IN_PROGRESS ? "IO_IN_PROG " : "",
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set_flags&BUF_NEWPAGE ? "NEWPAGE " : "",
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unset_flags&BUF_DIRTY ? "DIRTY " : "",
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unset_flags&BUF_VALID ? "VALID " : "",
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unset_flags&BUF_PINNED ? "PINNED " : "",
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unset_flags&BUF_IO_ERROR ? "IO_ERROR " : "",
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unset_flags&BUF_IO_IN_PROGRESS ? "IO_IN_PROG " : "",
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unset_flags&BUF_NEWPAGE ? "NEWPAGE " : "" );
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#endif
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if (!ADDR_OK(addr)) {
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error_log1 ( "buf_pin: Invalid Buffer Address %x\n", addr );
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return(1);
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}
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bufid = ((BUF_T *)addr) - buf_table;
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assert ( bufid < NUM_BUFS);
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bhp = &bufhdr_table[bufid];
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if (GET_MASTER) {
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return(1);
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}
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bhp->flags |= set_flags;
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if ( set_flags & BUF_PINNED ) {
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bhp->refcount++;
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}
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if ( set_flags & BUF_DIRTY ) {
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unset_flags |= BUF_NEWPAGE;
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}
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if ( unset_flags & BUF_PINNED ) {
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bhp->refcount--;
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if ( bhp->refcount ) {
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/* Turn off pin bit so it doesn't get unset */
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unset_flags &= ~BUF_PINNED;
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}
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}
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bhp->flags &= ~unset_flags;
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MAKE_MRU(bhp);
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if (RELEASE_MASTER) {
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return(1);
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}
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return(0);
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}
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/*
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Take a string name and produce an fid.
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returns -1 on error
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MIS -- this is a potential problem -- you keep actual names
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here -- what if people run from different directories?
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*/
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extern int
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buf_name_lookup ( fname )
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char *fname;
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{
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int i;
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int fid;
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int ndx;
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fid = -1;
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if (GET_MASTER) {
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return(-1);
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}
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for ( i = 0; i < NUM_FILE_ENTRIES; i++ ) {
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if ( buf_fids[i].offset == -1 ) {
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fid = i;
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} else {
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if (!strcmp (fname, buf_strings+buf_fids[i].offset)) {
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if (RELEASE_MASTER) {
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return(-1);
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}
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buf_fids[i].refcount++;
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return(i);
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}
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}
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}
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if ( fid == -1 ) {
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error_log0 ( "No more file ID's\n" );
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} else {
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ndx = *buf_sp - strlen(fname) - 1;
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if ( ndx < 0 ) {
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error_log0 ( "Out of string space\n" );
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fid = -1;
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} else {
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*buf_sp = ndx;
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strcpy ( buf_strings+ndx, fname );
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buf_fids[fid].offset = ndx;
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}
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buf_fids[fid].refcount = 1;
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}
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if (RELEASE_MASTER) {
|
|
return(-1);
|
|
}
|
|
return(fid);
|
|
}
|
|
|
|
static int
|
|
bf_fid_to_fd ( fid )
|
|
int fid;
|
|
{
|
|
struct stat sbuf;
|
|
|
|
assert ( (fid < NUM_FILE_ENTRIES) && (buf_fids[fid].offset != -1) );
|
|
if ( fds[fid] != -1 ) {
|
|
return(fds[fid]);
|
|
|
|
}
|
|
fds[fid] = open ( buf_strings+buf_fids[fid].offset, O_RDWR|O_CREAT,
|
|
0666 );
|
|
if ( fds[fid] < 0 ) {
|
|
error_log3 ( "Error Opening File %s FID: %d FD: %d. Errno = %d\n",
|
|
buf_strings+buf_fids[fid].offset, fid, fds[fid],
|
|
errno );
|
|
return(-1);
|
|
}
|
|
error_log3 ( "Opening File %s FID: %d FD: %d\n",
|
|
buf_strings+buf_fids[fid].offset, fid, fds[fid] );
|
|
if ( buf_fids[fid].npages == -1 ) {
|
|
/* Initialize the npages field */
|
|
if ( fstat ( fds[fid], &sbuf ) ) {
|
|
error_log3 ( "Error Fstating %s FID: %d. Errno = %d\n",
|
|
buf_strings+buf_fids[fid].offset, fid, errno );
|
|
} else {
|
|
buf_fids[fid].npages = ( sbuf.st_size / BUFSIZE );
|
|
}
|
|
}
|
|
|
|
return ( fds[fid] );
|
|
}
|
|
|
|
static int
|
|
bf_put_page ( fd, bhp )
|
|
int fd;
|
|
BUFHDR_T *bhp;
|
|
{
|
|
int nbytes;
|
|
|
|
assert ( (bhp-bufhdr_table) < NUM_BUFS );
|
|
if ( lseek ( fd, bhp->id.obj_id << BUFSHIFT, L_SET ) < 0 ) {
|
|
return(-1);
|
|
}
|
|
bhp->flags |= BUF_IO_IN_PROGRESS;
|
|
if (RELEASE_MASTER) {
|
|
return(-1);
|
|
}
|
|
nbytes = write(fd, buf_table[bhp-bufhdr_table], BUFSIZE);
|
|
if (GET_MASTER) {
|
|
return(-2);
|
|
}
|
|
if ( nbytes < 0 ) {
|
|
error_log1 ("Write failed with error code %d\n", errno);
|
|
return(-1);
|
|
} else if ( nbytes != BUFSIZE ) {
|
|
error_log1 ("Short write: %d bytes of %d\n", nbytes, BUFSIZE );
|
|
}
|
|
bhp->flags &= ~(BUF_DIRTY|BUF_IO_IN_PROGRESS);
|
|
return (0);
|
|
}
|
|
|
|
static BUFHDR_T *
|
|
bf_assign_buf ( ndx, obj, flags, len )
|
|
int ndx;
|
|
OBJ_T *obj;
|
|
u_long flags;
|
|
int *len; /* Number of bytes read */
|
|
{
|
|
BUFHDR_T *bhp;
|
|
int fd;
|
|
|
|
assert ( obj->file_id < NUM_FILE_ENTRIES );
|
|
bhp = bf_newbuf();
|
|
if ( !bhp ) {
|
|
return(NULL);
|
|
}
|
|
OBJ_ASSIGN ( (*obj), bhp->id );
|
|
if ( buf_hash_table[ndx] >= NUM_BUFS ) {
|
|
buf_hash_table[ndx] = bhp-bufhdr_table;
|
|
} else {
|
|
LISTPE_INSERT ( bufhdr_table, hash, bhp, buf_hash_table[ndx] );
|
|
}
|
|
|
|
bhp->flags |= BUF_VALID;
|
|
if ( flags & BF_PIN ) {
|
|
bhp->flags |= BUF_PINNED;
|
|
bhp->refcount++;
|
|
#ifdef PIN_DEBUG
|
|
fprintf(stderr, "bf_assign_buf: %X PINNED (%d)\n",
|
|
buf_table + (bhp-bufhdr_table), bhp->refcount);
|
|
#endif
|
|
}
|
|
fd = bf_fid_to_fd(obj->file_id);
|
|
if ( fd == -1 ) {
|
|
error_log1 ("Invalid fid %d\n", obj->file_id);
|
|
bhp->flags |= ~BUF_IO_ERROR;
|
|
return(NULL);
|
|
}
|
|
if ( obj->obj_id >= buf_fids[obj->file_id].npages) {
|
|
buf_fids[obj->file_id].npages = obj->obj_id+1;
|
|
*len = 0;
|
|
} else if ( flags & BF_EMPTY ) {
|
|
*len = 0;
|
|
} else {
|
|
bhp->flags |= BUF_IO_IN_PROGRESS;
|
|
if (RELEASE_MASTER) {
|
|
return(NULL);
|
|
}
|
|
if ( lseek ( fd, obj->obj_id << BUFSHIFT, L_SET ) < -1 ) {
|
|
error_log2 ("Unable to perform seek on file: %d to page %d",
|
|
obj->file_id, obj->obj_id );
|
|
bhp->flags &= ~BUF_IO_IN_PROGRESS;
|
|
bhp->flags |= ~BUF_IO_ERROR;
|
|
return(NULL);
|
|
}
|
|
*len = read(fd, buf_table[bhp-bufhdr_table], BUFSIZE);
|
|
if ( *len < 0 ) {
|
|
error_log2 ("Unable to perform read on file: %d to page %d",
|
|
obj->file_id, obj->obj_id );
|
|
bhp->flags &= ~BUF_IO_IN_PROGRESS;
|
|
bhp->flags |= ~BUF_IO_ERROR;
|
|
return(NULL);
|
|
}
|
|
if (GET_MASTER) {
|
|
return(NULL);
|
|
}
|
|
bhp->flags &= ~BUF_IO_IN_PROGRESS;
|
|
if ( bhp->wait_proc != -1 ) {
|
|
/* wake up waiter and anyone waiting on it */
|
|
#ifdef DEBUG
|
|
printf("Waking transaction %d due to completed I/O\n",
|
|
bhp->wait_proc);
|
|
#endif
|
|
proc_wake_id ( bhp->wait_proc );
|
|
bhp->wait_proc = -1;
|
|
}
|
|
MAKE_MRU(bhp);
|
|
}
|
|
|
|
if ( flags & BF_DIRTY ) {
|
|
bhp->flags |= BUF_DIRTY;
|
|
} else if ( *len < BUFSIZE ) {
|
|
bhp->flags |= BUF_NEWPAGE;
|
|
}
|
|
return ( bhp );
|
|
}
|
|
|
|
int
|
|
buf_last ( fid )
|
|
int fid;
|
|
{
|
|
int val;
|
|
|
|
if (GET_MASTER) {
|
|
return(-1);
|
|
}
|
|
assert ( fid < NUM_FILE_ENTRIES );
|
|
if ( buf_fids[fid].npages == -1 ) {
|
|
/* initialize npages field */
|
|
(void) bf_fid_to_fd ( fid );
|
|
}
|
|
val = buf_fids[fid].npages;
|
|
if ( val ) {
|
|
val--; /* Convert to page number */
|
|
}
|
|
if (RELEASE_MASTER) {
|
|
return(-1);
|
|
}
|
|
return(val);
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
extern void
|
|
buf_dump ( id, all )
|
|
int id;
|
|
int all;
|
|
{
|
|
int i;
|
|
BUFHDR_T *bhp;
|
|
|
|
printf ( "LRU + %d\n", *buf_lru );
|
|
if ( all ) {
|
|
printf("ID\tFID\tPID\tLNEXT\tLPREV\tHNEXT\tHPREV\tSLEEP\tFLAG\tREFS\n");
|
|
for ( bhp = bufhdr_table, i = 0; i < NUM_BUFS; bhp++, i++ ) {
|
|
printf ( "%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\t%x\t%d\n", i,
|
|
bhp->id.file_id, bhp->id.obj_id,
|
|
bhp->lru.next, bhp->lru.prev,
|
|
bhp->hash.next, bhp->hash.prev,
|
|
bhp->wait_proc, bhp->flags, bhp->refcount );
|
|
}
|
|
} else {
|
|
if ( id >= NUM_BUFS ) {
|
|
printf ( "Buffer ID (%d) too high\n", id );
|
|
return;
|
|
}
|
|
bhp = bufhdr_table+id;
|
|
printf ( "%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\t%x\t%d\n", i,
|
|
bhp->id.file_id, bhp->id.obj_id,
|
|
bhp->lru.next, bhp->lru.prev,
|
|
bhp->hash.next, bhp->hash.prev,
|
|
bhp->wait_proc, bhp->flags, bhp->refcount );
|
|
}
|
|
return;
|
|
}
|
|
#endif
|
|
|