database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-07 02:42:48 +03:00
Code Activity

The code is in place to replace GDBM with BTree. But I have not yet

Browse Source 
attempted to compile it.  I am sure the code contains bugs. (CVS 238)

FossilOrigin-Name: 6ecc8b20d4f402f45f03d46d8d4fa40dea666e97
This commit is contained in:
drh
2001-09-13 13:46:56 +00:00
parent 5c4d9703d9
commit 5e00f6c7d5
20 changed files with 3910 additions and 2679 deletions
Download Patch File Download Diff File Expand all files Collapse all files

95
src/pager.c
View File

@@ -25,9 +25,9 @@
**
** The page cache is used to access a database file. The pager journals
** all writes in order to support rollback. Locking is used to limit
** access to one or more reader or one writer.
** access to one or more reader or to one writer.
**
** @(#) $Id: pager.c,v 1.13 2001/07/02 17:51:46 drh Exp $
** @(#) $Id: pager.c,v 1.14 2001/09/13 13:46:57 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
@@ -122,6 +122,8 @@ struct Pager {
int nHit, nMiss, nOvfl; /* Cache hits, missing, and LRU overflows */
unsigned char state; /* SQLITE_UNLOCK, _READLOCK or _WRITELOCK */
unsigned char errMask; /* One of several kinds of errors */
unsigned char tempFile; /* zFilename is a temporary file */
unsigned char readOnly; /* True for a read-only database */
unsigned char *aInJournal; /* One bit for each page in the database file */
PgHdr *pFirst, *pLast; /* List of free pages */
PgHdr *pAll; /* List of all pages */
@@ -147,8 +149,8 @@ struct PageRecord {
};
/*
** Journal files begin with the following magic string. This data
** is completely random. It is used only as a sanity check.
** Journal files begin with the following magic string. The data
** was obtained from /dev/random. It is used only as a sanity check.
*/
static const unsigned char aJournalMagic[] = {
0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd4,
@@ -163,7 +165,7 @@ static const unsigned char aJournalMagic[] = {
** Enable reference count tracking here:
*/
#if SQLITE_TEST
int pager_refinfo_enable = 0;
int pager_refinfo_enable = 0;
static void pager_refinfo(PgHdr *p){
static int cnt = 0;
if( !pager_refinfo_enable ) return;
@@ -457,9 +459,33 @@ static int pager_playback(Pager *pPager){
return rc;
}
/*
** Locate a directory where we can potentially create a temporary
** file.
*/
static const char *findTempDir(void){
static const char *azDirs[] = {
".",
"/var/tmp",
"/usr/tmp",
"/tmp",
"/temp",
"./temp",
};
int i;
struct stat buf;
for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
if( stat(azDirs[i], &buf)==0 && S_ISDIR(buf.st_mode)
&& S_IWUSR(buf.st_mode) ){
return azDirs[i];
}
}
return 0;
}
/*
** Create a new page cache and put a pointer to the page cache in *ppPager.
** The file to be cached need not exist. The file is not opened until
** The file to be cached need not exist. The file is not locked until
** the first call to sqlitepager_get() and is only held open until the
** last page is released using sqlitepager_unref().
*/
@@ -472,12 +498,33 @@ int sqlitepager_open(
Pager *pPager;
int nameLen;
int fd;
int tempFile;
int readOnly = 0;
char zTemp[300];
*ppPager = 0;
if( sqlite_malloc_failed ){
return SQLITE_NOMEM;
}
fd = open(zFilename, O_RDWR|O_CREAT, 0644);
if( zFilename ){
fd = open(zFilename, O_RDWR|O_CREAT, 0644);
if( fd<0 ){
fd = open(zFilename, O_RDONLY, 0);
readOnly = 1;
}
tempFile = 0;
}else{
int cnt = 8;
char *zDir = findTempDir();
if( zDir==0 ) return SQLITE_CANTOPEN;
do{
cnt--;
sprintf(zTemp,"%s/_sqlite_%u",(unsigned)sqliteRandomInteger());
fd = open(zTemp, O_RDWR|O_CREAT|O_EXCL, 0600);
}while( cnt>0 && fd<0 );
zFilename = zTemp;
tempFile = 1;
}
if( fd<0 ){
return SQLITE_CANTOPEN;
}
@@ -500,6 +547,8 @@ int sqlitepager_open(
pPager->mxPage = mxPage>5 ? mxPage : 10;
pPager->state = SQLITE_UNLOCK;
pPager->errMask = 0;
pPager->tempFile = tempFile;
pPager->readOnly = readOnly;
pPager->pFirst = 0;
pPager->pLast = 0;
pPager->nExtra = nExtra;
@@ -510,7 +559,8 @@ int sqlitepager_open(
/*
** Set the destructor for this pager. If not NULL, the destructor is called
** when the reference count on the page reaches zero.
** when the reference count on each page reaches zero. The destructor can
** be used to clean up information in the extra segment appended to each page.
**
** The destructor is not called as a result sqlitepager_close().
** Destructors are only called by sqlitepager_unref().
@@ -520,7 +570,8 @@ void sqlitepager_set_destructor(Pager *pPager, void (*xDesc)(void*)){
}
/*
** Return the total number of pages in the file opened by pPager.
** Return the total number of pages in the disk file associated with
** pPager.
*/
int sqlitepager_pagecount(Pager *pPager){
int n;
@@ -572,12 +623,15 @@ int sqlitepager_close(Pager *pPager){
}
if( pPager->fd>=0 ) close(pPager->fd);
assert( pPager->jfd<0 );
if( pPager->tempFile ){
unlink(pPager->zFilename);
}
sqliteFree(pPager);
return SQLITE_OK;
}
/*
** Return the page number for the given page data
** Return the page number for the given page data.
*/
Pgno sqlitepager_pagenumber(void *pData){
PgHdr *p = DATA_TO_PGHDR(pData);
@@ -621,8 +675,8 @@ int sqlitepager_ref(void *pData){
/*
** Acquire a page.
**
** A read lock is obtained for the first page acquired. The lock
** is dropped when the last page is released.
** A read lock on the disk file is obtained when the first page acquired.
** This read lock is dropped when the last page is released.
**
** A _get works for any page number greater than 0. If the database
** file is smaller than the requested page, then no actual disk
@@ -635,7 +689,7 @@ int sqlitepager_ref(void *pData){
**
** See also sqlitepager_lookup(). Both this routine and _lookup() attempt
** to find a page in the in-memory cache first. If the page is not already
** in cache, this routine goes to disk to read it in whereas _lookup()
** in memory, this routine goes to disk to read it in whereas _lookup()
** just returns 0. This routine acquires a read-lock the first time it
** has to go to disk, and could also playback an old journal if necessary.
** Since _lookup() never goes to disk, it never has to deal with locks
@@ -829,8 +883,8 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
** See also sqlitepager_get(). The difference between this routine
** and sqlitepager_get() is that _get() will go to the disk and read
** in the page if the page is not already in cache. This routine
** returns NULL if the page is not in cache of if a disk I/O has ever
** happened.
** returns NULL if the page is not in cache or if a disk I/O error
** has ever happened.
*/
void *sqlitepager_lookup(Pager *pPager, Pgno pgno){
PgHdr *pPg;
@@ -925,6 +979,9 @@ int sqlitepager_write(void *pData){
if( pPager->errMask ){
return pager_errcode(pPager);
}
if( pPager->readOnly ){
return SQLITE_PERM;
}
pPg->dirty = 1;
if( pPg->inJournal ){ return SQLITE_OK; }
assert( pPager->state!=SQLITE_UNLOCK );
@@ -1076,6 +1133,14 @@ int sqlitepager_rollback(Pager *pPager){
return rc;
};
/*
** Return TRUE if the database file is opened read-only. Return FALSE
** if the database is (in theory) writable.
*/
int sqlitepager_isreadonly(Pager *pPager){
return pPager->readonly;
}
/*
** This routine is used for testing and analysis only.
*/