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Rework the changes for ticket #176 (check-ins (760) and (761)) to be

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more consistent with the rest of the source code. (CVS 768)

FossilOrigin-Name: f50a177b4239bc7a83563ac9361e830ec04e81fb
This commit is contained in:
drh 2002-10-20 18:19:45 +00:00
parent 3c2007a546
commit edbbbdf8f7
3 changed files with 95 additions and 109 deletions
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12
manifest
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@ -1,5 +1,5 @@
C The\s"table_info"\spragma\sreports\sunspecified\scolumn\stypes\sas\s"numeric"\sinstead\nof\s"text".\s\sFix\sfor\sticket\s#174.\s(CVS\s767)
D 2002-10-20T16:00:28
C Rework\sthe\schanges\sfor\sticket\s#176\s(check-ins\s(760)\sand\s(761))\sto\sbe\nmore\sconsistent\swith\sthe\srest\sof\sthe\ssource\scode.\s(CVS\s768)
D 2002-10-20T18:19:45
F Makefile.in d6c9a85c2a5e696843201d090dcf8bf2f8716f2a
F Makefile.linux-gcc b86a99c493a5bfb402d1d9178dcdc4bd4b32f906
F README f1de682fbbd94899d50aca13d387d1b3fd3be2dd
@ -30,7 +30,7 @@ F src/hash.h cd0433998bc1a3759d244e1637fe5a3c13b53bf8
F src/insert.c 764300a0bd8074a2174946c0bf8a550bd833397a
F src/main.c ff7c05ef88fa1374e5540ce20173ae8e1836f8a4
F src/md5.c fe4f9c9c6f71dfc26af8da63e4d04489b1430565
F src/os.c c045297aae5a99710222baf939985498c5bb76d4
F src/os.c ede7346dffdbab40c6de20d2f325981f3f1168fd
F src/os.h 3009379b06941e7796a9812d1b6cbc59b26248c8
F src/pager.c 592e5931fdc65e952a6c3e152bc822580856532a
F src/pager.h 6991c9c2dc5e4c7f2df4d4ba47d1c6458f763a32
@ -149,7 +149,7 @@ F www/speed.tcl a20a792738475b68756ea7a19321600f23d1d803
F www/sqlite.tcl ae3dcfb077e53833b59d4fcc94d8a12c50a44098
F www/tclsqlite.tcl 1db15abeb446aad0caf0b95b8b9579720e4ea331
F www/vdbe.tcl 2013852c27a02a091d39a766bc87cff329f21218
P d5470dfe102ef9b1dac3b15a2f5cc225e3c26129
R 7ecb20627c80bbfd79b6dbcc45bd92d1
P 395ab5fac201a37d6eca833ffd6f58ac8a0121a2
R 839af7b0330753291020e1f24ae79a14
U drh
Z fbad8ba3d35f7e19e8e9a6b0f6544aa0
Z 224ddb64edfd2ea0e4f95e777cac97ff

2
manifest.uuid
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@ -1 +1 @@
395ab5fac201a37d6eca833ffd6f58ac8a0121a2
f50a177b4239bc7a83563ac9361e830ec04e81fb

190
src/os.c
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@ -90,14 +90,14 @@ static int last_page = 0;
** cnt>0 means there are cnt shared locks on the file.
**
** Any attempt to lock or unlock a file first checks the locking
** structure. The fcntl() system call is only invoked to set a
** structure. The fcntl() system call is only invoked to set a
** POSIX lock if the internal lock structure transitions between
** a locked and an unlocked state.
*/
/*
** An instance of the following structure serves as the key used
** to locate a particular lockInfo structure given its inode.
** to locate a particular lockInfo structure given its inode.
*/
struct inodeKey {
dev_t dev; /* Device number */
@ -116,7 +116,7 @@ struct lockInfo {
int nRef; /* Number of pointers to this structure */
};
/*
/*
** This hash table maps inodes (in the form of inodeKey structures) into
** pointers to lockInfo structures.
*/
@ -236,7 +236,7 @@ int sqliteOsOpenReadWrite(
if( id->fd<0 ){
id->fd = open(zFilename, O_RDONLY);
if( id->fd<0 ){
return SQLITE_CANTOPEN;
return SQLITE_CANTOPEN;
}
*pReadonly = 1;
}else{
@ -328,7 +328,7 @@ int sqliteOsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
HANDLE h;
int fileflags;
if( delFlag ){
fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS
fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS
| FILE_FLAG_DELETE_ON_CLOSE;
}else{
fileflags = FILE_FLAG_RANDOM_ACCESS;
@ -448,7 +448,7 @@ int sqliteOsTempFileName(char *zBuf){
if( !sqliteOsFileExists(zBuf) ) break;
}
#endif
return SQLITE_OK;
return SQLITE_OK;
}
/*
@ -492,7 +492,7 @@ int sqliteOsRead(OsFile *id, void *pBuf, int amt){
if( !ReadFile(id->h, pBuf, amt, &got, 0) ){
got = 0;
}
if( (int)got==amt ){
if( got==(DWORD)amt ){
return SQLITE_OK;
}else{
return SQLITE_IOERR;
@ -605,6 +605,23 @@ int sqliteOsFileSize(OsFile *id, int *pSize){
#endif
}
#if OS_WIN
/*
** Return true (non-zero) if we are running under WinNT, Win2K or WinXP.
** Return false (zero) for Win95, Win98, or WinME.
*/
int isNT(void){
static osType = 0; /* 0=unknown 1=win95 2=winNT */
if( osType==0 ){
OSVERSIONINFO sInfo;
sInfo.dwOSVersionInfoSize = sizeof(sInfo);
GetVersionEx(&sInfo);
osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
}
return osType==2;
}
#endif
/*
** Windows file locking notes:
**
@ -612,84 +629,36 @@ int sqliteOsFileSize(OsFile *id, int *pSize){
** are not available under Win95/98/ME. So we use only LockFile() and
** UnlockFile().
**
** A read lock is obtained by locking a single random byte in the
** range of 1 to MX_LOCKBYTE. The lock byte is obtained at random so
** two separate readers can probably access the file at the same time,
** unless they are unlucky and choose the same lock byte. A write lock
** is obtained by locking all bytes in the range of 1 to MX_LOCKBYTE.
** LockFile() prevents not just writing but also reading by other processes.
** (This is a design error on the part of Windows, but there is nothing
** we can do about that.) So the region used for locking is at the
** end of the file where it is unlikely to ever interfere with an
** actual read attempt.
**
** A database read lock is obtained by locking a single randomly-chosen
** byte out of a specific range of bytes. The lock byte is obtained at
** random so two separate readers can probably access the file at the
** same time, unless they are unlucky and choose the same lock byte.
** A database write lock is obtained by locking all bytes in the range.
** There can only be one writer.
**
** A lock is obtained on byte 0 before acquiring either a read lock or
** a write lock. This prevents two processes from attempting to get a
** lock at a same time. The semantics of sqliteOsReadLock() require that
** if there is already a write lock, that lock is converted into a read
** lock atomically. The lock on byte 0 allows us to drop the old write
** lock and get the read lock without another process jumping into the
** middle and messing us up. The same argument applies to sqliteOsWriteLock().
** A lock is obtained on the first byte of the lock range before acquiring
** either a read lock or a write lock. This prevents two processes from
** attempting to get a lock at a same time. The semantics of
** sqliteOsReadLock() require that if there is already a write lock, that
** lock is converted into a read lock atomically. The lock on the first
** byte allows us to drop the old write lock and get the read lock without
** another process jumping into the middle and messing us up. The same
** argument applies to sqliteOsWriteLock().
**
** Locks must be obtained in an area that does not overlap the "real data area"
** otherwise read/write operations will conflict with lock operations. Locking beyond EOF
** is allowed in windows.
**
** There are a finite number of read locks under windows. That number
** is determined by the following variable:
** The following #defines specify the range of bytes used for locking.
** N_LOCKBYTE is the number of bytes available for doing the locking.
** The first byte used to hold the lock while the lock is changing does
** not count toward this number. FIRST_LOCKBYTE is the address of
** the first byte in the range of bytes used for locking.
*/
#define MX_LOCKBYTE 0xFFF0
#if OS_WIN
// get the platform id to decide how to calculate the lock offset
int mkPlatformId(void){
static long init=0;
static long lock=0;
static int pid=VER_PLATFORM_WIN32_WINDOWS;
OSVERSIONINFOA info;
while (!init) {
if (InterlockedIncrement(&lock)==1)
{
info.dwOSVersionInfoSize=sizeof(info);
if (GetVersionEx(&info)) pid=info.dwPlatformId;
init=1;
}
else
Sleep(1);
}
return pid;
}
// locks and unlocks beyond eof. uses platformid to move the lock as far as possible.
int mklock(HANDLE h, WORD base, WORD size)
{
if (mkPlatformId()==VER_PLATFORM_WIN32_WINDOWS)
return LockFile(h,0xFFFF0000+base,0,size,0);
else
return LockFile(h,base,0xFFFFFFFF,size,0);
}
int mkunlock(HANDLE h, WORD base, WORD size)
{
if (mkPlatformId()==VER_PLATFORM_WIN32_WINDOWS)
return UnlockFile(h,0xFFFF0000+base,0,size,0);
else
return UnlockFile(h,base,0xFFFFFFFF,size,0);
}
//obtain the sync lock on a handle
void synclock(HANDLE h){
while (!mklock(h,0,1)) Sleep(1);
}
void syncunlock(HANDLE h){
mkunlock(h,0,1);
}
#endif
#define N_LOCKBYTE 10239
#define FIRST_LOCKBYTE (0xffffffff - N_LOCKBYTE)
/*
** Change the status of the lock on the file "id" to be a readlock.
@ -698,7 +667,6 @@ void syncunlock(HANDLE h){
**
** Return SQLITE_OK on success and SQLITE_BUSY on failure.
*/
int sqliteOsReadLock(OsFile *id){
#if OS_UNIX
int rc;
@ -732,14 +700,18 @@ int sqliteOsReadLock(OsFile *id){
if( id->locked>0 ){
rc = SQLITE_OK;
}else{
int lk = (sqliteRandomInteger() & 0x7ffffff)%MX_LOCKBYTE + 1;
int lk = (sqliteRandomInteger() & 0x7ffffff)%N_LOCKBYTE+1;
int res;
synclock(id->h);
if (id->locked<0) mkunlock(id->h,1,MX_LOCKBYTE); // release write lock if we have it
res=mklock(id->h,lk,1);
syncunlock(id->h);
int cnt = 100;
int page = isNT() ? 0xffffffff : 0;
while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, page, 1, 0))==0 ){
Sleep(1);
}
if( res ){
UnlockFile(id->h, FIRST_LOCKBYTE+1, page, N_LOCKBYTE, 0);
res = LockFile(id->h, FIRST_LOCKBYTE+lk, page, 1, 0);
UnlockFile(id->h, FIRST_LOCKBYTE, page, 1, 0);
}
if( res ){
id->locked = lk;
rc = SQLITE_OK;
@ -783,13 +755,21 @@ int sqliteOsWriteLock(OsFile *id){
rc = SQLITE_OK;
}else{
int res;
synclock(id->h);
if (id->locked>0) mkunlock(id->h,id->locked,1); // release read lock
res=mklock(id->h,1,MX_LOCKBYTE);
syncunlock(id->h);
if(res){
int cnt = 100;
int page = isNT() ? 0xffffffff : 0;
while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, page, 1, 0))==0 ){
Sleep(1);
}
if( res ){
if( id->locked==0
|| UnlockFile(id->h, FIRST_LOCKBYTE + id->locked, page, 1, 0) ){
res = LockFile(id->h, FIRST_LOCKBYTE+1, page, N_LOCKBYTE, 0);
}else{
res = 0;
}
UnlockFile(id->h, FIRST_LOCKBYTE, page, 1, 0);
}
if( res ){
id->locked = -1;
rc = SQLITE_OK;
}else{
@ -831,13 +811,19 @@ int sqliteOsUnlock(OsFile *id){
#endif
#if OS_WIN
int rc;
if(id->locked<0 ) {
mkunlock(id->h,1,MX_LOCKBYTE);
}else if (id->locked>0) {
mkunlock(id->h,id->locked,1);
int page = isNT() ? 0xffffffff : 0;
if( id->locked==0 ){
rc = SQLITE_OK;
}else if( id->locked<0 ){
UnlockFile(id->h, FIRST_LOCKBYTE+1, page, N_LOCKBYTE, 0);
rc = SQLITE_OK;
id->locked = 0;
}else{
UnlockFile(id->h, FIRST_LOCKBYTE+id->locked, page, 1, 0);
rc = SQLITE_OK;
id->locked = 0;
}
id->locked = 0;
return SQLITE_OK;
return rc;
#endif
}