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The shared-memory used by WAL on linux now really is shared memory in /dev/shm.

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On other unix flavors, the file is in a temporary directory rather than in the
same directory as the database.

FossilOrigin-Name: fc18c4aadb908c3b6f9b6481a2efca6a0daadc64
This commit is contained in:
drh
2010-06-01 21:02:51 +00:00
parent 0235ab9944
commit 8b3cf82ddf
4 changed files with 77 additions and 36 deletions
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84
src/os_unix.c
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@@ -3275,6 +3275,9 @@ static void unixShmPurge(unixFile *pFd){
}
}
/* Forward reference */
static const char *unixTempFileDir(int);
/*
** Open a shared-memory area. This particular implementation uses
** mmapped files.
@@ -3297,7 +3300,9 @@ static int unixShmOpen(
struct unixShmNode *pShmNode = 0; /* The underlying mmapped file */
int rc; /* Result code */
struct unixFile *pDbFd; /* Underlying database file */
int nPath; /* Size of pDbFd->zPath in bytes */
unixInodeInfo *pInode; /* The inode of fd */
const char *zTempDir; /* Directory for temporary files */
int nTempDir; /* Size of the zTempDir string */
/* Allocate space for the new sqlite3_shm object.
*/
@@ -3311,18 +3316,26 @@ static int unixShmOpen(
** one if present. Create a new one if necessary.
*/
unixEnterMutex();
pShmNode = pDbFd->pInode->pShmNode;
pInode = pDbFd->pInode;
pShmNode = pInode->pShmNode;
if( pShmNode==0 ){
nPath = strlen(pDbFd->zPath);
pShmNode = sqlite3_malloc( sizeof(*pShmNode) + nPath + 15 );
zTempDir = unixTempFileDir(1);
if( zTempDir==0 ){
unixLeaveMutex();
sqlite3_free(p);
return SQLITE_CANTOPEN_NOTEMPDIR;
}
nTempDir = strlen(zTempDir);
pShmNode = sqlite3_malloc( sizeof(*pShmNode) + nTempDir + 50 );
if( pShmNode==0 ){
rc = SQLITE_NOMEM;
goto shm_open_err;
}
memset(pShmNode, 0, sizeof(*pShmNode));
pShmNode->zFilename = (char*)&pShmNode[1];
sqlite3_snprintf(nPath+15, pShmNode->zFilename,
"%s-wal-index", pDbFd->zPath);
sqlite3_snprintf(nTempDir+50, pShmNode->zFilename,
"%s/sqlite-wi-%x-%x", zTempDir,
(u32)pInode->fileId.dev, (u32)pInode->fileId.ino);
pShmNode->h = -1;
pDbFd->pInode->pShmNode = pShmNode;
pShmNode->pInode = pDbFd->pInode;
@@ -4199,26 +4212,54 @@ static int openDirectory(const char *zFilename, int *pFd){
}
/*
** Create a temporary file name in zBuf. zBuf must be allocated
** by the calling process and must be big enough to hold at least
** pVfs->mxPathname bytes.
** Return the name of a directory in which to put temporary files.
** If no suitable temporary file directory can be found, return NULL.
*/
static int getTempname(int nBuf, char *zBuf){
static const char *unixTempFileDir(int allowShm){
static const char *azDirs[] = {
0,
0,
"/var/tmp",
"/usr/tmp",
"/tmp",
".",
0 /* List terminator */
};
unsigned int i;
struct stat buf;
const char *zDir = 0;
azDirs[0] = sqlite3_temp_directory;
if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
if( allowShm ){
zDir = "/dev/shm";
i = 0;
}else{
zDir = azDirs[0];
i = 1;
}
for(; i<sizeof(azDirs)/sizeof(azDirs[0]); zDir=azDirs[i++]){
if( zDir==0 ) continue;
if( stat(zDir, &buf) ) continue;
if( !S_ISDIR(buf.st_mode) ) continue;
if( access(zDir, 07) ) continue;
break;
}
return zDir;
}
/*
** Create a temporary file name in zBuf. zBuf must be allocated
** by the calling process and must be big enough to hold at least
** pVfs->mxPathname bytes.
*/
static int unixGetTempname(int nBuf, char *zBuf){
static const unsigned char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789";
unsigned int i, j;
struct stat buf;
const char *zDir = ".";
const char *zDir;
/* It's odd to simulate an io-error here, but really this is just
** using the io-error infrastructure to test that SQLite handles this
@@ -4226,19 +4267,8 @@ static int getTempname(int nBuf, char *zBuf){
*/
SimulateIOError( return SQLITE_IOERR );
azDirs[0] = sqlite3_temp_directory;
if (NULL == azDirs[1]) {
azDirs[1] = getenv("TMPDIR");
}
for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
if( azDirs[i]==0 ) continue;
if( stat(azDirs[i], &buf) ) continue;
if( !S_ISDIR(buf.st_mode) ) continue;
if( access(azDirs[i], 07) ) continue;
zDir = azDirs[i];
break;
}
zDir = unixTempFileDir(0);
if( zDir==0 ) zDir = ".";
/* Check that the output buffer is large enough for the temporary file
** name. If it is not, return SQLITE_ERROR.
@@ -4428,7 +4458,7 @@ static int unixOpen(
}else if( !zName ){
/* If zName is NULL, the upper layer is requesting a temp file. */
assert(isDelete && !isOpenDirectory);
rc = getTempname(MAX_PATHNAME+1, zTmpname);
rc = unixGetTempname(MAX_PATHNAME+1, zTmpname);
if( rc!=SQLITE_OK ){
return rc;
}