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Fix comments and refactor some names associated with shared-memory locking

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in the Unix VFS.  No logical changes.

FossilOrigin-Name: 3e9f1635271c92dce5324728b4ee1cc1a1856ec3c60b1b512a652c21e010e63e
This commit is contained in:
drh
2018-10-02 19:36:40 +00:00
parent ba160891de
commit 24efa5444d
3 changed files with 38 additions and 38 deletions
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61
src/os_unix.c
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@@ -136,12 +136,10 @@
#define SQLITE_FSFLAGS_IS_MSDOS 0x1
/*
** If we are to be thread-safe, include the pthreads header and define
** the SQLITE_UNIX_THREADS macro.
** If we are to be thread-safe, include the pthreads header.
*/
#if SQLITE_THREADSAFE
# include <pthread.h>
# define SQLITE_UNIX_THREADS 1
#endif
/*
@@ -1119,8 +1117,7 @@ struct unixFileId {
/*
** An instance of the following structure is allocated for each open
** inode. Or, on LinuxThreads, there is one of these structures for
** each inode opened by each thread.
** inode.
**
** A single inode can have multiple file descriptors, so each unixFile
** structure contains a pointer to an instance of this object and this
@@ -1166,13 +1163,16 @@ struct unixInodeInfo {
/*
** A lists of all unixInodeInfo objects.
**
** Must hold unixBigLock in order to read or write this variable.
*/
static unixInodeInfo *inodeList = 0; /* All unixInodeInfo objects */
#ifdef SQLITE_DEBUG
/*
** True if the inode mutex is held, or not. Used only within assert()
** to help verify correct mutex usage.
** True if the inode mutex (on the unixFile.pFileMutex field) is held, or not.
** This routine is used only within assert() to help verify correct mutex
** usage.
*/
int unixFileMutexHeld(unixFile *pFile){
assert( pFile->pInode );
@@ -1300,8 +1300,8 @@ static void closePendingFds(unixFile *pFile){
/*
** Release a unixInodeInfo structure previously allocated by findInodeInfo().
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
** The global mutex must be held when this routine is called, but the mutex
** on the inode being deleted must NOT be held.
*/
static void releaseInodeInfo(unixFile *pFile){
unixInodeInfo *pInode = pFile->pInode;
@@ -1336,8 +1336,7 @@ static void releaseInodeInfo(unixFile *pFile){
** describes that file descriptor. Create a new one if necessary. The
** return value might be uninitialized if an error occurs.
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
** The global mutex must held when calling this routine.
**
** Return an appropriate error code.
*/
@@ -1398,6 +1397,7 @@ static int findInodeInfo(
#else
fileId.ino = (u64)statbuf.st_ino;
#endif
assert( unixMutexHeld() );
pInode = inodeList;
while( pInode && memcmp(&fileId, &pInode->fileId, sizeof(fileId)) ){
pInode = pInode->pNext;
@@ -1417,6 +1417,7 @@ static int findInodeInfo(
}
}
pInode->nRef = 1;
assert( unixMutexHeld() );
pInode->pNext = inodeList;
pInode->pPrev = 0;
if( inodeList ) inodeList->pPrev = pInode;
@@ -4223,7 +4224,7 @@ static int unixGetpagesize(void){
*/
struct unixShmNode {
unixInodeInfo *pInode; /* unixInodeInfo that owns this SHM node */
sqlite3_mutex *mutex; /* Mutex to access this object */
sqlite3_mutex *pShmMutex; /* Mutex to access this object */
char *zFilename; /* Name of the mmapped file */
int h; /* Open file descriptor */
int szRegion; /* Size of shared-memory regions */
@@ -4247,16 +4248,16 @@ struct unixShmNode {
** The following fields are initialized when this object is created and
** are read-only thereafter:
**
** unixShm.pFile
** unixShm.pShmNode
** unixShm.id
**
** All other fields are read/write. The unixShm.pFile->mutex must be held
** while accessing any read/write fields.
** All other fields are read/write. The unixShm.pShmNode->pShmMutex must
** be held while accessing any read/write fields.
*/
struct unixShm {
unixShmNode *pShmNode; /* The underlying unixShmNode object */
unixShm *pNext; /* Next unixShm with the same unixShmNode */
u8 hasMutex; /* True if holding the unixShmNode mutex */
u8 hasMutex; /* True if holding the unixShmNode->pShmMutex */
u8 id; /* Id of this connection within its unixShmNode */
u16 sharedMask; /* Mask of shared locks held */
u16 exclMask; /* Mask of exclusive locks held */
@@ -4286,7 +4287,7 @@ static int unixShmSystemLock(
/* Access to the unixShmNode object is serialized by the caller */
pShmNode = pFile->pInode->pShmNode;
assert( pShmNode->nRef==0 || sqlite3_mutex_held(pShmNode->mutex) );
assert( pShmNode->nRef==0 || sqlite3_mutex_held(pShmNode->pShmMutex) );
/* Shared locks never span more than one byte */
assert( n==1 || lockType!=F_RDLCK );
@@ -4372,7 +4373,7 @@ static void unixShmPurge(unixFile *pFd){
int nShmPerMap = unixShmRegionPerMap();
int i;
assert( p->pInode==pFd->pInode );
sqlite3_mutex_free(p->mutex);
sqlite3_mutex_free(p->pShmMutex);
for(i=0; i<p->nRegion; i+=nShmPerMap){
if( p->h>=0 ){
osMunmap(p->apRegion[i], p->szRegion);
@@ -4543,8 +4544,8 @@ static int unixOpenSharedMemory(unixFile *pDbFd){
pDbFd->pInode->pShmNode = pShmNode;
pShmNode->pInode = pDbFd->pInode;
if( sqlite3GlobalConfig.bCoreMutex ){
pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
if( pShmNode->mutex==0 ){
pShmNode->pShmMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
if( pShmNode->pShmMutex==0 ){
rc = SQLITE_NOMEM_BKPT;
goto shm_open_err;
}
@@ -4587,13 +4588,13 @@ static int unixOpenSharedMemory(unixFile *pDbFd){
** the cover of the unixEnterMutex() mutex and the pointer from the
** new (struct unixShm) object to the pShmNode has been set. All that is
** left to do is to link the new object into the linked list starting
** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex
** mutex.
** at pShmNode->pFirst. This must be done while holding the
** pShmNode->pShmMutex.
*/
sqlite3_mutex_enter(pShmNode->mutex);
sqlite3_mutex_enter(pShmNode->pShmMutex);
p->pNext = pShmNode->pFirst;
pShmNode->pFirst = p;
sqlite3_mutex_leave(pShmNode->mutex);
sqlite3_mutex_leave(pShmNode->pShmMutex);
return rc;
/* Jump here on any error */
@@ -4645,7 +4646,7 @@ static int unixShmMap(
p = pDbFd->pShm;
pShmNode = p->pShmNode;
sqlite3_mutex_enter(pShmNode->mutex);
sqlite3_mutex_enter(pShmNode->pShmMutex);
if( pShmNode->isUnlocked ){
rc = unixLockSharedMemory(pDbFd, pShmNode);
if( rc!=SQLITE_OK ) goto shmpage_out;
@@ -4754,7 +4755,7 @@ shmpage_out:
*pp = 0;
}
if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY;
sqlite3_mutex_leave(pShmNode->mutex);
sqlite3_mutex_leave(pShmNode->pShmMutex);
return rc;
}
@@ -4793,7 +4794,7 @@ static int unixShmLock(
mask = (1<<(ofst+n)) - (1<<ofst);
assert( n>1 || mask==(1<<ofst) );
sqlite3_mutex_enter(pShmNode->mutex);
sqlite3_mutex_enter(pShmNode->pShmMutex);
if( flags & SQLITE_SHM_UNLOCK ){
u16 allMask = 0; /* Mask of locks held by siblings */
@@ -4866,7 +4867,7 @@ static int unixShmLock(
}
}
}
sqlite3_mutex_leave(pShmNode->mutex);
sqlite3_mutex_leave(pShmNode->pShmMutex);
OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n",
p->id, osGetpid(0), p->sharedMask, p->exclMask));
return rc;
@@ -4916,14 +4917,14 @@ static int unixShmUnmap(
/* Remove connection p from the set of connections associated
** with pShmNode */
sqlite3_mutex_enter(pShmNode->mutex);
sqlite3_mutex_enter(pShmNode->pShmMutex);
for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
*pp = p->pNext;
/* Free the connection p */
sqlite3_free(p);
pDbFd->pShm = 0;
sqlite3_mutex_leave(pShmNode->mutex);
sqlite3_mutex_leave(pShmNode->pShmMutex);
/* If pShmNode->nRef has reached 0, then close the underlying
** shared-memory file, too */