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Add test files for the asynchronous IO concept. (CVS 2853)

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FossilOrigin-Name: 7c3492c8404c39c808af4429b4fcdb7413539ab3
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danielk1977
2006-01-03 13:39:25 +00:00
parent dddca28608
commit 34e8494202
4 changed files with 1012 additions and 7 deletions
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src/test_async.c Normal file
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/*
** 2005 December 14
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains an example implementation of an asynchronous IO
** backend for SQLite. It is used to test that the concept of asynchronous
** IO in SQLite is valid.
*/
#include "sqliteInt.h"
#include "os.h"
#define MIN(x,y) ((x)<(y)?(x):(y))
#define MAX(x,y) ((x)>(y)?(x):(y))
typedef struct AsyncWrite AsyncWrite;
typedef struct AsyncFile AsyncFile;
/*
** TODO:
** * File locks...
*/
/*
** THREAD SAFETY NOTES
**
** Basic rules:
**
** * Both read and write access to the global write-op queue must be
** protected by the sqlite3Os mutex functions.
** * The file handles from the underlying system are assumed not to
** be thread safe.
** * See the last paragraph under "sqlite3_async_flush() Threads" for
** an assumption to do with file-handle synchronization by the Os.
**
** File system operations (invoked by SQLite thread):
**
** xOpenXXX (three versions)
** xDelete
** xFileExists
**
** Todo:
** xSyncDirectory
**
** File handle operations (invoked by SQLite thread):
**
** The following operations add an entry to the global write-op list. They
** prepare the entry, aquire the mutex momentarily while list pointers are
** manipulated to insert the new entry, and release the mutex.
**
** asyncWrite, asyncClose, asyncTruncate, asyncSync,
** asyncSetFullSync, asyncOpenDirectory.
**
** Read operations. Both of these read from both the underlying file and
** the write-op list. So we grab the mutex for the whole call (even
** while performing a blocking read on the file).
**
** asyncRead, asyncFileSize.
**
** These locking primitives become no-ops. Files are always opened for
** exclusive access when using this IO backend:
**
** asyncLock, asyncUnlock, asyncLockState, asyncCheckReservedLock
**
** The sqlite3OsFileHandle() function is currently only used when
** debugging the pager module. Unless sqlite3OsClose() is called on the
** file (shouldn't be possible for other reasons), the underlying
** implementations are safe to call without grabbing any mutex. So we just
** go ahead and call it no matter what any other thread is doing.
**
** asyncFileHandle.
**
** Calling this method just manipulates the AsyncFile.iOffset variable.
** Since this variable is never accessed by an sqlite3_async_flush() thread,
** this function does not require the mutex. Actual calls to OsSeek() take
** place just before OsWrite() or OsRead(), which are always protected by
** the mutex.
**
** asyncSeek.
**
** sqlite3_async_flush() (any thread):
**
** A pseudo-mutex (a global boolean variable) is used to make sure only
** one thread is inside the sqlite3_async_flush() thread at any one time.
** If the variable is set when a thread enters _flush(), then it
** immediately returns SQLITE_BUSY. Otherwise, it sets the variable,
** executes the body of the function, and clears the variable just before
** returning. Both read and write access to said global variable
** (sqlite3_asyncIoBusy) is protected by sqlite3Os mutex, of course.
**
** Inside sqlite3_async_flush() is a loop that works like this:
**
** WHILE (write-op list is not empty)
** Do IO operation at head of write-op list
** Remove entry from head of write-op list
** END WHILE
**
** The mutex is always obtained during the <write-op list is not empty>
** test, and when the entry is removed from the head of the write-op
** list. Sometimes it is held for the interim period (while the IO is
** performed), and sometimes it is relinquished. It is relinquished if
** (a) the IO op is an ASYNC_CLOSE or (b) when the file handle was
** opened, two of the underlying systems handles were opened on the
** same file-system entry.
**
** If condition (b) above is true, then one file-handle
** (AsyncFile.pBaseRead) is used exclusively by sqlite threads to read the
** file, the other (AsyncFile.pBaseWrite) by sqlite3_async_flush()
** threads to perform write() operations. This means that read
** operations are not blocked by asynchronous writes (although
** asynchronous writes may still be blocked by reads).
**
** This assumes that the OS keeps two handles open on the same file
** properly in sync. That is, any read operation that starts after a
** write operation on the same file system entry has completed returns
** data consistent with the write. We also assume that if one thread
** reads a file while another is writing it all bytes other than the
** ones actually being written contain valid data.
**
** If the above assumptions are not true, set the preprocessor symbol
** SQLITE_ASYNC_TWO_FILEHANDLES to 0.
*/
#ifndef SQLITE_ASYNC_TWO_FILEHANDLES
/* #define SQLITE_ASYNC_TWO_FILEHANDLES 0 */
#define SQLITE_ASYNC_TWO_FILEHANDLES 1
#endif
/*
** First and last elements of the global write-op list.
**
** Whenever an OsWrite(), OsSync(), OsTrunc() or OsClose() operation is
** requested, instead of performing the file IO immediately, a new AsyncWrite
** structure is allocated and added to the global linked list that starts at
** sqlite3_asyncListFirst. The next time to sqlite3_async_flush() is called,
** all operations are realised and the list elements deleted.
*/
static AsyncWrite *sqlite3_asyncListFirst = 0;
static AsyncWrite *sqlite3_asyncListLast = 0;
/* True after an IO error has occured */
/* static int *sqlite3_asyncIoError = 0; */
/* True if some thread is currently inside sqlite3_async_flush() */
static int sqlite3_asyncIoBusy = 0;
/* Possible values of AsyncWrite.op */
#define ASYNC_WRITE 1
#define ASYNC_SYNC 2
#define ASYNC_TRUNCATE 3
#define ASYNC_CLOSE 4
#define ASYNC_OPENDIRECTORY 5
#define ASYNC_SETFULLSYNC 6
#define ASYNC_DELETE 7
#define ASYNC_OPENEXCLUSIVE 8
#define ASYNC_SYNCDIRECTORY 9
/*
** The interpretation of the iOffset and nByte variables varies depending
** on the value of AsyncWrite.op:
**
** ASYNC_WRITE:
** iOffset -> Offset in file to write to.
** nByte -> Number of bytes of data to write (pointed to by zBuf).
**
** ASYNC_SYNC:
** iOffset -> Unused.
** nByte -> Value of "fullsync" flag to pass to sqlite3OsSync().
**
** ASYNC_TRUNCATE:
** iOffset -> Size to truncate file to.
** nByte -> Unused.
**
** ASYNC_CLOSE:
** iOffset -> Unused.
** nByte -> Unused.
**
** ASYNC_OPENDIRECTORY:
** iOffset -> Unused.
** nByte -> Number of bytes of zBuf points to (directory name).
**
** ASYNC_SETFULLSYNC:
** iOffset -> Unused.
** nByte -> New value for the full-sync flag.
**
**
** ASYNC_DELETE:
** iOffset -> Unused.
** nByte -> Number of bytes of zBuf points to (file name).
**
** ASYNC_OPENEXCLUSIVE:
** iOffset -> Value of "delflag".
** nByte -> Number of bytes of zBuf points to (file name).
**
** For an ASYNC_WRITE operation, zBuf points to the data to write to the file.
** This space is sqliteMalloc()d along with the AsyncWrite structure in a
** single blob, so is deleted when sqliteFree() is called on the parent
** structure.
*/
struct AsyncWrite {
AsyncFile *pFile; /* File to write data to or sync */
int op; /* One of ASYNC_xxx etc. */
i64 iOffset; /* See above */
int nByte; /* See above */
char *zBuf; /* Data to write to file (or NULL if op!=ASYNC_WRITE) */
AsyncWrite *pNext; /* Next write operation (to any file) */
};
/*
** The AsyncFile structure is a subclass of OsFile used for asynchronous IO.
*/
struct AsyncFile {
IoMethod *pMethod; /* Must be first */
i64 iOffset; /* Current seek() offset in file */
OsFile *pBaseRead; /* Read handle to the underlying Os file */
OsFile *pBaseWrite; /* Write handle to the underlying Os file */
};
/*
** Add an entry to the end of the global write-op list. pWrite should point
** to an AsyncWrite structure allocated using sqliteMalloc(). A future call
** to sqlite3_async_flush() is responsible for calling sqliteFree().
**
** Once an AsyncWrite structure has been added to the list, it must not be
** read or modified by the caller (in case another thread calls
** sqlite3_async_flush() ).
*/
static void addAsyncWrite(AsyncWrite *pWrite){
sqlite3_os_enter_mutex();
assert( !pWrite->pNext );
if( sqlite3_asyncListLast ){
assert( sqlite3_asyncListFirst );
sqlite3_asyncListLast->pNext = pWrite;
}else{
sqlite3_asyncListFirst = pWrite;
}
sqlite3_asyncListLast = pWrite;
sqlite3_os_leave_mutex();
}
/*
** The caller should already hold the mutex when this is called.
*/
static void removeAsyncWrite(AsyncWrite *p){
assert( p==sqlite3_asyncListFirst );
assert( sqlite3_asyncListLast );
if( sqlite3_asyncListFirst==sqlite3_asyncListLast ){
assert( !sqlite3_asyncListFirst->pNext );
sqlite3_asyncListLast = 0;
}
sqlite3_asyncListFirst = sqlite3_asyncListFirst->pNext;
}
/*
** This is a utility function to allocate and populate a new AsyncWrite
** structure and insert it (via addAsyncWrite() ) into the global list.
*/
static int addNewAsyncWrite(
AsyncFile *pFile,
int op,
i64 iOffset,
int nByte,
const char *zByte
){
AsyncWrite *p = sqlite3Os.xMalloc(sizeof(AsyncWrite) + (zByte?nByte:0));
if( !p ){
return SQLITE_NOMEM;
}
p->op = op;
p->iOffset = iOffset;
p->nByte = nByte;
p->pFile = pFile;
p->pNext = 0;
if( zByte ){
p->zBuf = (char *)&p[1];
memcpy(p->zBuf, zByte, nByte);
}else{
p->zBuf = 0;
}
addAsyncWrite(p);
return SQLITE_OK;
}
/*
** Close the file. This just adds an entry to the write-op list, the file is
** not actually closed.
*/
static int asyncClose(OsFile **pId){
return addNewAsyncWrite((AsyncFile *)*pId, ASYNC_CLOSE, 0, 0, 0);
}
/*
** Implementation of sqlite3OsWrite() for asynchronous files. Instead of
** writing to the underlying file, this function adds an entry to the end of
** the global AsyncWrite list. Either SQLITE_OK or SQLITE_NOMEM may be
** returned.
*/
static int asyncWrite(OsFile *id, const void *pBuf, int amt){
AsyncFile *pFile = (AsyncFile *)id;
int rc = addNewAsyncWrite(pFile, ASYNC_WRITE, pFile->iOffset, amt, pBuf);
pFile->iOffset += (i64)amt;
return rc;
}
/*
** Truncate the file to nByte bytes in length. This just adds an entry to
** the write-op list, no IO actually takes place.
*/
static int asyncTruncate(OsFile *id, i64 nByte){
return addNewAsyncWrite((AsyncFile *)id, ASYNC_TRUNCATE, nByte, 0, 0);
}
/*
** Open the directory identified by zName and associate it with the
** specified file. This just adds an entry to the write-op list, the
** directory is opened later by sqlite3_async_flush().
*/
static int asyncOpenDirectory(OsFile *id, const char *zName){
AsyncFile *pFile = (AsyncFile *)id;
return addNewAsyncWrite(pFile, ASYNC_OPENDIRECTORY, 0, strlen(zName)+1,zName);
}
/*
** Sync the file. This just adds an entry to the write-op list, the
** sync() is done later by sqlite3_async_flush().
*/
static int asyncSync(OsFile *id, int fullsync){
return addNewAsyncWrite((AsyncFile *)id, ASYNC_SYNC, 0, fullsync, 0);
}
/*
** Set (or clear) the full-sync flag on the underlying file. This operation
** is queued and performed later by sqlite3_async_flush().
*/
static void asyncSetFullSync(OsFile *id, int value){
addNewAsyncWrite((AsyncFile *)id, ASYNC_SETFULLSYNC, 0, value, 0);
}
/*
** Read data from the file. First we read from the filesystem, then adjust
** the contents of the buffer based on ASYNC_WRITE operations in the
** write-op queue. Todo: Do we need to think about ASYNC_TRUNCATE in
** this method as well?
**
** This method holds the mutex from start to finish.
*/
static int asyncRead(OsFile *id, void *obuf, int amt){
int rc = SQLITE_OK;
i64 filesize;
int nRead;
AsyncFile *pFile = (AsyncFile *)id;
/* Grab the mutex for the duration of the call */
sqlite3_os_enter_mutex();
if( pFile->pBaseRead ){
rc = sqlite3OsFileSize(pFile->pBaseRead, &filesize);
if( rc!=SQLITE_OK ){
goto asyncread_out;
}
rc = sqlite3OsSeek(pFile->pBaseRead, pFile->iOffset);
if( rc!=SQLITE_OK ){
goto asyncread_out;
}
nRead = MIN(filesize - pFile->iOffset, amt);
if( nRead>0 ){
rc = sqlite3OsRead(((AsyncFile *)id)->pBaseRead, obuf, nRead);
}
}
if( rc==SQLITE_OK ){
AsyncWrite *p;
i64 iOffset = pFile->iOffset; /* Current seek offset */
for(p=sqlite3_asyncListFirst; p; p = p->pNext){
if( p->pFile==pFile && p->op==ASYNC_WRITE ){
int iBeginIn = (p->iOffset - iOffset);
int iBeginOut = (iOffset - p->iOffset);
int nCopy;
if( iBeginIn<0 ) iBeginIn = 0;
if( iBeginOut<0 ) iBeginOut = 0;
nCopy = MIN(p->nByte-iBeginIn, amt-iBeginOut);
if( nCopy>0 ){
memcpy(&((char *)obuf)[iBeginOut], &p->zBuf[iBeginIn], nCopy);
}
}
}
pFile->iOffset += (i64)amt;
}
asyncread_out:
sqlite3_os_leave_mutex();
return rc;
}
/*
** Seek to the specified offset. This just adjusts the AsyncFile.iOffset
** variable - calling seek() on the underlying file is defered until the
** next read() or write() operation.
*/
static int asyncSeek(OsFile *id, i64 offset){
AsyncFile *pFile = (AsyncFile *)id;
pFile->iOffset = offset;
return SQLITE_OK;
}
/*
** Read the size of the file. First we read the size of the file system
** entry, then adjust for any ASYNC_WRITE or ASYNC_TRUNCATE operations
** currently in the write-op list.
**
** This method holds the mutex from start to finish.
*/
int asyncFileSize(OsFile *id, i64 *pSize){
int rc = SQLITE_OK;
i64 s = 0;
OsFile *pBase;
sqlite3_os_enter_mutex();
/* Read the filesystem size from the base file. If pBaseRead is NULL, this
** means the file hasn't been opened yet. In this case all relevant data
** must be in the write-op queue anyway, so we can omit reading from the
** file-system.
*/
pBase = ((AsyncFile *)id)->pBaseRead;
if( pBase ){
rc = sqlite3OsFileSize(pBase, &s);
}
if( rc==SQLITE_OK ){
AsyncWrite *p;
for(p=sqlite3_asyncListFirst; p; p = p->pNext){
if( p->pFile==(AsyncFile *)id ){
switch( p->op ){
case ASYNC_WRITE:
s = MAX(p->iOffset + (i64)(p->nByte), s);
break;
case ASYNC_TRUNCATE:
s = MIN(s, p->nByte);
break;
}
}
}
*pSize = s;
}
sqlite3_os_leave_mutex();
return rc;
}
/*
** Return the operating system file handle. This is only used for debugging
** at the moment anyway.
*/
static int asyncFileHandle(OsFile *id){
return sqlite3OsFileHandle(((AsyncFile *)id)->pBaseRead);
}
static int asyncLock(OsFile *id, int lockType){
return SQLITE_OK;
}
static int asyncUnlock(OsFile *id, int lockType){
return SQLITE_OK;
}
/*
** This function is called when the pager layer first opens a database file
** and is checking for a hot-journal.
*/
static int asyncCheckReservedLock(OsFile *id){
return SQLITE_OK;
}
/*
** This is broken. But sqlite3OsLockState() is only used for testing anyway.
*/
static int asyncLockState(OsFile *id){
return SQLITE_OK;
}
/*
** The three file-open functions for the underlying file system layer.
*/
static int (*xOrigOpenReadWrite)(const char*, OsFile**, int*) = 0;
static int (*xOrigOpenExclusive)(const char*, OsFile**, int) = 0;
static int (*xOrigOpenReadOnly)(const char*, OsFile**) = 0;
/*
** Pointers to the original versions of other overridden file-system
** operations.
*/
static int (*xOrigDelete)(const char*) = 0;
static int (*xOrigFileExists)(const char*) = 0;
static int (*xOrigSyncDirectory)(const char*) = 0;
static int asyncOpenFile(
const char *zName,
OsFile **pFile,
OsFile *pBaseRead,
int openSecondFile
){
int rc;
AsyncFile *p;
OsFile *pBaseWrite = 0;
static IoMethod iomethod = {
asyncClose,
asyncOpenDirectory,
asyncRead,
asyncWrite,
asyncSeek,
asyncTruncate,
asyncSync,
asyncSetFullSync,
asyncFileHandle,
asyncFileSize,
asyncLock,
asyncUnlock,
asyncLockState,
asyncCheckReservedLock
};
if( openSecondFile && SQLITE_ASYNC_TWO_FILEHANDLES ){
int dummy;
rc = xOrigOpenReadWrite(zName, &pBaseWrite, &dummy);
if( rc!=SQLITE_OK ){
goto error_out;
}
}
p = (AsyncFile *)sqlite3Os.xMalloc(sizeof(AsyncFile));
if( !p ){
rc = SQLITE_NOMEM;
goto error_out;
}
memset(p, 0, sizeof(AsyncFile));
p->pMethod = &iomethod;
p->pBaseRead = pBaseRead;
p->pBaseWrite = pBaseWrite;
*pFile = (OsFile *)p;
return SQLITE_OK;
error_out:
assert(!p);
sqlite3OsClose(&pBaseRead);
sqlite3OsClose(&pBaseWrite);
*pFile = 0;
return rc;
}
/*
** The async-IO backends implementation of the three functions used to open
** a file (xOpenExclusive, xOpenReadWrite and xOpenReadOnly). Most of the
** work is done in function asyncOpenFile() - see above.
*/
static int asyncOpenExclusive(const char *z, OsFile **ppFile, int delFlag){
int rc = asyncOpenFile(z, ppFile, 0, 0);
if( rc==SQLITE_OK ){
AsyncFile *pFile = (AsyncFile *)(*ppFile);
int nByte = strlen(z)+1;
i64 i = (i64)(delFlag);
rc = addNewAsyncWrite(pFile, ASYNC_OPENEXCLUSIVE, i, nByte, z);
if( rc!=SQLITE_OK ){
sqlite3Os.xFree(pFile);
*ppFile = 0;
}
}
return rc;
}
static int asyncOpenReadOnly(const char *z, OsFile **ppFile){
OsFile *pBase = 0;
int rc = xOrigOpenReadOnly(z, &pBase);
if( rc==SQLITE_OK ){
rc = asyncOpenFile(z, ppFile, pBase, 0);
}
return rc;
}
static int asyncOpenReadWrite(const char *z, OsFile **ppFile, int *pReadOnly){
OsFile *pBase = 0;
int rc = xOrigOpenReadWrite(z, &pBase, pReadOnly);
if( rc==SQLITE_OK ){
rc = asyncOpenFile(z, ppFile, pBase, (*pReadOnly ? 0 : 1));
}
return rc;
}
/*
** Implementation of sqlite3Os.xDelete. Add an entry to the end of the
** write-op queue to perform the delete.
*/
static int asyncDelete(const char *z){
return addNewAsyncWrite(0, ASYNC_DELETE, 0, strlen(z)+1, z);
}
/*
** Implementation of sqlite3Os.xDelete. Add an entry to the end of the
** write-op queue to perform the delete.
*/
static int asyncSyncDirectory(const char *z){
return addNewAsyncWrite(0, ASYNC_SYNCDIRECTORY, 0, strlen(z)+1, z);
}
/*
** Implementation of sqlite3Os.xFileExists. Return true if file 'z' exists
** in the file system.
**
** This method holds the mutex from start to finish.
*/
static int asyncFileExists(const char *z){
int ret;
AsyncWrite *p;
sqlite3_os_enter_mutex();
/* See if the real file system contains the specified file. */
ret = xOrigFileExists(z);
for(p=sqlite3_asyncListFirst; p; p = p->pNext){
if( p->op==ASYNC_DELETE && 0==strcmp(p->zBuf, z) ){
ret = 0;
}else if( p->op==ASYNC_OPENEXCLUSIVE && 0==strcmp(p->zBuf, z) ){
ret = 1;
}
}
sqlite3_os_leave_mutex();
return ret;
}
/*
** The following routine is one of two exported symbols in this module (along
** with sqlite3_async_flush(), see below). This routine should be called
** once to enable the asynchronous IO features implemented in this file. If
** the features are successfully enabled (or if they have already been
** enabled) then SQLITE_OK is returned. Otherwise, SQLITE_MISUSE.
*/
int sqlite3_async_enable(void){
if( xOrigOpenReadWrite==0 ){
#define ROUTINE(a,b,c) {(void**)&a,SQLITE_OS_ROUTINE_ ## b,(void *)c}
struct ReplacementOp {
void ** pOldRoutine;
int eRoutine;
void * pNewRoutine;
} aRoutines[] = {
ROUTINE(xOrigOpenReadWrite, OPENREADWRITE, asyncOpenReadWrite),
ROUTINE(xOrigOpenReadOnly, OPENREADONLY, asyncOpenReadOnly),
ROUTINE(xOrigOpenExclusive, OPENEXCLUSIVE, asyncOpenExclusive),
ROUTINE(xOrigDelete, DELETE, asyncDelete),
ROUTINE(xOrigFileExists, FILEEXISTS, asyncFileExists),
ROUTINE(xOrigSyncDirectory, SYNCDIRECTORY, asyncSyncDirectory)
};
#undef ROUTINE
int i;
sqlite3_os_enter_mutex();
for(i=0; i<sizeof(aRoutines)/sizeof(aRoutines[0]); i++){
struct ReplacementOp *p = &aRoutines[i];
*(p->pOldRoutine) = sqlite3_os_routine_set(p->eRoutine, p->pNewRoutine);
}
sqlite3_os_leave_mutex();
}
return SQLITE_OK;
}
/*
** This function is called externally to perform queued write and sync
** operations. It returns when an IO error occurs or there are no more queued
** operations to perform.
*/
int sqlite3_async_flush(void){
AsyncWrite *p = 0;
int rc = SQLITE_OK;
/* Grab the mutex and set the sqlite3_asyncIoBusy flag to make sure this
** is the only thread performing an sqlite3_async_flush() at this time.
** Or, if some other thread is already inside this function, return
** SQLITE_BUSY to the caller.
*/
sqlite3_os_enter_mutex();
if( sqlite3_asyncIoBusy ){
sqlite3_os_leave_mutex();
return SQLITE_BUSY;
}
sqlite3_asyncIoBusy = 1;
while( (p = sqlite3_asyncListFirst) && rc==SQLITE_OK ){
int isInsideMutex = 1;
/* Right now this thread is holding the global mutex. Variable 'p' points
** to the first entry in the write-op queue. In the general case, we
** hold on to the mutex for the entire body of the loop.
**
** However in the cases enumerated below, we relinquish the mutex,
** perform the IO, and then re-request the mutex before removing 'p' from
** the head of the write-op queue. The idea is to increase concurrency with
** sqlite threads.
**
** * An ASYNC_CLOSE operation.
** * An ASYNC_OPENEXCLUSIVE operation. For this one, we relinquish
** the mutex, call the underlying xOpenExclusive() function, then
** re-aquire the mutex before seting the AsyncFile.pBaseRead
** variable.
** * ASYNC_SYNC and ASYNC_WRITE operations, if
** SQLITE_ASYNC_TWO_FILEHANDLES was set at compile time and two
** file-handles are open for the particular file being "synced".
*/
OsFile *pBase = 0;
if( p->pFile ){
pBase = p->pFile->pBaseWrite;
if(
p->op==ASYNC_CLOSE ||
p->op==ASYNC_OPENEXCLUSIVE ||
(pBase && (p->op==ASYNC_SYNC || p->op==ASYNC_WRITE) )
){
sqlite3_os_leave_mutex();
isInsideMutex = 0;
}
if( !pBase ){
pBase = p->pFile->pBaseRead;
}
}
switch( p->op ){
case ASYNC_WRITE:
assert( pBase );
rc = sqlite3OsSeek(pBase, p->iOffset);
if( rc==SQLITE_OK ){
rc = sqlite3OsWrite(pBase, (const void *)(p->zBuf), p->nByte);
}
break;
case ASYNC_SYNC:
assert( pBase );
rc = sqlite3OsSync(pBase, p->nByte);
break;
case ASYNC_TRUNCATE:
assert( pBase );
rc = sqlite3OsTruncate(pBase, p->nByte);
break;
case ASYNC_CLOSE:
sqlite3OsClose(&p->pFile->pBaseRead);
sqlite3OsClose(&p->pFile->pBaseWrite);
sqlite3Os.xFree(p->pFile);
break;
case ASYNC_OPENDIRECTORY:
assert( pBase );
sqlite3OsOpenDirectory(pBase, p->zBuf);
break;
case ASYNC_SETFULLSYNC:
assert( pBase );
sqlite3OsSetFullSync(pBase, p->nByte);
break;
case ASYNC_DELETE:
rc = xOrigDelete(p->zBuf);
break;
case ASYNC_SYNCDIRECTORY:
rc = xOrigSyncDirectory(p->zBuf);
break;
case ASYNC_OPENEXCLUSIVE: {
AsyncFile *pFile = p->pFile;
int delFlag = ((p->iOffset)?1:0);
OsFile *pBase = 0;
rc = xOrigOpenExclusive(p->zBuf, &pBase, delFlag);
sqlite3_os_enter_mutex();
isInsideMutex = 1;
if( rc==SQLITE_OK ){
pFile->pBaseRead = pBase;
}
break;
}
default: assert(!"Illegal value for AsyncWrite.op");
}
/* If we didn't hang on to the mutex during the IO op, obtain it now
** so that the AsyncWrite structure can be safely removed from the
** global write-op queue.
*/
if( !isInsideMutex ){
sqlite3_os_enter_mutex();
}
if( rc==SQLITE_OK ){
removeAsyncWrite(p);
sqlite3Os.xFree(p);
}
}
/* Clear the io-busy flag and exit the mutex */
assert( sqlite3_asyncIoBusy );
sqlite3_asyncIoBusy = 0;
sqlite3_os_leave_mutex();
return rc;
}
/*
** The following code defines a Tcl interface for testing the asynchronous
** IO implementation in this file.
*/
#if defined(SQLITE_TEST) && defined(TCLSH)
#include <tcl.h>
/*
** sqlite3_async_enable
*/
static int testAsyncEnable(
void * clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
if( sqlite3_async_enable() ){
Tcl_SetResult(interp, "sqlite3_async_enable() failed", TCL_STATIC);
return TCL_ERROR;
}
return TCL_OK;
}
/*
** This is the main proc for a thread spawned by the Tcl command
** [sqlite3_async_flush -start]. The client data is a pointer to an integer
** variable that will be set to non-zero when this thread should exit.
*/
static void testAsyncFlushThread(ClientData clientData){
int *pStop = (int *)clientData;
int rc = 0;
/* Run in a loop until an IO error occurs or we are told to stop via
** the *pStop variable. Each iteration of the loop, call
** sqlite3_async_flush() and then sleep for a tenth of a second.
*/
while( !(*pStop) && !rc ){
rc = sqlite3_async_flush();
assert( rc==SQLITE_OK );
Tcl_Sleep(100);
}
if( rc==0 ){
rc = sqlite3_async_flush();
}
Tcl_ExitThread(rc);
}
/*
** sqlite3_async_flush
** sqlite3_async_flush -start
** sqlite3_async_flush -stop
*/
static int testAsyncFlush(
void * clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
static Tcl_ThreadId thread_id = 0;
static int stop = 0;
assert(stop==0);
if( objc!=1 && objc!=2 ){
Tcl_WrongNumArgs(interp, 1, objv, "?-start | -stop?");
return TCL_ERROR;
}
if( objc==2 ){
char *zOpt = Tcl_GetString(objv[1]);
if( 0==strcmp(zOpt, "-start") ){
/* Unless it is already running, kick off the _flush() thread */
if( thread_id ){
Tcl_AppendResult(interp, "Thread has already started", 0);
return TCL_ERROR;
}else{
int rc = Tcl_CreateThread(
&thread_id,
testAsyncFlushThread,
&stop,
TCL_THREAD_STACK_DEFAULT,
TCL_THREAD_JOINABLE
);
if( rc!=TCL_OK ){
Tcl_AppendResult(interp, "Tcl_CreateThread() failed", 0);
return TCL_ERROR;
}
}
}else if( 0==strcmp(zOpt, "-stop") ){
int dummy;
stop = 1;
Tcl_JoinThread(thread_id, &dummy);
stop = 0;
thread_id = 0;
}else{
Tcl_AppendResult(interp, "Invalid option: \"", zOpt, "\"", 0);
return TCL_ERROR;
}
}else if( sqlite3_async_flush() ){
Tcl_SetResult(interp, "sqlite3_async_flush() failed", TCL_STATIC);
return TCL_ERROR;
}
return TCL_OK;
}
int Sqlitetestasync_Init(Tcl_Interp *interp){
Tcl_CreateObjCommand(interp,"sqlite3_async_enable",testAsyncEnable,0,0);
Tcl_CreateObjCommand(interp,"sqlite3_async_flush",testAsyncFlush,0,0);
return TCL_OK;
}
#endif