On 11/03/2016 04:53 PM, sanhua.zh wrote:
Here is a part of code in [unixWrite]. (os_unix.h)
Is not it written by mmap ?
It changed to avoid writing via mmap for version 3.10.0.
http://www.sqlite.org/src/info/67c5d3c646
And I don't think mmap() was used on IOS until 3.11.0.
http://www.sqlite.org/src/info/e9a51d2a580daa0f
Dan.
#if SQLITE_MAX_MMAP_SIZE0
/* Deal with as much of this write request as possible by transfering
** data from the memory mapping using memcpy(). */
if( offsetpFile-mmapSize ){
if( offset+amt = pFile-mmapSize ){
int size = -1;
struct stat buf; /* Used to hold return values of fstat() */
if( !osFstat(pFile-h, buf) ){
size = (int)buf.st_size;
}
memcpy(((u8 *)(pFile-pMapRegion))[offset], pBuf, amt);
return SQLITE_OK;
}else{
int nCopy = (int)(pFile-mmapSize - offset);
memcpy(((u8 *)(pFile-pMapRegion))[offset], pBuf, nCopy);
pBuf = ((u8 *)pBuf)[nCopy];
amt -= nCopy;
offset += nCopy;
}
}
#endif
原始邮件
发件人:Richard hipp...@sqlite.org
收件人:SQLite mailing listsqlite-us...@mailinglists.sqlite.org
发送时间:2016年11月3日(周四) 17:49
主题:Re: [sqlite] Is msync necessary for SQLite?
On 11/3/16, sanhua.zh sanhua...@foxmail.com wrote: I run in iOS. The mmap is
enable in recent version. So, once a mmap enable, data may lost after os crash
unless msync. But I can’t find anywhere in the source of SQLite call the
msync. Is it a bug? No. Mmap() is only used for reading, not writing. All
changes are implemented by calling write() and fsync(). -- D. Richard Hipp
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