bool
TEightTrack::ReadNextSegment ()
{
char track;
sector_t sector;
size_t x;
if (!segmentsToRead)
{
// read all there is to read
return FALSE;
}
// BUGBUG, this is an inefficient way to check befor reading track byte
if (CacheIsFull())
{
return FALSE;
}
// read byte, gives track number
x = fread (&track, 1, 1, fpPhysFile);
ASSERT (x == 1);
// if this fails, we are out of synch with file
ASSERT (track < 8);
// update count
segmentsToRead--;
if (aTracks[track].fIgnoreThisTrack)
{
// We are ignoring this track. This can happen if
// there is no sound driver.
fseek (fpPhysFile, SECTOR_SIZE, SEEK_CUR);
return TRUE;
}
// alloc sector, read into it
sector = AllocSector (track);
// CacheIsFull() should have caught this, but just to be sure
ASSERT (sector != -1);
SetSegmentSector(track, sector);
// read segment
x = fread (GetSectorPtr(sector), SECTOR_SIZE, 1, fpPhysFile);
ASSERT (x == 1);
// return successful
return TRUE;
}
/**
Implementation of pure virtual function.
@see MWTCacheInterface::MakePageMRU()
*/
void CDynamicDirCache::MakePageMRU(TInt64 aPos)
{
__PRINT1(_L("MakePageMRU (%lx)"), aPos);
// __PRINT4(_L("Current Cache State: iLockedQCount=%d, iUnlockedQCount=%d, iLookupTbl=%d, iMaxSizeInPages=%d"), iLockedQCount, iUnlockedQCount, iLookupTable.Count(), iMaxSizeInPages);
// check the MRU page first, if it is already the MRU page, we can return immediately
TInt64 pageStartMedPos = CalcPageStartPos(aPos);
if (!iLockedQ.IsEmpty())
{
if (iLockedQ.First()->StartPos() == pageStartMedPos)
{
return;
}
}
TDynamicDirCachePage* pPage = FindPageByPos(aPos);
if (pPage)
{
ASSERT(pPage->IsValid());
// lock page before make it MRU
if (pPage->PageType() == TDynamicDirCachePage::EUnlocked)
{
ASSERT(!pPage->IsLocked());
if (LockPage(pPage) == NULL)
{
DeQueue(pPage);
LookupTblRemove(pPage->StartPos());
DecommitPage(pPage);
delete pPage;
pPage = NULL;
}
}
else
{
// error checking: page should either be locked or active
ASSERT(LockPage(pPage) != NULL);
}
}
// if page not found or page data not valid anymore, use active page to read data
if (!pPage)
{
TRAPD(err, pPage = UpdateActivePageL(aPos));
if (err != KErrNone)
{
// problem occurred reading active page, return immediately.
return;
}
}
// by now, the page is either locked or active page
ASSERT(pPage && pPage->IsValid() && pPage->IsLocked());
switch (pPage->PageType())
{
// if the page is the active page, we will need to find a new active page for replacement
case TDynamicDirCachePage::EActivePage:
{
TDynamicDirCachePage* newAP = NULL;
// if there is more cache room available, try to create a new page first
if (!CacheIsFull())
{
// allocate and lock a new page
TRAPD(err, newAP = AllocateAndLockNewPageL(0));
// if any error ocurrs, return immediately
if (err != KErrNone)
{
// unlock the page that was originally unlocked before leave
if (pPage->PageType() == TDynamicDirCachePage::EUnlocked)
{
UnlockPage(pPage);
}
return;
}
if (newAP)
{
// replace the active page with the new page
newAP->SetPageType(TDynamicDirCachePage::EActivePage);
iActivePage = newAP;
}
}
// if cache has grown to its max size, or new page allocation failed
if (!newAP)
{
// try to lock the LRU page on the unlocked page queque first
if (!iUnlockedQ.IsEmpty())
{
newAP = iUnlockedQ.Last();
ASSERT(newAP->IsValid());
if (LockPage(newAP) != NULL)
{
// deque, reset pos, set new type
DeQueue(newAP);
LookupTblRemove(newAP->StartPos());
ResetPagePos(newAP);
newAP->SetPageType(TDynamicDirCachePage::EActivePage);
// replace active page
iActivePage = newAP;
}
// if falied locking the LRU page from unclocked queque,
// delete it
else
{
DeQueue(newAP);
LookupTblRemove(newAP->StartPos());
DecommitPage(newAP);
delete newAP;
newAP = NULL;
}
}
}
// if still have not found new active page
// grab the LRU page from Locked Page Queue for active page
if (!newAP)
{
ASSERT(!iLockedQ.IsEmpty());
newAP = iLockedQ.Last();
// deque, reset pos, set new type
DeQueue(newAP);
LookupTblRemove(newAP->StartPos());
ResetPagePos(newAP);
newAP->SetPageType(TDynamicDirCachePage::EActivePage);
// replace active page
iActivePage = newAP;
}
// we should always be able to find a locked page for active page
ASSERT(newAP != NULL);
// make original page (i.e. former active page) MRU
// add onto locked queue
AddFirstOntoQueue(pPage, TDynamicDirCachePage::ELocked);
// add onto lookuptbl, as active page is not on lookup tbl originally
LookupTblAdd(pPage);
// check cache limit
CheckThresholds();
return;
}
case TDynamicDirCachePage::EUnlocked:
{
// if page was originally on Unlocked Page Queque, remove it from Unlocked Page Queue, add it
// to the Locked Page Queue and make it MRU
DeQueue(pPage);
AddFirstOntoQueue(pPage, TDynamicDirCachePage::ELocked);
// check cache limit
CheckThresholds();
return;
}
case TDynamicDirCachePage::ELocked:
{
// otherwise the page was on Locked Page Queue, make it MRU
// no need to check cache limit
if (pPage != iLockedQ.First())
{
DeQueue(pPage);
AddFirstOntoQueue(pPage, TDynamicDirCachePage::ELocked);
return;
}
break;
}
default:
ASSERT(0);
}
}
