Difference between revisions of "TIncrementalCache"

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<pre style="border: 0; padding-bottom:0px;">function TIncrementalCache.PrepareDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;</pre>
 
<pre style="border: 0; padding-bottom:0px;">function TIncrementalCache.PrepareDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;</pre>
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<div style="font-size: 14px; padding-left: 12px;">'''Description:''' Prepare an incremental Cache Page for Write by ensuring that required sectors are cached</div>
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<div style="font-size: 14px; padding-left: 12px;">'''Description:''' Prepare an incremental Cache Page for Write by ensuring that all required sectors are cached</div>
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{| class="wikitable" style="font-size: 14px; background: white;"
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! Sector
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| Passed Sector will be the starting sector for the write to this Page
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! Count
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| Passed Count will be the write count to this Page (Calculated by caller)
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! Note
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| Only called internally by DeviceWrite
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Caller must hold the lock
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<pre style="border: 0; padding-bottom:0px;">function TIncrementalCache.CompleteDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;</pre>
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<div style="font-size: 14px; padding-left: 12px;">'''Description:''' Complete an incremental Cache Page Write by ensuring that all written sectors are marked dirty</div>
 
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"

Latest revision as of 04:21, 20 July 2023

Return to Unit Filesystem


Description

To be documented

Class definitions


TIncrementalCache = class(TObject)

Note: An expanded THashCache with incremental read ahead and dirty region write back.
 
constructor Create(ADriver:TFileSysDriver);  
destructor Destroy; override;  
private
FDriver:TFileSysDriver;  
 
FLock:TCriticalSectionHandle;  
 
FKeyBits:Byte;  
FKeyMask:LongWord;  
FKeyShift:LongWord;  
FKeyBuckets:Pointer;  
 
FBuffer:Pointer;  
FPageSize:LongWord;  
FPageCount:LongWord;  
FCacheSize:LongWord;  
FCacheKeys:LongWord;  
FCacheMode:TCacheMode;  
FCacheState:TCacheState;  
FFlushTimeout:LongWord;  
FDiscardTimeout:LongWord;  
 
FReadCached:Int64;  
FReadDirect:Int64;  
 
FWriteBack:Int64;  
FWriteThrough:Int64;  
FWriteDirect:Int64;  
 
FHitCount:Int64;  
FMissCount:Int64;  
 
FFailCount:Int64;  
FSuccessCount:Int64;  
 
FFlushCount:Int64;  
FDiscardCount:Int64;  
FUnknownCount:Int64;  
 
FFirstPage:TCachePage; First Cache Page (Any State)
FLastPage:TCachePage; Last Cache Page (Any State)
FFirstEmpty:TCachePage; First Free Page
FLastEmpty:TCachePage; Last Free Page
FFirstClean:TCachePage; First Clean Page (Used with no Write pending)
FLastClean:TCachePage; Last Clean Page (Used with no Write pending)
FFirstDirty:TCachePage; First Dirty Page (Used with Write pending)
FLastDirty:TCachePage; Last Dirty Page (Used with Write pending)
 
FTimer:TIncrementalCacheTimer;  
FThread:TIncrementalCacheThread;  
 
function AcquireLock:Boolean;  
function ReleaseLock:Boolean;  
 
function AddPage(APage:TCachePage):Boolean;  
function RemovePage(APage:TCachePage):Boolean;  
function AddEmpty(APage:TCachePage):Boolean;  
function AddClean(APage:TCachePage):Boolean;  
function AddDirty(APage:TCachePage):Boolean;  
function AddUnknown(APage:TCachePage):Boolean;  
 
function UpdateClean(APage:TCachePage):Boolean;  
function UpdateDirty(APage:TCachePage):Boolean;  
 
function RoundPageSize(APageSize:LongWord):LongWord;  
function RoundCacheSize(ACacheSize,APageSize:LongWord):LongWord;  
function AdjustCacheKeys(ACacheKeys:LongWord):LongWord;  
 
function CalculatePageCount(ADevice:TDiskDevice):Word;  
function CalculatePageShift(ADevice:TDiskDevice):Word;  
function CalculatePageMask(ADevice:TDiskDevice):LongWord;  
 
function KeyLink(APage:THashCachePage):Boolean;  
function KeyUnlink(APage:THashCachePage):Boolean;  
function KeyFirst(AKeyHash:LongWord):THashCachePage;  
 
function LinkPage(APage:TCachePage):Boolean;  
function UnlinkPage(APage:TCachePage):Boolean;  
function LinkEmpty(APage:TCachePage):Boolean;  
function UnlinkEmpty(APage:TCachePage):Boolean;  
function LinkClean(APage:TCachePage):Boolean;  
function UnlinkClean(APage:TCachePage):Boolean;  
function LinkDirty(APage:TCachePage):Boolean;  
function UnlinkDirty(APage:TCachePage):Boolean;  
 
function PrepareDeviceRead(ADevice:TDiskDevice; APage:TCachePage; var ASector:LongWord; var ACount:Word):Boolean;  
function PrepareDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; var ASector:LongWord; var ACount:Word):Boolean;  
function CompleteDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;  
function CalculateDevicePage(ADevice:TDiskDevice; ASector:LongWord; var ACount:LongWord):Boolean;  
public
property PageSize:LongWord read FPageSize;  
property PageCount:LongWord read FPageCount;  
property CacheSize:LongWord read FCacheSize;  
property CacheKeys:LongWord read FCacheKeys;  
property CacheMode:TCacheMode read FCacheMode;  
property CacheState:TCacheState read FCacheState;  
property FlushTimeout:LongWord read FFlushTimeout;  
property DiscardTimeout:LongWord read FDiscardTimeout;  
 
property ReadCached:Int64 read FReadCached;  
property ReadDirect:Int64 read FReadDirect;  
 
property WriteBack:Int64 read FWriteBack;  
property WriteThrough:Int64 read FWriteThrough;  
property WriteDirect:Int64 read FWriteDirect;  
 
property HitCount:Int64 read FHitCount;  
property MissCount:Int64 read FMissCount;  
 
property FailCount:Int64 read FFailCount;  
property SuccessCount:Int64 read FSuccessCount;  
 
property FlushCount:Int64 read FFlushCount;  
property DiscardCount:Int64 read FDiscardCount;  
property UnknownCount:Int64 read FUnknownCount;  
 
function OpenCache(ACacheSize,ACacheKeys,APageSize:LongWord; ACacheMode:TCacheMode):Boolean;  
function CloseCache:Boolean;  
 
function DeviceRead(ADevice:TDiskDevice; ASector:LongWord; ACount:Word; var ABuffer):Boolean;  
function DeviceWrite(ADevice:TDiskDevice; ASector:LongWord; ACount:Word; const ABuffer):Boolean;  
function DeviceErase(ADevice:TDiskDevice; ASector:LongWord; ACount:Word):Boolean;  
 
function GetDevicePage(ADevice:TDiskDevice; ASector:LongWord):TCachePage; virtual;  
function GetEmptyPage:TCachePage;  
 
function AllocDevicePage(ADevice:TDiskDevice; ASector:LongWord; AWrite:Boolean):TCachePage; virtual;  
 
function DiscardPage(APage:TCachePage):Boolean;  
function DiscardCache(AFirst,AAll:Boolean):Boolean;  
 
function ReleaseDevicePages(ADevice:TDiskDevice):Boolean;  
 
function FlushPage(APage:TCachePage):Boolean;  
function FlushPageEx(APage:TCachePage):Boolean;  
function FlushCache(AFirst,AAll:Boolean):Boolean;  
 
function CheckTimer:Boolean;  
function ProcessTimer:Boolean;  
 
function SchedulePage(APage:TCachePage; ATimeout:LongWord):Boolean;  
function UnschedulePage(APage:TCachePage):Boolean;  


Function declarations


constructor TIncrementalCache.Create(ADriver:TFileSysDriver);
Description: To be documented
Note None documented 


destructor TIncrementalCache.Destroy;
Description: To be documented
Note None documented 


function TIncrementalCache.AcquireLock:Boolean;
Description: To be documented
Note None documented 


function TIncrementalCache.ReleaseLock:Boolean;
Description: To be documented
Note None documented 


function TIncrementalCache.AddPage(APage:TCachePage):Boolean;
Description: Add a new page to the Page list and the Empty list
Note None documented 


function TIncrementalCache.RemovePage(APage:TCachePage):Boolean;
Description: Remove a Page from the Page list and any other lists then Free the Page
Note None documented 


function TIncrementalCache.AddEmpty(APage:TCachePage):Boolean;
Description: Add a Page to the Empty list, removing from other lists if needed
Note None documented 


function TIncrementalCache.AddClean(APage:TCachePage):Boolean;
Description: Add a Page to the Clean list, removing from other lists if needed
Note None documented 


function TIncrementalCache.AddDirty(APage:TCachePage):Boolean;
Description: Add a Page to the Dirty list, removing from other lists if needed
Note None documented 


function TIncrementalCache.AddUnknown(APage:TCachePage):Boolean;
Description: Make a Page Unknown by removing from any other lists if needed
Note None documented 


function TIncrementalCache.UpdateClean(APage:TCachePage):Boolean;
Description: Move a Page to the end of the Clean list
Note None documented 


function TIncrementalCache.UpdateDirty(APage:TCachePage):Boolean;
Description: Move a Page to the end of the Dirty list
Note None documented 


function TIncrementalCache.RoundPageSize(APageSize:LongWord):LongWord;
Description: Round Page Size to the power of 2 of Sector Size
Note Caller must hold the lock 


function TIncrementalCache.RoundCacheSize(ACacheSize,APageSize:LongWord):LongWord;
Description: Round Cache Size to the next multiple of Page Size
Note Caller must hold the lock 


function TIncrementalCache.AdjustCacheKeys(ACacheKeys:LongWord):LongWord;
Description: Adjust Cache Keys to be within safe limits
Note Caller must hold the lock 


function TIncrementalCache.CalculatePageCount(ADevice:TDiskDevice):Word;
Description: Calculate the power of 2 multiple of sector size which will fit within the page
Note Caller must hold the lock 


function TIncrementalCache.CalculatePageShift(ADevice:TDiskDevice):Word;
Description: Calculate the shift count for Page to Key conversion
Note Caller must hold the lock 


function TIncrementalCache.CalculatePageMask(ADevice:TDiskDevice):LongWord;
Description: Calculate the mask for Sector to Page conversion
Note Caller must hold the lock 


function TIncrementalCache.KeyLink(APage:THashCachePage):Boolean;
Description: Link APage to KeyPrev,KeyNext siblings and Adjust First
Note Caller must hold the lock 


function TIncrementalCache.KeyUnlink(APage:THashCachePage):Boolean;
Description: Unlink APage from KeyPrev,KeyNext siblings and Adjust First
Note None documented 


function TIncrementalCache.KeyFirst(AKeyHash:LongWord):THashCachePage;
Description: To be documented
Note Caller must hold the lock 


function TIncrementalCache.LinkPage(APage:TCachePage):Boolean;
Description: Link APage to PrevPage,NextPage siblings and Adjust FirstPage/LastPage
Note Caller must hold the lock 


function TIncrementalCache.UnlinkPage(APage:TCachePage):Boolean;
Description: Unlink APage from PrevPage,NextPage Siblings and Adjust FirstPage/LastPage
Note Caller must hold the lock 


function TIncrementalCache.LinkEmpty(APage:TCachePage):Boolean;
Description: Link APage to PrevLink,NextLink siblings and Adjust FirstEmpty/LastEmpty
Note Caller must hold the lock 


function TIncrementalCache.UnlinkEmpty(APage:TCachePage):Boolean;
Description: Unlink APage from PrevLink,NextLink Siblings and Adjust FirstEmpty/LastEmpty
Note Caller must hold the lock 


function TIncrementalCache.LinkClean(APage:TCachePage):Boolean;
Description: Link APage to PrevLink,NextLink siblings and Adjust FirstClean/LastClean
Note Caller must hold the lock 


function TIncrementalCache.UnlinkClean(APage:TCachePage):Boolean;
Description: Unlink APage from PrevLink,NextLink Siblings and Adjust FirstClean/LastClean
Note Caller must hold the lock 


function TIncrementalCache.LinkDirty(APage:TCachePage):Boolean;
Description: Link APage to PrevLink,NextLink siblings and Adjust FirstDirty/LastDirty
Note Caller must hold the lock 


function TIncrementalCache.UnlinkDirty(APage:TCachePage):Boolean;
Description: Unlink APage from PrevLink,NextLink Siblings and Adjust FirstDirty/LastDirty
Note Caller must hold the lock 


function TIncrementalCache.PrepareDeviceRead(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;
Description: Prepare an incremental Cache Page for Read by ensuring that all required sectors are cached
Sector Passed Sector will be the starting sector for the read from this Page
Count Passed Count will be the read count from this Page (Calculated by caller)
Note Only called internally by DeviceRead

Caller must hold the lock 


function TIncrementalCache.PrepareDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;
Description: Prepare an incremental Cache Page for Write by ensuring that all required sectors are cached
Sector Passed Sector will be the starting sector for the write to this Page
Count Passed Count will be the write count to this Page (Calculated by caller)
Note Only called internally by DeviceWrite

Caller must hold the lock 


function TIncrementalCache.CompleteDeviceWrite(ADevice:TDiskDevice; APage:TCachePage; ASector,ACount:LongWord):Boolean;
Description: Complete an incremental Cache Page Write by ensuring that all written sectors are marked dirty
Sector Passed Sector will be the starting sector for the write to this Page
Count Passed Count will be the write count to this Page (Calculated by caller)
Note Only called internally by DeviceWrite

Caller must hold the lock 


function TIncrementalCache.CalculateDevicePage(ADevice:TDiskDevice; ASector:LongWord; var ACount:LongWord):Boolean;
Description: Calculate the number of sectors remaining in a page given the starting sector
Note Only called internally by DeviceRead/DeviceWrite/DeviceErase

Caller must hold the lock 


function TIncrementalCache.OpenCache(ACacheSize,ACacheKeys,APageSize:LongWord; ACacheMode:TCacheMode):Boolean;
Description: Allocate the Memory, Create the Empty Pages and Open Cache
Note None documented 


function TIncrementalCache.CloseCache:Boolean;
Description: Flush all Dirty Pages, Release the Memory and Close the Cache
Note None documented 


function TIncrementalCache.DeviceRead(ADevice:TDiskDevice; ASector,ACount:LongWord; var ABuffer):Boolean;
Description: Read Data from the Physical Device using either Cached or Direct access
Note AllocDevicePage does all checks for Size, Sector and Count. 


function TIncrementalCache.DeviceWrite(ADevice:TDiskDevice; ASector,ACount:LongWord; const ABuffer):Boolean;
Description: Write Data to the Physical Device using either Cached or Direct access
Note AllocDevicePage does all checks for Size, Sector and Count. 


function TIncrementalCache.DeviceErase(ADevice:TDiskDevice; ASector,ACount:LongWord):Boolean;
Description: Erase Data from the Physical Device and update cached pages accordingly
Note None documented 


function TIncrementalCache.GetDevicePage(ADevice:TDiskDevice; ASector:LongWord):TCachePage;
Description: Get the Clean or Dirty Page that contains this Sector on this Device
Note None documented 


function TIncrementalCache.GetEmptyPage:TCachePage;
Description: Get the First Empty Page, Discard First Clean Page if none Empty
Note None documented 


function TIncrementalCache.AllocDevicePage(ADevice:TDiskDevice; ASector:LongWord; AWrite:Boolean):TCachePage;
Description: Allocate an Empty Page to the Device and mark as Clean or Dirty
Note None documented 


function TIncrementalCache.DiscardPage(APage:TCachePage):Boolean;
Description: Return a Clean Page to Empty
Note None documented 


function TIncrementalCache.DiscardCache(AFirst,AAll:Boolean):Boolean;
Description: Find any Clean Pages older than DiscardTimeout and Discard them
Note None documented 


function TIncrementalCache.ReleaseDevicePages(ADevice:TDiskDevice):Boolean;
Description: Return all Clean or Dirty Pages on the Device to Empty
Note None documented 


function TIncrementalCache.FlushPage(APage:TCachePage):Boolean;
Description: Return a Dirty Page to Clean
Note None documented 


function TIncrementalCache.FlushPageEx(APage:TCachePage):Boolean;
Description: Return a Dirty Page to Clean if it is older than FlushTimeout
Note Only called by CacheThread with page scheduled from CacheTimer 


function TIncrementalCache.FlushCache(AFirst,AAll:Boolean):Boolean;
Description: Find any Dirty Pages older than FlushTimeout and Flush them
Note None documented 


function TIncrementalCache.CheckTimer:Boolean;
Description: To be documented
Note None documented 


function TIncrementalCache.ProcessTimer:Boolean;
Description: To be documented
Note None documented 


function TIncrementalCache.SchedulePage(APage:TCachePage; ATimeout:LongWord):Boolean;
Description: To be documented
Note None documented 


function TIncrementalCache.UnschedulePage(APage:TCachePage):Boolean;
Description: To be documented
Note None documented


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