TransactionalCacheAccessor Class Reference

TransactionalCacheAccessor implements the CacheAccessor::setTxnId method, allowing it to be used to lock pages on behalf of a particular transaction without the caller being aware of the association. More...

#include <TransactionalCacheAccessor.h>

Inheritance diagram for TransactionalCacheAccessor:

DelegatingCacheAccessor CacheAccessor QuotaCacheAccessor List of all members.

Public Member Functions

 TransactionalCacheAccessor (SharedCacheAccessor pDelegate)
 Constructor.
virtual ~TransactionalCacheAccessor ()
virtual CachePagelockPage (BlockId blockId, LockMode lockMode, bool readIfUnmapped=true, MappedPageListener *pMappedPageListener=NULL, TxnId txnId=IMPLICIT_TXN_ID)
 Locks a page into memory with the specified concurrency mode.
virtual void unlockPage (CachePage &page, LockMode lockMode, TxnId txnId=IMPLICIT_TXN_ID)
 Releases lock held on page.
virtual void setTxnId (TxnId txnId)
 Sets a default TxnId to use for locking pages (to be used when IMPLICIT_TXN_ID is specified).
virtual TxnId getTxnId () const
 
Returns:
default TxnId associated with this accessor

virtual void discardPage (BlockId blockId)
 Unmaps a page from the cache if already mapped, discarding its contents if dirty.
virtual bool prefetchPage (BlockId blockId, MappedPageListener *pMappedPageListener=NULL)
 Hints that a page should be prefetched in preparation for a future lock request.
virtual void prefetchBatch (BlockId blockId, uint nPages, MappedPageListener *pMappedPageListener=NULL)
 Hints that a contiguous run of pages should be prefetched.
virtual void flushPage (CachePage &page, bool async)
 Forces the contents of a dirty page to its mapped location.
virtual void nicePage (CachePage &page)
 Marks a page as nice, indicating that it is very unlikely the page's mapping will be needed again any time soon, so it is a good candidate for victimization.
virtual SharedCache getCache ()
 
Returns:
the underlying Cache accessed by this CacheAccessor

virtual uint getMaxLockedPages ()
 
Returns:
the page lock quota on this accessor

virtual void setMaxLockedPages (uint nPages)
 Sets the page lock quota on this accessor.
virtual void getPrefetchParams (uint &prefetchPagesMax, uint &prefetchThrottleRate)
 Retrieves the current pre-fetch caching parameters that determine how many pages should be pre-fetched and how often the pre-fetches should occur.

Private Attributes

TxnId implicitTxnId

Detailed Description

TransactionalCacheAccessor implements the CacheAccessor::setTxnId method, allowing it to be used to lock pages on behalf of a particular transaction without the caller being aware of the association.

Author:
John Sichi
Version:
Id
//open/dev/fennel/cache/TransactionalCacheAccessor.h#5

Definition at line 38 of file TransactionalCacheAccessor.h.


Constructor & Destructor Documentation

TransactionalCacheAccessor::TransactionalCacheAccessor ( SharedCacheAccessor  pDelegate  )  [explicit]

Constructor.

Parameters:
pDelegate the underlying CacheAccessor

Definition at line 28 of file TransactionalCacheAccessor.cpp.

References IMPLICIT_TXN_ID, and implicitTxnId.

00030     : DelegatingCacheAccessor(pDelegateInit)
00031 {
00032     implicitTxnId = IMPLICIT_TXN_ID;
00033 }

TransactionalCacheAccessor::~TransactionalCacheAccessor (  )  [virtual]

Definition at line 35 of file TransactionalCacheAccessor.cpp.

00036 {
00037 }


Member Function Documentation

CachePage * TransactionalCacheAccessor::lockPage ( BlockId  blockId,
LockMode  lockMode,
bool  readIfUnmapped = true,
MappedPageListener pMappedPageListener = NULL,
TxnId  txnId = IMPLICIT_TXN_ID 
) [virtual]

Locks a page into memory with the specified concurrency mode.

When the page contents are no longer needed, the caller must invoke the unlockPage() method with the same concurrency mode to release it. If the desired page is already locked by another thread with an incompatible concurrency mode, blocks until the page becomes available (unless the lock mode is of the NoWait variety, in which case returns NULL immediately). Note that NoWait locking only applies to lock contention, not I/O, so if an unmapped page is locked in NoWait mode, blocks until the read completes.

The device referenced by the requested blockId must already be registered with the cache and must remain registered for the duration of the lock.

Notes on concurrency modes:

Parameters:
blockId the BlockId of the page to be locked
lockMode the desired concurrency mode
readIfUnmapped if true (the default) the page data is read as part of mapping; if false, the page data is left invalid until first write (used when allocating a new block with invalid contents)
pMappedPageListener optional listener to receive notifications when this page is written; if specified, it must match all prior and subsequent lock requests for the same page mapping
txnId optional TxnId to associate with lock; default is IMPLICIT_TXN_ID, which uses current thread ID as an implicit TxnId
Returns:
the locked CachePage, or NULL if a NoWait attempt failed

Reimplemented from DelegatingCacheAccessor.

Reimplemented in QuotaCacheAccessor.

Definition at line 39 of file TransactionalCacheAccessor.cpp.

References IMPLICIT_TXN_ID, implicitTxnId, and DelegatingCacheAccessor::lockPage().

Referenced by QuotaCacheAccessor::lockPage().

00045 {
00046     if (txnId == IMPLICIT_TXN_ID) {
00047         txnId = implicitTxnId;
00048     }
00049     CachePage *pPage = DelegatingCacheAccessor::lockPage(
00050         blockId,lockMode,readIfUnmapped,pMappedPageListener,txnId);
00051     return pPage;
00052 }

void TransactionalCacheAccessor::unlockPage ( CachePage page,
LockMode  lockMode,
TxnId  txnId = IMPLICIT_TXN_ID 
) [virtual]

Releases lock held on page.

Parameters:
page the page to be unlocked
lockMode must correspond to value passed to Cache::lockPage; however, for pages locked with NOWAIT, the equivalent unlock type should be normal (e.g. LOCKMODE_S instead of LOCKMODE_S_NOWAIT)
txnId must correspond to value passed to Cache::lockPage

Reimplemented from DelegatingCacheAccessor.

Reimplemented in QuotaCacheAccessor.

Definition at line 54 of file TransactionalCacheAccessor.cpp.

References IMPLICIT_TXN_ID, implicitTxnId, and DelegatingCacheAccessor::unlockPage().

Referenced by QuotaCacheAccessor::unlockPage().

00058 {
00059     if (txnId == IMPLICIT_TXN_ID) {
00060         txnId = implicitTxnId;
00061     }
00062     DelegatingCacheAccessor::unlockPage(page,lockMode,txnId);
00063 }

void TransactionalCacheAccessor::setTxnId ( TxnId  txnId  )  [virtual]

Sets a default TxnId to use for locking pages (to be used when IMPLICIT_TXN_ID is specified).

Not all CacheAccessor implementations support this behavior.

Parameters:
txnId new default txn ID

Reimplemented from DelegatingCacheAccessor.

Definition at line 65 of file TransactionalCacheAccessor.cpp.

References implicitTxnId.

00066 {
00067     implicitTxnId = txnId;
00068 }

TxnId TransactionalCacheAccessor::getTxnId (  )  const [virtual]

Returns:
default TxnId associated with this accessor

Reimplemented from DelegatingCacheAccessor.

Definition at line 70 of file TransactionalCacheAccessor.cpp.

References implicitTxnId.

00071 {
00072     return implicitTxnId;
00073 }

void DelegatingCacheAccessor::discardPage ( BlockId  blockId  )  [virtual, inherited]

Unmaps a page from the cache if already mapped, discarding its contents if dirty.

The caller must ensure that no other thread has the page locked.

Parameters:
blockId the BlockId of the page to be discarded

Implements CacheAccessor.

Definition at line 54 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00056 {
00057     pDelegate->discardPage(blockId);
00058 }

bool DelegatingCacheAccessor::prefetchPage ( BlockId  blockId,
MappedPageListener pMappedPageListener = NULL 
) [virtual, inherited]

Hints that a page should be prefetched in preparation for a future lock request.

Parameters:
blockId the BlockId of the page to be prefetched
pMappedPageListener optional listener to receive notifications when this page is written; if specified, it must match all prior and subsequent lock requests for the same page mapping
Returns:
true if the pre-fetch request was successful

Implements CacheAccessor.

Definition at line 60 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00063 {
00064     return pDelegate->prefetchPage(blockId,pMappedPageListener);
00065 }

void DelegatingCacheAccessor::prefetchBatch ( BlockId  blockId,
uint  nPages,
MappedPageListener pMappedPageListener = NULL 
) [virtual, inherited]

Hints that a contiguous run of pages should be prefetched.

Parameters:
blockId the BlockId of the first page to be prefetched; more will be prefetched depending on the configured batch size
nPages number of pages in batch
pMappedPageListener optional listener to receive notifications when this page is written; if specified, it must match all prior and subsequent lock requests for the same page mapping

Implements CacheAccessor.

Definition at line 67 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00070 {
00071     pDelegate->prefetchBatch(blockId,nPages,pMappedPageListener);
00072 }

void DelegatingCacheAccessor::flushPage ( CachePage page,
bool  async 
) [virtual, inherited]

Forces the contents of a dirty page to its mapped location.

Page must already be locked in exclusive mode. For an asynchronous flush, the caller must ensure that the page contents remain unchanged until the flush completes.

Parameters:
page the page to be flushed
async true to schedle async write and return immediately; false to wait for write to complete

Implements CacheAccessor.

Definition at line 74 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00075 {
00076     pDelegate->flushPage(page,async);
00077 }

void DelegatingCacheAccessor::nicePage ( CachePage page  )  [virtual, inherited]

Marks a page as nice, indicating that it is very unlikely the page's mapping will be needed again any time soon, so it is a good candidate for victimization.

Parameters:
page the page to be marked

Implements CacheAccessor.

Definition at line 79 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00080 {
00081     pDelegate->nicePage(page);
00082 }

SharedCache DelegatingCacheAccessor::getCache (  )  [virtual, inherited]

Returns:
the underlying Cache accessed by this CacheAccessor

Implements CacheAccessor.

Definition at line 84 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00085 {
00086     return pDelegate->getCache();
00087 }

uint DelegatingCacheAccessor::getMaxLockedPages (  )  [virtual, inherited]

Returns:
the page lock quota on this accessor

Implements CacheAccessor.

Reimplemented in QuotaCacheAccessor.

Definition at line 89 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00090 {
00091     return pDelegate->getMaxLockedPages();
00092 }

void DelegatingCacheAccessor::setMaxLockedPages ( uint  nPages  )  [virtual, inherited]

Sets the page lock quota on this accessor.

Ignored for accessor implementations that don't support quotas.

Parameters:
nPages new quota

Implements CacheAccessor.

Reimplemented in QuotaCacheAccessor.

Definition at line 94 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00095 {
00096     pDelegate->setMaxLockedPages(nPages);
00097 }

void DelegatingCacheAccessor::getPrefetchParams ( uint prefetchPagesMax,
uint prefetchThrottleRate 
) [virtual, inherited]

Retrieves the current pre-fetch caching parameters that determine how many pages should be pre-fetched and how often the pre-fetches should occur.

Parameters:
[out] prefetchPagesMax max number of outstanding pre-fetch pages
[out] prefetchThrottleRate the number of successful pre-fetches that have to occur before the pre-fetch rate is throttled back up, in the event that it has been throttled down due to rejected requests

Implements CacheAccessor.

Definition at line 109 of file DelegatingCacheAccessor.cpp.

References DelegatingCacheAccessor::pDelegate.

00112 {
00113     pDelegate->getPrefetchParams(prefetchPagesMax, prefetchThrottleRate);
00114 }


Member Data Documentation

TxnId TransactionalCacheAccessor::implicitTxnId [private]

Definition at line 41 of file TransactionalCacheAccessor.h.

Referenced by getTxnId(), lockPage(), setTxnId(), TransactionalCacheAccessor(), and unlockPage().


The documentation for this class was generated from the following files:
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