Disk Cache keeps track of what files are on disk, and manages a helper thread to retrieve it. More...

#include <DiskCacheLayer.hpp>

Inheritance diagram for Sirikata::Transfer::DiskCacheLayer:

Collaboration diagram for Sirikata::Transfer::DiskCacheLayer:

Classes
struct	CacheData
struct	DiskRequest
Public Member Functions
void	workerThread ()
void	unserialize ()
void	readDataFromDisk (const Fingerprint &fileId, const Range &requestedRange, const TransferCallback &callback)
void	serializeRanges (const RangeList &list, std::string &out)
void	unserializeRanges (RangeList &rlist, std::istream &iranges)
	DiskCacheLayer (CachePolicy policy, const std::string &prefix, CacheLayer tryNext)
virtual	~DiskCacheLayer ()
virtual void	purgeFromCache (const Fingerprint &fileId)
	Purges this hash from all subsequent caches.
virtual void	getData (const Fingerprint &fileId, const Range &requestedRange, const TransferCallback &callback)
	Query this cache layer.
Protected Member Functions
virtual void	populateCache (const Fingerprint &fileId, const DenseDataPtr &data)
	Goes up the heirararchy of cache layers filling in data.
virtual void	destroyCacheEntry (const Fingerprint &fileId, CacheEntry *cacheLayerData, cache_usize_type releaseSize)
	Called after a cache entry has been destroyed-- Does not remove the item from other caches in the chain.
Private Attributes
ThreadSafeQueue < std::tr1::shared_ptr < DiskRequest > >	mRequestQueue
Thread *	mWorkerThread
CacheMap	mFiles
std::string	mPrefix
boost::mutex	destroyLock
boost::condition_variable	destroyCV
bool	mCleaningUp

Detailed Description

Disk Cache keeps track of what files are on disk, and manages a helper thread to retrieve it.

Constructor & Destructor Documentation

Sirikata::Transfer::DiskCacheLayer::DiskCacheLayer	(	CachePolicy *	policy,
		const std::string &	prefix,
		CacheLayer *	tryNext
	)

do nothing

References Sirikata::Path::DIR_TEMP, Sirikata::Logging::fatal, Sirikata::Path::Get(), mFiles, mPrefix, mWorkerThread, Sirikata::Transfer::CacheMap::setOwner(), SILOG, unserialize(), and workerThread().

virtual Sirikata::Transfer::DiskCacheLayer::~DiskCacheLayer ( ) [inline, virtual]

Member Function Documentation

virtual void Sirikata::Transfer::DiskCacheLayer::destroyCacheEntry	(	const Fingerprint &	fileId,
		CacheEntry *	cacheLayerData,
		cache_usize_type	releaseSize
	)		`[inline, protected, virtual]`

Called after a cache entry has been destroyed-- Does not remove the item from other caches in the chain.

Should be called only from CacheMap.

Reimplemented from Sirikata::Transfer::CacheLayer.

References Sirikata::SHA256::convertToHexString().

virtual void Sirikata::Transfer::DiskCacheLayer::getData	(	const Fingerprint &	fileId,
		const Range &	requestedRange,
		const TransferCallback &	callback
	)		`[inline, virtual]`

Query this cache layer.

If successful, call callback with the data and also call populateCache in order to populate the previous cache levels.

Parameters:

fid	A unique identifier corresponding to the file (contains a hash).
requestedRange	A Range object specifying a single range that you need.
callback	To be called with the data if successful, or NULL if failed.

Returns:: false, if the callback happened synchronously (i.e. in memory cache)

Reimplemented from Sirikata::Transfer::CacheLayer.

References Sirikata::Transfer::DiskCacheLayer::CacheData::contains(), Sirikata::Transfer::CacheMap::read_iterator::find(), Sirikata::Transfer::CacheLayer::getData(), and Sirikata::Transfer::CacheMap::read_iterator::use().

Referenced by workerThread().

virtual void Sirikata::Transfer::DiskCacheLayer::populateCache	(	const Fingerprint &	fileId,
		const DenseDataPtr &	data
	)		`[inline, protected, virtual]`

Goes up the heirararchy of cache layers filling in data.

Parameters:

fileId	the Fingerprint to store this data in CacheMap.
data	Data to be stored in this CacheLayer.

Reimplemented from Sirikata::Transfer::CacheLayer.

References Sirikata::Transfer::CacheLayer::populateParentCaches().

virtual void Sirikata::Transfer::DiskCacheLayer::purgeFromCache ( const Fingerprint & fileId ) [inline, virtual]

Purges this hash from all subsequent caches.

In general, it is not useful to do this manually, since the CachePolicy handles freeing extra data, and it is usually assumed that the cache is correct.

Validity checking should probably be added elsewhere--though it is not really feasable for incomplete downloads if we used a range.

Reimplemented from Sirikata::Transfer::CacheLayer.

References Sirikata::Transfer::CacheMap::write_iterator::erase(), Sirikata::Transfer::CacheMap::write_iterator::find(), and Sirikata::Transfer::CacheLayer::purgeFromCache().

void Sirikata::Transfer::DiskCacheLayer::readDataFromDisk	(	const Fingerprint &	fileId,
		const Range &	requestedRange,
		const TransferCallback &	callback
	)		`[inline]`