e57::PacketReadCache Class Reference

#include <Packet.h>

Classes
struct	CacheEntry

Public Member Functions
std::unique_ptr< PacketLock >	lock (uint64_t packetLogicalOffset, char *&pkt)
	PacketReadCache (CheckedFile *cFile, unsigned packetCount)

Protected Member Functions
void	readPacket (unsigned oldestEntry, uint64_t packetLogicalOffset)
void	unlock (unsigned cacheIndex)

Protected Attributes
CheckedFile *	cFile_ = nullptr
std::vector< CacheEntry >	entries_
unsigned	lockCount_ = 0
unsigned	useCount_ = 0

Friends
class	PacketLock
	Only PacketLock can unlock the cache. More...

Constructor & Destructor Documentation

PacketReadCache()

PacketReadCache::PacketReadCache	(	CheckedFile *	cFile,
		unsigned	packetCount
	)

References e57::E57_ERROR_INTERNAL, and e57::toString().

Member Function Documentation

lock()

std::unique_ptr< PacketLock > PacketReadCache::lock	(	uint64_t	packetLogicalOffset,
		char *&	pkt
	)

Only allow one locked packet at a time.

Offset can't be 0

Linear scan for matching packet offset in cache

Found a match, so don't have to read anything

Mark entry with current useCount (keeps track of age of entry).

Publish buffer address to caller

Create lock so we are sure that we will be unlocked when use is finished.

Increment cache lock just before return

Get here if didn't find a match already in cache.

Find least recently used (LRU) packet buffer

Publish buffer address to caller

Create lock so we are sure we will be unlocked when use is finished.

Increment cache lock just before return

References e57::E57_ERROR_INTERNAL, entries_, lockCount_, PacketLock, readPacket(), e57::toString(), and useCount_.

Referenced by e57::CompressedVectorReaderImpl::CompressedVectorReaderImpl(), AddonManager.CommandAddonManager::on_package_updated(), drafttaskpanels.task_scale.ScaleTaskPanel::retranslateUi(), drafttaskpanels.task_scale.ScaleTaskPanel::setValue(), addonmanager_workers.CacheMacroCode::terminate(), and addonmanager_workers.CacheMacroCode::update_and_advance().

readPacket()

void PacketReadCache::readPacket ( unsigned  oldestEntry, uint64_t  packetLogicalOffset  )

protected

Read header of packet first to get length. Use EmptyPacketHeader since it has the fields common to all packets.

Can't verify packet header here, because it is not really an EmptyPacketHeader.

Be paranoid about packetLength before read

Now read in whole packet into preallocated buffer_. Note buffer is

Verify that packet is good.

Mark entry with current useCount (keeps track of age of entry). This is a cache, so a small hiccup when useCount_ overflows won't hurt.

References cFile_, e57::DATA_PACKET, e57::DATA_PACKET_MAX, e57::E57_ERROR_BAD_CV_PACKET, e57::E57_ERROR_INTERNAL, e57::EMPTY_PACKET, entries_, e57::INDEX_PACKET, e57::CheckedFile::Logical, EmptyPacketHeader::packetLogicalLengthMinus1, EmptyPacketHeader::packetType, e57::CheckedFile::read(), e57::CheckedFile::seek(), e57::toString(), useCount_, EmptyPacketHeader::verify(), e57::DataPacket::verify(), and IndexPacket::verify().

Referenced by lock().

unlock()

void PacketReadCache::unlock ( unsigned  cacheIndex )

protected

References e57::E57_ERROR_INTERNAL, lockCount_, and e57::toString().

Referenced by e57::PacketLock::~PacketLock().

Friends And Related Function Documentation

PacketLock

friend class PacketLock

friend

Only PacketLock can unlock the cache.

Referenced by lock().

Member Data Documentation

cFile_

CheckedFile* e57::PacketReadCache::cFile_ = nullptr

protected

Referenced by readPacket().

entries_

std::vector<CacheEntry> e57::PacketReadCache::entries_

protected

Referenced by lock(), and readPacket().

lockCount_

unsigned e57::PacketReadCache::lockCount_ = 0

protected

Referenced by lock(), and unlock().

useCount_

unsigned e57::PacketReadCache::useCount_ = 0

protected

Referenced by lock(), and readPacket().

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

• FreeCAD/src/3rdParty/libE57Format/src/Packet.h
• FreeCAD/src/3rdParty/libE57Format/src/Packet.cpp