isc::ddns_tuning::ExpressionCache Class Reference

ExpressionCache stores expressions per subnet. More...

#include <expression_cache.h>

Inheritance diagram for isc::ddns_tuning::ExpressionCache:

Public Member Functions
	ExpressionCache ()
	Constructor.
virtual	~ExpressionCache ()
	Destructor.
void	cacheExpression (const dhcp::SubnetID &subnet_id, dhcp::ExpressionPtr &expression)
	Adds (or replaces) the expression for a given subnet to the cache.
void	clear ()
	Delete all the entries in the cache.
bool	findExpression (const dhcp::SubnetID &subnet_id, dhcp::ExpressionPtr &expression)
	Fetches the expression for a given subnet.
boost::posix_time::ptime	getLastFlushTime ()
	Returns the last time the cache was flushed (or the time it was created if it has never been flushed).
dhcp::ExpressionPtr	parseAndCacheExpression (const dhcp::SubnetID &subnet_id, const std::string &expression_str, uint32_t family)
	Parses an expression string and caches for the given subnet.
size_t	size ()
	Returns number of entries in the cache.
Public Member Functions inherited from isc::data::BaseStampedElement
	BaseStampedElement ()
	Constructor.
uint64_t	getId () const
	Returns element's database identifier.
boost::posix_time::ptime	getModificationTime () const
	Returns timestamp.
void	setId (const uint64_t id)
	Sets element's database identifier.
void	setModificationTime (const boost::posix_time::ptime &timestamp)
	Sets timestamp to the explicitly provided value.
void	updateModificationTime ()
	Sets timestamp to the current time.

Additional Inherited Members
Protected Attributes inherited from isc::data::BaseStampedElement
uint64_t	id_
	Database identifier of the configuration element.
boost::posix_time::ptime	timestamp_
	Holds timestamp value.

Detailed Description

ExpressionCache stores expressions per subnet.

For every subnet (lazy init) we store:

1. subnet id
2. expression pointer where:
   • empty pointer means that subnet does not define an expression
   • empty expression means that subnet overrides a global expression with no expression
   • non-empty means subnet overrides a global expression with an expression

Each time we clear the cache we update the modification time.

When presented with a subnet:

1. no cache entry: cache it

2. entry exists: subnet mod time >= last flush cache is stale flush it cache it

   subnet mod time < last flush use it

Definition at line 54 of file expression_cache.h.

Constructor & Destructor Documentation

ExpressionCache()

isc::ddns_tuning::ExpressionCache::ExpressionCache ( )

inline

Constructor.

Definition at line 57 of file expression_cache.h.

~ExpressionCache()

virtual isc::ddns_tuning::ExpressionCache::~ExpressionCache ( )

inlinevirtual

Destructor.

Definition at line 61 of file expression_cache.h.

Member Function Documentation

cacheExpression()

void isc::ddns_tuning::ExpressionCache::cacheExpression	(	const dhcp::SubnetID &	subnet_id,
		dhcp::ExpressionPtr &	expression )

Adds (or replaces) the expression for a given subnet to the cache.

Parameters

subnet_id	ID of the subnet for which the expression is desired.
expression	pointer to the expression to store. This may be an empty pointer.

Definition at line 68 of file expression_cache.cc.

References isc::util::MultiThreadingMgr::instance().

Referenced by parseAndCacheExpression().

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clear()

void isc::ddns_tuning::ExpressionCache::clear

(

)

Delete all the entries in the cache.

Definition at line 78 of file expression_cache.cc.

References isc::util::MultiThreadingMgr::instance(), and isc::data::BaseStampedElement::updateModificationTime().

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findExpression()

bool isc::ddns_tuning::ExpressionCache::findExpression	(	const dhcp::SubnetID &	subnet_id,
		dhcp::ExpressionPtr &	expression )

Fetches the expression for a given subnet.

Parameters

	subnet_id	ID of the subnet for which the expression is desired.
[out]	expression	a reference to a pointer in which to store the expression if found. If there is no entry for the subnet, it will be set to an empty pointer.

Returns

True if an entry for subnet was found, false otherwise. This allows callers to distinguish between unknown subnets (entries that do not exist) and subnets that are known but do not define an expression.

Definition at line 23 of file expression_cache.cc.

References isc::util::MultiThreadingMgr::instance().

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getLastFlushTime()

boost::posix_time::ptime isc::ddns_tuning::ExpressionCache::getLastFlushTime

(

)

Returns the last time the cache was flushed (or the time it was created if it has never been flushed).

Definition at line 106 of file expression_cache.cc.

References isc::data::BaseStampedElement::getModificationTime(), and isc::util::MultiThreadingMgr::instance().

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parseAndCacheExpression()

ExpressionPtr isc::ddns_tuning::ExpressionCache::parseAndCacheExpression	(	const dhcp::SubnetID &	subnet_id,
		const std::string &	expression_str,
		uint32_t	family )

Parses an expression string and caches for the given subnet.

Parameters

subnet_id	ID of the subnet for which the expression is desired.
expression_str	string containing the expression to parse and cache.
family	protocol family (AF_INET or AF_INET6) of the subnet/expression.

Returns

pointer to the parsed expression.

Exceptions

BadValue

if an error occurred during expression parsing.

Definition at line 45 of file expression_cache.cc.

References cacheExpression(), isc::eval::EvalContext::expression_, isc_throw, isc::eval::EvalContext::PARSER_STRING, isc::eval::EvalContext::parseString(), isc::dhcp::Option::V4, and isc::dhcp::Option::V6.

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size()

size_t isc::ddns_tuning::ExpressionCache::size

(

)

Returns number of entries in the cache.

Definition at line 96 of file expression_cache.cc.

References isc::util::MultiThreadingMgr::instance().

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

• expression_cache.h
• expression_cache.cc