net_instaweb::PropertyCache Class Reference

Adds property-semantics to a raw cache API. More...

#include "property_cache.h"

List of all members.

Classes

class  Cohort

Public Member Functions

 PropertyCache (const GoogleString &cache_key_prefix, CacheInterface *cache, Timer *timer, ThreadSystem *threads)
void Read (PropertyPage *property_page) const
void WriteCohort (const Cohort *cohort, PropertyPage *property_page) const
bool IsStable (const PropertyValue *property) const
 Determines whether a value that was read is reasonably stable.
bool IsExpired (const PropertyValue *property_value, int64 ttl_ms) const
void UpdateValue (const StringPiece &value, PropertyValue *property) const
void set_mutations_per_1000_writes_threshold (int x)
const CohortAddCohort (const StringPiece &cohort_name)
 Establishes a new Cohort for this property cache.
const CohortGetCohort (const StringPiece &cohort_name) const
void set_enabled (bool x)
bool enabled () const
 Indicates if the property cache is enabled.
GoogleString CacheKey (const StringPiece &key, const Cohort *cohort) const
const CacheInterfacecache_backend () const

Static Public Attributes

static const char kPagePropertyCacheKeyPrefix []
 Property cache key prefixes.
static const char kClientPropertyCacheKeyPrefix []

Detailed Description

Adds property-semantics to a raw cache API.


Member Function Documentation

GoogleString net_instaweb::PropertyCache::CacheKey ( const StringPiece &  key,
const Cohort cohort 
) const

Gets the underlying key associated with cache_key and a Cohort. This is the key used for the CacheInterface provided to the constructor. This is made visible for testing, to make it possible to inject delays into the cache via DelayCache::DelayKey.

const Cohort* net_instaweb::PropertyCache::GetCohort ( const StringPiece &  cohort_name  )  const

Returns the specified Cohort* or NULL if not found. Cohorts must be established at startup time, via AddCohort before any pages are processed via Read & Write.

bool net_instaweb::PropertyCache::IsExpired ( const PropertyValue property_value,
int64  ttl_ms 
) const

Determines whether a value is expired relative to the specified TTL.

It is an error (DCHECK) to call this method when !property->has_value().

Note; we could also store the TTL in the cache-value itself. That would be useful if we derived the TTL from the data or other transients. But our envisioned usage has the TTL coming from a configuration that is available at read-time, so for now we just use that.

void net_instaweb::PropertyCache::Read ( PropertyPage property_page  )  const

Reads the all the PropertyValues in all the known Cohorts from cache, calling PropertyPage::Done when done. It is essential that the Cohorts are established prior to calling this function.

void net_instaweb::PropertyCache::set_enabled ( bool  x  )  [inline]

Allows turning off all reads/writes with a switch. Writes to a disabled cache are ignored. Reads cause Done(false) to be called immediately.

void net_instaweb::PropertyCache::UpdateValue ( const StringPiece &  value,
PropertyValue property 
) const

Updates the value of a property, tracking stability & discarding writes when the existing data is more up-to-date.

void net_instaweb::PropertyCache::WriteCohort ( const Cohort cohort,
PropertyPage property_page 
) const

Updates a Cohort of properties into the cache. It is a programming error (dcheck-fail) to Write a PropertyPage that was not read first. It is fine to Write after a failed Read.

Even if a PropertyValue was not changed since it was read, Write should be called periodically to update stability metrics.


The documentation for this class was generated from the following file:
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Generated on Tue May 29 16:34:14 2012 for Page Speed Optimization Libraries by  doxygen 1.6.3