Page Speed Optimization Libraries  1.4.26.1
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net_instaweb::CriticalImagesFinder Class Reference

#include "critical_images_finder.h"

Inheritance diagram for net_instaweb::CriticalImagesFinder:
net_instaweb::BeaconCriticalImagesFinder

List of all members.

Public Member Functions

 CriticalImagesFinder (Statistics *stats)
virtual bool IsMeaningful (const RewriteDriver *driver) const =0
virtual int PercentSeenForCritical () const
virtual int NumSetsToKeep () const
virtual bool IsHtmlCriticalImage (const GoogleString &image_url, RewriteDriver *driver)
virtual bool IsCssCriticalImage (const GoogleString &image_url, RewriteDriver *driver)
const StringSet & GetHtmlCriticalImages (RewriteDriver *driver)
const StringSet & GetCssCriticalImages (RewriteDriver *driver)
StringSet * mutable_html_critical_images (RewriteDriver *driver)
StringSet * mutable_css_critical_images (RewriteDriver *driver)
virtual void ComputeCriticalImages (StringPiece url, RewriteDriver *driver)=0
 Compute the critical images for the given url.
virtual const char * GetCriticalImagesCohort () const =0
bool UpdateCriticalImagesCacheEntryFromDriver (RewriteDriver *driver, StringSet *critical_images_set, StringSet *css_critical_images_set)
bool UpdateCriticalImagesCacheEntry (PropertyPage *page, PropertyCache *page_property_cache, StringSet *critical_images_set, StringSet *css_critical_images_set)

Static Public Member Functions

static void InitStats (Statistics *statistics)

Static Public Attributes

static const char kCriticalImagesValidCount []
static const char kCriticalImagesExpiredCount []
static const char kCriticalImagesNotFoundCount []
static const char kCriticalImagesPropertyName []

Protected Member Functions

virtual void UpdateCriticalImagesSetInDriver (RewriteDriver *driver)
void ExtractCriticalImagesFromCache (RewriteDriver *driver, const PropertyValue *property_value, bool track_stats, CriticalImagesInfo *critical_images_info)

Friends

class CriticalImagesFinderTestBase

Detailed Description

Finds critical images i.e. images which are above the fold for a given url. This information may be used by DelayImagesFilter.


Member Function Documentation

void net_instaweb::CriticalImagesFinder::ExtractCriticalImagesFromCache ( RewriteDriver driver,
const PropertyValue property_value,
bool  track_stats,
CriticalImagesInfo critical_images_info 
) [protected]

Extracts the critical images from the given property_value into critical_images_info, after checking if the property value is still valid using the provided TTL. It also updates stats variables if track_stats is true.

virtual const char* net_instaweb::CriticalImagesFinder::GetCriticalImagesCohort ( ) const [pure virtual]

Identifies which cohort in the PropertyCache the critical image information is located in.

Implemented in net_instaweb::BeaconCriticalImagesFinder.

Get the critical image sets. Returns an empty set if there is no critical image information.

virtual bool net_instaweb::CriticalImagesFinder::IsHtmlCriticalImage ( const GoogleString image_url,
RewriteDriver driver 
) [virtual]

Checks whether the requested image is present in the critical set or not. Users of this function should also check IsMeaningful() to see if the implementation of this function returns meaningful results and provide a default behavior if it does not.

Reimplemented in net_instaweb::BeaconCriticalImagesFinder.

virtual bool net_instaweb::CriticalImagesFinder::IsMeaningful ( const RewriteDriver driver) const [pure virtual]

Checks whether IsHtmlCriticalImage will return meaningful results about critical images. Users of IsHtmlCriticalImage should check this function and supply a default behavior if IsMeaningful returns false.

Implemented in net_instaweb::BeaconCriticalImagesFinder.

Utility functions for manually setting the critical image sets. These should only be used by unit tests that need to setup a specific set of critical images. For normal users of CriticalImagesFinder, the critical images will be populated from entries in the property cache.

virtual int net_instaweb::CriticalImagesFinder::NumSetsToKeep ( ) const [inline, virtual]

The number of past critical image sets to keep. By default, we only keep the most recent one. The beacon critical image finder should override this to store a larger number of sets.

Reimplemented in net_instaweb::BeaconCriticalImagesFinder.

virtual int net_instaweb::CriticalImagesFinder::PercentSeenForCritical ( ) const [inline, virtual]

In order to handle varying critical image sets returned by the beacon, we store a history of the last N critical images, and only declare an image critical if it appears critical in the last M out of N sets reported. This function returns what percentage of the sets need to include the image for it be considered critical.

Reimplemented in net_instaweb::BeaconCriticalImagesFinder.

bool net_instaweb::CriticalImagesFinder::UpdateCriticalImagesCacheEntry ( PropertyPage page,
PropertyCache page_property_cache,
StringSet *  critical_images_set,
StringSet *  css_critical_images_set 
)

Alternative interface to update the critical images cache entry. This is useful in contexts like the beacon handler where the RewriteDriver for the original request no longer exists. This will take ownership of critical_images_set.

Todo:
TODO(jud): Modify to not take ownership of the sets. This will make the memory management of BeaconPropertyCallback clearer.
bool net_instaweb::CriticalImagesFinder::UpdateCriticalImagesCacheEntryFromDriver ( RewriteDriver driver,
StringSet *  critical_images_set,
StringSet *  css_critical_images_set 
)

Updates the critical images property cache entry. This will take the ownership of the critical_images_set. Returns whether the update succeeded or not. Note that this base implementation does not call WriteCohort. This should be called in the subclass if the cohort is not written elsewhere.

Gets critical images if present in the property cache and updates the critical_images set in RewriteDriver with the obtained set. If you override this method, driver->critical_images_info() must not return NULL after this function has been called.


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