Context used by CssFilter under async flow that flattens . More...

#include "css_flatten_imports_context.h"

Inheritance diagram for net_instaweb::CssFlattenImportsContext:

Public Member Functions
	CssFlattenImportsContext (RewriteContext parent, CssFilter filter, CssFilter::Context rewriter, CssHierarchy hierarchy)

virtual GoogleString	CacheKeySuffix () const

virtual void	RewriteSingle (const ResourcePtr &input_resource, const OutputResourcePtr &output_resource)
	Subclasses of SingleRewriteContext must override this: More...

void	Harvest ()

bool	PolicyPermitsRendering () const

virtual void	Render ()

virtual const char *	id () const
	Returns the filter ID.

virtual OutputResourceKind	kind () const

Public Member Functions inherited from net_instaweb::SingleRewriteContext
	SingleRewriteContext (RewriteDriver driver, RewriteContext parent, ResourceContext *resource_context)

Public Member Functions inherited from net_instaweb::RewriteContext
	RewriteContext (RewriteDriver driver, RewriteContext parent, ResourceContext *resource_context)

int	num_slots () const

ResourceSlotPtr	slot (int index) const

int	num_outputs () const

OutputResourcePtr	output (int i) const

int	num_output_partitions () const

const CachedResult *	output_partition (int i) const

CachedResult *	mutable_output_partition (int i)

bool	chained () const

void	AddSlot (const ResourceSlotPtr &slot)

void	RemoveLastSlot ()

void	AddNestedContext (RewriteContext *context)

void	CallFetchInputs ()

void	CallLockFailed ()

void	CallStartFetchImpl ()

void	Initiate ()

bool	Fetch (const OutputResourcePtr &output_resource, AsyncFetch fetch, MessageHandler message_handler)

bool	slow () const

bool	is_metadata_cache_miss () const
	This particular rewrite was a metadata cache miss.

bool	has_parent () const
	Returns true if this is a nested rewriter.

bool	IsNestedIn (StringPiece id) const

void	CheckNotFrozen ()

RewriteContext *	parent ()
	Allows a nested rewriter to walk up its parent hierarchy.

const RewriteContext *	parent () const

int	num_nested () const
	Accessors for the nested rewrites.

RewriteContext *	nested (int i) const

RewriteDriver *	Driver () const

void	set_force_rewrite (bool x)
	If called with true, forces a rewrite and re-generates the output.

bool	rewrite_uncacheable () const

void	set_rewrite_uncacheable (bool rewrite_uncacheable)

const ResourceContext *	resource_context () const

GoogleString	ToString () const
	Returns debug information about this RewriteContext.

GoogleString	ToStringWithPrefix (StringPiece prefix) const

Additional Inherited Members
Public Types inherited from net_instaweb::RewriteContext
typedef std::vector< InputInfo * >	InputInfoStarVector

Static Public Member Functions inherited from net_instaweb::RewriteContext
static void	InitStats (Statistics *stats)
	Initializes statistics.

Static Public Attributes inherited from net_instaweb::RewriteContext
static const char	kNumRewritesAbandonedForLockContention []

static const char	kNumDeadlineAlarmInvocations []

static const char	kHashMismatchMessage []

Protected Types inherited from net_instaweb::RewriteContext
typedef std::vector< GoogleUrl * >	GoogleUrlStarVector

Protected Member Functions inherited from net_instaweb::SingleRewriteContext
virtual bool	Partition (OutputPartitions partitions, OutputResourceVector outputs)
	SingleRewriteContext takes care of these methods from RewriteContext:

virtual void	Rewrite (int partition_index, CachedResult *partition, const OutputResourcePtr &output)

void	AddLinkRelCanonical (const ResourcePtr &input, ResponseHeaders *output)
	Adds a link: rel=canonical header pointing to the input URL as canonical.

void	AddLinkRelCanonicalForFallbackHeaders (ResponseHeaders *output)
	Helper for using above in FixFetchFallbackHeaders()

Protected Member Functions inherited from net_instaweb::RewriteContext
ServerContext *	FindServerContext () const

const RewriteOptions *	Options () const

OutputPartitions *	partitions ()

void	AddRecheckDependency ()

virtual bool	OptimizationOnly () const

virtual void	PartitionAsync (OutputPartitions partitions, OutputResourceVector outputs)

void	PartitionDone (RewriteResult result)

void	CrossThreadPartitionDone (RewriteResult result)

void	RewriteDone (RewriteResult result, int partition_index)

virtual bool	SendFallbackResponse (StringPiece output_url_base, StringPiece contents, AsyncFetch async_fetch, MessageHandler handler)

void	StartNestedTasks ()

bool	AreOutputsAllowedByCsp (CspDirective role) const
	Helper that checks that all output resources are OK with CSP as given role.

virtual void	WillNotRender ()

virtual void	Cancel ()

virtual const UrlSegmentEncoder *	encoder () const

virtual GoogleString	UserAgentCacheKey (const ResourceContext *context) const

virtual void	EncodeUserAgentIntoResourceContext (ResourceContext *context)

void	AttachDependentRequestTrace (const StringPiece &label)

RequestTrace *	dependent_request_trace ()

void	TracePrintf (const char *fmt,...)

virtual void	StartFetchReconstruction ()

void	DetachFetch ()

virtual bool	DecodeFetchUrls (const OutputResourcePtr &output_resource, MessageHandler message_handler, GoogleUrlStarVector url_vector)

virtual void	FixFetchFallbackHeaders (const CachedResult &cached_result, ResponseHeaders *headers)

virtual void	FetchCallbackDone (bool success)

virtual void	FetchTryFallback (const GoogleString &url, const StringPiece &hash)

void	Freshen ()
	Freshens resources proactively to avoid expiration in the near future.

bool	notify_driver_on_fetch_done () const

void	set_notify_driver_on_fetch_done (bool value)

AsyncFetch *	async_fetch ()
	Note that the following must only be called in the fetch flow.

bool	FetchContextDetached ()
	Is fetch_ detached? Only call this in the fetch flow.

MessageHandler *	fetch_message_handler ()
	The message handler for the fetch.

bool	stale_rewrite () const
	Indicates whether we are serving a stale rewrite.

virtual int64	GetRewriteDeadlineAlarmMs () const

virtual bool	CreationLockBeforeStartFetch () const
	Should the context call LockForCreation before checking the cache?

virtual bool	FailOnHashMismatch () const

virtual bool	ScheduleViaCentralController ()

virtual bool	ScheduleNestedContextViaCentalController () const

void	ObtainLockForCreation (ServerContext server_context, Function callback)

void	ReleaseCreationLock (bool succeeded)

Static Protected Member Functions inherited from net_instaweb::RewriteContext
static bool	LookupMetadataForOutputResourceImpl (OutputResourcePtr output_resource, const GoogleUrl &gurl, RewriteContext rewrite_context, RewriteDriver driver, GoogleString error_out, CacheLookupResultCallback callback)

Detailed Description

Context used by CssFilter under async flow that flattens .

Constructor & Destructor Documentation

net_instaweb::CssFlattenImportsContext::CssFlattenImportsContext	(	RewriteContext *	parent,
		CssFilter *	filter,
		CssFilter::Context *	rewriter,
		CssHierarchy *	hierarchy
	)

inline

no resource_context

Member Function Documentation

virtual GoogleString net_instaweb::CssFlattenImportsContext::CacheKeySuffix ( ) const

inlinevirtual

Allows subclasses to add additional text to be appended to the metadata cache key. The default implementation returns "".

We have to include the media that applies to this context in its key so that, if someone 's the same file but with a different set of media on the rule, we don't fetch the cached file, since it has been minified based on the original set of applicable media.

Reimplemented from net_instaweb::RewriteContext.

void net_instaweb::CssFlattenImportsContext::Harvest ( )

inlinevirtual

Once any nested rewrites have completed, the results of these can be incorporated into the rewritten data. For contexts that do not require any nested RewriteContexts, it is OK to skip overriding this method – the empty default implementation is fine.

Propagate any info on images from child rewrites.

Roll up the rewritten CSS(s) regardless of success or failure. Failure means we can't flatten it for some reason, such as incompatible charsets or invalid CSS, but we still need to cache the unflattened version so we don't try to flatten it again and again, so even in that case we don't return kRewriteFailed.

Our result is the combination of all our imports and our own rules.

Reimplemented from net_instaweb::RewriteContext.

virtual OutputResourceKind net_instaweb::CssFlattenImportsContext::kind ( ) const

inlinevirtual

Rewrites come in three flavors, as described in output_resource_kind.h, so this method must be defined by subclasses to indicate which it is.

For example, we will avoid caching output_resource content in the HTTP cache for rewrites that are so quick to complete that it's fine to do the rewrite on every request. extend_cache is obviously in this category, and it's arguable we could treat js minification that way too (though we don't at the moment).

Implements net_instaweb::RewriteContext.

bool net_instaweb::CssFlattenImportsContext::PolicyPermitsRendering ( ) const

inlinevirtual

This method gives the context a chance to verify that rendering the result is consistent with the current document's (Content Security) Policy, which may be different than that of the page for which the result was first computed + cached. Most subclasses can just call AreOutputsAllowedByCsp(), with appropriate role.

We apply CSP policy for flattening at top-level, not here.

Implements net_instaweb::RewriteContext.

virtual void net_instaweb::CssFlattenImportsContext::Render ( )

inlinevirtual

Performs rendering activities that span multiple HTML slots. For example, in a filter that combines N slots to 1, N-1 of the HTML elements might need to be removed. That can be performed in Render(). This method is optional; the base-class implementation is empty.

Note that unlike Harvest(), this method runs in the HTML thread (for top-level rewrites), and only runs if the rewrite completes prior to the rewrite-deadline. If the rewrite does make it by the deadline, RewriteContext::Render() will be invoked regardless of whether any slots were actually optimized successfully.

If we have flattened the imported file ...

If Harvest() was called, directly or from RewriteSingle(), then the minified contents are already set as are the stylesheet and input contents - in that case we don't actually have to do anything. If they haven't been called then the minified contents are empty and the result was found in the cache, in which case we have to set the input and minified contents to this result; the minified because we know that cached values are minified (we only cache minified contents), the input because we will need that to generate the stylesheet from when RollUpStylesheets is eventually called.

Parse() will compute flattening_succeeded_, which needs to be restored. See https://github.com/pagespeed/mod_pagespeed/issues/1092

Something has gone wrong earlier. It could be that the resource is not valid and cacheable (see SingleRewriteContext::Partition) or it could be that we're handling a cached failure, but it's hard to tell. So, mark flattening as failed but don't record a failure statistic nor a failure reason.

Reimplemented from net_instaweb::RewriteContext.

virtual void net_instaweb::CssFlattenImportsContext::RewriteSingle	(	const ResourcePtr &	input,
		const OutputResourcePtr &	output
	)

inlinevirtual

Subclasses of SingleRewriteContext must override this:

We have to fix relative URLs in the CSS as they break if used in a CSS file that itself was loaded via a relative path from the base (for example, if styles/screen.css references ../images/icon.png, then the correct path for the image is /images/icon.png). We also need to absolutify or left-trim URLs in flattened CSS if no other rewriter is going to do it (cache extend, css image rewriter, etc), but it's hard to tell if that will happen so we transform URLs here regardless and note that for CssHierarchy::css_resolution_base().

If we rewrite the input resource's contents we need somewhere to store it; that's what the hierarchy's backing store is for.

See RewriteDriver::ResolveCssUrls about why we disable trimming in proxy mode. We also disable it if trimming is not enabled.

If we cannot parse the CSS then we cannot flatten it.

< Initiates rewriting of 'd files.

< Harvest centralizes all the output generation.

Implements net_instaweb::SingleRewriteContext.

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

net/instaweb/rewriter/public/css_flatten_imports_context.h

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation