net_instaweb::PurgeSet Class Reference

#include "purge_set.h"

Public Types
typedef Lru::Iterator	Iterator

Public Member Functions
	PurgeSet ()
	PurgeSet (size_t max_size)
	PurgeSet (const PurgeSet &src)
void	set_max_size (size_t x)
	Call this immediately after construction.
PurgeSet &	operator= (const PurgeSet &src)
bool	UpdateGlobalInvalidationTimestampMs (int64 timestamp_ms)
bool	Put (const GoogleString &key, int64 timestamp_ms)
void	Merge (const PurgeSet &src)
	Merge two invalidation records.
bool	IsValid (const GoogleString &key, int64 timestamp_ms) const
int64	global_invalidation_timestamp_ms () const
bool	has_global_invalidation_timestamp_ms () const
Iterator	Begin () const
Iterator	End () const
int	num_elements () const
void	Clear ()
void	Swap (PurgeSet *that)
bool	Equals (const PurgeSet &that) const
bool	empty () const
GoogleString	ToString () const

Static Public Attributes
static const int64	kClockSkewAllowanceMs = 10 * Timer::kMinuteMs
static const int64	kInitialTimestampMs = -1

Friends
class	InvalidationTimestampHelper

Detailed Description

Maintains a bounded collection of cache-purge records. These can be used to validate data read from a cache.

The entire cache can be flushed as of a certain point in time by calling UpdateInvalidationTimestampMs.

We bound the cache-purge data to a certain number of bytes. When we exceed that, we discard old invalidation records, and bump up the global invalidation timestamp to cover the evicted purges.

Constructor & Destructor Documentation

net_instaweb::PurgeSet::PurgeSet

(

)

The default constructor makes a 1-byte invalidation set. Use set_max_size after construction. The default constructor is needed for CopyOnWrite.

Member Function Documentation

bool net_instaweb::PurgeSet::IsValid	(	const GoogleString &	key,
		int64	timestamp_ms
	)		const

Validates a key against specific invalidation records for that key, and against the overall invalidation timestamp/

bool net_instaweb::PurgeSet::Put	(	const GoogleString &	key,
		int64	timestamp_ms
	)

Adds a new cache purge record to the set. If we spill over our invalidation limit, we will reset the global cache purge-point based on the evicted node.

Returns false if this request represents an excessive warp back in time.

bool net_instaweb::PurgeSet::UpdateGlobalInvalidationTimestampMs

(

int64

timestamp_ms

)

Flushes any item in the cache older than timestamp_ms.

Returns false if this request represents an excessive warp back in time.

Member Data Documentation

const int64 net_instaweb::PurgeSet::kClockSkewAllowanceMs = 10 * Timer::kMinuteMs

static

Used for sanity checking timestamps read from the cache.flush file, allowing for small skew and system clock adjustments. Setting this to 10 minutes means that we can prevent any cache entries from being valid for 10 minutes, disabling whatever functionality is dependent on that.

const int64 net_instaweb::PurgeSet::kInitialTimestampMs = -1

static

Initial value used for the global timestamp. This means there is no valid timestamp.

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

• pagespeed/kernel/cache/purge_set.h