net_instaweb::MutexedScalar Class Reference

#include "statistics.h"

Inheritance diagram for net_instaweb::MutexedScalar:

Public Member Functions
int64	Get () const
void	Set (int64 value)
int64	SetReturningPreviousValue (int64 value)
int64	AddHelper (int64 delta)

Protected Member Functions
virtual AbstractMutex *	mutex () const =0
virtual int64	GetLockHeld () const =0
	Get/Setters that may only be called if you already hold the mutex.
virtual int64	SetReturningPreviousValueLockHeld (int64 value)=0
void	SetLockHeld (int64 value)
int64	AddLockHeld (int64 delta)

Friends
class	StatisticsLogger

Detailed Description

Scalar value protected by a mutex. Mutex must fully protect access to underlying scalar. For example, in mod_pagespeed and ngx_pagespeed, variables are stored in shared memory and accessible from any process on a machine, so the mutex must provide protection across separate processes.

StatisticsLogger depends upon these mutexes being cross-process so that several processes using the same file system don't clobber each others logs.

Todo:

TODO(jmarantz): this could be done using templates rather than using virtual methods, as MutexedScalar does not implement an abstract interface.

Member Function Documentation

int64 net_instaweb::MutexedScalar::Get

(

)

const

Subclasses should not define these methods, instead define the *LockHeld() methods below.

void net_instaweb::MutexedScalar::SetLockHeld ( int64  value )

protected

These are implemented based on GetLockHeld() and SetReturningPreviousLockHeld().

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

• pagespeed/kernel/base/statistics.h