attr_stats.hh File Reference

Program statistics and profiling. More...

#include "impl/attr_stats_impl.hh"

Go to the source code of this file.

Macros
#define	ATTR_ADD(attr, val)
	Increase an attribute atomically. More...
#define	ATTR_SET(attr, val)
	Modify an attribute atomically. More...
#define	ATTR_SET_EX(attr, val, old)
	Get an attribute and then modify it atomically. More...

Functions
bool	ATTR_INIT (size_t capacity=1000)
	Initialize statistics APIs. More...
bool	ATTR_ADD_SLOW (int attr, uint64_t val)
	Increase an attribute atomically. More...
bool	ATTR_SET_SLOW (int attr, uint64_t val, uint64_t *old=NULL)
	Get an attribute and then modify it atomically. More...
template<class Op >
void	ATTR_ITERATE (Op op)
	Iterate and apply an operation to all attributes. More...

Detailed Description

Program statistics and profiling.

APIs for profiling program based on lock-free, thread-safe counters.
Each counter is called an attribute, identified by an positive integer. You can put as many attributes in program as you want.

Author

Zhao DAI

Macro Definition Documentation

#define ATTR_ADD	(		attr,
			val
	)

Increase an attribute atomically.

An example usage shows below:

// init statistics APIs before use
ATTR_INIT();
...
...
// attributes 100, 101, 102 and 103 are used to save number
// of commands for Login, Logout, Query and others, respectively.
void process(Command & cmd){
    switch(cmd.type){
        case Login: ATTR_ADD(100, 1); break;
        case Logout:ATTR_ADD(101, 1); break;
        case Query: ATTR_ADD(102, 1); break;
        default:    ATTR_ADD(103, 1); break;
    }
}

Parameters

attr	A positive number identifying the attribute
val	A non-negative number to add to the attribute

Note

For performance reason, attr must be a constant expression, i.e. can be evaluated at compile time. And this is the recommended way of usage.
But if that is not the case, please use ATTR_ADD_SLOW instead.

See also

ATTR_ADD_SLOW

#define ATTR_SET	(		attr,
			val
	)

Modify an attribute atomically.

An example usage shows below:

// init statistics APIs before use
ATTR_INIT();
...
// a message queue shared between threads or processes
MessageQueue queue;
...
// attributes 104 is used to monitor the length of 'queue' in a dedicated thread
void monitorThread(){
    for(;;sleep(1)){
        ATTR_SET(104, queue.length());
    }
}

Parameters

attr	A positive number identifying the attribute
val	A non-negative number

Note

For performance reason, attr must be a constant expression, i.e. can be evaluated at compile time. And this is the recommended way of usage.
But if that is not the case, please use ATTR_SET_SLOW instead.

See also

ATTR_SET_SLOW

#define ATTR_SET_EX	(		attr,
			val,
			old
	)

Get an attribute and then modify it atomically.

Parameters

[in]	attr	A positive number identifying the attribute
[in]	val	A non-negative number
[out]	old	Pointer to a variable to receive the value of attribute before modification; or NULL if not interested

Note

For performance reason, attr must be a constant expression, i.e. can be evaluated at compile time. And this is the recommended way of usage.
But if that is not the case, please use ATTR_SET_SLOW instead.

See also

ATTR_SET_SLOW

Function Documentation

bool ATTR_ADD_SLOW ( int  attr, uint64_t  val  )

inline

Increase an attribute atomically.

Parameters

attr	A positive number identifying the attribute
val	A non-negative number to add to the attribute

Returns

true if succeeded; otherwise false

See also

ATTR_ADD

bool ATTR_INIT ( size_t  capacity = 1000 )

inline

Initialize statistics APIs.

This function must be called once only before any other statistics APIs.

Parameters

capacity

The maximum number of attributes in the program

Returns

true if succeeded; otherwise false

template<class Op >

void ATTR_ITERATE ( Op  op )

inline

Iterate and apply an operation to all attributes.

Parameters

op	Operation to apply to all attributes, should implement: void operator ()(int attr, uint64_t value) const; In which: attr is a positive number identifying the attribute value is the current value of the attribute

Note

After the operation, each attribute will be reset to 0 for a new turn of counting.

bool ATTR_SET_SLOW ( int  attr, uint64_t  val, uint64_t *  old = NULL  )

inline

Get an attribute and then modify it atomically.

Parameters

[in]	attr	A positive number identifying the attribute
[in]	val	A non-negative number
[out]	old	Pointer to a variable to receive the value of attribute before modification; or NULL if not interested

See also

ATTR_SET ATTR_SET_EX