Measure the time a query takes on iPad - iphone

Question

I'm trying to see where my expensive queries are and want to measure if it's the query that's the bottleneck, or something else. And also measure if certain queries are faster than others within our app. I was wondering how I could do this with Instruments. I see that there's a time profiler tool and was wondering if I could use this.
I tried running Time Profiler, clicking on the button that presents my viewController that accesses the database. I don't see my sql call itself and was wondering what the best way to measure the time a method takes from start to finish. Thanks.

Answer 1

Why you don't print in console the time when it starts and when it finish. I do that in many languages like iOS/Java[Android]/PHP. To debug plugins times
I hope it helps

Answer 2

For finding time differences between calls, I usually use a StopWatch class that uses the machine time (at least milliseconds, maybe microseconds accuracy).
This version is designed specifically for autorelease and objective-c. It has a method, stopWithContext:, which will also log a message with the time. This is handy for start/stop measurements in multiple functions. Tailor it as you see fit.
I have a c++ version as well if needed. [You can find the c++ version here][1].
StopWatch.h
#import <Foundation/Foundation.h>
#interface StopWatch : NSObject
{
uint64_t _start;
uint64_t _stop;
uint64_t _elapsed;
}
-(void) Start;
-(void) Stop;
-(void) StopWithContext:(NSString*) context;
-(double) seconds;
-(NSString*) description;
+(StopWatch*) stopWatch;
-(StopWatch*) init;
#end
StopWatch.m
#import "StopWatch.h"
#include <mach/mach_time.h>
#implementation StopWatch
-(void) Start
{
_stop = 0;
_elapsed = 0;
_start = mach_absolute_time();
}
-(void) Stop
{
_stop = mach_absolute_time();
if(_stop > _start)
{
_elapsed = _stop - _start;
}
else
{
_elapsed = 0;
}
_start = mach_absolute_time();
}
-(void) StopWithContext:(NSString*) context
{
_stop = mach_absolute_time();
if(_stop > _start)
{
_elapsed = _stop - _start;
}
else
{
_elapsed = 0;
}
NSLog([NSString stringWithFormat:#"[%#] Stopped at %f",context,[self seconds]]);
_start = mach_absolute_time();
}
-(double) seconds
{
if(_elapsed > 0)
{
uint64_t elapsedTimeNano = 0;
mach_timebase_info_data_t timeBaseInfo;
mach_timebase_info(&timeBaseInfo);
elapsedTimeNano = _elapsed * timeBaseInfo.numer / timeBaseInfo.denom;
double elapsedSeconds = elapsedTimeNano * 1.0E-9;
return elapsedSeconds;
}
return 0.0;
}
-(NSString*) description
{
return [NSString stringWithFormat:#"%f secs.",[self seconds]];
}
+(StopWatch*) stopWatch
{
StopWatch* obj = [[[StopWatch alloc] init] autorelease];
return obj;
}
-(StopWatch*) init
{
[super init];
return self;
}
#end
The class has a static stopWatch method that returns an autoreleased object.
Once you call start, use the seconds method to get the elapsed time. Call start again to restart it. Or stop to stop it. You can still read the time (call seconds) anytime after calling stop.
Example In A Function (Timing call of execution)
-(void)SomeFunc
{
StopWatch* stopWatch = [StopWatch stopWatch];
[stopWatch Start];
... do stuff
[stopWatch StopWithContext:[NSString stringWithFormat:#"Created %d Records",[records count]]];
}