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How efficient is locking an unlocked mutex? What is the cost of a mutex?
...tefultask-testsuite/blob/b69b112e2e91d35b56a39f41809d3e3de2f9e4b8/src/mutex_test.cxx
Note that it has a few hardcoded values specific for my box (xrange, yrange and rdtsc overhead), so you probably have to experiment with it before it will work for you.
The graph it produces in that state is:
T...
Random number generation in C++11: how to generate, how does it work? [closed]
... MyRNG; // the Mersenne Twister with a popular choice of parameters
uint32_t seed_val; // populate somehow
MyRNG rng; // e.g. keep one global instance (per thread)
void initialize()
{
rng.seed(seed_val);
}
Now we can create distributions:
std::uniform_int_distribu...
Python nonlocal statement
...so that it looks more like the idioms of languages with closures.
def make_counter():
count = 0
def counter():
nonlocal count
count += 1
return count
return counter
Obviously, you could write this as a generator, like:
def counter_generator():
count = 0
...
Refresh a page using JavaScript or HTML [duplicate]
...g (ajax) at loading. for example: www.yoursite.com/page/about?getVer=1&__[date]
Compare it to the stored versionnumber (stored in cookie or localStorage) if user has visited the page once, otherwise store it directly.
If version is not the same as local version, refresh the page using window.loc...
What's the difference between eval, exec, and compile?
...n Python is whatever you can have as the value in a variable assignment:
a_variable = (anything you can put within these parentheses is an expression)
eval returns the value of the given expression, whereas exec ignores the return value from its code, and always returns None (in Python 2 it is a s...
Better way to cast object to int
... to signify a Nullable<int>. The "as" operator works like Convert.To____(), but think TryParse() rather than Parse(): it returns null rather than throwing an exception if the conversion fails.
Of these, I would prefer (int) if the object really is just a boxed integer. Otherwise use Conver...
Rails: fields_for with index?
...s there a method (or way to pull off similar functionality) to do a fields_for_with_index ?
9 Answers
...
Repeat a task with a time delay?
...er());
private Runnable mStatusChecker;
private int UPDATE_INTERVAL = 2000;
/**
* Creates an UIUpdater object, that can be used to
* perform UIUpdates on a specified time interval.
*
* @param uiUpdater A runnable containing the update ro...
How can I restore the MySQL root user’s full privileges?
...ue the following commands in the mysql client:
UPDATE mysql.user SET Grant_priv='Y', Super_priv='Y' WHERE User='root';
FLUSH PRIVILEGES;
After that, you should be able to run GRANT ALL ON *.* TO 'root'@'localhost'; and have it work.
...
How to iterate a loop with index and element in Swift
...100, height: 100)
button.addTarget(self, action: #selector(iterate(_:)), for: .touchUpInside)
view.addSubview(button)
}
@objc func iterate(_ sender: UIButton) {
let tuple = generator.next()
print(String(describing: tuple))
}
}
PlaygroundPage.current.liv...