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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...
What's the best way to parse command line arguments? [closed]
...ter on.
Here's a typical line to add an option to your parser:
parser.add_option('-q', '--query',
action="store", dest="query",
help="query string", default="spam")
It pretty much speaks for itself; at processing time, it will accept -q or --query as options, store the ar...
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...
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...
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...
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...
How to run a PowerShell script from a batch file
...y Bypass Invoke-WebRequest https://www.example.com/example.ics -OutFile C:\_my\script.ics' -Verb RunAs}"; or powershell -Command "Invoke-WebRequest https://www.example.com/example.ics -OutFile c:\_my\file.ics", or using the -File option to same in a .ps1 file, or (New-Object Net.WebClient).DownloadF...
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
...
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
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