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Compelling examples of custom C++ allocators?
... custom STL allocator significantly improve performance of a multithreaded app simply by changing a single
std::vector<T>
to
std::vector<T,tbb::scalable_allocator<T> >
(this is a quick and convenient way of switching the allocator to use TBB's nifty thread-private heaps; se...
iPhone - Grand Central Dispatch main thread
I have been using with success, grand central dispatch in my apps, but I was wondering what is the real advantage of using something like this:
...
Return a value if no rows are found in Microsoft tSQL
...
Some apps does not allow you "simply" check
– Nadia Solovyeva
Twitter Bootstrap Form File Element Upload Button
...luding IE9+. If you need support for old IE as well, please use the legacy approach shown below.
This techniques relies on the HTML5 hidden attribute. Bootstrap 4 uses the following CSS to shim this feature in unsupportive browsers. You may need to add if you're using Bootstrap 3.
[hidden] {
dis...
What does “Auto packing the repository for optimum performance” mean?
...invocation of git gc --auto.
If you let Git finish repacking, this won't happen again for a while. It can indeed take a while, especially if you have a lot of large binary objects, but if it's triggering, then it's a sign that it will probably drastically reduce the amount of disk space taken by th...
Can a foreign key be NULL and/or duplicate?
...at record. A separate table can be "ProposalAssignedTo" or some such, with appropriate constraints. A query writer can then join to that table, and supply their own logic for whatever we want to do when a proposal doesn't have a salesperson. NULL doesn't just mean "we don't know" - it can be used fo...
How do I get user IP address in django?
...n any address they want (instead of their real one). See esd.io/blog/flask-apps-heroku-real-ip-spoofing.html
– Eli
Jun 6 '14 at 19:06
8
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What are named pipes?
...tain the credentials of the thing on the other end etc).
Unix named pipes appear as a special file in the filesystem and can be accessed with normal file IO commands including the shell. Windows ones don't, and need to be opened with a special system call (after which they behave mostly like a norm...
Error: Cannot access file bin/Debug/… because it is being used by another process
...n, but there are a couple of workarounds. Start researching here.
What's happening is that VS is acquiring a lock on a file and then not releasing it. Ironically, that lock prevents VS itself from deleting the file so that it can recreate it when you rebuild the application. The only apparent solut...
How should I validate an e-mail address?
...
Don't use a reg-ex.
Apparently the following is a reg-ex that correctly validates most e-mails addresses that conform to RFC 2822, (and will still fail on things like "user@gmail.com.nospam", as will org.apache.commons.validator.routines.EmailVa...