There are two atomic CAS operations in C++11: atomic_compare_exchange_weak and atomic_compare_exchange_strong. According to cppreference: The weak forms of the functions are allowed to fail spurio...
In addition (and more importantly), note that std::atomic must support all operations for all possible data types, so even if you declare a ten million byte struct, you can use compare_exchange on this.
Morning Overview on MSN: Atomic clocks may probe whether time has a measurable quantum limit
Yahoo: Using atomic nuclei could allow scientists to read time more precisely than ever – what this research could mean for future clocks
Atomic clocks exploit the properties of atoms to create incredibly precise 'ticks.' Nate Phillips, NIST Most clocks, from wristwatches to the systems that run GPS and the internet, work by tracking ...
Using atomic nuclei could allow scientists to read time more precisely than ever – what this research could mean for future clocks
compare_exchange_weak() is one of compare-exchange primitives provided in the std::atomic library introduced in C++11. It's weak in the sense that it could return false even if the value of the object is equal to expected. This is due to spurious failure on some platforms where a sequence of instructions (instead of one as on x86) are used to implement it. On such platforms, context switch ...
Objects of atomic types are the only C++ objects that are free from data races; that is, if one thread writes to an atomic object while another thread reads from it, the behavior is well-defined. In addition, accesses to atomic objects may establish inter-thread synchronization and order non-atomic memory accesses as specified by std::memory_order.
I had a 25-hr debugging marathon in < 2 days and then wrote this answer here. See also the bottom of this question for more info. and documentation on 8-bit variables having naturally atomic writes and naturally atomic reads for AVR 8-bit microcontrollers when compiled with the gcc compiler which uses the AVR-libc library.
Which types on a 64-bit computer are naturally atomic in gnu C and gnu ...
22 Atomic vs. Non-Atomic Operations "An operation acting on shared memory is atomic if it completes in a single step relative to other threads. When an atomic store is performed on a shared memory, no other thread can observe the modification half-complete.
Remark: The weak compare-and-exchange operations may fail spuriously, that is, return false while leaving the contents of memory pointed to by expected before the operation is the same that same as that of the object and the same as that of expected after the operation. [ Note: This spurious failure enables implementation of compare-and-exchange on a broader class of machines, e.g., loadlocked ...
When can 64-bit writes be guaranteed to be atomic, when programming in C on an Intel x86-based platform (in particular, an Intel-based Mac running MacOSX 10.4 using the Intel compiler)? For exampl...
So, this means that Richard Barry is saying that 4-byte reads and writes are atomic on these 32-bit microcontrollers. This means that he, at least, is 100% sure 4-byte reads and writes are atomic on STM32. He doesn't mention smaller-byte reads, but for 4-byte reads he is conclusively sure.
Are C/C++ fundamental types, like int, double, etc., atomic, e.g. threadsafe? Are they free from data races; that is, if one thread writes to an object of such a type while another thread reads fr...
Yes and no. rename () is atomic assuming the OS does not crash. It cannot be split by any other filesystem op. If the system crashes you might see a ln () operation instead. (But see discussion on journalled filesystems in comments.) Also note, when operating on a network filesystem, you might get ENOENT when the operation succeeded successfully. Local filesystem can't do that to you.
Ah, but new experts will rise up and embrace the new, friendly Stack Overflow that they have always wanted. And maybe rediscover the same things the bitter, hateful old guard found.
Moving to a new branch WARNING: This method works because you are creating a new branch with the first command: git branch newbranch. If you want to move commits to an existing branch you need to merge your changes into the existing branch before executing git reset --hard HEAD~3 (see Moving to an existing branch above).
It's all determined by your browser's settings. Using window.open tells the browser to open something new, then the browser opens up what is chosen in its settings - tab or window. In the browsers you tested with, change the settings to open in a new window instead of a tab and you'll see the others' solutions are wrong.
You should use new when you wish an object to remain in existence until you delete it. If you do not use new then the object will be destroyed when it goes out of scope.
4042 I started some work on a new feature and after coding for a bit, I decided this feature should be on its own branch. How do I move the existing uncommitted changes to a new branch and reset my current one? I want to reset my current branch while preserving existing work on the new feature.
The most precise clocks ever built can now detect gravity’s warping of time across a distance shorter than a pencil tip. That achievement, remarkable on its own, has physicists asking a deeper ...
Adelaide University researchers have successfully tested a new type of portable atomic clock at sea for the first time, using technology that could help power the next generation of navigation, ...
Phys.org: Ytterbium atomic clock could open a new window on fundamental physics
For the first time, an international team of physicists has successfully harnessed a rare orbital transition in atoms of ytterbium to create a new type of atomic clock that is both highly precise and ...
MSN: Time for change? Scientists create a clock so precise it could redefine the second
Time for change? Scientists create a clock so precise it could redefine the second
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