約定

含義

單詞 volatile 的含義

A situation that is volatile is likely to change suddenly and unexpectedly.

程序中 volatile 的含義

此處說(shuō)的「讀取內(nèi)存」，包括了讀取 CPU 緩存和讀取計(jì)算機(jī)主存。

關(guān)鍵字 volatile 的含義

C 語(yǔ)言：Every access (both read and write) made through an lvalue expression of volatile-qualified type is considered an observable side effect for the purpose of optimization and is evaluated strictly according to the rules of the abstract machine (that is, all writes are completed at some time before the next sequence point). This means that within a single thread of execution, a volatile access cannot be optimized out or reordered relative to another visible side effect that is separated by a sequence point from the volatile access.
C 語(yǔ)言：Every access (read or write operation, member function call, etc.) made through a glvalue expression of volatile-qualified type is treated as a visible side-effect for the purposes of optimization (that is, within a single thread of execution, volatile accesses cannot be optimized out or reordered with another visible side effect that is sequenced-before or sequenced-after the volatile access. This makes volatile objects suitable for communication with a signal handler, but not with another thread of execution, see std::memory_order). Any attempt to refer to a volatile object through a non-volatile glvalue (e.g. through a reference or pointer to non-volatile type) results in undefined behavior.

volatile 與多線程