[C++] RCU

Reference:
[Kernel Doc] What is RCU? -- “Read, Copy, Update”
[NMI] Contents hide (Top) History See also Notes External links Non-maskable interrupt
[Kernel Doc] False Sharing with how to detect and analyze

Source code:
https://android.googlesource.com/kernel/common/+/refs/heads/android-mainline/kernel/rcu/rcu.h

Kernel doc has most concise details about RCU, here we jot down
main idea for fast fresh up the concept.

RCU(Read, Copy, Update) is a synchronization mechanism that was added to the Linux kernel during the 2.5 development effort that is optimized for read-mostly situations.

The basic idea behind RCU is to split updates into 

• “removal” and 
• “reclamation” phases.

The removal phase removes references to data items within a data structure (possibly by replacing them with references to new versions of these data items), and can run concurrently with readers.