shmutil

some utilities of shared memory.

Feature

shmutil implements a mutli-reader-single-writer hashtable and ring queue in shared memory.

Features of hashtable:

• Support mutli-reader-single-writer operating hashtable concurrently, not support multi-writers operating hashtable at same time.

  If you want to handle problem of multi processes writing the hashtable, please use cross-process lock(such as file-lock) utility to synchronize multiple processes.

• Note: the key size can not be longer than 96 bytes.

  If you wish to support large key longer than 96 bytes, please change _Q_HASHARR_KEYSIZE value in qlibc.h.

• Support LRU elimination while shm space is full.

Features of ring queue:

• Support single-reader-single-writer lock-free operating queue concurrently, and also provide locked version to handle multiple reader or multiple writer operating queue at same time.

• Its a FIFO queue. If shm space is full while pushing, shmutil will return kErrNotEnoughSpace error.

Usage

Please refer to example directory for how to use it.

Thanks

Some ideas are inspired from other open-source projects, thanks for MSEC, QCONF, libshmcache projects.