shmem

The shmem scanner is a proof of concept for converting eb log entries into elos events over a shared buffer data structure.

Configuration

The scanner is configured via the elosd.json file, with a block like the following located under root/elos/Scanner/Plugins/:

"<Name for the scanner>": {
    "File": "scanner_shmem.so",
    "Run": "always",
    "Config": {
        "ShmemFile": "scanner_shmem",
        "ShmemCreate": true,
        "ShmemLogEntries": 256,
        "ShmemOffset": 0,
        "SemFile": "scanner_shmem_sem",
        "SemCreate": true
    }
}

Note that all options are currently mandatory, leaving options out will cause the shmem scanner to abort with errors during initialization.

• ShmemFile, string: Filename of the shared memory. Due to the way shm_open() works an absolute path can’t be specified, the file will be placed under /dev/shm/<ShmemFile> instead.

• ShmemCreate, boolean: Creates and initializes the shared memory when set to true. Will open an existing shared memory when set to false.

• ShmemLogEntries, int: How many eb logging entries the ringbuffer can hold before overflowing.

• ShmemOffset, int: Offset within the shared memory region at which the eb log ringbuffer data resides.

• SemFile, string: FIlename of the shared semaphore. Same behaviour as with ShmemFile, with the semaphore being created as /dev/shm/<SemFile>.

• SemCreate, boolean: Create the semaphore when set to true, open it when set to false

Attention: This is a proof of concept, so implementation details as well as the configurationn options may change.