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When creating a new key, it is essential to check that it is not already present in memcached. |
| Info |
Memcached canonical keys |
When a memcached key
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Memcached free keys
When a memcached key is associated with a system element element but refers to data non belonging to its static or dynamic datasets (e.g. a waveform not included in the dynamic dataset), it takes the name of the element with the _BUF extension (e.g. DCTEL001_BUF is the acquisition buffer of the MRe Current Monitor)
When many different keys are associated with the same system element, they take different names but always end up with the _BUF extension (eg. ORBP*DAT_BUF, ORBP*AVG_BUF, ORBP*VAR_BUF are respectively: the last acquired, the average and the variance buffers of the MRp orbit).
When a memcached key is not calculated by a front-end DEVIL and/or is not directly associated to a system element, it take a name defined by the developer.
Memcached traffic monitoring
As root user root on the memcached server (192.168.192.107)
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> iftop -i eth0 -B |
does not directly refer to a system element but – for example – to derived quantities, the format of its name is free and can be arbitrary defined, provided that it is not already used.
Even though the name format is arbitrary, it is advisable to always use UPPERCASE and append an extension separated by a "_" (e.g. MY-ARBITRARY-NAME_DAT). In any case, do not use the "_AUX" extension for a "free key".
To avoid the proliferation of extensions, try using the ones listed in the table below:
| Extension | Description |
|---|---|
| _BUF, _JBUF* | Data buffers (FIFOs , circular buffers, etc...), not necessarily associated with a system element. |
| _INFO, _JINFO* | Static metadata, not necessarily associated with a system element. |
| _DAT, _JDAT* | Generic data structures, not necessarily associated with a system element. |
(*) "J" prefix indicates that the key content is a Json document.
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