All EVM API functions are thread-safe. In few cases where
it is necessary to use internal static storage, the APIs use locks
to protect the storage from simultaneous access by separate threads.
Nevertheless, if you are using EVM API calls in a multithreaded
program, you must take certain precautions to avoid the following synchronization
errors:
If possible, restrict the use
of any entity returned by any API function to the thread in which
it was established. Table 3-1 “Entities to be Thread Safe” lists
the entities that must be thread-safe.
Table 3-1 Entities to be Thread Safe
| Entity | Type | Returned by |
|---|
| Connection context | EvmConnection_t | EvmConnCreate() |
| Event | EvmEvent_t | | EvmEventCreate() | | EvmEventCreateVa() | | EvmEventRead() | | EvmEventDup() |
|
| Data item | EvmItemValue_t | EvmItemGet() |
| Data item list | EvmItemList_t | EvmItemListGet() |
| Variable | EvmVarValue_t | EvmVarGet() |
| Variable list | EvmVarList_t | EvmVarListGet() |
| Event filter | EvmFilter_t | EvmFilterCreate() |
| Connection fd | EvmFd_t | EvmConnFdGet() |
If it is necessary to refer to these entities in
more than one thread, you must protect them against simultaneous
access, or perform updates by using locks.
If you do not follow these rules, random errors can occur.
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