Dispatch table implemented by the eBPF runtime to provide RCU / epoch operations.
Notes:
Functions epoch_enter and epoch_exit allow a thread to enter and exit an epoch-protected region, which is necessary when calling the epoch memory operations. These functions are re-entrant, but should always be called in pairs.
Below is the list of epoch memory related functions exposed by eBPF runtime:
epoch_allocate_with_tag: Allocate memory under epoch control with tag.epoch_allocate_cache_aligned_with_tag: Allocate cache aligned memory under epoch control with tag.epoch_free: Free memory under epoch control.epoch_free_cache_aligned: Free cache aligned memory under epoch control.
Each of the above four functions MUST be called within an epoch-protected region (i.e., after ebpf_epoch_enter() and before ebpf_epoch_exit()). Failure to do so may lead to undefined behavior. Provider dispatch function invocations (defined in ebpf_base_map_provider_dispatch_table_t), and BPF helper function callbacks already are epoch-protected, hence these APIs can be directly called in those contexts. If the provider intends to use these APIs outside the above mentioned contexts, it must ensure that the calls are made within an epoch-protected region.
Similarly, find_element_function can only be invoked in an epoch-protected region, as explained above. Calling it from outside an epoch-protected region may lead to undefined behavior.
