Resolved Rewindable Allocator, what's the point ?

One use case is Netcode, that uses rewindable allocator for the fixed update groups and prediction groups too.
Just to mention one.

 

Greetings,

We appreciate your questions and apologize for the inconvenience caused by the broken links. The broken links seem to be documents directing to the Collections package. You can find these documents at https://docs.unity.cn/Packages/com.unity.collections@2.1/manual/allocator-overview.html

Rewindable allocator is a custom allocator which is a fast and thread-safe allocator, also useful to build other custom allocators. For instance, WorldUpdate allocator, EntityCommandBuffer Allocator and SystemGroup allocator are all constructed from Rewindable allocator. Rewindable allocator operates like a memory pool where memory blocks are pre-allocated in advance. When a user requests memory, it identifies available memory in a block and returns back, so it is fast. One of its advantages is that Rewindable allocator eliminates the need to manually free individual allocations, it rewinds and frees all allocations at one point. For details of Rewindable allocator and sample code as how to use it, please refer to https://docs.unity.cn/Packages/com.unity.collections@2.1/manual/allocator-rewindable.html

Each entity command buffer system creates its own dedicated EntityCommandBuffer allocator. This allocator is responsible for memory allocations during the recording of the entity command buffer and deallocates the memory after the buffer is played back. It operates behind the scenes, requiring no explicit code changes from the user's end. For details, please refer to https://docs.unity3d.com/Packages/c.../manual/allocators-entity-command-buffer.html

Every world creates a WorldUpdate allocator, which contains a double Rewindable allocators. It is useful for fast, thread-safe temporary allocations which do not need to be explicitly disposed. All allocations from WorldUpdate allocator are automatically disposed after two full world updates, so there isn't any memory leakage. It's like garbage collection, but significantly faster. Unlike Allocator.Temp, you can pass allocations from the WorldUpdate allocator into a job. Because the two Rewindable allocators of the WorldUpdate allocator are switched in each world update, it's advised not to cache the WorldUpdate allocator. For details and sample code, please refer to https://docs.unity3d.com/Packages/com.unity.entities@1.0/manual/allocators-world-update.html

The primary objective behind the SystemGroup allocator is to manage allocations within a system that updates at a different rate - either fixed or variable - from the world update. It serves as an alternative to the WorldUpdate allocator for system groups updating in fixed or variable rates, where the default WorldUpdate allocator might not be suitable. Allocations by SystemGroup allocator last for two system group updates, eliminating the requirement for manual deallocations. As an optional feature, users are expected to create a SystemGroup allocator when setting a system group's rate manager. For details and sample code, please refer to https://docs.unity3d.com/Packages/com.unity.entities@1.0/manual/allocators-system-group.html

This link is an overview of the allocators we currently have, https://docs.unity3d.com/Packages/com.unity.entities@1.0/manual/allocators-overview.html

Thank you and have a good day!