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5c299dee5a
This patch looks huge, but it has a very simple goal: protect all accessed to shared stats pointers (either read or writes), because we know consider that these pointers may be NULL. The reason behind this is despite all precautions taken to ensure the pointers shouldn't be NULL when not expected, there are still corner cases (ie: frontends stats used on a backend which no FE cap and vice versa) where we could try to access a memory area which is not allocated. Willy stumbled on such cases while playing with the rings servers upon connection error, which eventually led to process crashes (since 3.3 when shared stats were implemented) Also, we may decide later that shared stats are optional and should be disabled on the proxy to save memory and CPU, and this patch is a step further towards that goal. So in essence, this patch ensures shared stats pointers are always initialized (including NULL), and adds necessary guards before shared stats pointers are de-referenced. Since we already had some checks for backends and listeners stats, and the pointer address retrieval should stay in cpu cache, let's hope that this patch doesn't impact stats performance much.