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0846638f7f
It is not rare to see configurations with a large number of "tcp-request content" or "http-request" rules for instance. A large number of rules combined with cpu-demanding actions (e.g.: actions that work on content) may create thread contention as all the rules from a given ruleset are evaluated under the same polling loop if the evaluation is not interrupted Thus, in this patch we add extra logic around "tcp-request content", "tcp-response content", "http-request" and "http-response" rulesets, so that when a certain number of rules are evaluated under the single polling loop, we force the evaluating function to yield. As such, the rule which was about to be evaluated is saved, and the function starts evaluating rules from the save pointer when it returns (in the next polling loop). We use task_wakeup(task, TASK_WOKEN_MSG) to explicitly wake the task so that no time is wasted and the processing is resumed ASAP. TASK_WOKEN_MSG is mandatory here because process_stream() expects TASK_WOKEN_MSG for explicit analyzers re-evaluation. rules_bcount stream's attribute was added to count how manu rules were evaluated since last interruption (yield). Also, SF_RULE_FYIELD flag was added to know that the s->current_rule was assigned due to forced yield and not regular yield. By default haproxy will enforce a yield every 50 rules, this behavior can be configured using the "tune.max-rules-at-once" global keyword. There is a limitation though: for now, if the ACT_OPT_FINAL flag is set on act_opts, we consider it is not safe to yield (as it is already the case for automatic yield). In this case instead of yielding an taking the risk of not being called back, we skip the yield and hope it will not create contention. This is something we should ideally try to improve in order to yield in all conditions.
