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61 lines
1.9 KiB
C++
61 lines
1.9 KiB
C++
#pragma once
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#include <IO/ISchedulerNode.h>
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#include <IO/ResourceBudget.h>
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#include <IO/ResourceRequest.h>
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#include <memory>
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namespace DB
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{
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/*
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* Queue for pending requests for specific resource, leaf of hierarchy.
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* Note that every queue has budget associated with it.
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*/
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class ISchedulerQueue : public ISchedulerNode
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{
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public:
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explicit ISchedulerQueue(EventQueue * event_queue_, const Poco::Util::AbstractConfiguration & config = emptyConfig(), const String & config_prefix = {})
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: ISchedulerNode(event_queue_, config, config_prefix)
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{}
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// Wrapper for `enqueueRequest()` that should be used to account for available resource budget
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void enqueueRequestUsingBudget(ResourceRequest * request)
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{
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request->cost = budget.ask(request->cost);
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enqueueRequest(request);
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}
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// Should be called to account for difference between real and estimated costs
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void adjustBudget(ResourceCost estimated_cost, ResourceCost real_cost)
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{
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budget.adjust(estimated_cost, real_cost);
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}
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// Adjust budget to account for extra consumption of `cost` resource units
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void consumeBudget(ResourceCost cost)
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{
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adjustBudget(0, cost);
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}
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// Adjust budget to account for requested, but not consumed `cost` resource units
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void accumulateBudget(ResourceCost cost)
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{
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adjustBudget(cost, 0);
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}
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/// Enqueue new request to be executed using underlying resource.
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/// Should be called outside of scheduling subsystem, implementation must be thread-safe.
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virtual void enqueueRequest(ResourceRequest * request) = 0;
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private:
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// Allows multiple consumers to synchronize with common "debit/credit" balance.
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// 1) (positive) to avoid wasting of allocated but not used resource (e.g in case of a failure);
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// 2) (negative) to account for overconsumption (e.g. if cost is not know in advance and estimation from below is applied).
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ResourceBudget budget;
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};
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}
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