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query_context.go
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query_context.go
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// Copyright (c) 2019 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package models
import (
"context"
"github.com/m3db/m3/src/metrics/policy"
"github.com/m3db/m3/src/query/cost"
"github.com/uber-go/tally"
)
// QueryContext provides all external state needed to execute and track a query.
// It acts as a hook back into the execution engine for things like
// cost accounting.
type QueryContext struct {
Ctx context.Context
Scope tally.Scope
Enforcer cost.ChainedEnforcer
Options QueryContextOptions
}
// QueryContextOptions contains optional configuration for the query context.
type QueryContextOptions struct {
// LimitMaxTimeseries limits the number of time series returned by each
// storage node.
LimitMaxTimeseries int
// LimitMaxDocs limits the number of docs returned by each storage node.
LimitMaxDocs int
// RequireExhaustive results in an error if the query exceeds the series limit.
RequireExhaustive bool
RestrictFetchType *RestrictFetchTypeQueryContextOptions
}
// RestrictFetchTypeQueryContextOptions allows for specifying the
// restrict options for a query.
type RestrictFetchTypeQueryContextOptions struct {
MetricsType uint
StoragePolicy policy.StoragePolicy
}
// NewQueryContext constructs a QueryContext using the given Enforcer to
// enforce per query limits.
func NewQueryContext(
ctx context.Context,
scope tally.Scope,
enforcer cost.ChainedEnforcer,
options QueryContextOptions,
) *QueryContext {
return &QueryContext{
Ctx: ctx,
Scope: scope,
Enforcer: enforcer,
Options: options,
}
}
// NoopQueryContext returns a query context with no active components.
func NoopQueryContext() *QueryContext {
return NewQueryContext(context.Background(), tally.NoopScope,
cost.NoopChainedEnforcer(), QueryContextOptions{})
}
// WithContext creates a shallow copy of this QueryContext using the new context.
// Sample usage:
//
// ctx, cancel := context.WithTimeout(qc.Ctx, 5*time.Second)
// defer cancel()
// qc = qc.WithContext(ctx)
func (qc *QueryContext) WithContext(ctx context.Context) *QueryContext {
if qc == nil {
return nil
}
clone := *qc
clone.Ctx = ctx
return &clone
}