github.com/m3db/m3@v1.5.0/src/metrics/policy/staged_policy.go

// Copyright (c) 2017 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 policy

import (
	"encoding/json"
	"fmt"
)

var (
	// DefaultStagedPolicies represents a default staged policies.
	DefaultStagedPolicies StagedPolicies

	// DefaultPoliciesList represents a default policies list.
	DefaultPoliciesList = PoliciesList{DefaultStagedPolicies}
)

// StagedPolicies represent a list of policies at a specified version.
type StagedPolicies struct {
	// Cutover is when the policies take effect.
	CutoverNanos int64

	// Tombstoned determines whether the associated (rollup) metric has been tombstoned.
	Tombstoned bool

	// policies represent the list of policies.
	policies []Policy
}

// NewStagedPolicies create a new staged policies.
func NewStagedPolicies(cutoverNanos int64, tombstoned bool, policies []Policy) StagedPolicies {
	return StagedPolicies{CutoverNanos: cutoverNanos, Tombstoned: tombstoned, policies: policies}
}

// Reset resets the staged policies.
func (p *StagedPolicies) Reset() { *p = DefaultStagedPolicies }

// IsDefault returns whether this is a default staged policies.
func (p StagedPolicies) IsDefault() bool {
	return p.CutoverNanos == 0 && !p.Tombstoned && p.hasDefaultPolicies()
}

// Policies returns the policies and whether the policies are the default policies.
func (p StagedPolicies) Policies() ([]Policy, bool) {
	return p.policies, p.hasDefaultPolicies()
}

// Equals returns whether two staged policies are equal.
func (p StagedPolicies) Equals(other StagedPolicies) bool {
	if p.CutoverNanos != other.CutoverNanos || p.Tombstoned != other.Tombstoned {
		return false
	}
	currPolicies, currIsDefault := p.Policies()
	otherPolicies, otherIsDefault := other.Policies()
	if currIsDefault && otherIsDefault {
		return true
	}
	if currIsDefault || otherIsDefault {
		return false
	}
	if len(currPolicies) != len(otherPolicies) {
		return false
	}
	for i := 0; i < len(currPolicies); i++ {
		if currPolicies[i] != otherPolicies[i] {
			return false
		}
	}
	return true
}

// String is the representation of staged policies.
func (p StagedPolicies) String() string {
	b, err := json.Marshal(p)
	if err != nil {
		return fmt.Sprintf("[invalid staged policies: %v]", err)
	}
	return string(b)
}

func (p StagedPolicies) hasDefaultPolicies() bool {
	return IsDefaultPolicies(p.policies)
}

// MarshalJSON returns the JSON encoding of staged policies.
func (p StagedPolicies) MarshalJSON() ([]byte, error) {
	return json.Marshal(newStagedPoliciesJSON(p))
}

// UnmarshalJSON unmarshals JSON-encoded data into staged policies.
func (p *StagedPolicies) UnmarshalJSON(data []byte) error {
	var spj stagedPoliciesJSON
	err := json.Unmarshal(data, &spj)
	if err != nil {
		return err
	}
	*p = spj.StagedPolicies()
	return nil
}

// stagedPoliciesJSON is used for marshaling and unmarshaling staged policies.
type stagedPoliciesJSON struct {
	CutoverNanos int64    `json:"cutoverNanos"`
	Tombstoned   bool     `json:"tombstoned"`
	Policies     []Policy `json:"policies"`
}

func newStagedPoliciesJSON(sp StagedPolicies) stagedPoliciesJSON {
	return stagedPoliciesJSON{
		CutoverNanos: sp.CutoverNanos,
		Tombstoned:   sp.Tombstoned,
		Policies:     sp.policies,
	}
}

func (spj stagedPoliciesJSON) StagedPolicies() StagedPolicies {
	return NewStagedPolicies(spj.CutoverNanos, spj.Tombstoned, spj.Policies)
}

// PoliciesList is a list of staged policies.
type PoliciesList []StagedPolicies

// IsDefault determines whether this is a default policies list.
func (l PoliciesList) IsDefault() bool {
	return len(l) == 1 && l[0].IsDefault()
}

// VersionedPoliciesList is a versioned policies list.
type VersionedPoliciesList struct {
	// Version is the version associcated with the policies in the list.
	Version int `json:"version"`

	// PoliciesList contains the list of staged policies.
	PoliciesList PoliciesList `json:"policiesList"`
}