github.com/m3db/m3@v1.5.0/src/dbnode/storage/series/policy.go (about)

     1  // Copyright (c) 2017 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package series
    22  
    23  import (
    24  	"errors"
    25  	"fmt"
    26  )
    27  
    28  var (
    29  	errCachePolicyUnspecified = errors.New("series cache policy unspecified")
    30  )
    31  
    32  // CachePolicy is the series cache policy.
    33  type CachePolicy uint
    34  
    35  const (
    36  	// CacheNone specifies that no series will be cached by default.
    37  	CacheNone CachePolicy = iota
    38  	// CacheAll specifies that all series must be cached at all times
    39  	// which requires loading all into cache on bootstrap and never
    40  	// expiring series from memory until expired from retention.
    41  	CacheAll
    42  	// CacheRecentlyRead specifies that series that are recently read
    43  	// must be cached, configurable by the namespace block expiry after
    44  	// not accessed period.
    45  	CacheRecentlyRead
    46  	// CacheLRU specifies that series that are read will be cached
    47  	// using an LRU of fixed capacity. Series that are least recently
    48  	// used will be evicted first.
    49  	CacheLRU
    50  
    51  	// DefaultCachePolicy is the default cache policy.
    52  	DefaultCachePolicy = CacheLRU
    53  )
    54  
    55  // ValidCachePolicies returns the valid series cache policies.
    56  func ValidCachePolicies() []CachePolicy {
    57  	return []CachePolicy{CacheNone, CacheAll, CacheRecentlyRead, CacheLRU}
    58  }
    59  
    60  func (p CachePolicy) String() string {
    61  	switch p {
    62  	case CacheNone:
    63  		return "none"
    64  	case CacheAll:
    65  		return "all"
    66  	case CacheRecentlyRead:
    67  		return "recently_read"
    68  	case CacheLRU:
    69  		return "lru"
    70  	}
    71  	return "unknown"
    72  }
    73  
    74  // ValidateCachePolicy validates a cache policy.
    75  func ValidateCachePolicy(v CachePolicy) error {
    76  	validSeriesCachePolicy := false
    77  	for _, valid := range ValidCachePolicies() {
    78  		if valid == v {
    79  			validSeriesCachePolicy = true
    80  			break
    81  		}
    82  	}
    83  	if !validSeriesCachePolicy {
    84  		return fmt.Errorf("invalid series CachePolicy '%d' valid types are: %v",
    85  			uint(v), ValidCachePolicies())
    86  	}
    87  	return nil
    88  }
    89  
    90  // ParseCachePolicy parses a CachePolicy from a string.
    91  func ParseCachePolicy(str string) (CachePolicy, error) {
    92  	var r CachePolicy
    93  	if str == "" {
    94  		return r, errCachePolicyUnspecified
    95  	}
    96  	for _, valid := range ValidCachePolicies() {
    97  		if str == valid.String() {
    98  			r = valid
    99  			return r, nil
   100  		}
   101  	}
   102  	return r, fmt.Errorf("invalid series CachePolicy '%s' valid types are: %v",
   103  		str, ValidCachePolicies())
   104  }
   105  
   106  // UnmarshalYAML unmarshals an CachePolicy into a valid type from string.
   107  func (p *CachePolicy) UnmarshalYAML(unmarshal func(interface{}) error) error {
   108  	var str string
   109  	if err := unmarshal(&str); err != nil {
   110  		return err
   111  	}
   112  	r, err := ParseCachePolicy(str)
   113  	if err != nil {
   114  		return err
   115  	}
   116  	*p = r
   117  	return nil
   118  }