github.com/bhojpur/cache@v0.0.4/pkg/temporal/temporal.go (about)

     1  package temporal
     2  
     3  // Copyright (c) 2018 Bhojpur Consulting Private Limited, India. All rights reserved.
     4  
     5  // Permission is hereby granted, free of charge, to any person obtaining a copy
     6  // of this software and associated documentation files (the "Software"), to deal
     7  // in the Software without restriction, including without limitation the rights
     8  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     9  // copies of the Software, and to permit persons to whom the Software is
    10  // furnished to do so, subject to the following conditions:
    11  
    12  // The above copyright notice and this permission notice shall be included in
    13  // all copies or substantial portions of the Software.
    14  
    15  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    16  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    17  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    18  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    19  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    20  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    21  // THE SOFTWARE.
    22  
    23  import (
    24  	"fmt"
    25  	"os"
    26  	"sync"
    27  )
    28  
    29  const (
    30  	ASC  = "asc"
    31  	DESC = "desc"
    32  )
    33  
    34  type MemCacheConfig struct {
    35  	Path string
    36  	Mode os.FileMode
    37  }
    38  
    39  type TimeEntry struct {
    40  	Time  int64
    41  	Value []byte
    42  }
    43  
    44  type Query struct {
    45  	Series string
    46  
    47  	From int64
    48  	To   int64
    49  	// Sorting order:
    50  	// Possible values are ASC and DESC
    51  	// ASC : The time Series will have the oldest data first
    52  	// DESC: The time Series will have the latest  data first.
    53  	Sort string
    54  
    55  	// Number of entries to be returned per page. This is used for pagination.
    56  	// The next sequence is found out using NextEntry variable of a query response.
    57  	MaxEntries int
    58  }
    59  
    60  type TimeSeries []TimeEntry
    61  
    62  type Database interface {
    63  
    64  	// Create a new bucket
    65  	Create(name string) error
    66  
    67  	// This function adds the records
    68  	Add(name string, timeseries TimeSeries) error
    69  
    70  	// Get the records
    71  	Query(q Query) (timeSeries TimeSeries, nextEntry *int64, err error)
    72  
    73  	QueryOnChannel(q Query) (timeseries <-chan TimeEntry, nextEntry chan *int64, err chan error)
    74  	// Get the total pages for a particular query.
    75  	// This helps for any client to call multiple queries
    76  	GetPages(q Query) (seriesList []int64, count int, err error)
    77  
    78  	// Get the records
    79  	Get(series string) (timeSeries TimeSeries, err error)
    80  	// Returns two channels, one for Time entries and one for error.
    81  	// This avoids the usage of an extra buffer by the database
    82  	// Caution: first read the channel and then read the error. Error channel shall be written only after the timeseries channel is closed
    83  	GetOnChannel(series string) (timeseries <-chan TimeEntry, err chan error)
    84  
    85  	// Delete a complete Series
    86  	Delete(series string) error
    87  
    88  	// Close the database
    89  	Close() error
    90  }
    91  
    92  var ds Database    // It will be used as a singleton DB object
    93  var once sync.Once // make thread safe singleton
    94  
    95  func Open(config interface{}) (Database, error) {
    96  	switch config.(type) {
    97  	case MemCacheConfig:
    98  		retDB := new(MemCacheDB)
    99  		err := retDB.open(config.(MemCacheConfig))
   100  		return retDB, err
   101  	default:
   102  		return nil, fmt.Errorf("Unsupported storage configuration")
   103  	}
   104  }