github.imxd.top/hashicorp/consul@v1.4.5/agent/consul/state/prepared_query_index.go (about)

     1  package state
     2  
     3  import (
     4  	"fmt"
     5  	"strings"
     6  
     7  	"github.com/hashicorp/consul/agent/consul/prepared_query"
     8  )
     9  
    10  // PreparedQueryIndex is a custom memdb indexer used to manage index prepared
    11  // query templates. None of the built-in indexers do what we need, and our
    12  // use case is pretty specific so it's better to put the logic here.
    13  type PreparedQueryIndex struct {
    14  }
    15  
    16  // FromObject is used to compute the index key when inserting or updating an
    17  // object.
    18  func (*PreparedQueryIndex) FromObject(obj interface{}) (bool, []byte, error) {
    19  	wrapped, ok := obj.(*queryWrapper)
    20  	if !ok {
    21  		return false, nil, fmt.Errorf("invalid object given to index as prepared query")
    22  	}
    23  
    24  	query := toPreparedQuery(wrapped)
    25  	if !prepared_query.IsTemplate(query) {
    26  		return false, nil, nil
    27  	}
    28  
    29  	// Always prepend a null so that we can represent even an empty name.
    30  	out := "\x00" + strings.ToLower(query.Name)
    31  	return true, []byte(out), nil
    32  }
    33  
    34  // FromArgs is used when querying for an exact match. Since we don't add any
    35  // suffix we can just call the prefix version.
    36  func (p *PreparedQueryIndex) FromArgs(args ...interface{}) ([]byte, error) {
    37  	return p.PrefixFromArgs(args...)
    38  }
    39  
    40  // PrefixFromArgs is used when doing a prefix scan for an object.
    41  func (*PreparedQueryIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
    42  	if len(args) != 1 {
    43  		return nil, fmt.Errorf("must provide only a single argument")
    44  	}
    45  	arg, ok := args[0].(string)
    46  	if !ok {
    47  		return nil, fmt.Errorf("argument must be a string: %#v", args[0])
    48  	}
    49  	arg = "\x00" + strings.ToLower(arg)
    50  	return []byte(arg), nil
    51  }