cmd_keys.go

cmd_keys.go - Overview

This file implements the KEYS command for the DiceDB, which retrieves all keys matching a given pattern.

Detailed Documentation

cKEYS

var cKEYS = &CommandMeta{
	Name:      "KEYS",
	Syntax:    "KEYS pattern",
	HelpShort: "KEYS returns all keys matching the pattern",
	HelpLong: `
KEYS returns all keys matching the pattern.

The pattern can contain the following special characters to match multiple keys.
Supports glob-style patterns:
- *: matches any sequence of characters
- ?: matches any single character`,
	Examples: `
localhost:7379> SET k1 v1
OK OK
localhost:7379> SET k2 v2
OK OK
localhost:7379> SET k33 v33
OK OK
localhost:7379> KEYS k?
OK
1) "k1"
2) "k2"
localhost:7379> KEYS k*
OK
1) "k1"
2) "k2"
3) "k33"
localhost:7379> KEYS *
OK
1) "k1"
2) "k2"
3) "k33"
	`,
	Eval:    evalKEYS,
	Execute: executeKEYS,
}

• Purpose: Defines the metadata for the KEYS command, including its name, syntax, help text, examples, and the functions to evaluate and execute it.
• Members:
  • Name: The name of the command ("KEYS").
  • Syntax: The command's syntax ("KEYS pattern").
  • HelpShort: A short description of the command.
  • HelpLong: A longer, more detailed description of the command, including supported patterns.
  • Examples: Example usages of the command.
  • Eval: The function to evaluate the command on a single store (evalKEYS).
  • Execute: The function to execute the command across shards (executeKEYS).

init()

func init() {
	CommandRegistry.AddCommand(cKEYS)
}

• Purpose: Registers the KEYS command with the CommandRegistry during package initialization.

evalKEYS(c *Cmd, s *dstore.Store) (*CmdRes, error)

func evalKEYS(c *Cmd, s *dstore.Store) (*CmdRes, error) {
	if len(c.C.Args) != 1 {
		return cmdResNil, errors.ErrWrongArgumentCount("KEYS")
	}
	pattern := c.C.Args[0]
	keys, err := s.Keys(pattern)
	if err != nil {
		return nil, err
	}
	return createResponseFromArray(keys), nil
}

• Purpose: Evaluates the KEYS command on a single store.
• Parameters:
  • c: A pointer to the Cmd struct representing the command.
  • s: A pointer to the dstore.Store struct representing the store.
• Returns:
  • *CmdRes: A pointer to the CmdRes struct representing the command result.
  • error: An error if one occurred, or nil if the command was successful.
• Functionality:
  • Checks if the number of arguments is correct (1).
  • Retrieves the pattern from the command arguments.
  • Calls the Keys method on the store to get the matching keys.
  • Creates a response from the array of keys using createResponseFromArray.

executeKEYS(c *Cmd, sm *shardmanager.ShardManager) (*CmdRes, error)

func executeKEYS(c *Cmd, sm *shardmanager.ShardManager) (*CmdRes, error) {
	if len(c.C.Args) != 1 {
		return cmdResNil, errors.ErrWrongArgumentCount("KEYS")
	}
	var keys []string
	for _, shard := range sm.Shards() {
		res, err := evalKEYS(c, shard.Thread.Store())
		if err != nil {
			return nil, err
		}
		for _, v := range res.R.GetVList() {
			keys = append(keys, v.GetStringValue())
		}
	}
	finalRes := createResponseFromArray(keys)
	return finalRes, nil
}

• Purpose: Executes the KEYS command across multiple shards.
• Parameters:
  • c: A pointer to the Cmd struct representing the command.
  • sm: A pointer to the shardmanager.ShardManager struct representing the shard manager.
• Returns:
  • *CmdRes: A pointer to the CmdRes struct representing the command result.
  • error: An error if one occurred, or nil if the command was successful.
• Functionality:
  • Checks if the number of arguments is correct (1).
  • Iterates over each shard in the shard manager.
  • Evaluates the KEYS command on each shard using evalKEYS.
  • Appends the keys from each shard's response to a final list of keys.
  • Creates a response from the final list of keys using createResponseFromArray.

createResponseFromArray(arr []string) *CmdRes

func createResponseFromArray(arr []string) *CmdRes {
	if len(arr) == 0 {
		return cmdResNil
	}
	var res []*structpb.Value
	for _, v := range arr {
		val := structpb.NewStringValue(v)
		res = append(res, val)
	}
	return &CmdRes{R: &wire.Response{
		VList: res}}
}

• Purpose: Creates a CmdRes struct from an array of strings.
• Parameters:
  • arr: An array of strings representing the keys.
• Returns:
  • *CmdRes: A pointer to the CmdRes struct representing the command result.
• Functionality:
  • Creates a structpb.Value for each string in the input array.
  • Appends each structpb.Value to a list.
  • Creates a wire.Response with the list of structpb.Values.
  • Creates a CmdRes with the wire.Response.

Getting Started Relevance