ets v0.8.0 ETS.Set View Source

Module for creating and interacting with :ets tables of the type :set and :ordered_set.

Sets contain "records" which are tuples. Sets are configured with a key position via the keypos: integer option. If not specified, the default key position is 1. The element of the tuple record at the key position is that records key. For example, setting the keypos to 2 means the key of an inserted record {:a, :b} is :b:

iex> {:ok, set} = Set.new(keypos: 2)
iex> Set.put!(set, {:a, :b})
iex> Set.get(set, :a)
{:ok, nil}
iex> Set.get(set, :b)
{:ok, {:a, :b}}

When a record is added to the table with put, it will overwrite an existing record with the same key. put_new will only put the record if a matching key doesn't already exist.

Examples

iex> {:ok, set} = Set.new(ordered: true)
iex> Set.put_new!(set, {:a, :b, :c})
iex> Set.to_list!(set)
[{:a, :b, :c}]
iex> Set.put_new!(set, {:d, :e, :f})
iex> Set.to_list!(set)
[{:a, :b, :c}, {:d, :e, :f}]
iex> Set.put_new!(set, {:a, :g, :h})
iex> Set.to_list!(set)
[{:a, :b, :c}, {:d, :e, :f}]

put and put_new take either a single tuple or a list of tuples. When inserting multiple records, they are inserted in an atomic an isolated manner. put_new doesn't insert any records if any of the new keys already exist in the set.

To make your set ordered (which maps to the :ets table type :ordered_set), specify ordered: true in the options list. An ordered set will store records in term order of the key of the record. This is helpful when using things like first, last, previous, next, and to_list, but comes with the penalty of log(n) insert time vs consistent insert time of an unordered set.

Working with named tables

The functions on ETS.Set require that you pass in an ETS.Set as the first argument. In some design patterns, you may have the table name but an instance of an ETS.Set may not be available to you. If this is the case, you should use wrap_existing/1 to turn your table name atom into an ETS.Set. For example, a GenServer that handles writes within the server, but reads in the client process would be implemented like this:

defmodule MyExampleGenServer do
  use GenServer

  # Client Functions

  def get_token_for_user(user_id) do
    :my_token_table
    |> ETS.Set.wrap_existing!()
    |> ETS.Set.get!(user_id)
    |> elem(1)
  end

  def set_token_for_user(user_id, token) do
    GenServer.call(__MODULE__, {:set_token_for_user, user_id, token})
  end

  # Server Functions

  def init(_) do
    {:ok, %{set: ETS.Set.new!(name: :my_token_table)}}
  end

  def handle_call({:set_token_for_user, user_id, token}, _from, %{set: set}) do
    ETS.Set.put(set, user_id, token)
  end
end

Link to this section Summary

Types

set_options()

t()

Functions

delete(set)

Deletes specified Set.

delete(set, key)

Deletes record with specified key in specified Set.

delete!(set)

Same as delete/1 but unwraps or raises on error.

delete!(set, key)

Same as delete/2 but unwraps or raises on error.

delete_all(set)

Deletes all records in specified Set.

delete_all!(set)

Same as delete_all/1 but unwraps or raises on error.

first(set)

Returns the first key in the specified Set. Set must be ordered or error is returned.

first!(set)

Same as first/1 but unwraps or raises on error

get(set, key, default \\ nil)

Returns record with specified key or the provided default (nil if not specified) if no record found.

get!(set, key, default \\ nil)

Same as get/3 but unwraps or raises on error.

get_element(set, key, pos)

Returns element in specified position of record with specified key.

get_element!(set, key, pos)

Same as get_element/3 but unwraps or raises on error.

get_table(set)

Returns underlying :ets table reference.

get_table!(set)

Same as get_table/1 but unwraps or raises on error

has_key(set, key)

Determines if specified key exists in specified set.

has_key!(set, key)

Same as has_key/2 but unwraps or raises on error.

info(set, force_update \\ false)

Returns information on the set.

info!(set, force_update \\ false)

Same as info/1 but unwraps or raises on error.

last(set)

Returns the last key in the specified Set. Set must be ordered or error is returned.

last!(set)

Same as last/1 but unwraps or raises on error

match(continuation)

Matches next set of records from a match/3 or match/1 continuation.

match(set, pattern)

Returns records in the specified Set that match the specified pattern.

match(set, pattern, limit)

Same as match/2 but limits number of results to the specified limit.

match!(continuation)

Same as match/1 but unwraps or raises on error.

match!(set, pattern)

Same as match/2 but unwraps or raises on error.

match!(set, pattern, limit)

Same as match/3 but unwraps or raises on error.

new(opts \\ [])

Creates new set module with the specified options.

new!(opts \\ [])

Same as new/1 but unwraps or raises on error.

next(set, key)

Returns the next key in the specified Set.

next!(set, key)

Same as next/1 but unwraps or raises on error

previous(set, key)

Returns the previous key in the specified Set.

previous!(set, key)

Same as previous/1 but raises on :error

put(set, record)

Puts tuple record or list of tuple records into table. Overwrites records for existing key(s).

put!(set, record_or_records)

Same as put/2 but unwraps or raises on error.

put_new(set, record)

Same as put/2 but doesn't put any records if one of the given keys already exists.

put_new!(set, record_or_records)

Same as put_new/2 but unwraps or raises on error.

select(continuation)

select(set, spec)

Returns records in the specified Set that match the specified match specification.

select(set, spec, limit)

Same as select/2 but limits the number of results returned.

select!(continuation)

select!(set, spec)

Same as select/2 but unwraps or raises on error.

select!(set, spec, limit)

Same as select/3 but unwraps or raises on error.

select_delete(set, spec)

Deletes records in the specified Set that match the specified match specification.

select_delete!(set, spec)

Same as select_delete/2 but unwraps or raises on error.

to_list(set)

Returns contents of table as a list.

to_list!(set)

Same as to_list/1 but unwraps or raises on error.

wrap_existing(table_identifier)

Wraps an existing :ets :set or :ordered_set in a Set struct.

wrap_existing!(table_identifier)

Same as wrap_existing/1 but unwraps or raises on error.

Link to this section Types

set_options()

set_options() :: [ETS.Base.option() | {:ordered, boolean()}]

t()

t() :: %ETS.Set{
  info: keyword(),
  ordered: boolean(),
  table: ETS.table_reference()
}

Link to this section Functions

delete(set)

delete(ETS.Set.t()) :: {:ok, ETS.Set.t()} | {:error, any()}

Deletes specified Set.

Examples

iex> {:ok, set} = Set.new()
iex> {:ok, _} = Set.info(set, true)
iex> {:ok, _} = Set.delete(set)
iex> Set.info(set, true)
{:error, :table_not_found}

delete(set, key)

delete(ETS.Set.t(), any()) :: {:ok, ETS.Set.t()} | {:error, any()}

Deletes record with specified key in specified Set.

Examples

iex> set = Set.new!()
iex> Set.put(set, {:a, :b, :c})
iex> Set.delete(set, :a)
iex> Set.get!(set, :a)
nil

delete!(set)

delete!(ETS.Set.t()) :: ETS.Set.t()

Same as delete/1 but unwraps or raises on error.

delete!(set, key)

delete!(ETS.Set.t(), any()) :: ETS.Set.t()

Same as delete/2 but unwraps or raises on error.

delete_all(set)

delete_all(ETS.Set.t()) :: {:ok, ETS.Set.t()} | {:error, any()}

Deletes all records in specified Set.

Examples

iex> set = Set.new!()
iex> set
iex> |> Set.put!({:a, :b, :c})
iex> |> Set.put!({:b, :b, :c})
iex> |> Set.put!({:c, :b, :c})
iex> |> Set.to_list!()
[{:c, :b, :c}, {:b, :b, :c}, {:a, :b, :c}]
iex> Set.delete_all(set)
iex> Set.to_list!(set)
[]

delete_all!(set)

delete_all!(ETS.Set.t()) :: ETS.Set.t()

Same as delete_all/1 but unwraps or raises on error.

first(set)

first(ETS.Set.t()) :: {:ok, any()} | {:error, any()}

Returns the first key in the specified Set. Set must be ordered or error is returned.

Examples

iex> set = Set.new!(ordered: true)
iex> Set.first(set)
{:error, :empty_table}
iex> Set.put!(set, {:key1, :val})
iex> Set.put!(set, {:key2, :val})
iex> Set.first(set)
{:ok, :key1}

first!(set)

first!(ETS.Set.t()) :: any()

Same as first/1 but unwraps or raises on error

get(set, key, default \\ nil)

get(ETS.Set.t(), any(), any()) :: {:ok, tuple() | nil} | {:error, any()}

Returns record with specified key or the provided default (nil if not specified) if no record found.

Examples

iex> Set.new!()
iex> |> Set.put!({:a, :b, :c})
iex> |> Set.put!({:d, :e, :f})
iex> |> Set.get(:d)
{:ok, {:d, :e, :f}}

get!(set, key, default \\ nil)

get!(ETS.Set.t(), any(), any()) :: tuple() | nil

Same as get/3 but unwraps or raises on error.

get_element(set, key, pos)

get_element(ETS.Set.t(), any(), non_neg_integer()) ::
  {:ok, any()} | {:error, any()}

Returns element in specified position of record with specified key.

Examples

iex> Set.new!()
iex> |> Set.put!({:a, :b, :c})
iex> |> Set.put!({:d, :e, :f})
iex> |> Set.get_element(:d, 2)
{:ok, :e}

get_element!(set, key, pos)

get_element!(ETS.Set.t(), any(), non_neg_integer()) :: any()

Same as get_element/3 but unwraps or raises on error.

get_table(set)

get_table(ETS.Set.t()) :: {:ok, ETS.table_reference()}

Returns underlying :ets table reference.

For use in functions that are not yet implemented. If you find yourself using this, please consider submitting a PR to add the necessary function to ETS.

Examples

iex> set = Set.new!(name: :my_ets_table)
iex> {:ok, table} = Set.get_table(set)
iex> info = :ets.info(table)
iex> info[:name]
:my_ets_table

get_table!(set)

get_table!(ETS.Set.t()) :: ETS.table_reference()

Same as get_table/1 but unwraps or raises on error

has_key(set, key)

has_key(ETS.Set.t(), any()) :: {:ok, boolean()} | {:error, any()}

Determines if specified key exists in specified set.

Examples

iex> set = Set.new!()
iex> Set.has_key(set, :key)
{:ok, false}
iex> Set.put(set, {:key, :value})
iex> Set.has_key(set, :key)
{:ok, true}

has_key!(set, key)

has_key!(ETS.Set.t(), any()) :: boolean()

Same as has_key/2 but unwraps or raises on error.

info(set, force_update \\ false)

info(ETS.Set.t(), boolean()) :: {:ok, keyword()} | {:error, any()}

Returns information on the set.

Second parameter forces updated information from ets, default (false) uses in-struct cached information. Force should be used when requesting size and memory.

Examples

iex> {:ok, set} = Set.new(ordered: true, keypos: 3, read_concurrency: true, compressed: false)
iex> {:ok, info} = Set.info(set)
iex> info[:read_concurrency]
true
iex> {:ok, _} = Set.put(set, {:a, :b, :c})
iex> {:ok, info} = Set.info(set)
iex> info[:size]
0
iex> {:ok, info} = Set.info(set, true)
iex> info[:size]
1

info!(set, force_update \\ false)

info!(ETS.Set.t(), boolean()) :: keyword()

Same as info/1 but unwraps or raises on error.

last(set)

last(ETS.Set.t()) :: {:ok, any()} | {:error, any()}

Returns the last key in the specified Set. Set must be ordered or error is returned.

Examples

iex> set = Set.new!(ordered: true)
iex> Set.last(set)
{:error, :empty_table}
iex> Set.put!(set, {:key1, :val})
iex> Set.put!(set, {:key2, :val})
iex> Set.last(set)
{:ok, :key2}

last!(set)

last!(ETS.Set.t()) :: any()

Same as last/1 but unwraps or raises on error

match(continuation)

match(any()) :: {:ok, {[tuple()], any() | :end_of_table}} | {:error, any()}

Matches next set of records from a match/3 or match/1 continuation.

Examples

iex> set = Set.new!(ordered: true)
iex> Set.put!(set, [{:a, :b, :c, :d}, {:e, :b, :f, :g}, {:h, :b, :i, :j}])
iex> {:ok, {results, continuation}} = Set.match(set, {:"$1", :b, :"$2", :_}, 2)
iex> results
[[:a, :c], [:e, :f]]
iex> {:ok, {records2, continuation2}} = Set.match(continuation)
iex> records2
[[:h, :i]]
iex> continuation2
:end_of_table

match(set, pattern)

match(ETS.Set.t(), ETS.match_pattern()) :: {:ok, [tuple()]} | {:error, any()}

Returns records in the specified Set that match the specified pattern.

For more information on the match pattern, see the erlang documentation

Examples

iex> Set.new!(ordered: true)
iex> |> Set.put!([{:a, :b, :c, :d}, {:e, :c, :f, :g}, {:h, :b, :i, :j}])
iex> |> Set.match({:"$1", :b, :"$2", :_})
{:ok, [[:a, :c], [:h, :i]]}

match(set, pattern, limit)

match(ETS.Set.t(), ETS.match_pattern(), non_neg_integer()) ::
  {:ok, {[tuple()], any() | :end_of_table}} | {:error, any()}

Same as match/2 but limits number of results to the specified limit.

Examples

iex> set = Set.new!(ordered: true)
iex> Set.put!(set, [{:a, :b, :c, :d}, {:e, :b, :f, :g}, {:h, :b, :i, :j}])
iex> {:ok, {results, _continuation}} = Set.match(set, {:"$1", :b, :"$2", :_}, 2)
iex> results
[[:a, :c], [:e, :f]]

match!(continuation)

match!(any()) :: {[tuple()], any() | :end_of_table}

Same as match/1 but unwraps or raises on error.

match!(set, pattern)

match!(ETS.Set.t(), ETS.match_pattern()) :: [tuple()]

Same as match/2 but unwraps or raises on error.

match!(set, pattern, limit)

match!(ETS.Set.t(), ETS.match_pattern(), non_neg_integer()) ::
  {[tuple()], any() | :end_of_table}

Same as match/3 but unwraps or raises on error.

new(opts \\ [])

new(set_options()) :: {:error, any()} | {:ok, ETS.Set.t()}

Creates new set module with the specified options.

Note that the underlying :ets table will be attached to the process that calls new and will be destroyed if that process dies.

Possible options:

name: when specified, creates a named table with the specified name
ordered: when true, records in set are ordered (default false)
protection: :private, :protected, :public (default :protected)
heir: :none | {heir_pid, heir_data} (default :none)
keypos: integer (default 1)
read_concurrency: boolean (default false)
write_concurrency: boolean (default false)
compressed: boolean (default false)

Examples

iex> {:ok, set} = Set.new(ordered: true, keypos: 3, read_concurrency: true, compressed: false)
iex> Set.info!(set)[:read_concurrency]
true

# Named :ets tables via the name keyword
iex> {:ok, set} = Set.new(name: :my_ets_table)
iex> Set.info!(set)[:name]
:my_ets_table

new!(opts \\ [])

new!(set_options()) :: ETS.Set.t()

Same as new/1 but unwraps or raises on error.

next(set, key)

next(ETS.Set.t(), any()) :: {:ok, any()} | {:error, any()}

Returns the next key in the specified Set.

The given key does not need to exist in the set. The key returned will be the first key that exists in the set which is subsequent in term order to the key given.

Set must be ordered or error is returned.

Examples

iex> set = Set.new!(ordered: true)
iex> Set.put!(set, {:key1, :val})
iex> Set.put!(set, {:key2, :val})
iex> Set.put!(set, {:key3, :val})
iex> Set.first(set)
{:ok, :key1}
iex> Set.next(set, :key1)
{:ok, :key2}
iex> Set.next(set, :key2)
{:ok, :key3}
iex> Set.next(set, :key3)
{:error, :end_of_table}
iex> Set.next(set, :a)
{:ok, :key1}
iex> Set.next(set, :z)
{:error, :end_of_table}

next!(set, key)

next!(ETS.Set.t(), any()) :: any()

Same as next/1 but unwraps or raises on error

previous(set, key)

previous(ETS.Set.t(), any()) :: {:ok, any()} | {:error, any()}

Returns the previous key in the specified Set.

The given key does not need to exist in the set. The key returned will be the first key that exists in the set which is previous in term order to the key given.

Set must be ordered or error is returned.

Examples

iex> set = Set.new!(ordered: true)
iex> Set.put!(set, {:key1, :val})
iex> Set.put!(set, {:key2, :val})
iex> Set.put!(set, {:key3, :val})
iex> Set.last(set)
{:ok, :key3}
iex> Set.previous(set, :key3)
{:ok, :key2}
iex> Set.previous(set, :key2)
{:ok, :key1}
iex> Set.previous(set, :key1)
{:error, :start_of_table}
iex> Set.previous(set, :a)
{:error, :start_of_table}
iex> Set.previous(set, :z)
{:ok, :key3}

previous!(set, key)

previous!(ETS.Set.t(), any()) :: any()

Same as previous/1 but raises on :error

Returns previous key in table.

put(set, record)

put(ETS.Set.t(), tuple() | [tuple()]) :: {:ok, ETS.Set.t()} | {:error, any()}

Puts tuple record or list of tuple records into table. Overwrites records for existing key(s).

Inserts multiple records in an atomic and isolated manner.

Examples

iex> {:ok, set} = Set.new(ordered: true)
iex> {:ok, _} = Set.put(set, [{:a, :b, :c}, {:d, :e, :f}])
iex> {:ok, _} = Set.put(set, {:g, :h, :i})
iex> {:ok, _} = Set.put(set, {:d, :x, :y})
iex> Set.to_list(set)
{:ok, [{:a, :b, :c}, {:d, :x, :y}, {:g, :h, :i}]}

put!(set, record_or_records)

put!(ETS.Set.t(), tuple() | [tuple()]) :: ETS.Set.t()

Same as put/2 but unwraps or raises on error.

put_new(set, record)

put_new(ETS.Set.t(), tuple() | [tuple()]) ::
  {:ok, ETS.Set.t()} | {:error, any()}

Same as put/2 but doesn't put any records if one of the given keys already exists.

Examples

iex> set = Set.new!(ordered: true)
iex> {:ok, _} = Set.put_new(set, [{:a, :b, :c}, {:d, :e, :f}])
iex> {:ok, _} = Set.put_new(set, [{:a, :x, :y}, {:g, :h, :i}]) # skips due to duplicate :a key
iex> {:ok, _} = Set.put_new(set, {:d, :z, :zz}) # skips due to duplicate :d key
iex> Set.to_list!(set)
[{:a, :b, :c}, {:d, :e, :f}]

put_new!(set, record_or_records)

put_new!(ETS.Set.t(), tuple() | [tuple()]) :: ETS.Set.t()

Same as put_new/2 but unwraps or raises on error.

select(continuation)

select(ETS.continuation()) ::
  {:ok, {[tuple()], ETS.continuation()} | ETS.end_of_table()} | {:error, any()}

select(set, spec)

select(ETS.Set.t(), ETS.match_spec()) :: {:ok, [tuple()]} | {:error, any()}

Returns records in the specified Set that match the specified match specification.

For more information on the match specification, see the erlang documentation

Examples

iex> Set.new!(ordered: true)
iex> |> Set.put!([{:a, :b, :c, :d}, {:e, :c, :f, :g}, {:h, :b, :i, :j}])
iex> |> Set.select([{{:"$1", :b, :"$2", :_},[],[:"$$"]}])
{:ok, [[:a, :c], [:h, :i]]}

select(set, spec, limit)

select(ETS.Set.t(), ETS.match_spec(), limit :: integer()) ::
  {:ok, {[tuple()], ETS.continuation()} | ETS.end_of_table()} | {:error, any()}

Same as select/2 but limits the number of results returned.

select!(continuation)

select!(ETS.continuation()) ::
  {[tuple()], ETS.continuation()} | ETS.end_of_table()

select!(set, spec)

select!(ETS.Set.t(), ETS.match_spec()) :: [tuple()]

Same as select/2 but unwraps or raises on error.

select!(set, spec, limit)

select!(ETS.Set.t(), ETS.match_spec(), limit :: integer()) ::
  {[tuple()], ETS.continuation()} | ETS.end_of_table()

Same as select/3 but unwraps or raises on error.

select_delete(set, spec)

select_delete(ETS.Set.t(), ETS.match_spec()) ::
  {:ok, non_neg_integer()} | {:error, any()}

Deletes records in the specified Set that match the specified match specification.

For more information on the match specification, see the erlang documentation

Examples

iex> set = Set.new!(ordered: true)
iex> set
iex> |> Set.put!([{:a, :b, :c, :d}, {:e, :c, :f, :g}, {:h, :b, :c, :h}])
iex> |> Set.select_delete([{{:"$1", :b, :"$2", :_},[{:"==", :"$2", :c}],[true]}])
{:ok, 2}
iex> Set.to_list!(set)
[{:e, :c, :f, :g}]

select_delete!(set, spec)

select_delete!(ETS.Set.t(), ETS.match_spec()) :: non_neg_integer()

Same as select_delete/2 but unwraps or raises on error.

to_list(set)

to_list(ETS.Set.t()) :: {:ok, [tuple()]} | {:error, any()}

Returns contents of table as a list.

Examples

iex> Set.new!(ordered: true)
iex> |> Set.put!({:a, :b, :c})
iex> |> Set.put!({:d, :e, :f})
iex> |> Set.put!({:d, :e, :f})
iex> |> Set.to_list()
{:ok, [{:a, :b, :c}, {:d, :e, :f}]}

to_list!(set)

to_list!(ETS.Set.t()) :: [tuple()]

Same as to_list/1 but unwraps or raises on error.

wrap_existing(table_identifier)

wrap_existing(ETS.table_identifier()) :: {:ok, ETS.Set.t()} | {:error, any()}

Wraps an existing :ets :set or :ordered_set in a Set struct.

Examples

iex> :ets.new(:my_ets_table, [:set, :named_table])
iex> {:ok, set} = Set.wrap_existing(:my_ets_table)
iex> Set.info!(set)[:name]
:my_ets_table

wrap_existing!(table_identifier)

wrap_existing!(ETS.table_identifier()) :: ETS.Set.t()

Same as wrap_existing/1 but unwraps or raises on error.