roger

v2.0.1

roger v2.0.1 Roger.KeySet View Source

An opaque interface to storing keys and testing set member ship of keys. Like a bloom filter, but 100% probabilistic.

iex> {:ok, pid} = Roger.KeySet.start_link
iex> Roger.KeySet.add(pid, "bla")
:ok
iex> Roger.KeySet.contains?(pid, "bla")
true
iex> Roger.KeySet.contains?(pid, "beh")
false

Keys can also be removed:

iex> {:ok, pid} = Roger.KeySet.start_link
iex> Roger.KeySet.add(pid, "bla")
iex> Roger.KeySet.remove(pid, "bla")
:ok
iex> Roger.KeySet.contains?(pid, "bla")
false

The state of the keyset can be retrieved in binary format. This state is to be treated as an opaque datastructure. We can then load the state into a new keyset process.

The state can also be given as an argument when the keyset process is started.

iex> {:ok, pid} = Roger.KeySet.start_link
iex> Roger.KeySet.add(pid, "existing")
iex> {:ok, state} = Roger.KeySet.get_state(pid)
iex> {:ok, pid2} = Roger.KeySet.start_link(state: state)
iex> Roger.KeySet.contains?(pid2, "existing")
true

Many keys can also be added at once:

iex> {:ok, pid} = Roger.KeySet.start_link
iex> Roger.KeySet.add_many(pid, ~w(a b c))
:ok
iex> Roger.KeySet.contains?(pid, "a")
true
iex> Roger.KeySet.contains?(pid, "b")
true
iex> Roger.KeySet.contains?(pid, "c")
true

Two keysets can also be used in set operations. These will always be applied to the first keyset; the second is left untouched:

iex> {:ok, a} = Roger.KeySet.start_link
iex> Roger.KeySet.add_many(a, ~w(a1 a2 a3))
iex> {:ok, b} = Roger.KeySet.start_link
iex> Roger.KeySet.add_many(b, ~w(b1 b2))
iex> Roger.KeySet.union(a, b)
:ok
iex> Roger.KeySet.contains?(a, "b1")
true
iex> Roger.KeySet.contains?(b, "a1")
false
iex> Roger.KeySet.difference(a, b)
:ok
iex> Roger.KeySet.contains?(a, "b1")
false

Note: the current implementation is a MapSet but this is an implementation detail and likely to change.

Link to this section Summary

Functions

add(pid, key)
add_many(pid, keys)
child_spec(arg)

Returns a specification to start this module under a supervisor

contains?(pid, key)
difference(pid, pid2)
get_state(pid)
init(list)

Invoked when the server is started. start_link/3 or start/3 will block until it returns

put_state(pid, state)
remove(pid, key)
start_link(opts \\ [])
union(pid, pid2)

Link to this section Functions

Link to this function child_spec(arg) View Source

Returns a specification to start this module under a supervisor.

See Supervisor.

Link to this function init(list) View Source

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be (re)started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

  • The GenServer is disabled by configuration but might be enabled later.
  • An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.