added real_timestamp_of_id, default_config, and ability

added Helper.real_timestamp_of_id
added default configuration so app doesn’t crash if user didn’t set
config
added Erlang Node name as an option for nodes
updated documentation, version, and change_log

changelog.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## v 0.0.2
+
+- added Helper.real_timestamp_of_id
+- added default configuration so app doesn’t crash if user didn’t set config
+- added Erlang Node name as an option for nodes
+- updated documentation
+
 ## v 0.0.1
 
 Initial Release

lib/snowflake/helper.ex

@@ -9,13 +9,21 @@ defmodule Snowflake.Helper do
   use Bitwise
 
   @doc """
-  Get timestamp in ms from epoch from any snowflake ID
+  Get timestamp in ms from your config epoch from any snowflake ID
   """
   @spec timestamp_of_id(integer) :: integer
   def timestamp_of_id(id) do
     id >>> 22
   end
 
+  @doc """
+  Get timestamp from computer epoch - January 1, 1970, Midnight
+  """
+  @spec real_timestamp_of_id(integer) :: integer
+  def real_timestamp_of_id(id) do
+    timestamp_of_id(id) + Snowflake.Utils.epoch()
+  end
+
   @doc """
   Get bucket value based on segments of N days
   """

lib/snowflake/utils.ex

@@ -3,13 +3,17 @@ defmodule Snowflake.Utils do
   Utility functions intended for Snowflake application.
   epoch() and machine_id() are useful for inspecting in production.
   """
+  @default_config [
+    nodes: [],
+    epoch: 0
+  ]
 
   @doc """
   Grabs epoch from config value
   """
   @spec epoch() :: integer
   def epoch() do
-    Application.get_env(:snowflake, :epoch)
+    Application.get_env(:snowflake, :epoch) || @default_config[:epoch]
   end
 
   @doc """
@@ -18,8 +22,8 @@ defmodule Snowflake.Utils do
   """
   @spec machine_id() :: integer
   def machine_id() do
-    nodes = Application.get_env(:snowflake, :nodes)
-    host_addrs = [hostname(), fqdn()] ++ ip_addrs()
+    nodes = Application.get_env(:snowflake, :nodes) || @default_config[:nodes]
+    host_addrs = [hostname(), fqdn(), Node.self()] ++ ip_addrs()
 
     case MapSet.intersection(MapSet.new(host_addrs), MapSet.new(nodes)) |> Enum.take(1) do
       [matching_node] -> Enum.find_index(nodes, fn node -> node == matching_node end)

mix.exs

@@ -1,7 +1,7 @@
 defmodule Snowflake.Mixfile do
   use Mix.Project
 
-  @version "0.0.1"
+  @version "0.0.2"
   @url "https://github.com/blitzstudios/snowflake"
   @maintainers ["Weixi Yen"]
 

readme.md

@@ -12,9 +12,15 @@ def deps do
 end
 ```
 
-Specify the nodes in your config.  If your running a cluster, specify all the nodes in the cluster that snowflake runs on.  
+```elixir
+def application do
+  [applications: [:snowflake]]
+end
+```
+
+Specify the nodes in your config.  If you're running a cluster, specify all the nodes in the cluster that snowflake runs on.  
 
-- **nodes** can be Public IPs, Private IPs, Hostnames, or FQDNs
+- **nodes** can be Erlang Node Names, Public IPs, Private IPs, Hostnames, or FQDNs
 - **epoch** should not be changed once you begin generating IDs and want to maintain sorting
 - There should be no more than 1 snowflake generator per node, or you risk duplicate potential duplicate snowflakes on the same node.
 
@@ -28,7 +34,7 @@ Generating an ID is simple.
 
 ```elixir
 Snowflake.next_id()
-# => 828746161129414660
+# => {:ok, 54974240033603584}
 ```
 
 ## Helper functions
@@ -46,27 +52,33 @@ Snowflake.Helper.bucket(30, :days)
 Or if we want to know which bucket a snowflake ID should belong to, given we are
 bucketing by every 30 days.
 ```elixir
-Snowflake.Helper.bucket(30, :days, 828746161129414661)
-# => 76
+Snowflake.Helper.bucket(30, :days, 54974240033603584)
+# => 5
 ```
 
 Or if we want to know how many ms elapsed from epoch
 ```elixir
-Snowflake.Helper.timestamp_of_id(828746161129414661)
+Snowflake.Helper.timestamp_of_id(54974240033603584)
 # => 197588482172
 ```
 
+Or if we want to know how many ms elapsed from computer epoch (January 1, 1970 midnight).  We can use this to derive an actual calendar date.
+```elixir
+Snowflake.Helper.real_timestamp_of_id(54974240033603584)
+# => 1486669389497
+```
+
 ## NTP
 
 Keep your nodes in sync with [ntpd](https://en.wikipedia.org/wiki/Ntpd) or use
 your VM equivalent as snowflake depends on OS time.  ntpd's job is to slow down
-or speed up the clock so that it syncs the time with the network time.
+or speed up the clock so that it syncs os time with your network time.
 
 ## Architecture
 
-Snowflake allows the user to specify the nodes in the cluster, each representing a machine.  Snowflake at startup inspects itself for IP and Host information and derives its machine_id from the location of itself in the list of nodes defined in the config.
+Snowflake allows the user to specify the nodes in the cluster, each representing a machine.  Snowflake at startup inspects itself for Node, IP and Host information and derives its machine_id from the location of itself in the list of nodes defined in the config.
 
-Machine ID is defaulted to **1023** if there is no configuration or if snowflake does not find a match to remain highly available.  It is important to specify the correct IPs / Hostnames / FQDNs for the nodes in a production environment to avoid any chance of snowflake collision.
+Machine ID is defaulted to **1023** if snowflake is not able to find itself within the specified config.  It is important to specify the correct IPs / Hostnames / FQDNs for the nodes in a production environment to avoid any chance of snowflake collision.
 
 ## Benchmarks