https://github.com/jur0/eid

Erlang unique id generator based on UNIX timestamp.
https://github.com/jur0/eid

erlang id-generator unique-id unix-timestamp

Last synced: about 1 month ago
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Erlang unique id generator based on UNIX timestamp.

• Host: GitHub
• URL: https://github.com/jur0/eid
• Owner: jur0
• License: isc
• Created: 2013-05-25T12:21:30.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2019-06-25T11:21:44.000Z (over 5 years ago)
• Last Synced: 2024-12-26T12:35:35.421Z (about 1 month ago)
• Topics: erlang, id-generator, unique-id, unix-timestamp
• Language: Erlang
• Size: 82 KB
• Stars: 14
• Watchers: 3
• Forks: 4
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# eid

Erlang unique ID generator.

## ID types

An ID is composed of the UNIX timestamp in milliseconds (upper 48 bits) and a

sequence number (lower 16 bits). The sequence number is used when two UNIX

timestamp are equal. This happens when the IDs are generated quickly (more

than one ID per millisecond). The sequence number makes sure that even in this

case the IDs are unique.

There are two formats of the IDs that can be generated:

 * binary - upper 48 bits is UNIX timestamp in milliseconds and the lower 16

bits is the sequence number

 * integer - the same as binary, but expressed as a positive integer

Moreover, the generated IDs are either ascending or descending. This feature

makes it possible to sort the IDs according to when they were generated.

## Usage

In order to generate IDs, the `eid` application must be started. The API

contains the following functions:

 * `eid:get_bin()` - returns a binary ID, the generated IDs are ascending;

 * `eid:get_bin(ascend)` - the same as the previous function;

 * `eid:get_bin(descend)` - returns a binary ID, the generated IDs are

descending;

 * `eid:get_int()` - returns an integer ID, the generated IDs are ascending;

 * `eid:get_int(ascend)` - the same as the previous function;

 * `eid:get_int(descend)` - returns an integer id, the generated ids are

descending.

The functions return either `{ok, Id}` or `{error, Reason}`. The error is

returned when the sequence number is exceeded (which could theoretically

happen when there are more then 2^16 IDs generated within 1 millisecond).

*The IDs are unique just on one node!*

### Rebar dependency

The `deps` part of the `rebar.config` should include:

```erlang

  {deps, [

    ...

    {eid, {git, "https://github.com/jur0/eid.git", {branch, "master"}}},

    ...

  ]}.

```