https://github.com/mmzeeman/rrets

Round Robin Erlang Term Storage
https://github.com/mmzeeman/rrets

Last synced: about 16 hours ago
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Round Robin Erlang Term Storage

• Host: GitHub
• URL: https://github.com/mmzeeman/rrets
• Owner: mmzeeman
• License: apache-2.0
• Created: 2014-09-17T13:02:57.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-11-18T19:50:07.000Z (about 10 years ago)
• Last Synced: 2024-11-16T06:50:13.599Z (about 2 months ago)
• Language: Erlang
• Size: 191 KB
• Stars: 0
• Watchers: 2
• Forks: 2
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        


# RRets - Round Robin Erlang Term Storage #

Copyright (c) 2014 MM Zeeman, All Rights Reserved.

### Introduction ###

The RRets packages allows for an easy way to store erlang terms into a round robin database. The 

terms are stored until the storage has reached a predefined maximum and are then overwritten by newer items. 

Each term added to the storage gets a second resolution unix_time timestamp attached to it. 

The storage can be used to easily, and quickly, store terms. Example usage:

* Logs

* System statistics

* Audit logs

The storage can be queried with a match specification which allows quick, and streaming, access 

to your data.

For example:

```erlang

MatchSpec = ets:fun2ms(fun({Timestamp, {example, 2, X}}) -> {Timestamp, {example, 2, X}} end),

Continuation = rrets_reader:open("my_storage", MatchSpec),

{Records, Continuation1} = rrets_reader:match(Continuation),

...

```

After opening a reader a continuation is returned. This continuation can be used to repeatedly

receive lists with matching records. In this case, all tuples matching `{example, 2, _}` terms 

are retrieved from the storage. Each matching record is returned with the timestamp when the term

was stored.

### Opening a rrets storage ###

RRets storages can be opened by using a name, filename and a specification on how large the

storage files need to become. The name can later be used add terms to the storage.

```erlang

Storage = rrets:open([{name, my_storage}, {file, "my_storage"}, {size, {10475520, 10}}]).

```

### Storing a term ###

```erlang

Ts = rrets:log(my_storage, {nasi, 3})

````

### Closing the storage ###

It is important that the storage is properly closed.

```erlang

rrets:close(my_storage)

````