Content

Design goal of the Content storage/serialization backend.

Simple implementation of Content trait for any type

When implementing Content for your type, you need to provide only two methods, to_content that takes a Read, and produces a Self, and from_content, an example for u8: rust impl Content for u8 { fn to_content(&self, sink: &mut Write, _: &mut Backend) -> Result<()> { sink.write_all(&[*self]) } fn from_content(source: &mut Read, _: &NewHash) -> Result<Self> { let b = &mut [0u8]; try!(source.read_exact(b)); Ok(b[0]) } }

The Backend trait

The backend trait makes a type act as as storage for content addressed bytestreams, be it Vec<u8> or File. But it could also be a network interface, for example.

The type is the schema

Things that implement Content, implicitly know how to serialize and deserialize themselves, including knowing their length. And since types can nest other Content types within themselves, you basically get the whole schema and de/serialization for free.

Zero copy io

When a Content is put into a store, Reads and Writes are connected directly.

Transparant lazy references

If you have a type implementing Content that is larger than would make sense to serialize directly, such as a tree structure, you can put the children behind Lazy reference types, which means they will only be lazily loaded off disk and cached as they are needed.

Hash while writing, only hash once

Hashing is much more expensive than serialization, therefore we assure that any data is only hashed once