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It's been discussed in several issues and PRs already that we might want to explore various ways of implementing CIDs for maximum performance and ease-of-use because they show up extremely often. Current CIDs are pointers, which generally speaking means you can't get one without a malloc; and also, they're not particularly well-suited for use in map keys. This branch is to attempt to consolidate all the proposals so far -- and do so in a single branch which can be checked out and contains all the proposals at once, because this will make it easy to do benchmarks and compare all of the various ways we could implement this in one place (and also easier for humans to track what the latest of each proposal is, since they're all in one place). To start with: a Cid implementation backed by a string; and matching interface. (I'm also taking this opportunity to be as minimalistic as possible in what I port over into these experimental new Cid implementations. This might not last; but as long as all this work is to be done, it's a more convenient time than usual to see what can be stripped down and still get work done.) More to come.
go-cid
A package to handle content IDs in Go.
This is an implementation in Go of the CID spec.
It is used in go-ipfs and related packages to refer to a typed hunk of data.
Table of Contents
Install
go-cid is a standard Go module which can be installed with:
go get github.com/ipfs/go-cid
Note that go-cid is packaged with Gx, so it is recommended to use Gx to install and use it (see Usage section).
Usage
Using Gx and Gx-go
This module is packaged with Gx. In order to use it in your own project it is recommended that you:
go get -u github.com/whyrusleeping/gx
go get -u github.com/whyrusleeping/gx-go
cd <your-project-repository>
gx init
gx import github.com/ipfs/go-cid
gx install --global
gx-go --rewrite
Please check Gx and Gx-go documentation for more information.
Running tests
Before running tests, please run:
make deps
This will make sure that dependencies are rewritten to known working versions.
Examples
Parsing string input from users
// Create a cid from a marshaled string
c, err := cid.Decode("zdvgqEMYmNeH5fKciougvQcfzMcNjF3Z1tPouJ8C7pc3pe63k")
if err != nil {...}
fmt.Println("Got CID: ", c)
Creating a CID from scratch
// Create a cid manually by specifying the 'prefix' parameters
pref := cid.Prefix{
Version: 1,
Codec: cid.Raw,
MhType: mh.SHA2_256,
MhLength: -1, // default length
}
// And then feed it some data
c, err := pref.Sum([]byte("Hello World!"))
if err != nil {...}
fmt.Println("Created CID: ", c)
Check if two CIDs match
// To test if two cid's are equivalent, be sure to use the 'Equals' method:
if c1.Equals(c2) {
fmt.Println("These two refer to the same exact data!")
}
Check if some data matches a given CID
// To check if some data matches a given cid,
// Get your CIDs prefix, and use that to sum the data in question:
other, err := c.Prefix().Sum(mydata)
if err != nil {...}
if !c.Equals(other) {
fmt.Println("This data is different.")
}
Contribute
PRs are welcome!
Small note: If editing the Readme, please conform to the standard-readme specification.
License
MIT © Jeromy Johnson