Adds support to open local repositories and to use file-based object storage (#55)v3.1.0

* remove some comments

* idx writer/reader

* Shut up ssh tests, they are annoying

* Add file scheme test to clients

* Add dummy file client

* Add test fot file client

* Make tests use fixture endpoint

* add parser for packed-refs format

* add parser for packed-refs format

* WIP adding dir.Refs() tests

* Add test for fixture refs

* refs parser for the refs directory

* Documentation

* Add Capabilities to file client

* tgz.Exatract now accpets a path instead of a Reader

* fix bug in idxfile fanout calculation

* remove dead code

* packfile documentation

* clean packfile parser code

* add core.Object.Content() and returns errors for core.ObjectStorage.Iter()

* add seekable storage

* add dir repos to NewRepository

* clean prints

* Add dir client documentation to README

* Organize the README

* README

* Clean tgz package

* Clean temp dirs after tgz tests

* Gometalinter on gitdir

* Clean pattern function

* metalinter tgz

* metalinter gitdir

* gitdir coverage and remove seekable packfile filedescriptor leak

* gitdir Idxfile tests and remove file descriptor leak

* gitdir Idxfile tests when no idx is found

* clean storage/seekable/internal/index and some formats/idxfile API issues

* clean storage/seekable

* clean formats/idx

* turn packfile/doc.go into packfile/doc.txt

* move formats/packfile/reader to decoder

* fix packfile decoder error names

* improve documentation

* comment packfile decoder errors

* comment public API (format/packfile)

* remve duplicated code in packfile decoder test

* move tracking_reader into an internal package and clean it

* use iota for packfile format

* rename packfile parse.go to packfile object_at.go

* clean packfile deltas

* fix delta header size bug

* improve delta documentation

* clean packfile deltas

* clean packfiles deltas

* clean repository.go

* Remove go 1.5 from Travis CI

Because go 1.5 does not suport internal packages.

* change local repo scheme to local://

* change "local://" to "file://" as the local scheme

* fix broken indentation

* shortens names of variables in short scopes

* more shortening of variable names

* more shortening of variable names

* Rename git dir client to "file", as the scheme used for it

* Fix file format ctor name, now that the package name has change

* Sortcut local repo constructor to not use remotes

The object storage is build directly in the repository ctor, instead
of creating a remote and waiting for the user to pull it.

* update README and fix some errors in it

* remove file scheme client

* Local respositories has now a new ctor

This is, they are no longer identified by the scheme of the URL, but are
created different from inception.

* remove unused URL field form Repository

* move all git dir logic to seekable sotrage ctor

* fix documentation

* Make formats/file/dir an internal package to storage/seekable

* change package storage/seekable to storage/fs

* clean storage/fs

* overall storage/fs clean

* more cleaning

* some metalinter fixes

* upgrade cshared to last changes

* remove dead code

* fix test error info

* remove file scheme check from clients

* fix test error message

* fix test error message

* fix error messages

* style changes

* fix comments everywhere

* style changes

* style changes

* scaffolding and tests for local packfiles without ifx files

* outsource index building from packfile to the packfile decoder

* refactor packfile header reading into a new function

* move code to generate index from packfile back to index package

* add header parsing

* fix documentation errata

* add undeltified and OFS delta support for index building from the packfile

* add tests for packfile with ref-deltas

* support for packfiles with ref-deltas and no idx

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* WIP refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* remove prints from tests

* remove prints from tests

* refactor packfile.core into packfile.parser

* rename packfile reader to something that shows it is a recaller

* rename cannot recall error

* rename packfile.Reader to packfile.ReadRecaller and document

* speed up test by using StreamReader instead of SeekableReader when possible

* clean packfile StreamReader

* stream_reader tests

* refactor packfile.StreamReader into packfile.StreamReadRecaller

* refactor packfile.SeekableReader into packfile.SeekableReadRecaller and document it

* generalize packfile.StreamReadRecaller test to all packfile.ReadRecaller implementations

* speed up storage/fs tests

* speed up tests in . by loading packfiles in memory

* speed up repository tests by using and smaller fixture

* restore doc.go files

* rename packfile.ReadRecaller implementations to shorter names

* update comments to type changes

* packfile.Parser test (WIP)

* packfile.Parser tests and add ForgetAll() to packfile.ReadRecaller

* add test for packfile.ReadRecaller.ForgetAll()

* clarify seekable being able to recallByOffset forgetted objects

* use better names for internal maps

* metalinter packfile package

* speed up some tests

* documentation fixes

* change storage.fs package name to storage.proxy to avoid confusion with new filesystem support

* New fs package and os transparent implementation

Now NewRepositoryFromFS receives a fs and a path and tests are
modified accordingly, but it is still not using for anything.

* add fs to gitdir and proxy.store

* reduce fs interface for easier implementation

* remove garbage dirs from tgz tests

* change file name gitdir/dir.go to gitdir/gitdir.go

* fs.OS tests

* metalinter utils/fs

* add NewRepositoryFromFS documentation to README

* Readability fixes to README

* move tgz to an external dependency

* move filesystem impl. example to example dir

* rename proxy/store.go to proxy/storage.go for coherence with memory/storage.go

* rename proxy package to seekable

1 files changed, 46 insertions, 25 deletions

diff --git a/repository.go b/repository.go
index 65e0a5d..c05afdb 100644
--- a/repository.go
+++ b/repository.go
@@ -8,6 +8,8 @@ import (
 	"gopkg.in/src-d/go-git.v3/core"
 	"gopkg.in/src-d/go-git.v3/formats/packfile"
 	"gopkg.in/src-d/go-git.v3/storage/memory"
+	"gopkg.in/src-d/go-git.v3/storage/seekable"
+	"gopkg.in/src-d/go-git.v3/utils/fs"
 )
 
 var (
@@ -24,29 +26,39 @@ const (
 type Repository struct {
 	Remotes map[string]*Remote
 	Storage core.ObjectStorage
-	URL     string
 }
 
 // NewRepository creates a new repository setting remote as default remote
 func NewRepository(url string, auth common.AuthMethod) (*Repository, error) {
-	var remote *Remote
-	var err error
-
-	if auth == nil {
-		remote, err = NewRemote(url)
-	} else {
-		remote, err = NewAuthenticatedRemote(url, auth)
-	}
+	repo := NewPlainRepository()
 
+	r, err := NewAuthenticatedRemote(url, auth)
+	repo.Remotes[DefaultRemoteName] = r
 	if err != nil {
 		return nil, err
 	}
 
-	r := NewPlainRepository()
-	r.Remotes[DefaultRemoteName] = remote
-	r.URL = url
+	return repo, nil
+}
+
+// NewRepositoryFromFS creates a new repository from an standard git
+// repository on disk.
+//
+// Repositories created like this don't hold a local copy of the
+// original repository objects, instead all queries are resolved by
+// looking at the original repository packfile. This is very cheap in
+// terms of memory and allows to process repositories bigger than your
+// memory.
+//
+// To be able to use git repositories this way, you must run "git gc" on
+// them beforehand.
+func NewRepositoryFromFS(fs fs.FS, path string) (*Repository, error) {
+	repo := NewPlainRepository()
 
-	return r, nil
+	var err error
+	repo.Storage, err = seekable.New(fs, path)
+
+	return repo, err
 }
 
 // NewPlainRepository creates a new repository without remotes
@@ -66,7 +78,7 @@ func (r *Repository) Pull(remoteName, branch string) (err error) {
 		return fmt.Errorf("unable to find remote %q", remoteName)
 	}
 
-	if err := remote.Connect(); err != nil {
+	if err = remote.Connect(); err != nil {
 		return err
 	}
 
@@ -89,13 +101,12 @@ func (r *Repository) Pull(remoteName, branch string) (err error) {
 		return err
 	}
 	defer checkClose(reader, &err)
+	stream := packfile.NewStream(reader)
 
-	pr := packfile.NewReader(reader)
-	if _, err = pr.Read(r.Storage); err != nil {
-		return err
-	}
+	d := packfile.NewDecoder(stream)
+	err = d.Decode(r.Storage)
 
-	return nil
+	return err
 }
 
 // PullDefault like Pull but retrieve the default branch from the default remote
@@ -118,8 +129,13 @@ func (r *Repository) Commit(h core.Hash) (*Commit, error) {
 }
 
 // Commits decode the objects into commits
-func (r *Repository) Commits() *CommitIter {
-	return NewCommitIter(r, r.Storage.Iter(core.CommitObject))
+func (r *Repository) Commits() (*CommitIter, error) {
+	iter, err := r.Storage.Iter(core.CommitObject)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewCommitIter(r, iter), nil
 }
 
 // Tree return the tree with the given hash
@@ -160,14 +176,19 @@ func (r *Repository) Tag(h core.Hash) (*Tag, error) {
 		return nil, err
 	}
 
-	tag := &Tag{r: r}
-	return tag, tag.Decode(obj)
+	t := &Tag{r: r}
+	return t, t.Decode(obj)
 }
 
 // Tags returns a TagIter that can step through all of the annotated tags
 // in the repository.
-func (r *Repository) Tags() *TagIter {
-	return NewTagIter(r, r.Storage.Iter(core.TagObject))
+func (r *Repository) Tags() (*TagIter, error) {
+	iter, err := r.Storage.Iter(core.TagObject)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewTagIter(r, iter), nil
 }
 
 // Object returns an object with the given hash.