116.213.116.68 at 11:17, 27 July 2015

2015-07-27T11:17:29Z

New page

[[Category:Git|060]]

== GIT under the bonnet ==
* Object Database
* SHA1
* DAG (Directed Acyclical Graph)
* Index

== Object Types ==
'''blob'''
*store file data
'''tree'''
*ties one or more "blob" objects into a directory structure
*a tree object can refer to other tree objects, thus creating a directory hierarchy
'''commit'''
*ties such directory hierarchies together into a directed acyclic graph (DAG) of revisions
*each commit contains the object name of exactly one tree (snapshot of the tree)
*a commit refers to "parent" commit objects that describe the history of how we arrived at that directory hierarchy
'''tag'''
*symbolically identifies and can be used to sign other objects
*It contains
**object name (SHA1, e.g. 232A...)
**type of another object
**a symbolic name (e.g. version 1.0.1)
**optionally, a signature (PGP or GPG)

== Directed Acyclic Graph (DAG) ==
{| class="wikitable"
|-
| [[File:Git-dag.png|250px]]
||
*Stored as a '''linked list'''
*Uses SHA1 as references
*One root (object without parents)
*Multiple parents allowed
**merge (2 parents)
**octopus merge (3 or more)
|}

'''DAG and gitk'''

[[File:Git-gitk.png|500px]]

'''DAG and Git objects'''

[[File:Git-dag-git-o.png|350px]]

Git - Under the Bonnet - Revision history

116.213.116.68 at 11:17, 27 July 2015