# HG changeset patch # User Arne Babenhauserheide # Date 1332866118 -7200 # Node ID f86ed5a82723d0ee2fcd6b14621eb5e32bf21a3e # Parent 7151691b85efdd0bf2d2bcbbff7820e8a2de15bf docs: some fixes on the index and the first half of the obsolete concepts. diff -r 7151691b85ef -r f86ed5a82723 docs/index.rst --- a/docs/index.rst Tue Mar 27 17:29:16 2012 +0200 +++ b/docs/index.rst Tue Mar 27 18:35:18 2012 +0200 @@ -60,9 +60,9 @@ To enable the evolve extension use:: $ hg clone http://hg-dev.octopoid.net/hgwebdir.cgi/mutable-history/ - $ mutable-history/enable.sh > ~/.hgrc + $ mutable-history/enable.sh >> ~/.hgrc -You will probably want to use the associated version of hgview (QT viewer only) +You will probably want to use the associated version of hgview (QT viewer only):: $ hg clone http://hg-dev.octopoid.net/hgwebdir.cgi/hgview/ $ cd hgview diff -r 7151691b85ef -r f86ed5a82723 docs/obs-concept.rst --- a/docs/obs-concept.rst Tue Mar 27 17:29:16 2012 +0200 +++ b/docs/obs-concept.rst Tue Mar 27 18:35:18 2012 +0200 @@ -1,17 +1,17 @@ ------------------------------------------------------------ -Why Do We Need a New Concept ------------------------------------------------------------ +============================== + Why Do We Need a New Concept +============================== Current DVCS are great tool to forge a series of flawless changeset on your own. -But they perform poorly whe is comes to **share** work in progress and +But they perform poorly when is comes to **share** work in progress and **collaborate** on such work in progress. When people forge new version of a changeset they create a new changeset and get -ride of the original changeset. Difficultis to collaborate mostly came from the +ride of the original changeset. Difficulties to collaborate mostly came from the way old content are *removed* from repository. Mercurial Approach: Strip ------------------------------------------------------ +========================= With current version of mercurial, every changesets that exist in your repository are *visible* and *meaningful*. To get ride of old changeset you @@ -19,7 +19,7 @@ called *strip*. After the *strip* the repository looks like if the changeset never existed. -This approach is simple and effective but have a very big drawnback: You can +This approach is simple and effective but have a very big drawback: You can remove changesets from **your repository only**. If strip exists in other repositories it will show of again and again. This only cure for this is to strip the offending changeset from all repository. And operation at best @@ -29,23 +29,22 @@ As consequence, **you can not rewrite something once you exchange it with others**. The old version will still exists along side the new one [#]_. -Moreover backup are create stripped changeset in most case. This allow -restoration of old changeset but the process is painful. +Moreover stripping changesets creates backup bundles. This allows +restoration of the deleted changesets, but the process is painful. Finally, as the repository format is not optimized for deletion. stripping a -changeset may be slow in some situation. - +changeset may be slow in some situations. To sum up, the strip approach is very simple but does not handle interaction with the outer world. Which is unfortunate for a *Distributed* VCS. -.. [#] various work around exists but they are work around with their own flow. +.. [#] various work around exists but they require their own workflows which are distinct from the very elegant basic workflow of Mercurial. Git Approach: Overwrite Reference ------------------------------------------------------ +================================= -Git approach for repository is a bit more complex: They can be any amount of -changeset can exist in a repository. but **only changesets referenced by a git +Git approach for repository is a bit more complex: Any number of +changesets can exist in a repository. but **only changesets referenced by a git branch** are *visible* and *meaningful*. @@ -59,51 +58,51 @@ Only B and A are visible. -This ease the process of getting ride of old changeset. You can just leave them -in place and move the reference on the new one. You can then propagate those -change by moving the git-branch on remote host, newer version overwritting the -older one. +This simplifies the process of getting rid of old changesets. You can +just leave them in place and move the reference on the new one. You +can then propagate that change by moving the git-branch on remote host +with the newer version of the marker overwriting the older one. -This approach goes a bit further but still have major drawback: +This approach goes a bit further but still has a major drawback: -Because you **overwrite** git-branch you have no conflit resolution. The last -to spoke win. This make collaboration on multiple changeset difficult because -you can't merge concurent update on changeset. +Because you **overwrite** the git-branch, you have no conflict resolution. The last +to act wins. This makes collaboration on multiple changesets difficult because +you can't merge concurrent updates on a changeset. -Every overwrite is forced operation where the operator say "Yes I want this to -replace that. On higly distributed environment user may end with conflicting -reference with and no proper way to choose. +Every overwrite is a forced operation where the operator say "Yes I want this to +replace that. In highly distributed environments, a user may end up with conflicting +references and no proper way to choose. -Because of this way to visualize a repository, git-branches are a very core -part of git. This make user interface more complicated and move through history -more constrainted. +Because of this way to visualize a repository, git-branches are a core +part of git, which makes the user interface more complicated and +constrains the ways to move through history. -Finally, even if all older changeset still exist in the repository acces to them +Finally, even if all older changeset still exist in the repository, access to them is still painful. ------------------------------------------------------ -The Obsolete Marker Concept ------------------------------------------------------ +============================= + The Obsolete Marker Concept +============================= -As None of the concept was powerful enough to embrace the need to safely rewrite -history, easily share and collaborate on mutable history we needed another one. +As None of the concepts was powerful enough to fulfill the need of safely rewriting +history, including easy sharing and collaborating on mutable history, we needed another one. Basic concept ------------------------------------------------------ +============= -Every history rewriting operation stores the information that old rewritten -changesets has newer version available in a set of changeset. +Every history rewriting operation stores the information that the old rewritten +changeset is replaced by newer version in a given set of changeset. -All basic history rewriting operation can create a appropriate obsolete marker. +All basic history rewriting operation can create an appropriate obsolete marker. .. figure:: ./figures/example-1-update.* @@ -147,16 +146,15 @@ changesets to **1** old changeset. Basic Usage ------------------------------------------------------ +=========== -Obsolete markers create a perpendicular history: **a versionned version of the -changeset graph**. This means that we can have the same feature we have for +Obsolete markers create a perpendicular history: **a versioned changeset graph**. This means that offers the same features we have for versioned files but applied to changeset: -First: we can display a **coherent view** of the history graph with only a -single version of your changeset are displayed by the UI. +First: we can display a **coherent view** of the history graph in which only a +single version of your changesets are displayed by the UI. -Second, because obsolete changeset content are still **available**. You can +Second, because obsolete changeset content is still **available**. You can * **browse** the content of your obsolete commit, @@ -173,49 +171,49 @@ Detecting and solving tricky situation ------------------------------------------------------ +====================================== -History rewriting can lead to complex situation. Obsolete marker introduce a -simple representation this complex reality. But people using complex workflow -will one day or another you have to face the intrinsics complexity of some -situation. +History rewriting can lead to complex situations. Obsolete marker introduce a +simple representation of this complex reality. But people using complex workflows +will one day or another have to face the intrinsic complexity of some +situations. -This section describe possible situations, define precise set of changesets -involved in such situation and explains how error case can we automatically +This section describes possible situations, defines precise sets of changesets +involved in such situations and explains how error cases can automatically be resolved using available information. obsolete changesets -```````````````````` +------------------- -Old changesets left behind by obsolete operation are said **obsolete**. +Old changesets left behind by obsolete operation are called **obsolete**. -With current version of mercurial, this *obsolete* part is stripped from the -repository before the end of every rewritting operation. +With the current version of mercurial, this *obsolete* part is stripped from the +repository before the end of every rewriting operation. .. figure:: ./figures/error-obsolete.* Rebasing `B` and `C` on `A` (as `B'`, `C'`) This rebase operation added two obsolete markers from new changesets to old - changesets. These Two old changesets are now part of the *obsolete* part of the + changesets. These two old changesets are now part of the *obsolete* part of the history. -In most case the obsolete set will be fully hidden to both UI and discovery so -user do not have to care about them unless he wants to audit history rewriting +In most cases, the obsolete set will be fully hidden to both UI and discovery so +the user does not have to care about them unless he wants to audit the history rewriting operation. Unstable changesets -``````````````````` +------------------- -While exploring obsolete marker possibility a bit further you way end up with -*obsolete* changeset with *non-obsolete* children. There is two common ways to +While exploring the possibilities of the obsolete a bit further, you may end up with +*obsolete* changeset which have *non-obsolete* children. There is two common ways to achieve this: * Pull a changeset based of an old version of a changeset [#]_. * Use a partial rewriting operation. For example amend on a changeset with - childrens. + children. *Non-obsolete* changeset based on *obsolete* one are said **unstable** @@ -248,7 +246,7 @@ changeset. See phase help for details. The two part of the obsolete set -`````````````````````````````````````` +-------------------------------- The previous section show that it could be two kinds of *obsolete* changeset: @@ -274,7 +272,7 @@ Conflicting rewriting -`````````````````````` +--------------------- If people start to concurrently edit the same part of the history they will likely meet conflicting situation when a changeset have been rewritten in two @@ -298,7 +296,7 @@ splitted changeset from history rewriting conflict. Reliable history -`````````````````````` +---------------- Obsolete marker really help to smooth rewriting operation process. However they do not change the fact that **you should only rewrite the mutable part of the @@ -325,7 +323,7 @@ Conclusion ----------------- +========== Obsolete marker is a powerful concept that allow mercurial to safely handle history rewriting operations. It is a new type of relation between Mercurial @@ -336,7 +334,7 @@ - Very fast history rewriting operations, -- auditable and reversible history rewritting process, +- auditable and reversible history rewriting process, - clean final history,