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  \end{frame}
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\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[expert]{lucidabr}

\title{Mercurial}
\author{Martin Geisler}

\newcommand{\hgcmd}[1]{\texttt{\color{green!50!black}#1}}
\newcommand{\hgext}[1]{\texttt{#1}}

\begin{document}

\begin{frame}
  \maketitle
\end{frame}

\begin{frame}{Outline}
  \tableofcontents
\end{frame}

\section{Introduction}

\subsection{Basic Concepts}

\begin{frame}{What do we want from a version control system?}
  Very basic features:
  \begin{itemize}
  \item let you save changes
  \item browser the history
  \end{itemize}

  \pause
  Basic features:
  \begin{itemize}
  \item collaboration
  \item branches
  \item tags
  \end{itemize}

  \pause
  Nice features:
  \begin{itemize}
  \item speed!
  \item much more, as you will see\dots
  \end{itemize}
\end{frame}

\begin{frame}{Branches}
  A central concept:
  \begin{itemize}
  \item parallel lines of development
  \item used to track releases
  \item used to isolate disruptive changes
  \end{itemize}

  \begin{tikzpicture}
    \path[use as bounding box] (0, -1.5) rectangle (10, 1.5);

    \tikzstyle{branch}=[blue!60, ->, >=latex, line join=round]
    \tikzstyle{tag}=[draw=yellow!50!orange, fill=yellow!50]

    \draw<2->[->] (0, -1) -- +(10, 0) node[below left] {time};

    \draw<5>[branch, blue!30, line width=2mm]
      (v10) -- ++(1,1)
            -- coordinate[pos=0.4] (v101) ++(3,0);

    \draw<6->[branch, blue!30, line width=2mm]
      (v10) -- ++(1,1)
            -- coordinate[pos=0.2] (v101)
               coordinate[pos=0.7] (v102) ++(6,0);

    \draw<2-3>[branch, line width=3mm]
      (0,0) -- coordinate[pos=0.4] (v10) +(2.5,0);

    \draw<4-6>[branch, line width=3mm]
      (0,0) -- coordinate[pos=0.2] (v10) +(5,0);

    \draw<3-> (v10) ++(0, 0.3) -- ++(0, -0.6) node[below, tag] {1.0};
    \draw<5-> (v101) ++(0, 0.2) -- +(0, -0.4) node[below, tag] {1.0.1};
    \draw<6-> (v102) ++(0, 0.2) -- +(0, -0.4) node[below, tag] {1.0.2};
  \end{tikzpicture}
\end{frame}

\begin{frame}{Merging}
  The oposite of branching:
  \begin{itemize}
  \item combines two branches
  \item used to merge back bugfixes
  \item used to integrate feature branches
  \end{itemize}

  \begin{tikzpicture}
    \path[use as bounding box] (0, -1.5) rectangle (10, 1.5);

    \tikzstyle{branch}=[blue!60, ->, >=latex, line join=round]
    \tikzstyle{tag}=[draw=yellow!50!orange, fill=yellow!50]

    \draw[->] (0, -1) -- +(10, 0) node[below left] {time};

    \draw<1-2>[branch, blue!30, line width=2mm]
      (v10) -- ++(1,1)
            -- coordinate[pos=0.2] (v101)
               coordinate[pos=0.7] (v102) ++(6,0);

    \draw<3->[branch, blue!30, line width=2mm]
      (v10) -- ++(1,1)
            -- coordinate[pos=0.2] (v101)
               coordinate[pos=0.7] (v102) ++(6,0)
            -- +(1, -1);

    \draw<2->[branch, blue!30, line width=2mm]
      (v101) ++(0.8, 0) -- +(1,-1);

    \draw<1>[branch, line width=3mm]
      (0,0) -- coordinate[pos=0.2] (v10) +(5,0);

    \draw<2>[branch, line width=3mm]
      (0,0) -- coordinate[pos=0.125] (v10) +(8,0);

    \draw<3>[branch, line width=3mm]
      (0,0) -- coordinate[pos=0.1] (v10) +(10,0);

    \draw<1-> (v10) ++(0, 0.3) -- ++(0, -0.6) node[below, tag] {1.0};
    \draw<1-> (v101) ++(0, 0.2) -- +(0, -0.4) node[below, tag] {1.0.1};
    \draw<1-> (v102) ++(0, 0.2) -- +(0, -0.4) node[below, tag] {1.0.2};
  \end{tikzpicture}
\end{frame}



\subsection{Historic Context}

\begin{frame}{Revision Control System (RCS)}
  Version control from the 1980s:
  \begin{itemize}
  \item store changes (date, commit message)
  \item browse history
  \end{itemize}

  \bigskip

  \begin{tikzpicture}
    \begin{scope}[start chain]
      \node<2->[on chain,left] at (0, 0.5) {hello.c};
      \node<3->[on chain,xshift=-8mm, rev] {};
      \node<4->[on chain,join,rev] {};
      \node<5->[on chain,join,rev] {};
    \end{scope}
    \begin{scope}[start chain]
      \node<2->[on chain,left] at (0, 0) {Makefile};
      \node<3->[on chain,xshift=-8mm,rev] {};
      \node<6->[on chain,join,rev] {};
    \end{scope}
  \end{tikzpicture}
\end{frame}

\begin{frame}{Concurrent Versions System (CVS)}
  Version control in the 1990s:
  \begin{itemize}
  \item collaboration over the network
  \item several working copies
  \item one central repository
  \end{itemize}

  \pause

  \begin{center}
  \begin{tikzpicture}
    \begin{scope}[start chain, node distance=16mm]
      \node[working copy, on chain, label=above:Alice] (Alice)
           {hello.c\\ Makefile};
      \node[repository, on chain, label=above:CVS Server] (repository) {};
      \node[working copy, on chain, label=above:Bob] (Bob)
           {hello.c\\ Makefile};
    \end{scope}

    \begin{scope}[scale=0.5,transform shape]
      \begin{scope}[start chain]
        \node[on chain,left, yshift=3mm, xshift=-2mm] at (repository)
             {hello.c};
        \node[on chain,xshift=-8mm,rev] {};
        \node[on chain,join,rev] {};
      \end{scope}
      \begin{scope}[start chain]
        \node[on chain,left, yshift=-3mm, xshift=-2mm] at (repository)
             {Makefile};
        \node[on chain,xshift=-8mm,rev] {};
        \node<3->[on chain,join,rev] {};
      \end{scope}
    \end{scope}

    \draw<3>[->] (Alice) -- node[above] {commit} (repository);
    \draw<4>[->] (repository) -- node[above] {update} (Bob);
  \end{tikzpicture}
  \end{center}
\end{frame}

\begin{frame}{So, everything is good?}
  CVS has many limitations:
  \begin{itemize}
  \item no atomic commits
  \item no rename information
  \item branches? I hope you have a CVS guru at hand\dots
  \end{itemize}
\end{frame}

\begin{frame}{Subversion (SVN)}
  Version control from this millennia --- ``\emph{CVS done right}'':
  \begin{itemize}
  \item atomic commits
  \item tracks renames
  \item supports some operations without network access
  \end{itemize}
\end{frame}

\begin{frame}{Branches in SVN}
  Subversion knows nothing about branches!
  \begin{itemize}
  \item but SVN has a cheap copy mechanism
  \item used for tags and branches
  \end{itemize}

  \begin{tikzpicture}
    \node<2->[working copy, below, text width=20mm, label=above:r10]
             (a) at (0, 0) {
      trunk/\\
      \quad hello.c\\
      \quad Makefile\\
      branches/
    };
    \node<3->[working copy, below, text width=25mm, label=above:r11]
             (b) at (3.5, 0) {
      trunk/\\
      \quad hello.c\\
      \quad Makefile\\
      branches/\\
      \quad goodbye/\\
      \qquad hello.c\\
      \qquad Makefile\\
    };
    \node<4->[working copy, below, text width=30mm, label=above:r12]
             (c) at (7.5, 0) {
      trunk/\\
      \quad hello.c\\
      \quad Makefile\\
      branches/\\
      \quad goodbye/\\
      \qquad hello.c\\
      \qquad goodbye.c\\
      \qquad Makefile\\
    };

    \tikzstyle{s}=[yshift=-5mm]
    \tikzstyle{every pin edge}=[draw, red, <-]

    \draw<3->[->] ([s] a.north east) -- ([s] b.north west);
    \draw<4->[->] ([s] b.north east) -- ([s] c.north west);
  \end{tikzpicture}
\end{frame}

\begin{frame}{Merging Branches in SVN}
  Branches are only interesting if you can merge them:
  \begin{itemize}
  \item before SVN 1.5: no built-in support for merging(!)
  \item SVN 1.5 and later: tracks info needed for merging
  \end{itemize}

  \pause

  \begin{center}
  \begin{tikzpicture}
    \node[draw=structure, fill=structure!20!white, text justified,
      text width=0.9\textwidth, font=\small] {The bottom line is that
      Subversion's merge-tracking feature has an \alert{extremely
        complex} internal implementation, and the
      \texttt{svn:mergeinfo} property is the only window the user has
      into the machinery. Because the feature is \alert{relatively
        new}, a numbers of edge cases and possible unexpected
      behaviors may pop up. \hfill\itshape ---Version Control with
      Subversion};
  \end{tikzpicture}
  \end{center}

  (Mercurial has robust built-in support for merging branches.)
\end{frame}


%% \begin{frame}{Basic Version Control}
%%   Working alone:
%%   \begin{itemize}
%%   \item store changes (date, commit message)
%%   \item browse history
%%   \end{itemize}
%%   (RCS did this in the 1980s)
%% \end{frame}
%%
%% \begin{frame}{Working with Others}
%%   Distributing changes:
%%   \begin{itemize}
%%   \item get new changes from a server
%%   \item send new commits to a server
%%   \item \emph{resolve} conflicts between you and server
%%   \end{itemize}
%%   (CVS did this in 1990s)
%% \end{frame}


\section{Using Mercurial}

\subsection{Getting Started}

\begin{frame}
  \begin{center}
    \vfill
    \huge\bfseries Live Demo!
    \vfill
    \hyperlink{after-basics}{\beamerskipbutton{continue}}
  \end{center}
\end{frame}

\begin{frame}[fragile]{Getting Started}
  We will create a \path{hello-world} project:
\begin{lstlisting}
% hg init hello-world
% cd hello-world
\end{lstlisting}

A new repository is of course empty:
\begin{lstlisting}
% hg log
\end{lstlisting}
and has a clean status:
\begin{lstlisting}
% hg status
\end{lstlisting}
\end{frame}

\begin{frame}[fragile]{Adding Files}
  We copy some ready-made files into the working coyp:
\begin{lstlisting}
% cp ../hello-files/* .
% hg status
? Makefile
? hello.c
\end{lstlisting}

Put the new files under revision control:
\begin{lstlisting}
% hg add
adding Makefile
adding hello.c
% hg status
A Makefile
A hello.c
\end{lstlisting}
\end{frame}

\begin{frame}[fragile]{Making a Commit}
We can now commit the changes shown by \hgcmd{hg status}:
\begin{lstlisting}
% hg commit -m "Imported source code."
\end{lstlisting}

The changeset is shown in \hgcmd{hg log}:
\begin{lstlisting}
% hg log
changeset:   0:9cef08a0e941
tag:         tip
user:        Martin Geisler <mg@lazybytes.net>
date:        Sun Aug 16 00:22:11 2009 +0200
summary:     Imported source code.
\end{lstlisting}
\end{frame}

\begin{frame}[fragile]{Examining Differences}
Change the output from ``hello, world'' to ``Hello World!''.

Mercurial will list the file as changed:
\begin{lstlisting}
% hg status
M hello.c
\end{lstlisting}
and can list the change:
\begin{lstlisting}
% hg diff
diff -r 9cef08a0e941 hello.c
--- a/hello.c   Sun Aug 16 00:22:11 2009 +0200
+++ b/hello.c   Sun Aug 16 01:21:15 2009 +0200
@@ -1,5 +1,5 @@
 #include <stdio.h>
 
 int main(void) {
-    printf("hello, world\n");
+    printf("Hello World!\n");
 }
\end{lstlisting}

\end{frame}


\begin{frame}{Settings}
\end{frame}

\subsection{Working with a Repository}

\begin{frame}{Committing Changes}
\end{frame}

\subsection{Working with Remote Repositories}

\begin{frame}{Pushing and Pulling}
\end{frame}

\begin{frame}{Merging}
\end{frame}

\begin{frame}[label=after-basics]{Consistency and Subversion}
\end{frame}

\section{Cool Extensions}

\begin{frame}{Mercurial is Pluggable}
\end{frame}

\subsection{Changing History}

\begin{frame}{Moving Changesets Around}
  The \hgext{rebase} extension
\end{frame}

\begin{frame}{Maintaining Patch Series}
  The \hgext{mq} extesion
\end{frame}

\begin{frame}{Editing History}
  The \hgext{histedit} extension
\end{frame}

\subsection{Migrating History}

\begin{frame}{Migrating History}
  The \hgext{convert} extension can import history:
  \begin{itemize}
    \item CVS, SVN, Git, \dots
    \item incremental conversion
  \end{itemize}
\end{frame}

\subsection{Bi-Directional Gateways}

\begin{frame}{Interfacing with Subversion}
\end{frame}

\begin{frame}{Interfacing with Git}
\end{frame}

\section{Conclusion}

\begin{frame}{Mercurial in a Nutshell}
\begin{itemize}
\item elegance
\end{itemize}
\end{frame}

\subsection{More Information}

\begin{frame}{More Information}
  \begin{itemize}
  \item Mercurial homepage: \url{http://mercurial.selenic.com/}
  \end{itemize}
\end{frame}


\end{document}

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