(*:maxLineLen=78:*)
theory Sessions
imports Base
begin
chapter \<open>Isabelle sessions and build management \label{ch:session}\<close>
text \<open>
An Isabelle \<^emph>\<open>session\<close> consists of a collection of related theories that may
be associated with formal documents (\chref{ch:present}). There is also a
notion of \<^emph>\<open>persistent heap\<close> image to capture the state of a session,
similar to object-code in compiled programming languages. Thus the concept
of session resembles that of a ``project'' in common IDE environments, but
the specific name emphasizes the connection to interactive theorem proving:
the session wraps-up the results of user-interaction with the prover in a
persistent form.
Application sessions are built on a given parent session, which may be built
recursively on other parents. Following this path in the hierarchy
eventually leads to some major object-logic session like \<open>HOL\<close>, which itself
is based on \<open>Pure\<close> as the common root of all sessions.
Processing sessions may take considerable time. Isabelle build management
helps to organize this efficiently. This includes support for parallel build
jobs, in addition to the multithreaded theory and proof checking that is
already provided by the prover process itself.
\<close>
section \<open>Session ROOT specifications \label{sec:session-root}\<close>
text \<open>
Session specifications reside in files called \<^verbatim>\<open>ROOT\<close> within certain
directories, such as the home locations of registered Isabelle components or
additional project directories given by the user.
The ROOT file format follows the lexical conventions of the \<^emph>\<open>outer syntax\<close>
of Isabelle/Isar, see also @{cite "isabelle-isar-ref"}. This defines common
forms like identifiers, names, quoted strings, verbatim text, nested
comments etc. The grammar for @{syntax session_chapter} and @{syntax
session_entry} is given as syntax diagram below; each ROOT file may contain
multiple specifications like this. Chapters help to organize browser info
(\secref{sec:info}), but have no formal meaning. The default chapter is
``\<open>Unsorted\<close>''.
Isabelle/jEdit @{cite "isabelle-jedit"} includes a simple editing mode
\<^verbatim>\<open>isabelle-root\<close> for session ROOT files, which is enabled by default for any
file of that name.
@{rail \<open>
@{syntax_def session_chapter}: @'chapter' @{syntax name}
;
@{syntax_def session_entry}: @'session' spec '=' (@{syntax name} '+')? body
;
body: description? options? (theories+) \<newline> (document_files*)
;
spec: @{syntax name} groups? dir?
;
groups: '(' (@{syntax name} +) ')'
;
dir: @'in' @{syntax name}
;
description: @'description' @{syntax text}
;
options: @'options' opts
;
opts: '[' ( (@{syntax name} '=' value | @{syntax name}) + ',' ) ']'
;
value: @{syntax name} | @{syntax real}
;
sessions: @'sessions' (@{syntax name}+)
;
theories: @'theories' opts? (theory_entry*)
;
theory_entry: @{syntax name} ('(' @'global' ')')?
;
document_files: @'document_files' ('(' dir ')')? (@{syntax name}+)
\<close>}
\<^descr> \isakeyword{session}~\<open>A = B + body\<close> defines a new session \<open>A\<close> based on
parent session \<open>B\<close>, with its content given in \<open>body\<close> (imported sessions and
theories). Note that a parent (like \<open>HOL\<close>) is mandatory in practical
applications: only Isabelle/Pure can bootstrap itself from nothing.
All such session specifications together describe a hierarchy (graph) of
sessions, with globally unique names. The new session name \<open>A\<close> should be
sufficiently long and descriptive to stand on its own in a potentially large
library.
\<^descr> \isakeyword{session}~\<open>A (groups)\<close> indicates a collection of groups where
the new session is a member. Group names are uninterpreted and merely follow
certain conventions. For example, the Isabelle distribution tags some
important sessions by the group name called ``\<open>main\<close>''. Other projects may
invent their own conventions, but this requires some care to avoid clashes
within this unchecked name space.
\<^descr> \isakeyword{session}~\<open>A\<close>~\isakeyword{in}~\<open>dir\<close> specifies an explicit
directory for this session; by default this is the current directory of the
\<^verbatim>\<open>ROOT\<close> file.
All theory files are located relatively to the session directory. The prover
process is run within the same as its current working directory.
\<^descr> \isakeyword{description}~\<open>text\<close> is a free-form annotation for this
session.
\<^descr> \isakeyword{options}~\<open>[x = a, y = b, z]\<close> defines separate options
(\secref{sec:system-options}) that are used when processing this session,
but \<^emph>\<open>without\<close> propagation to child sessions. Note that \<open>z\<close> abbreviates \<open>z =
true\<close> for Boolean options.
\<^descr> \isakeyword{sessions}~\<open>names\<close> specifies sessions that are \<^emph>\<open>imported\<close> into
the current name space of theories. This allows to refer to a theory \<open>A\<close>
from session \<open>B\<close> by the qualified name \<open>B.A\<close> --- although it is loaded again
into the current ML process, which is in contrast to a theory that is
already present in the \<^emph>\<open>parent\<close> session.
Theories that are imported from other sessions are excluded from the current
session document.
\<^descr> \isakeyword{theories}~\<open>options names\<close> specifies a block of theories that
are processed within an environment that is augmented by the given options,
in addition to the global session options given before. Any number of blocks
of \isakeyword{theories} may be given. Options are only active for each
\isakeyword{theories} block separately.
A theory name that is followed by \<open>(\<close>\isakeyword{global}\<open>)\<close> is treated
literally in other session specifications or theory imports. In contrast,
the default is to qualify theory names by the session name, in order to
ensure globally unique names in big session graphs.
\<^descr> \isakeyword{document_files}~\<open>(\<close>\isakeyword{in}~\<open>base_dir) files\<close> lists
source files for document preparation, typically \<^verbatim>\<open>.tex\<close> and \<^verbatim>\<open>.sty\<close> for
{\LaTeX}. Only these explicitly given files are copied from the base
directory to the document output directory, before formal document
processing is started (see also \secref{sec:tool-document}). The local path
structure of the \<open>files\<close> is preserved, which allows to reconstruct the
original directory hierarchy of \<open>base_dir\<close>.
\<^descr> \isakeyword{document_files}~\<open>files\<close> abbreviates
\isakeyword{document_files}~\<open>(\<close>\isakeyword{in}~\<open>document) files\<close>, i.e.\
document sources are taken from the base directory \<^verbatim>\<open>document\<close> within the
session root directory.
\<close>
subsubsection \<open>Examples\<close>
text \<open>
See \<^file>\<open>~~/src/HOL/ROOT\<close> for a diversity of practically relevant situations,
although it uses relatively complex quasi-hierarchic naming conventions like
\<^verbatim>\<open>HOL-SPARK\<close>, \<^verbatim>\<open>HOL-SPARK-Examples\<close>. An alternative is to use unqualified
names that are relatively long and descriptive, as in the Archive of Formal
Proofs (\<^url>\<open>http://afp.sourceforge.net\<close>), for example.
\<close>
section \<open>System build options \label{sec:system-options}\<close>
text \<open>
See \<^file>\<open>~~/etc/options\<close> for the main defaults provided by the Isabelle
distribution. Isabelle/jEdit @{cite "isabelle-jedit"} includes a simple
editing mode \<^verbatim>\<open>isabelle-options\<close> for this file-format.
The following options are particularly relevant to build Isabelle sessions,
in particular with document preparation (\chref{ch:present}).
\<^item> @{system_option_def "browser_info"} controls output of HTML browser
info, see also \secref{sec:info}.
\<^item> @{system_option_def "document"} specifies the document output format,
see @{tool document} option \<^verbatim>\<open>-o\<close> in \secref{sec:tool-document}. In
practice, the most relevant values are \<^verbatim>\<open>document=false\<close> or
\<^verbatim>\<open>document=pdf\<close>.
\<^item> @{system_option_def "document_output"} specifies an alternative
directory for generated output of the document preparation system; the
default is within the @{setting "ISABELLE_BROWSER_INFO"} hierarchy as
explained in \secref{sec:info}. See also @{tool mkroot}, which generates a
default configuration with output readily available to the author of the
document.
\<^item> @{system_option_def "document_variants"} specifies document variants as
a colon-separated list of \<open>name=tags\<close> entries, corresponding to @{tool
document} options \<^verbatim>\<open>-n\<close> and \<^verbatim>\<open>-t\<close>.
For example, \<^verbatim>\<open>document_variants=document:outline=/proof,/ML\<close> indicates
two documents: the one called \<^verbatim>\<open>document\<close> with default tags, and the other
called \<^verbatim>\<open>outline\<close> where proofs and ML sections are folded.
Document variant names are just a matter of conventions. It is also
possible to use different document variant names (without tags) for
different document root entries, see also \secref{sec:tool-document}.
\<^item> @{system_option_def "threads"} determines the number of worker threads
for parallel checking of theories and proofs. The default \<open>0\<close> means that a
sensible maximum value is determined by the underlying hardware. For
machines with many cores or with hyperthreading, this is often requires
manual adjustment (on the command-line or within personal settings or
preferences, not within a session \<^verbatim>\<open>ROOT\<close>).
\<^item> @{system_option_def "checkpoint"} helps to fine-tune the global heap
space management. This is relevant for big sessions that may exhaust the
small 32-bit address space of the ML process (which is used by default).
When the option is enabled for some \isakeyword{theories} block, a full
sharing stage of immutable values in memory happens \<^emph>\<open>before\<close> loading the
specified theories.
\<^item> @{system_option_def "condition"} specifies a comma-separated list of
process environment variables (or Isabelle settings) that are required for
the subsequent theories to be processed. Conditions are considered
``true'' if the corresponding environment value is defined and non-empty.
\<^item> @{system_option_def "timeout"} and @{system_option_def "timeout_scale"}
specify a real wall-clock timeout for the session as a whole: the two
values are multiplied and taken as the number of seconds. Typically,
@{system_option "timeout"} is given for individual sessions, and
@{system_option "timeout_scale"} as global adjustment to overall hardware
performance.
The timer is controlled outside the ML process by the JVM that runs
Isabelle/Scala. Thus it is relatively reliable in canceling processes that
get out of control, even if there is a deadlock without CPU time usage.
\<^item> @{system_option_def "profiling"} specifies a mode for global ML
profiling. Possible values are the empty string (disabled), \<^verbatim>\<open>time\<close> for
@{ML profile_time} and \<^verbatim>\<open>allocations\<close> for @{ML profile_allocations}.
Results appear near the bottom of the session log file.
The @{tool_def options} tool prints Isabelle system options. Its
command-line usage is:
@{verbatim [display]
\<open>Usage: isabelle options [OPTIONS] [MORE_OPTIONS ...]
Options are:
-b include $ISABELLE_BUILD_OPTIONS
-g OPTION get value of OPTION
-l list options
-x FILE export to FILE in YXML format
Report Isabelle system options, augmented by MORE_OPTIONS given as
arguments NAME=VAL or NAME.\<close>}
The command line arguments provide additional system options of the form
\<open>name\<close>\<^verbatim>\<open>=\<close>\<open>value\<close> or \<open>name\<close> for Boolean options.
Option \<^verbatim>\<open>-b\<close> augments the implicit environment of system options by the ones
of @{setting ISABELLE_BUILD_OPTIONS}, cf.\ \secref{sec:tool-build}.
Option \<^verbatim>\<open>-g\<close> prints the value of the given option. Option \<^verbatim>\<open>-l\<close> lists all
options with their declaration and current value.
Option \<^verbatim>\<open>-x\<close> specifies a file to export the result in YXML format, instead
of printing it in human-readable form.
\<close>
section \<open>Invoking the build process \label{sec:tool-build}\<close>
text \<open>
The @{tool_def build} tool invokes the build process for Isabelle sessions.
It manages dependencies between sessions, related sources of theories and
auxiliary files, and target heap images. Accordingly, it runs instances of
the prover process with optional document preparation. Its command-line
usage is:\<^footnote>\<open>Isabelle/Scala provides the same functionality via
\<^verbatim>\<open>isabelle.Build.build\<close>.\<close>
@{verbatim [display]
\<open>Usage: isabelle build [OPTIONS] [SESSIONS ...]
Options are:
-B NAME include session NAME and all descendants
-D DIR include session directory and select its sessions
-N cyclic shuffling of NUMA CPU nodes (performance tuning)
-R operate on requirements of selected sessions
-S soft build: only observe changes of sources, not heap images
-X NAME exclude sessions from group NAME and all descendants
-a select all sessions
-b build heap images
-c clean build
-d DIR include session directory
-g NAME select session group NAME
-j INT maximum number of parallel jobs (default 1)
-k KEYWORD check theory sources for conflicts with proposed keywords
-l list session source files
-n no build -- test dependencies only
-o OPTION override Isabelle system OPTION (via NAME=VAL or NAME)
-s system build mode: produce output in ISABELLE_HOME
-v verbose
-x NAME exclude session NAME and all descendants
Build and manage Isabelle sessions, depending on implicit settings:
ISABELLE_BUILD_OPTIONS="..."
ML_PLATFORM="..."
ML_HOME="..."
ML_SYSTEM="..."
ML_OPTIONS="..."\<close>}
\<^medskip>
Isabelle sessions are defined via session ROOT files as described in
(\secref{sec:session-root}). The totality of sessions is determined by
collecting such specifications from all Isabelle component directories
(\secref{sec:components}), augmented by more directories given via options
\<^verbatim>\<open>-d\<close>~\<open>DIR\<close> on the command line. Each such directory may contain a session
\<^verbatim>\<open>ROOT\<close> file with several session specifications.
Any session root directory may refer recursively to further directories of
the same kind, by listing them in a catalog file \<^verbatim>\<open>ROOTS\<close> line-by-line. This
helps to organize large collections of session specifications, or to make
\<^verbatim>\<open>-d\<close> command line options persistent (e.g.\ in
\<^verbatim>\<open>$ISABELLE_HOME_USER/ROOTS\<close>).
\<^medskip>
The subset of sessions to be managed is determined via individual \<open>SESSIONS\<close>
given as command-line arguments, or session groups that are given via one or
more options \<^verbatim>\<open>-g\<close>~\<open>NAME\<close>. Option \<^verbatim>\<open>-a\<close> selects all sessions. The build tool
takes session dependencies into account: the set of selected sessions is
completed by including all ancestors.
\<^medskip>
One or more options \<^verbatim>\<open>-B\<close>~\<open>NAME\<close> specify base sessions. All descendants
are included.
\<^medskip>
One or more options \<^verbatim>\<open>-x\<close>~\<open>NAME\<close> specify sessions to be excluded. All
descendents of excluded sessions are removed from the selection as specified
above. Option \<^verbatim>\<open>-X\<close> is analogous to this, but excluded sessions are
specified by session group membership.
\<^medskip>
Option \<^verbatim>\<open>-R\<close> reverses the selection in the sense that it refers to its
requirements: all ancestor sessions excluding the original selection. This
allows to prepare the stage for some build process with different options,
before running the main build itself (without option \<^verbatim>\<open>-R\<close>).
\<^medskip>
Option \<^verbatim>\<open>-D\<close> is similar to \<^verbatim>\<open>-d\<close>, but selects all sessions that are defined
in the given directories.
\<^medskip>
Option \<^verbatim>\<open>-S\<close> indicates a ``soft build'': the selection is restricted to
those sessions that have changed sources (according to actually imported
theories). The status of heap images is ignored.
\<^medskip>
The build process depends on additional options
(\secref{sec:system-options}) that are passed to the prover eventually. The
settings variable @{setting_ref ISABELLE_BUILD_OPTIONS} allows to provide
additional defaults, e.g.\ \<^verbatim>\<open>ISABELLE_BUILD_OPTIONS="document=pdf threads=4"\<close>.
Moreover, the environment of system build options may be augmented on the
command line via \<^verbatim>\<open>-o\<close>~\<open>name\<close>\<^verbatim>\<open>=\<close>\<open>value\<close> or \<^verbatim>\<open>-o\<close>~\<open>name\<close>, which abbreviates
\<^verbatim>\<open>-o\<close>~\<open>name\<close>\<^verbatim>\<open>=true\<close> for Boolean options. Multiple occurrences of \<^verbatim>\<open>-o\<close> on
the command-line are applied in the given order.
\<^medskip>
Option \<^verbatim>\<open>-b\<close> ensures that heap images are produced for all selected
sessions. By default, images are only saved for inner nodes of the hierarchy
of sessions, as required for other sessions to continue later on.
\<^medskip>
Option \<^verbatim>\<open>-c\<close> cleans all descendants of the selected sessions before
performing the specified build operation.
\<^medskip>
Option \<^verbatim>\<open>-n\<close> omits the actual build process after the preparatory stage
(including optional cleanup). Note that the return code always indicates the
status of the set of selected sessions.
\<^medskip>
Option \<^verbatim>\<open>-j\<close> specifies the maximum number of parallel build jobs (prover
processes). Each prover process is subject to a separate limit of parallel
worker threads, cf.\ system option @{system_option_ref threads}.
\<^medskip>
Option \<^verbatim>\<open>-N\<close> enables cyclic shuffling of NUMA CPU nodes. This may help
performance tuning on Linux servers with separate CPU/memory modules.
\<^medskip>
Option \<^verbatim>\<open>-s\<close> enables \<^emph>\<open>system mode\<close>, which means that resulting heap images
and log files are stored in @{path "$ISABELLE_HOME/heaps"} instead of the
default location @{setting ISABELLE_OUTPUT} (which is normally in @{setting
ISABELLE_HOME_USER}, i.e.\ the user's home directory).
\<^medskip>
Option \<^verbatim>\<open>-v\<close> increases the general level of verbosity. Option \<^verbatim>\<open>-l\<close> lists
the source files that contribute to a session.
\<^medskip>
Option \<^verbatim>\<open>-k\<close> specifies a newly proposed keyword for outer syntax (multiple
uses allowed). The theory sources are checked for conflicts wrt.\ this
hypothetical change of syntax, e.g.\ to reveal occurrences of identifiers
that need to be quoted.
\<close>
subsubsection \<open>Examples\<close>
text \<open>
Build a specific logic image:
@{verbatim [display] \<open>isabelle build -b HOLCF\<close>}
\<^smallskip>
Build the main group of logic images:
@{verbatim [display] \<open>isabelle build -b -g main\<close>}
\<^smallskip>
Build all descendants (and requirements) of \<^verbatim>\<open>FOL\<close> and \<^verbatim>\<open>ZF\<close>:
@{verbatim [display] \<open>isabelle build -B FOL -B ZF\<close>}
\<^smallskip>
Build all sessions where sources have changed (ignoring heaps):
@{verbatim [display] \<open>isabelle build -a -S\<close>}
\<^smallskip>
Provide a general overview of the status of all Isabelle sessions, without
building anything:
@{verbatim [display] \<open>isabelle build -a -n -v\<close>}
\<^smallskip>
Build all sessions with HTML browser info and PDF document preparation:
@{verbatim [display] \<open>isabelle build -a -o browser_info -o document=pdf\<close>}
\<^smallskip>
Build all sessions with a maximum of 8 parallel prover processes and 4
worker threads each (on a machine with many cores):
@{verbatim [display] \<open>isabelle build -a -j8 -o threads=4\<close>}
\<^smallskip>
Build some session images with cleanup of their descendants, while retaining
their ancestry:
@{verbatim [display] \<open>isabelle build -b -c HOL-Algebra HOL-Word\<close>}
\<^smallskip>
Clean all sessions without building anything:
@{verbatim [display] \<open>isabelle build -a -n -c\<close>}
\<^smallskip>
Build all sessions from some other directory hierarchy, according to the
settings variable \<^verbatim>\<open>AFP\<close> that happens to be defined inside the Isabelle
environment:
@{verbatim [display] \<open>isabelle build -D '$AFP'\<close>}
\<^smallskip>
Inform about the status of all sessions required for AFP, without building
anything yet:
@{verbatim [display] \<open>isabelle build -D '$AFP' -R -v -n\<close>}
\<close>
section \<open>Maintain theory imports wrt.\ session structure\<close>
text \<open>
The @{tool_def "imports"} tool helps to maintain theory imports wrt.\
session structure. It supports three main operations via options \<^verbatim>\<open>-I\<close>,
\<^verbatim>\<open>-M\<close>, \<^verbatim>\<open>-U\<close>. Its command-line usage is: @{verbatim [display]
\<open>Usage: isabelle imports [OPTIONS] [SESSIONS ...]
Options are:
-B NAME include session NAME and all descendants
-D DIR include session directory and select its sessions
-I operation: report potential session imports
-M operation: Mercurial repository check for theory files
-R operate on requirements of selected sessions
-U operation: update theory imports to use session qualifiers
-X NAME exclude sessions from group NAME and all descendants
-a select all sessions
-d DIR include session directory
-g NAME select session group NAME
-i incremental update according to session graph structure
-o OPTION override Isabelle system OPTION (via NAME=VAL or NAME)
-v verbose
-x NAME exclude session NAME and all descendants
Maintain theory imports wrt. session structure. At least one operation
needs to be specified (see options -I -M -U).\<close>}
\<^medskip>
The selection of sessions and session directories works as for @{tool build}
via options \<^verbatim>\<open>-B\<close>, \<^verbatim>\<open>-D\<close>, \<^verbatim>\<open>-R\<close>, \<^verbatim>\<open>-X\<close>, \<^verbatim>\<open>-a\<close>, \<^verbatim>\<open>-d\<close>, \<^verbatim>\<open>-g\<close>, \<^verbatim>\<open>-x\<close> (see
\secref{sec:tool-build}).
\<^medskip>
Option \<^verbatim>\<open>-o\<close> overrides Isabelle system options as for @{tool build}
(see \secref{sec:tool-build}).
\<^medskip>
Option \<^verbatim>\<open>-v\<close> increases the general level of verbosity.
\<^medskip>
Option \<^verbatim>\<open>-I\<close> determines potential session imports, which may be turned into
\isakeyword{sessions} within the corresponding \<^verbatim>\<open>ROOT\<close> file entry. Thus
theory imports from other sessions may use session-qualified names. For
example, adhoc \<^theory_text>\<open>imports\<close> \<^verbatim>\<open>"~~/src/HOL/Library/Multiset"\<close> may become formal
\<^theory_text>\<open>imports\<close> \<^verbatim>\<open>"HOL-Library.Multiset"\<close> after adding \isakeyword{sessions}
\<^verbatim>\<open>"HOL-Library"\<close> to the \<^verbatim>\<open>ROOT\<close> entry.
\<^medskip>
Option \<^verbatim>\<open>-M\<close> checks imported theories against the Mercurial repositories of
the underlying session directories; non-repository directories are ignored.
This helps to find files that are accidentally ignored, e.g.\ due to
rearrangements of the session structure.
\<^medskip>
Option \<^verbatim>\<open>-U\<close> updates theory imports with old-style directory specifications
to canonical session-qualified theory names, according to the theory name
space imported via \isakeyword{sessions} within the \<^verbatim>\<open>ROOT\<close> specification.
Option \<^verbatim>\<open>-i\<close> modifies the meaning of option \<^verbatim>\<open>-U\<close> to proceed incrementally,
following to the session graph structure in bottom-up order. This may
lead to more accurate results in complex session hierarchies.
\<close>
subsubsection \<open>Examples\<close>
text \<open>
Determine potential session imports for some project directory:
@{verbatim [display] \<open>isabelle imports -I -D 'some/where/My_Project'\<close>}
\<^smallskip>
Mercurial repository check for some project directory:
@{verbatim [display] \<open>isabelle imports -M -D 'some/where/My_Project'\<close>}
\<^smallskip>
Incremental update of theory imports for some project directory:
@{verbatim [display] \<open>isabelle imports -U -i -D 'some/where/My_Project'\<close>}
\<close>
end