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% JUST GRAPH FILE(5) | File Formats Manual
NAME
====
just-graph-file - The format of the action graph used by **`just`**(1)
DESCRIPTION
===========
The file is read as JSON. Any other serialization describing the same
JSON object is equivalent. We assume, that in JSON objects, each key
occurs at most once; it is implementation defined how repetitions of the
same key are treated.
Artifacts and their serialization
---------------------------------
There are four different kind of artifacts. The serialization of the
artifact is always a JSON object with two keys: *`"type"`* and
*`"data"`*. The value for *`"type"`* is always on of the strings
*`"LOCAL"`*, *`"KNOWN"`*, *`"ACTION"`*, or *`"TREE"`*. The value for
*`"data"`* is a JSON object with keys depending on which type the
artifact is of.
- *`"LOCAL"`* artifacts refer to source files in a logical repository.
The describing data are
- the *`"repository"`*, given as its global name, and
- the *`"path"`*, given as path relative to the root of that
repository.
- *`"KNOWN"`* artifacts are described by the hash of their content. The
describing data are
- the *`"file_type"`*, which is a one-letter string,
- *`"f"`* for regular, non-executable files,
- *`"x"`* for executable files, or
- *`"t"`* for trees.
- the *`"id"`* specifying the (applicable) hash of the file given as
its hexadecimal encoding, a string, and
- the *`"size"`* of the artifact, a number, in bytes.
- *`"ACTION"`* artifacts are the outputs of actions. The defining data
are
- the *`"id"`*, a string with the name of the action, and
- the *`"path"`*, specifying the path of this output artifact,
relative to the root of the action directory
- *`"TREE"`* artifacts refer to trees defined in the action graph. The
defining data are
- the *`"id"`*, a string with the name of the tree.
Actions and their serialization
-------------------------------
Actions are given by the data described in the following sections. For
each item a key is associated and the serialization of the action is a
JSON object mapping those keys to the respective serialization of the
values. For some data items default values are given; if the value for
the respective item equals the default, the respective key-value pair
may be omitted in the serialization.
- *`"command"`* specifies the command to be executed. It is a non-empty
list of strings that forms the argument vector; the first entry is
taken as program. This key is mandatory.
- *`"env"`* specifies the environment variables the command should be
executed with. It is given as map from strings to strings. The
default is the empty map.
- *`"input"`* describes the files available to the action. The action
must not modify them in any way. They are specified as map from paths
to artifacts (the latter serialized as described). Paths have to be
relative paths and are taken relative to the working directory of the
action. The default is the empty map.
- *`"output"`* describes the files the action is supposed to generate,
if any. It is given as a list of strings, each specifying a file name
by a path relative to the working directory of the action. The
default is the empty list. However, every action has to produce some
form of output, so if *`"output"`* is empty, *`"output_dirs"`* cannot
be empty.
- *`"output_dirs"`* describes the directory output of the action, if
any. It is given as a list of strings, each specifying the a
directory name by a path relative to the working directory of the
action. The *`"output_dirs"`* may also specify directories from which
individual files are specified as *`"output"`*. The default value for
*`"output_dirs"`* is the empty list. However, every action to produce
some form of output, so if *`"output_dirs"`* is empty, *`"output"`*
cannot be empty.
- *`"may_fail"`* can either be *`null`* or a string. If it is a string,
the build should be continued, even if that action returns a non-zero
exit state. If the action returns a non-zero exit code, that string
should be shown to the user in a suitable way (e.g., printing on the
console). Otherwise (i.e., if no *`"may_fail"`* string is given), the
build should be aborted if the action returns a non-zero exit code.
The default for *`"may_fail"`* is *`null`*, i.e., abort on non-zero
exit code.
- *`"no_cache"`* is a boolean. If *`true`*, the action should never be
cached, not even on success. The default is *`false`*.
The graph format
----------------
The action graph is given by a JSON object.
- The value for the key *`"blobs"`* is a list of strings. Those strings
should be considered known; they might (additionally to what was
agreed ahead of time as known) referred to as *`"KNOWN"`* artifacts.
- The value for the key *`"trees"`* is a JSON object, mapping the names
of trees to their definition. The definition of a tree is JSON object
mapping paths to artifacts (serialized in the way described earlier).
The paths are always interpreted as relative paths, relative to the
root of the tree. It is not a requirement that a new tree is defined
for every subdirectory; if a path contains the hierarchy separator,
which is slash, then implicitly a subdirectory is present, and all
path going through that subdirectory contribute to its content. It
is, however, an error, if the a path is a prefix of another one (with
the comparison done in the canonical form of that path).
- The value for the key *`"actions"`* is a JSON object, mapping names
of actions to their respective definition (serialized as JSON).
Additional keys
---------------
Any JSON object described here might have additional keys on top of the
ones described. Implementations reading the graph have to accept and
ignore those. Implementations writing action-graph files should be aware
that a future version of this file format might give a specific meaning
to those extra keys.
Graphs written by **`just`**(1) have the additional key *`"origins"`* in
each action. The value is a list of all places where this action was
requested (so often, but not always, the list has length 1). Each such
place is described by a JSON object with the following keys.
- *`"target"`* The target in which the action was requested. It is
given as a list, either a full qualified named target given as
*`"@"`* followed by global repository name, module, and target name,
or an anonymous target, given by *`"#"`* followed by a hash of the
rule binding and the node name.
- *`"subtask"`* The running number, starting from 0, of the action, as
given by the (deterministic) evaluation order of he defining
expression for the rule that defined the target.
- *`"config"`* The effective configuration for that target, a JSON
object.
See also
========
**`just`**(1)
|
