read local file content in bazel build system - bazel

Hi I would like to read a content of local file in .bzl file.
print(onefile.basename)
#content = ctx.read
#content=ctx.file.onefile
#print(onefile.content)

.bzl code cannot read files, and can't make decisions based on contents of files.
You must create actions (e.g. ctx.actions.run), make the file an action input, and have the action read the file.
.bzl code can load other .bzl files though, you might find that useful.

Related

how to find and deploy the correct files with Bazel's pkg_tar() in Windows?

please take a look at the bin-win target in my repository here:
https://github.com/thinlizzy/bazelexample/blob/master/demo/BUILD#L28
it seems to be properly packing the executable inside a file named bin-win.tar.gz, but I still have some questions:
1- in my machine, the file is being generated at this directory:
C:\Users\John\AppData\Local\Temp_bazel_John\aS4O8v3V\execroot__main__\bazel-out\x64_windows-fastbuild\bin\demo
which makes finding the tar.gz file a cumbersome task.
The question is how can I make my bin-win target to move the file from there to a "better location"? (perhaps defined by an environment variable or a cmd line parameter/flag)
2- how can I include more files with my executable? My actual use case is I want to supply data files and some DLLs together with the executable. Should I use a filegroup() rule and refer its name in the "srcs" attribute as well?
2a- for the DLLs, is there a way to make a filegroup() rule to interpret environment variables? (e.g: the directories of the DLLs)
Thanks!
Look for the bazel-bin and bazel-genfiles directories in your workspace. These are actually junctions (directory symlinks) that Bazel updates after every build. If you bazel build //:demo, you can access its output as bazel-bin\demo.
(a) You can also set TMP and TEMP in your environment to point to e.g. c:\tmp. Bazel will pick those up instead of C:\Users\John\AppData\Local\Temp, so the full path for the output directory (that bazel-bin points to) will be c:\tmp\aS4O8v3V\execroot\__main__\bazel-out\x64_windows-fastbuild\bin.
(b) Or you can pass the --output_user_root startup flag, e.g. bazel--output_user_root=c:\tmp build //:demo. That will have the same effect as (a).
There's currently no way to get rid of the _bazel_John\aS4O8v3V\execroot part of the path.
Yes, I think you need to put those files in pkg_tar.srcs. Whether you use a filegroup() rule is irrelevant; filegroup just lets you group files together, so you can refer to the group by name, which is useful when you need to refer to the same files in multiple rules.
2.a. I don't think so.

How to deal with implicit dependency (e.g C++ include) for incremental build in custom Skylark rule

Problem
I wonder how to inform bazel about dependencies unknown at declaration time, but known at build time (a.k.a implicit dependencies, dynamic dependencies, ...). For instance when compiling C++ sources, the .cpp source file will depends on some header files and this information is not available when writing the BUILD file. It needs to be retrieve at build time. Whatever is the solution to get the information (dry-run, generating depfile, parsing stdout), it needs to be done at build time and the information need to be retrieved to bazel build graph.
Since skylark does not allow to do I/O, for instance to read a generated depfile or to parse stdout result containing a dependency list, I have no clue on how to deal with it.
Behind implicit dependencies, I am looking for correct incremental build.
Example
To experiment this problem I have created a simple tool, just_a_tool.exe which takes an input file, read a list of file from it, and concatenate the content of all these file to an output file.
command line example:
just_a_tool.exe --input input.txt --depfile dep.d output.txt
dep.d contains the list of all the read files.
Issue
If I change the content of test1.txt, test2.txt, or test3.txt, bazel does not rebuild output.txt file. Of course, because it does not know there were dependencies.
Example files
just_a_tool.bzl
def _impl(ctx):
exec_path = "C:/Code/JustATool/just_a_tool.exe"
for f in ctx.attr.source.files:
source_path = f.path
output_path = ctx.outputs.out.path
dep_file = ctx.actions.declare_file("dep.d")
args = ["--input", source_path, "--dep_file", dep_file.path, output_path]
ctx.actions.run(
outputs=[ctx.outputs.out, dep_file],
executable=exec_path,
inputs=ctx.attr.source.files,
arguments=args
)
jat_convert = rule(
implementation = _impl,
attrs = {
"source" : attr.label(mandatory=True, allow_files=True, single_file=True)
},
outputs = {"out": "%{name}.txt"}
)
BUILD
load("//tool:just_a_tool.bzl", "jat_convert")
jat_convert(
name="my_output",
source=":input.txt"
)
input.txt
test1.txt
test2.txt
test3.txt
Goal
I want to do correct and fast incremental build for the following situation:
Generate reflection data from C++ sources, this custom tool execution depends on header file included in my source files.
Use a internal tool to build asset file which can include other files
Run a custom preprocessor on my shaders allowing a #include feature
Thanks!
Bazel's extension language doesn't support creating actions with a dynamic set of inputs, where this set depends on the output of a previous action. In other words, custom rules cannot run an action, read the action's output, then create actions with those inputs or update (or prune the set of) inputs of already created actions.
Instead I suggest adding attribute(s) to your rule where the user can declare the set of files that the sources may include. I call this "the universe of headers". The actions you create depend on this user-defined universe, so the set of action inputs is completely defined. Of course this means these actions potentially depend on more files than the cpp files, which they process, include.
This approach is analogous to how the cc_* rules work: a file in cc_*.srcs can include other files in the srcs of the same rule and from hdrs of dependencies, but nothing else. Thus the union of srcs + hdrs of (direct & transitive) dependencies defines the universe of header files that a cpp file may include.

Is there a way to pass non-project .fs files into a command-line argument in an FSharp .exe?

Let's say that I have an exe that has a function called compareTwoThings. I'd like compareTwoThings to be able to take, as arguments, two directories that have identical file names in each: a .json and a .fs. In compareTwoThings, I want to be able to read in each .json (easy-peasy) and each .fs file. The contents of each .fs file will be known.
How can I read in each .fs file and use the values in those .fs files without them being a part of the overall project structure? Can I? I understand that to build a project and have the project "see" into the .fs files, they need to be added to the .fsproj file, but can I not use open on an external file that has a module name?
Example dir structure of the proj:
myProj
|-proj
|-compareTwoThings.fs
|-myProj.fs
|-myProj.fsproj
Thing1
|-Thing1.fs
|-Thing1.json
Thing2
|-Thing2.fs
|-Thing2.json
And ultimately, the CLI statement would be something like
myProj compareTwoThings [dir to Thing1] [dir to Thing2] [output dir]
I feel like I'm overlooking something very simple here.
Edit: I do not believe that this question is related as I'm asking how to open a non-project .fs file.

Flume "Spooling Directory Source" recursive-look for the the files within subdirectories

I am looking for the Flume "Spooling Directory Source" recursive-look for the the files within subdirectories.
There are some references here https://issues.apache.org/jira/browse/FLUME-1899
however since then multiple versions have come out, is there any way we can have recursive directory lookup within subdirectories for the files in Spooling Source.
I think you can use the patch FLUME-1899-2.patch directly.
set the "recursiveDirectorySearch" as ture in your config file.
NOTE: the regex in ignorePattern of config file will also affect the recursiveDirectory folder name. so you might need to modify the code in org/apache/flume/client/avro/ReliableSpoolingFileEventReader.java if you want to ignore the folder name.

How can I generate a SWC from asset files dynamically?

Lets say you have 3 swf files in a directory:
/game/assets/
1.swf
2.swf
3.swf
What I need to do, is package these up into a SWC File, and then move that SWC file to the libs/ directory.
I plan to use ant, so this step must always occur before the compliation stage.
Today I use a VBS file to generate a XML file. Then I use that XML file to generate a AssetMap which is a series of [Embeds] (1.swf, 2.swf, 3.swf) which are ByteArrays.
I then pass these byte arrays to a loader.loabytes to generate a MovieClip.
But this "real time bytearray conversion" as far too slow. Id prefer I could have direct access to instances like I do with a SWC.
Can anyone offer me advice?

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