Generating work

To submit a job:

• Write XML 'template files' that describe the job's input and outputs (typically the same template files can be used for many jobs).
• Create the job's input file(s), and put them in the right places (as determined by the file names) in the download directory hierarchy.
• Invoke a BOINC function or script that submits the job.

Once this is done, BOINC takes over: it creates one or more instances of the job, distributes them to client hosts, collects the output files, finds a canonical instance, assimilates the canonical instance, and deletes files.

Input and output template files

An input template file has the form

<file_info>
    <number>0</number>
    [ <sticky/>, other attributes]
</file_info>
[ ... ]
<workunit>
    <file_ref>
        <file_number>0</file_number>
        <open_name>NAME</open_name>
    </file_ref>
    [ ... ]
    [ <command_line>-flags xyz</command_line> ]
    [ <rsc_fpops_est>x</rsc_fpops_est> ]
    [ <rsc_fpops_bound>x</rsc_fpops_bound> ]
    [ <rsc_memory_bound>x</rsc_memory_bound> ]
    [ <rsc_disk_bound>x</rsc_disk_bound> ]
    [ <delay_bound>x</delay_bound> ]
    [ <min_quorum>x</min_quorum> ]
    [ <target_nresults>x</target_nresults> ]
    [ <max_error_results>x</max_error_results> ]
    [ <max_total_results>x</max_total_results> ]
    [ <max_success_results>x</max_success_results> ]
    [ <credit>X</credit> ]
</workunit>

Elements and tags must be on separate lines as shown. The components are:

<file_info>, <file_ref>

Each pair describes an input file and the way it's referenced.

<command_line>

The command-line arguments to be passed to the main program.

<credit>

The amount of credit to be granted for successful completion of this workunit. Use this only if you know in advance how many FLOPs it will take. Your validator must use get_credit_from_wu() as its compute_granted_credit() function.

Other elements

Work unit attributes

An output template file has the form

<file_info>
    <name><OUTFILE_0/></name>
    <generated_locally/>
    <upload_when_present/>
    <max_nbytes>32768</max_nbytes>
    <url><UPLOAD_URL/></url>
</file_info>
<result>
    <file_ref>
        <file_name><OUTFILE_0/></file_name>
        <open_name>result.sah</open_name>
    </file_ref>
</result>

Submitting a job manually

To move an input file to the download directory, use

dir_hier_path filename

which prints the full pathname and creates the directory if needed (run this in the project's root directory). For example:

cp test_files/12ja04aa `bin/dir_hier_path 12ja04aa`

copies an input file from the test_files directory to the download directory hierarchy.

To submit a job, run bin/create_work from the project root directory:

create_work [ arguments] infile_1 ... infile_n

Mandatory arguments are:

-appname name

application name

-wu_name name

workunit name

-wu_template filename

WU template filename relative to project root; usually in templates/

-result_template filename

result template filename, relative to project root; usually in templates/

Optional arguments are:

-batch n

-priority n

The following job parameters may be passed in the input template, or as command-line arguments to create_work, or not passed at all (defaults will be used)

-command_line "-flags foo"

-rsc_fpops_est x

-rsc_fpops_bound x

-rsc_memory_bound x

-rsc_disk_bound x

-delay_bound x

-min_quorum x

-target_nresults x

-max_error_results x

-max_total_results x

-max_success_results x

-additional_xml 'x'

This can be used to supply, for example, <credit>12.4</credit>.

Submitting jobs from a C++ program

BOINC's library provides the functions:

// convert filename to path in download hierarchy
//
SCHED_CONFIG::download_path(
    const char* filename,
    char* path,
);

// submit a job
//
int create_work(
    DB_WORKUNIT&,
    const char* wu_template,                  // contents, not path
    const char* result_template_filename,     // relative to project root
    const char* result_template_filepath,     // absolute or relative to current dir
    const char** infiles,                     // array of input file names
    int ninfiles
    SCHED_CONFIG&,
    const char* command_line = NULL,
    const char* additional_xml = NULL
);

The name and appid fields of the DB_WORKUNIT structure must always be initialized. Other job parameters may be passed either in the DB_WORKUNIT structure or in the input template file (the latter has priority).

Making one workunit

Here's a program that submits one job (error-checking is omitted for clarity):

#include "boinc_db.h"
#include "backend_lib.h"

int main() {
    DB_APP app;
    DB_WORKUNIT wu;
    char* wu_template;
    char* infiles[] = {"infile"};
    char path[1024];

    SCHED_CONFIG config;
    config.parse_file();

    boinc_db.open(config.db_name, config.db_host, config.db_user, config.db_passwd);
    app.lookup("where name='myappname'");

    // write input file in the download directory
    //
    config.download_path("infile", path);
    FILE* f = fopen(path, "w");
    fwrite(f, "random stuff");
    fclose(f);

    read_file_malloc("templates/input_template.xml", wu_template);
    wu.clear();     // zeroes all fields
    strcpy(wu.name, "test_name");
    wu.appid = app.id;
    wu.min_quorum = 2;
    wu.target_nresults = 2;
    wu.max_error_results = 5;
    wu.max_total_results = 5;
    wu.max_success_results = 5;
    wu.rsc_fpops_est = 1e10;
    wu.rsc_fpops_bound = 1e11;
    wu.rsc_memory_bound = 1e8;
    wu.rsc_disk_bound = 1e8;
    wu.delay_bound = 7*86400;
    create_work(
        wu,
        wu_template,
        "templates/output_template.xml",
        "templates/output_template.xml",
        infiles,
        1,
        config
    );
}

The program must be run in the project directory.

Making lots of workunits

If you're making lots of workunits (e.g. to do the various parts of a parallel computation) you'll want the workunits to differ either in their input files, their command-line arguments, or both.

For example, let's say you want to run a program on ten input files 'file0', 'file1', ..., 'file9'. You might modify the above program with the following code:

    char filename[256];
    char* infiles[1];
    infiles[0] = filename;
    ...
    for (i=0; i<10; i++) {
        sprintf(filename, "file%d", i);
        create_work(
            wu,
            wu_template,
            "templates/output_template.xml",
            "templates/output_template.xml",
            infiles,
            1,
            config
        );
    }

Note that you only need one workunit template file and one result template file.

Now suppose you want to run a program against a single input file, but with ten command lines, '-flag 0', '-flag 1', ..., '-flag 9'. You might modify the above program with the following code:

    char command_line[256];
    ...
    for (i=0; i<10; i++) {
        sprintf(command_line, "-flag %d", i);
        create_work(
            wu,
            wu_template,
            "templates/output_template.xml",
            "templates/output_template.xml",
            infiles,
            1,
            config,
            command_line
        );
    }

Again, you only need one input template file and one output template file.

Example work generators

Two work generator programs are supplied with BOINC.

Sample work generator

Many projects have an essentially infinite supply of work. This can be handled by a 'flow-controlled work generator' that tries to maintain a constant number of unsent jobs (typically a few hundred or thousand). It does this by periodically querying the BOINC database to find the number of unsent jobs. An example of this is sched/sample_work_generator.C. You can easily modify this program to suit your application.

make_work

During the testing phase of a project, you may want to replicate a given workunit as needed to maintain a constant supply of work. The daemon program

make_work -wu_name name [-wu_name name2 ... ] -cushion N

creates copies of the given workunits (cyclically) as needed to maintain a supply of at least N unsent results. This is useful for testing purposes.

Note: if you run the file_deleter and/or db_purge, the master workunit or its input files may be deleted (which will cause make_work to fail). To avoid this, give the master workunit a name that contains 'nodelete' as a substring. This causes the file_deleter and db_purge to skip over it.

It may be convenient to have a script that recreates the master workunit. For example:

cp test_workunits/12ja04aa `bin/dir_hier_path 12ja04aa`
bin/create_work -appname setiathome -wu_name sah_nodelete -wu_template templates/setiathome_wu_0 -result_template templates/setiathome_result_0 12ja04aa