Executing Work

SYNOPSIS

#include <libgearman/gearman.h>

gearman_task_st *gearman_execute(gearman_client_st *client, const char *function_name, size_t function_name_length, const char *unique, size_t unique_length, gearman_work_t *workload, gearman_argument_t *arguments, void *context)

gearman_task_st *gearman_execute_by_partition(gearman_client_st *client, const char *partition_function, const size_t partition_function_length, const char *function_name, const size_t function_name_length, const char *unique_str, const size_t unique_length, gearman_work_t *workload, gearman_argument_t *arguments, void *context)

Link with -lgearman

DESCRIPTION

gearman_execute() is used to create a new gearman_task_st that is executed against the function that is found via the function_name argument.

gearman_work_t can be used to describe the work that will be executed, it is built with gearman_argument_make(). The argument unique_str is optional, but if supplied it is used for coalescence by gearmand.

gearman_argument_t is the work that the client will send the to the server

If gearman_execute() is given a gearman_work_t that has been built with a reducer, it takes the gearman_argument_t and executes it against a function as it normally would, but it tells the function to then process the results through a reducer function that the gearman_work_t was created with.

What is happening is that the function is mappping/splitting work up into units, and then sending each of them to the reducer function. Once all work is completed, the mapper function will aggregate the work via an aggregator function, gearman_aggregator_fn, and return a result.

If any of the units of work error, the job will be aborted. The resulting value will be stored in the gearman_task_st.

The result can be obtained from the task by calling gearman_task_result() to gain the gearman_result_st.

RETURN VALUE

gearman_execute() returns a c:type:gearman_task_st.

Example

/*
  Example code to show how to send a string to a function called "reverse" and print the results.
*/

/*
# Gearman server and library
# Copyright (C) 2012 Data Differential, http://datadifferential.com/
# All rights reserved.
#
# Use and distribution licensed under the BSD license.  See
# the COPYING file in this directory for full text.
*/

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <libgearman/gearman.h>

int main(void)
{
  gearman_client_st *client= gearman_client_create(NULL);

  gearman_return_t ret= gearman_client_add_server(client, "localhost", 0);
  if (gearman_failed(ret))
  {
    return EXIT_FAILURE;
  }

  gearman_argument_t value= gearman_argument_make(0, 0, "Reverse Me", strlen("Reverse Me"));

  gearman_task_st *task= gearman_execute(client, 
                                         "reverse", strlen("reverse"),  // function
                                         NULL, 0,  // no unique value provided
                                         NULL, 
                                         &value, 0);

  if (task == NULL) // If gearman_execute() can return NULL on error
  {
    fprintf(stderr, "Error: %s\n", gearman_client_error(client));
    gearman_client_free(client);
    return EXIT_FAILURE;
  }

  // Make sure the task was run successfully
  if (gearman_success(gearman_task_return(task)))
  {
    // Make use of value
    gearman_result_st *result= gearman_task_result(task);
    printf("%.*s\n", (int)gearman_result_size(result), gearman_result_value(result));
  }

  gearman_client_free(client);

  return EXIT_SUCCESS;
}

HOME

To find out more information please check: http://gearman.info/

SEE ALSO

gearmand(8) libgearman(3)