Gearman分布式任务处理系统（八）开发讲解

这篇重点介绍C-Lib库及client和worker的开发，以0.14版libgearman for C来讲解

Client API

 

client初始化&析构

gearman_client_st *gearman_client_create(gearman_client_st *client)

void gearman_client_free(gearman_client_st *client)

gearman_return_t gearman_client_add_server(gearman_client_st *client, const char *host, in_port_t port);

gearman_return_t gearman_client_add_servers(gearman_client_st *client, const char *servers); (一次添加多个gearman job-server)

 

同步操作

void * gearman_client_do(gearman_client_st *client, const char *function_name, const char *unique, const void *workload, size_t workload_size, size_t *result_size, gearman_return_t *ret_ptr);

其中：

i. unique: 的作用是client添加job给worker的时候的一个唯一标识，可选，默认是NULL

ii. workload & workload_size指代执行任务的详细参数及其大小

iii. result_size [out]，指代返回数据的大小

iv. ret_ptr [out], 指代gearman的返回status，以下是官方对于返回status的一些说明：

In the case of GEARMAN_WORK_DATA, GEARMAN_WORK_WARNING, or GEARMAN_WORK_STATUS, the caller should take any actions to handle the event and then call this function again. This may happen multiple times until a GEARMAN_WORK_ERROR, GEARMAN_WORK_FAIL, or GEARMAN_SUCCESS (work complete) is returned. For GEARMAN_WORK_DATA or GEARMAN_WORK_WARNING, the result_size will be set to the intermediate data chunk being returned and an allocated data buffer will be returned. For GEARMAN_WORK_STATUS, the caller can use gearman_client_do_status() to get the current tasks status.

总而言之，只有GEARMAN_WORK_ERROR/GEARMAN_WORK_FAIL/GEARMAN_SUCCESS才是三个最终的返回结果，其他的只是临时中间结果，需要进一步调用接受结果的函数(感觉中间结果只有在异步调用过程中才会出现)

v. 输出是返回数据的起始地址，一旦用户用完之后，必须free，否则会出现内存泄露。

 

void gearman_set_timeout(gearman_universal_st *gearman, int timeout);

设置gearman_client_do多长时调用无返回则超时时间

 

异步callback操作

Gearman通过使用gearman_client_add_task()来望gearman_client_st中添加task，通过gearman_client_set_created_fn() / gearman_client_set_complete_fn()等来注册callback function，通过gearman_client_run_tasks()来运行gearman_client_st中的task。

 

异步background操作

系统在background运行job，client定期获得job运行结果，如果成功则返回，反之则继续等待。

gearman_return_t gearman_client_do_background(gearman_client_st *client, const char *function_name, const char *unique, const void *workload, size_t workload_size, char *job_handle);

i. job_handle [out]: 一个job的标识符

ii. 输出：返回状态

* gearman_return_t gearman_client_job_status(gearman_client_st *client, gearman_job_handle_t job_handle, bool *is_known, bool * is_running, uint32_t *numerator, uint32_t *denominator);

* 用户获得在background执行的job的状态

i. is_known [out]: Optional parameter to store the known status in

ii. is_running [out]: Optional parameter to store the running status in

iii. numerator [out]: Optional parameter to store the numerator in

iv. denominator [out]: Optional parameter to store the denominator in

PS: 好像background操作不怎么好使，不知道如何通过获得background的运行结果，这个是我一直困惑的

 

gearman_client_st的一些属性

gearman_client_st一共有以下3种运行属性：

i. GEARMAN_CLIENT_NON_BLOCKING: client运行在non-blocking mode

ii. GEARMAN_CLIENT_FREE_TASKS: 在task执行完成之后，自动的释放task

iii. GEARMAN_CLIENT_UNBUFFERED_RESULT: Allow the client to read data in chunks rather than have the library buffer the entire data result and pass that back。

可以通过函数gearman_client_add_options() / gearman_client_remove_options() / gearman_client_has_option() 等进行属性添加/删除/判断等

 

Worker API

/**
 * Initialize a worker structure. Always check the return value even if passing
 * in a pre-allocated structure. Some other initialization may have failed. It
 * is not required to memset() a structure before providing it.
 *
 * @param[in] worker Caller allocated structure, or NULL to allocate one.
 * @return On success, a pointer to the (possibly allocated) structure. On
 *  failure this will be NULL.
 */
GEARMAN_API
gearman_worker_st *gearman_worker_create(gearman_worker_st *worker);


/**
 * Free resources used by a worker structure.
 *
 * @param[in] worker Structure previously initialized with
 *  gearman_worker_create() or gearman_worker_clone().
 */
GEARMAN_API
void gearman_worker_free(gearman_worker_st *worker);


/**
 * Add a job server to a worker. This goes into a list of servers that can be
 * used to run tasks. No socket I/O happens here, it is just added to a list.
 *
 * @param[in] worker Structure previously initialized with
 *  gearman_worker_create() or gearman_worker_clone().
 * @param[in] host Hostname or IP address (IPv4 or IPv6) of the server to add.
 * @param[in] port Port of the server to add.
 * @return Standard gearman return value.
 */
GEARMAN_API
gearman_return_t gearman_worker_add_server(gearman_worker_st *worker,
                                           const char *host, in_port_t port);


/**
 * Add a list of job servers to a worker. The format for the server list is:
 * SERVER[:PORT][,SERVER[:PORT]]...
 * Some examples are:
 * 10.0.0.1,10.0.0.2,10.0.0.3
 * localhost LIBGEARMAN_BITFIELD234,jobserver2.domain.com:7003,10.0.0.3
 *
 * @param[in] worker Structure previously initialized with
 *  gearman_worker_create() or gearman_worker_clone().
 * @param[in] servers Server list described above.
 * @return Standard gearman return value.
 */
GEARMAN_API
gearman_return_t gearman_worker_add_servers(gearman_worker_st *worker,
                                            const char *servers);
                                            
/**
 * Register and add callback function for worker. To remove functions that have
 * been added, call gearman_worker_unregister() or
 * gearman_worker_unregister_all().
 *
 * @param[in] worker Structure previously initialized with
 *  gearman_worker_create() or gearman_worker_clone().
 * @param[in] function_name Function name to register.
 * @param[in] timeout Optional timeout (in seconds) that specifies the maximum
 *  time a job should. This is enforced on the job server. A value of 0 means
 *  an infinite time.
 * @param[in] function Function to run when there is a job ready.
 * @param[in] context Argument to pass into the callback function.
 * @return Standard gearman return value.
 */
GEARMAN_API
gearman_return_t gearman_worker_add_function(gearman_worker_st *worker,
                                             const char *function_name,
                                             uint32_t timeout,
                                             gearman_worker_fn *function,
                                             void *context);


/**
 * Wait for a job and call the appropriate callback function when it gets one.
 *
 * @param[in] worker Structure previously initialized with
 *  gearman_worker_create() or gearman_worker_clone().
 * @return Standard gearman return value.
 */
GEARMAN_API
gearman_return_t gearman_worker_work(gearman_worker_st *worker);

 

/**
 * See gearman_universal_set_timeout() for details.
 */
GEARMAN_API
void gearman_worker_set_timeout(gearman_worker_st *worker, int timeout);

 

开发实例

下面这个实例程序是，jfy_client发送test，jfy_worker返回test->result

 

[plain] view plaincopyprint?在CODE上查看代码片派生到我的代码片
  1. /*  
  2.   gearman client 测试程序  
  3.   gcc -o jfy_client jfy_client.c -I/usr/local/gearman/include -L/usr/local/gearman/lib -lgearman  
  4.   ./jfy_client "this is a test"  
  5. */  
  6.   
  7. #include <stdio.h>  
  8. #include <stdlib.h>  
  9. #include <string.h>  
  10. #include <unistd.h>  
  11.   
  12. #include <libgearman/gearman.h>  
  13.   
  14. static void usage(char *name);  
  15.   
  16. int main(int argc, char *argv[])  
  17. {  
  18.   int i;  
  19.   gearman_return_t ret;  
  20.   gearman_client_st client;  
  21.   char *result;  
  22.   size_t result_size;  
  23.   uint32_t numerator;  
  24.   uint32_t denominator;  
  25.   
  26.   char *host = "localhost", *port = "4730";  
  27.   
  28.   if (gearman_client_create(&client) == NULL)  
  29.   {  
  30.     fprintf(stderr, "Memory allocation failure on client creation\n");  
  31.     exit(1);  
  32.   }  
  33.   
  34.   gearman_client_set_options(&client, GEARMAN_CLIENT_FREE_TASKS);  
  35.   gearman_client_set_timeout(&client, 15000);  
  36.   
  37.   ret= gearman_client_add_server(&client, host, atoi(port));  
  38.   if (ret != GEARMAN_SUCCESS)  
  39.   {  
  40.     fprintf(stderr, "%s\n", gearman_client_error(&client));  
  41.     exit(1);  
  42.   }  
  43.   
  44.   for (i=0;i<10;i++)  
  45.   {  
  46.     result= (char *)gearman_client_do(&client, "jfytest", NULL,  
  47.                                       (void *)argv[1],  
  48.                                       (size_t)strlen(argv[1]),  
  49.                                       &result_size, &ret);  
  50.     if (ret == GEARMAN_WORK_DATA)  
  51.     {  
  52.       printf("Data=%.*s\n", (int)result_size, result);  
  53.       free(result);  
  54.     }  
  55.     else if (ret == GEARMAN_WORK_STATUS)  
  56.     {  
  57.       gearman_client_do_status(&client, &numerator, &denominator);  
  58.       printf("Status: %u/%u\n", numerator, denominator);  
  59.     }  
  60.     else if (ret == GEARMAN_SUCCESS)  
  61.     {  
  62.       char result2[1024];  
  63.       strncpy(result2, result, result_size);  
  64.       result2[result_size] = 0;  
  65.       printf("result_size=%d,result=%s=\n", (int)result_size, result2);  
  66.       free(result);  
  67.     }  
  68.     else if (ret == GEARMAN_WORK_FAIL)  
  69.       fprintf(stderr, "Work failed\n");  
  70.     else if (ret == GEARMAN_TIMEOUT)  
  71.     {  
  72.       fprintf(stderr, "Work timeout\n");  
  73.     } else {  
  74.       fprintf(stderr, "%d,%s\n", gearman_client_errno(&client), gearman_client_error(&client));  
  75.     }  
  76.     printf("sleep 5s ...\n");  
  77.     sleep(5);  
  78.   }  
  79.   
  80.   gearman_client_free(&client);  
  81.   
  82.   return 0;  
  83. }  

 

[plain] view plaincopyprint?在CODE上查看代码片派生到我的代码片
  1. /*  
  2.   gearman worker 测试程序  
  3.   gcc -o jfy_worker jfy_worker2.c -I/usr/local/gearman/include -L/usr/local/gearman/lib -lgearman  
  4.   ./jfy_worker ./jfy_worker.tr  
  5. */  
  6.   
  7. #include <errno.h>  
  8. #include <stdio.h>  
  9. #include <stdlib.h>  
  10. #include <string.h>  
  11. #include <unistd.h>  
  12.   
  13. #include <libgearman/gearman.h>  
  14.   
  15. static void *jfytest(gearman_job_st *job, void *context, size_t *result_size,  
  16.                      gearman_return_t *ret_ptr);  
  17.   
  18. int main(int argc, char *argv[])  
  19. {  
  20.   gearman_return_t ret;  
  21.   gearman_worker_st worker;  
  22.   
  23.   char *host = "localhost", *port = "4730";  
  24.   
  25.   if (gearman_worker_create(&worker) == NULL)  
  26.   {  
  27.     printf("%s\n", gearman_worker_error(&worker));  
  28.     exit(1);  
  29.   }  
  30.   
  31.   ret= gearman_worker_add_server(&worker, host, atoi(port));  
  32.   if (ret != GEARMAN_SUCCESS)  
  33.   {  
  34.     printf("%s\n", gearman_worker_error(&worker));  
  35.     exit(1);  
  36.   }  
  37.   
  38.   ret= gearman_worker_add_function(&worker, "jfytest", 0, jfytest, NULL);  
  39.   if (ret != GEARMAN_SUCCESS)  
  40.   {  
  41.     printf("%s\n", gearman_worker_error(&worker));  
  42.     exit(1);  
  43.   }  
  44.   
  45.   printf("wait job ...\n");  
  46.   while (1)  
  47.   {  
  48.     ret= gearman_worker_work(&worker);  
  49.     if (ret != GEARMAN_SUCCESS)  
  50.     {  
  51.       printf("%s\n", gearman_worker_error(&worker));  
  52.       break;  
  53.     }  
  54.   }  
  55.   
  56.   gearman_worker_free(&worker);  
  57.   
  58.   return 0;  
  59. }  
  60.   
  61. static void *jfytest(gearman_job_st *job, void *context, size_t *result_size,  
  62.                      gearman_return_t *ret_ptr)  
  63. {  
  64.   const uint8_t *workload;  
  65.   char *request,*result;  
  66.   
  67.   workload= gearman_job_workload(job);  
  68.   *result_size= gearman_job_workload_size(job);  
  69.   
  70.   request= malloc(1024);  
  71.   if (result == NULL)  
  72.   {  
  73.     printf("malloc request:%d\n", errno);  
  74.     *ret_ptr= GEARMAN_WORK_FAIL;  
  75.     return NULL;  
  76.   }  
  77.   
  78.   snprintf((char *)request, *result_size+1, "%s", (char *)workload);  
  79.   printf("job=%s,result_size=%d,request=%s\n", gearman_job_handle(job),*result_size,request);  
  80.   
  81.   result= malloc(1024);  
  82.   if (result == NULL)  
  83.   {  
  84.     printf("malloc result:%d\n", errno);  
  85.     *ret_ptr= GEARMAN_WORK_FAIL;  
  86.     return NULL;  
  87.   }  
  88.   
  89.   *ret_ptr= GEARMAN_SUCCESS;  
  90.   
  91.   sprintf((char *)result, "%s->result", (char *)request);  
  92.   *result_size= strlen((char *)result);  
  93.   
  94.   printf("job=%s,result_size=%d,result=%s\n", gearman_job_handle(job),*result_size,result);  
  95.   
  96.   return result;  
  97. }  

 

 

下面的实例是PHP程序，客户端发送"hello!"

worker端是两个程序，一个是阻塞方式的，一个是非阻塞方式的

[php] view plaincopyprint?在CODE上查看代码片派生到我的代码片
  1. <?php  
  2. /* 
  3.  * send "Hello!" 
  4.  */  
  5.   
  6. echo "Starting\n";  
  7.   
  8. # Create our client object.  
  9. $gmclient= new GearmanClient();  
  10.   
  11. # Add default server (localhost).  
  12. $gmclient->addServer();  
  13.   
  14. echo "Sending job\n";  
  15.   
  16. # Send reverse job  
  17. do  
  18. {  
  19.   $result= $gmclient->do("reverse", "Hello!");  
  20.   # Check for various return packets and errors.  
  21.   switch($gmclient->returnCode())  
  22.   {  
  23.     case GEARMAN_WORK_DATA:  
  24.       echo "Data: $result\n";  
  25.       break;  
  26.     case GEARMAN_WORK_STATUS:  
  27.       list($numerator, $denominator)= $gmclient->doStatus();  
  28.       echo "Status: $numerator/$denominator complete\n";  
  29.       break;  
  30.     case GEARMAN_SUCCESS:  
  31.       break;  
  32.     default:  
  33.       echo "RET: " . $gmclient->returnCode() . "\n";  
  34.       exit;  
  35.   }  
  36. }  
  37. while($gmclient->returnCode() != GEARMAN_SUCCESS);  
  38. echo "Success: $result\n";  
  39.   
  40. ?>  



[php] view plaincopyprint?在CODE上查看代码片派生到我的代码片
  1. <?php  
  2. /* 
  3.  * 阻塞方式Worker，处理"Hello!"转换为"!olleH" 
  4.  */  
  5.   
  6. echo "Starting\n";  
  7.   
  8. # Create our worker object.  
  9. $gmworker= new GearmanWorker();  
  10. $gmworker->setTimeout(5000);  
  11.   
  12. # Add default server (localhost).  
  13. $gmworker->addServer();  
  14.   
  15. # Register function "reverse" with the server. Change the worker function to  
  16. # "reverse_fn_fast" for a faster worker with no output.  
  17. $gmworker->addFunction("reverse", "reverse_fn");  
  18.   
  19. print "Waiting for job...\n";  
  20. while($gmworker->work())  
  21. {  
  22.   if ($gmworker->returnCode() != GEARMAN_SUCCESS)  
  23.   {  
  24.     echo "return_code: " . $gmworker->returnCode() . "\n";  
  25.     break;  
  26.   }  
  27.   echo "receve and proced a job!";  
  28. }  
  29.   
  30. function reverse_fn($job)  
  31. {  
  32.   echo "Received job: " . $job->handle() . "\n";  
  33.   
  34.   $workload= $job->workload();  
  35.   $workload_size= $job->workloadSize();  
  36.   
  37.   echo "Workload: $workload ($workload_size)\n";  
  38.   
  39.   # This status loop is not needed, just showing how it works  
  40.   for ($x= 0; $x < $workload_size; $x++)  
  41.   {  
  42.     echo "Sending status: $x/$workload_size complete\n";  
  43.     /* 
  44.     $job->sendStatus($x, $workload_size); 
  45.     sleep(1); 
  46.     */  
  47.   }  
  48.   
  49.   $result= strrev($workload);  
  50.   echo "Result: $result\n";  
  51.   
  52.   # Return what we want to send back to the client.  
  53.   return $result;  
  54. }  
  55.   
  56. # A much simpler and less verbose version of the above function would be:  
  57. function reverse_fn_fast($job)  
  58. {  
  59.   return strrev($job->workload());  
  60. }  
  61.   
  62. ?>  

 

[php] view plaincopyprint?在CODE上查看代码片派生到我的代码片
    1. <?php  
    2. /* 
    3.  * 非阻塞方式Worker，处理"Hello!"转换为"!olleH" 
    4.  */  
    5.   
    6. echo "Starting\n";  
    7.   
    8. # Create our worker object.  
    9. $gmworker= new GearmanWorker();  
    10. $gmworker->setTimeout(1000);  
    11. $gmworker->addOptions(GEARMAN_WORKER_NON_BLOCKING); # Make the worker non-blocking  
    12.   
    13. # Add default server (localhost).  
    14. $gmworker->addServer();  
    15.   
    16. # Register function "reverse" with the server. Change the worker function to  
    17. # "reverse_fn_fast" for a faster worker with no output.  
    18. $gmworker->addFunction("reverse", "reverse_fn");  
    19.   
    20. print "Waiting for job...\n";  
    21.   
    22. while ( ($ret = $gmworker->work()) || $gmworker->returnCode() == GEARMAN_IO_WAIT || $gmworker->returnCode() == GEARMAN_NO_JOBS) {  
    23.   echo "return_code: " . $gmworker->returnCode() . "\n";  
    24.   if ($gmworker->returnCode() == GEARMAN_SUCCESS) {  
    25.     continue;  
    26.   }  
    27.   if ( !$gmworker->wait() ) {  
    28.     echo "return_code: " . $gmworker->returnCode() . "\n";  
    29.     if ($gmworker->returnCode() == GEARMAN_NO_ACTIVE_FDS) {  
    30.       # We are not connected to any servers, so wait a bit before  
    31.       # trying to reconnect. sleep(5);  
    32.       continue;  
    33.     }  
    34.     break;  
    35.   }  
    36. }  
    37.   
    38. function reverse_fn($job)  
    39. {  
    40.   echo "Received job: " . $job->handle() . "\n";  
    41.   
    42.   $workload= $job->workload();  
    43.   $workload_size= $job->workloadSize();  
    44.   
    45.   echo "Workload: $workload ($workload_size)\n";  
    46.   
    47.   # This status loop is not needed, just showing how it works  
    48.   for ($x= 0; $x < $workload_size; $x++)  
    49.   {  
    50.     echo "Sending status: $x/$workload_size complete\n";  
    51.     /* 
    52.     $job->sendStatus($x, $workload_size); 
    53.     sleep(1); 
    54.     */  
    55.   }  
    56.   
    57.   $result= strrev($workload);  
    58.   echo "Result: $result\n";  
    59.   
    60.   # Return what we want to send back to the client.  
    61.   return $result;  
    62. }  
    63.   
    64. # A much simpler and less verbose version of the above function would be:  
    65. function reverse_fn_fast($job)  
    66. {  
    67.   return strrev($job->workload());  
    68. }  
    69.   
    70. ?> 
posted @ 2014-03-27 15:02  shenming  阅读(782)  评论(0)  编辑  收藏  举报