20.1.29 ead_get_node_next_key() (acquires the next key with EADS server specification)

(1) Description

This function acquires the key that immediately follows a specified key in ascending order based on its ASCII code value from among all the keys that are stored on a specified EADS server.

If the specified key does not exist on the connection-target EADS server, the function similarly acquires the key that immediately follows the specified key.

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(2) Format

#include <eads.h>
char* ead_get_node_next_key
(
  const EAD_CACHE     *cp,             /* In */
  const ead_node      *target_node,    /* In */ 
  const char          *key,            /* In */
  int                 *error_code      /* Out */
);

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(3) Arguments

cp

Specifies the handle (pointer) to the cache in which the key is to be acquired.

Specify the handle (pointer) obtained from ead_start_cache() when access to the cache was started.

target_node

Specifies the pointer to the EADS server (ead_node structure) from which the key is to be acquired.

You can only specify the pointer of the ead_node structure obtained by using the EADS client library. If you specify any other pointer, correct operation is not guaranteed.

For the format and details of the ead_node structure, see 20.1.50 ead_node structure (object used in a user function with an EADS server specified).

An error results if the address information (IP address and port number) managed by the specified ead_node structure does not match the address information of any EADS servers maintained by the EADS client.

key

Specifies the reference key.

For details about the data types that can be specified, see 15.2.2(1) Data types that can be specified as keys.

error_code

Specifies the pointer from which to retrieve the error code.

For details about error codes, see 20.2 Error codes in the client library (C).

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(4) Return value

This function returns the key that immediately follows the specified key in ascending order based on its ASCII code value from among all the keys that are stored on the specified server.

The function returns NULL in the following cases:

• No key follows the specified key.

• Acquisition of the key failed due to an error.

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(5) Notes

• If acquisition of the key is successful (the return value is not NULL), the memory area is not freed automatically. You must free it in the application program. For details, see 19.1.1(10) Freeing a memory area returned as a return value.

• The EADS server that stores the keys belonging to the specified group might change due to isolation, restoration, or addition (scale-out) processing on EADS servers other than the connection-target EADS server.

• Because groups are not locked on EADS servers, keys that belong to groups might be inserted or deleted by another process after ead_get_node_first_key() or ead_get_node_next_key() has executed.

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