1<!--$Id: rep_message.so,v 1.39 2007/03/20 20:20:26 alanb Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: DB_ENV->rep_process_message</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>DB_ENV->rep_process_message</b> 14</td> 15<td align=right> 16<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a> 17<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db.h> 23<p> 24int 25DB_ENV->rep_process_message(DB_ENV *env, 26 DBT *control, DBT *rec, int envid, DB_LSN *ret_lsnp) 27</pre></b> 28<hr size=1 noshade> 29<b>Description: DB_ENV->rep_process_message</b> 30<p>The DB_ENV->rep_process_message method processes an incoming replication message sent 31by a member of the replication group to the local database environment.</p> 32<p>The DB_ENV->rep_process_message method is not called by most replication 33applications. It should only be called by applications implementing 34their own network transport layer, explicitly holding replication group 35elections and handling replication messages outside of the replication 36manager framework.</p> 37<p>For implementation reasons, all incoming replication messages must be 38processed using the same <a href="../api_c/env_class.html">DB_ENV</a> handle. It is not required that 39a single thread of control process all messages, only that all threads 40of control processing messages use the same handle.</p> 41<p>The DB_ENV->rep_process_message method has additional return values:</p> 42<br> 43<b><a name="DB_REP_DUPMASTER">DB_REP_DUPMASTER</a></b><ul compact><li> 44<p>The DB_ENV->rep_process_message method 45will return DB_REP_DUPMASTER if the replication group has more than one master. 46The application should reconfigure itself as a client by calling the 47<a href="../api_c/rep_start.html">DB_ENV->rep_start</a> method, and then call for an election by calling 48<a href="../api_c/rep_elect.html">DB_ENV->rep_elect</a>. 49</p></ul> 50<b><a name="DB_REP_HOLDELECTION">DB_REP_HOLDELECTION</a></b><ul compact><li> 51<p>The DB_ENV->rep_process_message method 52will return DB_REP_HOLDELECTION if an election is needed. 53The application should call for an election by calling <a href="../api_c/rep_elect.html">DB_ENV->rep_elect</a>. 54</p></ul> 55<b><a name="DB_REP_IGNORE">DB_REP_IGNORE</a></b><ul compact><li> 56<p>The DB_ENV->rep_process_message method will return DB_REP_IGNORE if this message cannot be processed. 57This is an indication that this message is irrelevant to the current 58replication state (for example, an old message 59from a previous generation arrives and is processed late). 60</p></ul> 61<b><a name="DB_REP_ISPERM">DB_REP_ISPERM</a></b><ul compact><li> 62<p>The DB_ENV->rep_process_message method will return DB_REP_ISPERM if processing this message results in the processing of records 63that are permanent. 64The maximum LSN of the permanent records stored is returned. 65</p></ul> 66<b><a name="DB_REP_JOIN_FAILURE">DB_REP_JOIN_FAILURE</a></b><ul compact><li> 67<p>The DB_ENV->rep_process_message method will return DB_REP_JOIN_FAILURE if a new master has been chosen but the client is unable to synchronize 68with the new master (possibly because the client has been configured 69with the <a href="../api_c/rep_config.html#DB_REP_CONF_NOAUTOINIT">DB_REP_CONF_NOAUTOINIT</a> flag to turn-off automatic 70internal initialization). 71</p></ul> 72<b><a name="DB_REP_NEWSITE">DB_REP_NEWSITE</a></b><ul compact><li> 73<p>The DB_ENV->rep_process_message method will return DB_REP_NEWSITE if the system received contact information from a new environment. 74The <b>rec</b> parameter contains the opaque data specified in the 75<b>cdata</b> parameter to the <a href="../api_c/rep_start.html">DB_ENV->rep_start</a>. The application 76should take whatever action is needed to establish a communication 77channel with this new environment. 78</p></ul> 79<b><a name="DB_REP_NOTPERM">DB_REP_NOTPERM</a></b><ul compact><li> 80<p>The DB_ENV->rep_process_message method will return DB_REP_NOTPERM if a message carrying a <a href="../api_c/rep_transport.html#DB_REP_PERMANENT">DB_REP_PERMANENT</a> flag was processed 81successfully, but was not written to disk. 82The LSN of this record is returned. The application should take 83whatever action is deemed necessary to retain its recoverability 84characteristics. 85</p></ul> 86<br> 87<p>Unless otherwise specified, the DB_ENV->rep_process_message method 88returns a non-zero error value on failure 89and 0 on success. 90</p> 91<b>Parameters</b> <br> 92 <b>control</b><ul compact><li>The <b>control</b> parameter should reference a copy of the 93<b>control</b> parameter specified by Berkeley DB on the sending 94environment.</ul> 95 <b>envid</b><ul compact><li>The <b>envid</b> parameter should contain the local identifier that 96corresponds to the environment that sent the message to be processed 97(see <a href="../ref/rep/id.html">Replication environment IDs</a> for more 98information).</ul> 99 <b>rec</b><ul compact><li>The <b>rec</b> parameter should reference a copy of the <b>rec</b> 100parameter specified by Berkeley DB on the sending environment.</ul> 101 <b>ret_lsnp</b><ul compact><li>If DB_ENV->rep_process_message method returns DB_REP_NOTPERM then the <b>ret_lsnp</b> 102parameter will contain the log sequence number of this permanent log 103message that could not be written to disk. If DB_ENV->rep_process_message method 104returns DB_REP_ISPERM then the <b>ret_lsnp</b> parameter will contain 105largest log sequence number of the permanent records that are now 106written to disk as a result of processing this message. In all other 107cases the value of <b>ret_lsnp</b> is undefined.</ul> 108<br> 109<hr size=1 noshade> 110<br><b>Class</b> 111<a href="../api_c/env_class.html">DB_ENV</a> 112<br><b>See Also</b> 113<a href="../api_c/rep_list.html">Replication and Related Methods</a> 114</tt> 115<table width="100%"><tr><td><br></td><td align=right> 116<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> 117</td></tr></table> 118<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 119</body> 120</html> 121
