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diff --git a/bdb/docs/ref/env/region.html b/bdb/docs/ref/env/region.html deleted file mode 100644 index 0dfa19672e5..00000000000 --- a/bdb/docs/ref/env/region.html +++ /dev/null @@ -1,66 +0,0 @@ -<!--$Id: region.so,v 10.23 2000/08/09 15:45:52 sue Exp $--> -<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> -<!--All rights reserved.--> -<html> -<head> -<title>Berkeley DB Reference Guide: Shared Memory Regions</title> -<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> -<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"> -</head> -<body bgcolor=white> -<table><tr valign=top> -<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Environment</dl></h3></td> -<td width="1%"><a href="../../ref/env/security.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/env/remote.html"><img src="../../images/next.gif" alt="Next"></a> -</td></tr></table> -<p> -<h1 align=center>Shared Memory Regions</h1> -<p>Each of the Berkeley DB subsystems within an environment is described by one or -more regions. The regions contain all of the per-process and per-thread -shared information, including mutexes, that comprise a Berkeley DB environment. -These regions are created in one of three areas, depending on the flags -specified to the <a href="../../api_c/env_open.html">DBENV->open</a> function: -<p><ol> -<p><li>If the <a href="../../api_c/env_open.html#DB_PRIVATE">DB_PRIVATE</a> flag is specified to <a href="../../api_c/env_open.html">DBENV->open</a>, regions -are created in per-process heap memory, i.e., memory returned by -<b>malloc</b>(3). In this case, the Berkeley DB environment may only be -accessed by a single process, although that process may be -multi-threaded. -<p><li>If the <a href="../../api_c/env_open.html#DB_SYSTEM_MEM">DB_SYSTEM_MEM</a> flag is specified to <a href="../../api_c/env_open.html">DBENV->open</a>, -regions are created in system memory. When regions are created in system -memory, the Berkeley DB environment may be accessed by both multiple processes -and multiple threads within processes. -<p>The system memory used by Berkeley DB is potentially useful past the lifetime -of any particular process. Therefore, additional cleanup may be necessary -after an application fails, as there may be no way for Berkeley DB to ensure -that system resources backing the shared memory regions are returned to -the system. -<p>The system memory that is used is architecture-dependent. For example, -on systems supporting X/Open-style shared memory interfaces, e.g., UNIX -systems, the <b>shmget</b>(2) and related System V IPC interfaces are -used. Additionally, VxWorks systems use system memory. -In these cases, an initial segment ID must be specified by the -application to ensure that applications do not overwrite each other's -database environments, and so that the number of segments created does -not grow without bound. See the <a href="../../api_c/env_set_shm_key.html">DBENV->set_shm_key</a> function for more -information. -<p><li>If no memory-related flags are specified to <a href="../../api_c/env_open.html">DBENV->open</a>, then -memory backed by the filesystem is used to store the regions. On UNIX -systems, the Berkeley DB library will use the POSIX mmap interface. If mmap is -not available, the UNIX shmget interfaces will be used, assuming they are -available. -</ol> -<p>Any files created in the filesystem to back the regions are created in -the environment home directory specified to the <a href="../../api_c/env_open.html">DBENV->open</a> call. -These files are named __db.###, e.g., __db.001, __db.002 and so on. -When region files are backed by the filesystem, one file per region is -created. When region files are backed by system memory, a single file -will still be created, as there must be a well-known name in the -filesystem so that multiple processes can locate the system shared memory -that is being used by the environment. -<p>Statistics about the shared memory regions in the environment can be -displayed using the <b>-e</b> option to the <a href="../../utility/db_stat.html">db_stat</a> utility. -<table><tr><td><br></td><td width="1%"><a href="../../ref/env/security.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/env/remote.html"><img src="../../images/next.gif" alt="Next"></a> -</td></tr></table> -<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font> -</body> -</html> |