To open an existing environment with default attributes the application may use a default environment configuration object or null:
// Open an environment handle with default attributes.
Environment env = new Environment(home, new EnvironmentConfig());
or
Environment env = new Environment(home, null);
Note that many Environment objects may access a single environment.
To create an environment or customize attributes, the application should customize the configuration class. For example:
EnvironmentConfig envConfig = new EnvironmentConfig();
envConfig.setTransactional(true);
envConfig.setAllowCreate(true);
envConfig.setCacheSize(1000000);
Environment newlyCreatedEnv = new Environment(home, envConfig);
Environment handles are free-threaded unless {@link com.sleepycat.db.EnvironmentConfig#setThreaded EnvironmentConfig.setThreaded} is called to disable this before the environment is opened.
An environment handle is an Environment instance. More than one Environment instance may be created for the same physical directory, which is the same as saying that more than one Environment handle may be open at one time for a given environment.
The Environment handle should not be closed while any other handle remains open that is using it as a reference (for example, {@link com.sleepycat.db.Database Database} or {@link com.sleepycat.db.Transaction Transaction}. Once {@link com.sleepycat.db.Environment#close Environment.close} is called, this object may not be accessed again, regardless of whether or not it throws an exception. */ public class Environment { private DbEnv dbenv; private int autoCommitFlag; /* package */ Environment(final DbEnv dbenv) throws DatabaseException { this.dbenv = dbenv; dbenv.wrapper = this; } /** Create a database environment handle.
@param home
The database environment's home directory.
The environment variable DB_HOME may be used as
the path of the database home.
For more information on envHome and filename
resolution in general, see
File Naming.
@param config The database environment attributes. If null, default attributes are used.
@throws IllegalArgumentException if an invalid parameter was specified.
@throws DatabaseException if a failure occurs. */ public Environment(final java.io.File home, EnvironmentConfig config) throws DatabaseException, java.io.FileNotFoundException { this(EnvironmentConfig.checkNull(config).openEnvironment(home)); this.autoCommitFlag = ((dbenv.get_open_flags() & DbConstants.DB_INIT_TXN) == 0) ? 0 : DbConstants.DB_AUTO_COMMIT; } /** Close the database environment, freeing any allocated resources and closing any underlying subsystems.
The {@link com.sleepycat.db.Environment Environment} handle should not be closed while any other handle that refers to it is not yet closed; for example, database environment handles must not be closed while transactions in the environment have not yet been committed or aborted. Specifically, this includes {@link com.sleepycat.db.Transaction Transaction}, and {@link com.sleepycat.db.LogCursor LogCursor} handles.
This method automatically closes all open database handles but does not synchronize the database. To synchronize all open databases ensure that the last environment object is closed using the Environment.CloseForceSync() method. When the close operation fails, the method returns a non-zero error value for the first instance of such error, and continues to close the rest of the environment objects.
Where the environment was initialized with a locking subsystem, closing the environment does not release any locks still held by the closing process, providing functionality for long-lived locks.
Where the environment was initialized with a transaction subsystem, closing the environment aborts any unresolved transactions. Applications should not depend on this behavior for transactions involving databases; all such transactions should be explicitly resolved. The problem with depending on this semantic is that aborting an unresolved transaction involving database operations requires a database handle. Because the database handles should have been closed before closing the environment, it will not be possible to abort the transaction, and recovery will have to be run on the database environment before further operations are done.
Where log cursors were created, closing the environment does not imply closing those cursors.
In multithreaded applications, only a single thread may call this method.
After this method has been called, regardless of its return, the {@link com.sleepycat.db.Environment Environment} handle may not be accessed again.
@throws DatabaseException if a failure occurs. */ public void close() throws DatabaseException { dbenv.close(0); } /** Close the database environment, freeing any allocated resources and closing any underlying subsystems.
This function has verify similar behavior as Environment.close(), except the following: When each open database handle is closed, it's synced. */ public void closeForceSync() throws DatabaseException { dbenv.close(DbConstants.DB_FORCESYNC); } /* package */ DbEnv unwrap() { return dbenv; } /** Destroy a database environment.
If the environment is not in use, the environment regions, including any backing files, are removed. Any log or database files and the environment directory itself are not removed.
If there are processes currently using the database environment, this method will fail without further action (unless the force argument is true, in which case the environment will be removed, regardless of any processes still using it).
The result of attempting to forcibly destroy the environment when it is in use is unspecified. Processes using an environment often maintain open file descriptors for shared regions within it. On UNIX systems, the environment removal will usually succeed, and processes that have already joined the region will continue to run in that region without change. However, processes attempting to join the environment will either fail or create new regions. On other systems in which the unlink system call will fail if any process has an open file descriptor for the file (for example Windows/NT), the region removal will fail.
Calling this method should not be necessary for most applications because the environment is cleaned up as part of normal database recovery procedures. However, applications may want to call this method as part of application shut down to free up system resources. For example, if system shared memory was used to back the database environment, it may be useful to call this method in order to release system shared memory segments that have been allocated. Or, on architectures in which mutexes require allocation of underlying system resources, it may be useful to call this method in order to release those resources. Alternatively, if recovery is not required because no database state is maintained across failures, and no system resources need to be released, it is possible to clean up an environment by simply removing all the Berkeley DB files in the database environment's directories.
In multithreaded applications, only a single thread may call this method.
After this method has been called, regardless of its return, the {@link com.sleepycat.db.Environment Environment} handle may not be accessed again.
@param home The database environment to be removed. On Windows platforms, this argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.
@param force The environment is removed, regardless of any processes that may still using it, and no locks are acquired during this process. (Generally, the force argument is specified only when applications were unable to shut down cleanly, and there is a risk that an application may have died holding a Berkeley DB mutex or lock.
@throws DatabaseException if a failure occurs. */ public static void remove(final java.io.File home, final boolean force, EnvironmentConfig config) throws DatabaseException, java.io.FileNotFoundException { config = EnvironmentConfig.checkNull(config); int flags = force ? DbConstants.DB_FORCE : 0; flags |= config.getUseEnvironment() ? DbConstants.DB_USE_ENVIRON : 0; flags |= config.getUseEnvironmentRoot() ? DbConstants.DB_USE_ENVIRON_ROOT : 0; final DbEnv dbenv = config.createEnvironment(); dbenv.remove((home == null) ? null : home.toString(), flags); } /** Change the settings in an existing environment handle.
@param config The database environment attributes. If null, default attributes are used.
@throws IllegalArgumentException if an invalid parameter was specified.
@throws DatabaseException if a failure occurs. */ public void setConfig(final EnvironmentConfig config) throws DatabaseException { config.configureEnvironment(dbenv, new EnvironmentConfig(dbenv)); } /** Return this object's configuration.
@return This object's configuration.
@throws DatabaseException if a failure occurs. */ public EnvironmentConfig getConfig() throws DatabaseException { return new EnvironmentConfig(dbenv); } /* Manage databases. */ /** Open a database.
The database is represented by the file and database parameters.
The currently supported database file formats (or access methods) are Btree, Hash, Queue, and Recno. The Btree format is a representation of a sorted, balanced tree structure. The Hash format is an extensible, dynamic hashing scheme. The Queue format supports fast access to fixed-length records accessed sequentially or by logical record number. The Recno format supports fixed- or variable-length records, accessed sequentially or by logical record number, and optionally backed by a flat text file.
Storage and retrieval are based on key/data pairs; see {@link com.sleepycat.db.DatabaseEntry DatabaseEntry} for more information.
Opening a database is a relatively expensive operation, and maintaining a set of open databases will normally be preferable to repeatedly opening and closing the database for each new query.
In-memory databases never intended to be preserved on disk may be
created by setting both the fileName and databaseName parameters to
null. Note that in-memory databases can only ever be shared by sharing
the single database handle that created them, in circumstances where
doing so is safe. The environment variable TMPDIR may
be used as a directory in which to create temporary backing files.
@param txn For a transactional database, an explicit transaction may be specified, or null may be specified to use auto-commit. For a non-transactional database, null must be specified. Note that transactionally protected operations on a Database handle require that the Database handle itself be transactionally protected during its open, either with a non-null transaction handle, or by calling {@link com.sleepycat.db.DatabaseConfig#setTransactional DatabaseConfig.setTransactional} on the configuration object.
@param fileName The name of an underlying file that will be used to back the database. On Windows platforms, this argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.
@param databaseName An optional parameter that allows applications to have multiple databases in a single file. Although no databaseName parameter needs to be specified, it is an error to attempt to open a second database in a physical file that was not initially created using a databaseName parameter. Further, the databaseName parameter is not supported by the Queue format.
@param config The database open attributes. If null, default attributes are used. */ public Database openDatabase(final Transaction txn, final String fileName, final String databaseName, DatabaseConfig config) throws DatabaseException, java.io.FileNotFoundException { return new Database( DatabaseConfig.checkNull(config).openDatabase(dbenv, (txn == null) ? null : txn.txn, fileName, databaseName)); } /** Open a database.
The database is represented by the file and database parameters.
The currently supported database file formats (or access methods) are Btree, Hash, Queue, and Recno. The Btree format is a representation of a sorted, balanced tree structure. The Hash format is an extensible, dynamic hashing scheme. The Queue format supports fast access to fixed-length records accessed sequentially or by logical record number. The Recno format supports fixed- or variable-length records, accessed sequentially or by logical record number, and optionally backed by a flat text file.
Storage and retrieval are based on key/data pairs; see {@link com.sleepycat.db.DatabaseEntry DatabaseEntry} for more information.
Opening a database is a relatively expensive operation, and maintaining a set of open databases will normally be preferable to repeatedly opening and closing the database for each new query.
In-memory databases never intended to be preserved on disk may be
created by setting both the fileName and databaseName parameters to
null. Note that in-memory databases can only ever be shared by sharing
the single database handle that created them, in circumstances where
doing so is safe. The environment variable TMPDIR may
be used as a directory in which to create temporary backing files.
@param txn For a transactional database, an explicit transaction may be specified, or null may be specified to use auto-commit. For a non-transactional database, null must be specified. Note that transactionally protected operations on a Database handle require that the Database handle itself be transactionally protected during its open, either with a non-null transaction handle, or by calling {@link com.sleepycat.db.DatabaseConfig#setTransactional DatabaseConfig.setTransactional} on the configuration object.
@param fileName The name of an underlying file that will be used to back the database. On Windows platforms, this argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.
@param databaseName An optional parameter that allows applications to have multiple databases in a single file. Although no databaseName parameter needs to be specified, it is an error to attempt to open a second database in a physical file that was not initially created using a databaseName parameter. Further, the databaseName parameter is not supported by the Queue format.
@param primaryDatabase a database handle for the primary database that is to be indexed.
@param config The secondary database open attributes. If null, default attributes are used. */ public SecondaryDatabase openSecondaryDatabase( final Transaction txn, final String fileName, final String databaseName, final Database primaryDatabase, SecondaryConfig config) throws DatabaseException, java.io.FileNotFoundException { return new SecondaryDatabase( SecondaryConfig.checkNull(config).openSecondaryDatabase( dbenv, (txn == null) ? null : txn.txn, fileName, databaseName, primaryDatabase.db), primaryDatabase); } /**
Remove a database.
If no database is specified, the underlying file specified is removed.
Applications should never remove databases with open {@link com.sleepycat.db.Database Database} handles, or in the case of removing a file, when any database in the file has an open handle. For example, some architectures do not permit the removal of files with open system handles. On these architectures, attempts to remove databases currently in use by any thread of control in the system may fail.
The environment variable DB_HOME may be used as the path of the database environment home.
This method is affected by any database directory specified with {@link com.sleepycat.db.EnvironmentConfig#addDataDir EnvironmentConfig.addDataDir}, or by setting the "set_data_dir" string in the database environment's DB_CONFIG file.
The {@link com.sleepycat.db.Database Database} handle may not be accessed again after this method is called, regardless of this method's success or failure.
@param txn For a transactional database, an explicit transaction may be specified, or null may be specified to use auto-commit. For a non-transactional database, null must be specified.
@param fileName The physical file which contains the database to be removed. On Windows platforms, this argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.
@param databaseName The database to be removed.
@throws DeadlockException if the operation was selected to resolve a deadlock.
@throws DatabaseException if a failure occurs. */ public void removeDatabase(final Transaction txn, final String fileName, final String databaseName) throws DatabaseException, java.io.FileNotFoundException { dbenv.dbremove((txn == null) ? null : txn.txn, fileName, databaseName, (txn == null) ? autoCommitFlag : 0); } /**
Rename a database.
If no database name is specified, the underlying file specified is renamed, incidentally renaming all of the databases it contains.
Applications should never rename databases that are currently in use. If an underlying file is being renamed and logging is currently enabled in the database environment, no database in the file may be open when this method is called. In particular, some architectures do not permit renaming files with open handles. On these architectures, attempts to rename databases that are currently in use by any thread of control in the system may fail.
The environment variable DB_HOME may be used as the path of the database environment home.
This method is affected by any database directory specified with {@link com.sleepycat.db.EnvironmentConfig#addDataDir EnvironmentConfig.addDataDir}, or by setting the "set_data_dir" string in the database environment's DB_CONFIG file.
The {@link com.sleepycat.db.Database Database} handle may not be accessed again after this method is called, regardless of this method's success or failure.
@param txn For a transactional database, an explicit transaction may be specified, or null may be specified to use auto-commit. For a non-transactional database, null must be specified.
@param fileName The physical file which contains the database to be renamed. On Windows platforms, this argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.
@param databaseName The database to be renamed.
@param newName The new name of the database or file.
@throws DeadlockException if the operation was selected to resolve a deadlock.
@throws DatabaseException if a failure occurs. */ public void renameDatabase(final Transaction txn, final String fileName, final String databaseName, final String newName) throws DatabaseException, java.io.FileNotFoundException { dbenv.dbrename((txn == null) ? null : txn.txn, fileName, databaseName, newName, (txn == null) ? autoCommitFlag : 0); } /** Return the database environment home directory. This directory is normally identified in the {@link com.sleepycat.db.Environment} constructor.
@return the database environment home directory. */ public java.io.File getHome() throws DatabaseException { String home = dbenv.get_home(); return (home == null) ? null : new java.io.File(home); } /* Cache management. */ /** Ensure that a specified percent of the pages in the shared memory pool are clean, by writing dirty pages to their backing files.
The purpose of this method is to enable a memory pool manager to ensure that a page is always available for reading in new information without having to wait for a write.
@param percent The percent of the pages in the cache that should be clean.
@return The number of pages that were written to reach the specified percentage.
@throws DatabaseException if a failure occurs. */ public int trickleCacheWrite(int percent) throws DatabaseException { return dbenv.memp_trickle(percent); } /* Locking */ /** Run one iteration of the deadlock detector.
The deadlock detector traverses the lock table and marks one of the participating lock requesters for rejection in each deadlock it finds.
@param mode Which lock request(s) to reject.
@return The number of lock requests that were rejected.
@throws DatabaseException if a failure occurs. */ public int detectDeadlocks(LockDetectMode mode) throws DatabaseException { return dbenv.lock_detect(0, mode.getFlag()); } /** Acquire a lock from the lock table.
@param locker An unsigned 32-bit integer quantity representing the entity requesting the lock.
@param mode The lock mode.
@param noWait If a lock cannot be granted because the requested lock conflicts with an existing lock, throw a {@link com.sleepycat.db.LockNotGrantedException LockNotGrantedException} immediately instead of waiting for the lock to become available.
@param object An untyped byte string that specifies the object to be locked. Applications using the locking subsystem directly while also doing locking via the Berkeley DB access methods must take care not to inadvertently lock objects that happen to be equal to the unique file IDs used to lock files.
@throws DatabaseException if a failure occurs. */ public Lock getLock(int locker, boolean noWait, DatabaseEntry object, LockRequestMode mode) throws DatabaseException { return Lock.wrap( dbenv.lock_get(locker, noWait ? DbConstants.DB_LOCK_NOWAIT : 0, object, mode.getFlag())); } /** Release a lock.
@param lock The lock to be released.
@throws DatabaseException if a failure occurs. */ public void putLock(Lock lock) throws DatabaseException { dbenv.lock_put(lock.unwrap()); } /** Allocate a locker ID.
The locker ID is guaranteed to be unique for the database environment.
Call {@link com.sleepycat.db.Environment#freeLockerID Environment.freeLockerID} to return the locker ID to the environment when it is no longer needed.
@return A locker ID. */ public int createLockerID() throws DatabaseException { return dbenv.lock_id(); } /** Free a locker ID.
@param id The locker id to be freed.
@throws DatabaseException if a failure occurs. */ public void freeLockerID(int id) throws DatabaseException { dbenv.lock_id_free(id); } /** Return the deadlock priority for the given locker.
@param id The locker id
@throws DatabaseException if a failure occurs. */ public int getLockerPriority(int id) throws DatabaseException { return dbenv.get_lk_priority(id); } /** Assign a deadlock priority to a locker. The deadlock detector will reject lock requests from lower priority lockers are before those from higher priority lockers.
@param id The locker id to configure @param priority The priority to assign to the locker.
@throws DatabaseException if a failure occurs */ public void setLockerPriority(int id, int priority) throws DatabaseException { dbenv.set_lk_priority(id, priority); } /** Atomically obtain and release one or more locks from the lock table. This method is intended to support acquisition or trading of multiple locks under one lock table semaphore, as is needed for lock coupling or in multigranularity locking for lock escalation.
If any of the requested locks cannot be acquired, or any of the locks to be released cannot be released, the operations before the failing operation are guaranteed to have completed successfully, and the method throws an exception.
@param noWait If a lock cannot be granted because the requested lock conflicts with an existing lock, throw a {@link com.sleepycat.db.LockNotGrantedException LockNotGrantedException} immediately instead of waiting for the lock to become available. The index of the request that was not granted will be returned by {@link com.sleepycat.db.LockNotGrantedException#getIndex LockNotGrantedException.getIndex}.
@param locker An unsigned 32-bit integer quantity representing the entity requesting the lock.
@param list An array of {@link com.sleepycat.db.LockRequest LockRequest} objects, listing the requested lock operations.
@throws DatabaseException if a failure occurs. */ public void lockVector(int locker, boolean noWait, LockRequest[] list) throws DatabaseException { dbenv.lock_vec(locker, noWait ? DbConstants.DB_LOCK_NOWAIT : 0, list, 0, list.length); } /* Logging */ /** Return a log cursor.
@return A log cursor.
@throws DatabaseException if a failure occurs. */ public LogCursor openLogCursor() throws DatabaseException { return LogCursor.wrap(dbenv.log_cursor(0)); } /** Return the name of the log file that contains the log record specified by a LogSequenceNumber object.
This mapping of LogSequenceNumber objects to files is needed for database administration. For example, a transaction manager typically records the earliest LogSequenceNumber object needed for restart, and the database administrator may want to archive log files to tape when they contain only log records before the earliest one needed for restart.
@param lsn The LogSequenceNumber object for which a filename is wanted.
@return The name of the log file that contains the log record specified by a LogSequenceNumber object.
@throws IllegalArgumentException if an invalid parameter was specified.
@throws DatabaseException if a failure occurs. */ public String getLogFileName(LogSequenceNumber lsn) throws DatabaseException { return dbenv.log_file(lsn); } /** Verify log files.
@param config The LogVerifyConfig object which contains configurations for the log verification.
@return If the verification succeeds, return 0; otherwise non-zero. Error, warning and report messages are written to the environment's error report destination. */ public int logVerify(LogVerifyConfig config) { String env_home, dbfile, dbname; int caf, efile, eoffset, flags, ret, stfile, stoffset, verbose; long etime, stime; LogSequenceNumber endlsn, startlsn; caf = ret = verbose = 0; env_home = config.getEnvHome(); dbfile = config.getDbFile(); dbname = config.getDbName(); stime = 0; etime = 0; if (config.getContinueAfterFail()) caf = 1; if (config.getVerbose()) verbose = 1; if (config.getStartTime() != null) stime = config.getStartTime().getTime() / 1000; if (config.getEndTime() != null) etime = config.getEndTime().getTime() / 1000; startlsn = config.getStartLsn(); endlsn = config.getEndLsn(); efile = eoffset = stfile = stoffset = 0; if (endlsn != null) efile = endlsn.getFile(); if (endlsn != null) eoffset = endlsn.getOffset(); if (startlsn != null) stfile = startlsn.getFile(); if (startlsn != null) stoffset = startlsn.getOffset(); try { ret = dbenv.log_verify(env_home, config.getCacheSize(), dbfile, dbname, stime, etime, stfile, stoffset, efile, eoffset, caf, verbose); } catch (Exception ex) { } return (ret); } /* Replication support */ /** Configure the database environment as a client or master in a group of replicated database environments. Replication master environments are the only database environments where replicated databases may be modified. Replication client environments are read-only as long as they are clients. Replication client environments may be upgraded to be replication master environments in the case that the current master fails or there is no master present.
The enclosing database environment must already have been configured to send replication messages by calling {@link com.sleepycat.db.EnvironmentConfig#setReplicationTransport EnvironmentConfig.setReplicationTransport}.
@param cdata An opaque data item that is sent over the communication infrastructure when the client or master comes online. If no such information is useful, cdata should be null.
@param master Configure the environment as a replication master. If false, the environment will be configured as as a replication client.
@throws DatabaseException if a failure occurs. */ public void startReplication(DatabaseEntry cdata, boolean master) throws DatabaseException { dbenv.rep_start(cdata, master ? DbConstants.DB_REP_MASTER : DbConstants.DB_REP_CLIENT); } /** Hold an election for the master of a replication group.
If the election is successful, the new master's ID may be the ID of the previous master, or the ID of the current environment. The application is responsible for adjusting its usage of the other environments in the replication group, including directing all database updates to the newly selected master, in accordance with the results of this election.
The thread of control that calls this method must not be the thread of control that processes incoming messages; processing the incoming messages is necessary to successfully complete an election.
@param nsites The number of environments that the application believes are in the replication group. This number is used by Berkeley DB to avoid having two masters active simultaneously, even in the case of a network partition. During an election, a new master cannot be elected unless more than half of nsites agree on the new master. Thus, in the face of a network partition, the side of the partition with more than half the environments will elect a new master and continue, while the environments communicating with fewer than half the other environments will fail to find a new master.
@param nvotes The number of votes required by the application to successfully elect a new master. It must be a positive integer, no greater than nsites, or 0 if the election should use a simple majority of the nsites value as the requirement. A warning is given if half or fewer votes are required to win an election as that can potentially lead to multiple masters in the face of a network partition.
@throws DatabaseException if a failure occurs. */ public void electReplicationMaster(int nsites, int nvotes) throws DatabaseException { dbenv.rep_elect(nsites, nvotes, 0 /* unused flags */); } /** Internal method: re-push the last log record to all clients, in case they've lost messages and don't know it.
This method may not be called before the database environment is opened.
@throws DatabaseException if a failure occurs. **/ public void flushReplication() throws DatabaseException { dbenv.rep_flush(); } /** Process an incoming replication message sent by a member of the replication group to the local database environment.
For implementation reasons, all incoming replication messages must be processed using the same {@link com.sleepycat.db.Environment Environment} handle. It is not required that a single thread of control process all messages, only that all threads of control processing messages use the same handle.
@param control A copy of the control parameter specified by Berkeley DB on the sending environment.
@param envid The local identifier that corresponds to the environment that sent the message to be processed.
@param rec A copy of the rec parameter specified by Berkeley DB on the sending environment.
@return A {@link com.sleepycat.db.ReplicationStatus ReplicationStatus} object. */ public ReplicationStatus processReplicationMessage(DatabaseEntry control, DatabaseEntry rec, int envid) throws DatabaseException { // Create a new entry so that rec isn't overwritten final DatabaseEntry cdata = new DatabaseEntry(rec.getData(), rec.getOffset(), rec.getSize()); final LogSequenceNumber lsn = new LogSequenceNumber(); final int ret = dbenv.rep_process_message(control, cdata, envid, lsn); return ReplicationStatus.getStatus(ret, cdata, envid, lsn); } /** Configure the replication subsystem.
The database environment's replication subsystem may also be set using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "rep_set_config", one or more whitespace characters, and the method configuration parameter as a string; for example, "rep_set_config REP_CONF_NOWAIT". Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.
This method configures a database environment, including all threads of control accessing the database environment, not only the operations performed using a specified {@link com.sleepycat.db.Environment Environment} handle.
This method may be called at any time during the life of the application.
@param config A replication feature to be configured. @param onoff If true, the feature is enabled, otherwise it is disabled. **/ public void setReplicationConfig(ReplicationConfig config, boolean onoff) throws DatabaseException { dbenv.rep_set_config(config.getFlag(), onoff); } /** Get the configuration of the replication subsystem. This method may be called at any time during the life of the application. @return Whether the specified feature is enabled or disabled. **/ public boolean getReplicationConfig(ReplicationConfig config) throws DatabaseException { return dbenv.rep_get_config(config.getFlag()); } /** Sets the timeout applied to the specified timeout type. This method may be called at any time during the life of the application. @param type The type of timeout to set.
@param replicationTimeout The time in microseconds of the desired timeout. **/ public void setReplicationTimeout( final ReplicationTimeoutType type, final int replicationTimeout) throws DatabaseException { dbenv.rep_set_timeout(type.getId(), replicationTimeout); } /** Gets the timeout applied to the specified timeout type. @param type The type of timeout to retrieve.
@return The timeout applied to the specified timout type, in microseconds.
@throws DatabaseException if a failure occurs. **/ public int getReplicationTimeout(final ReplicationTimeoutType type) throws DatabaseException { return dbenv.rep_get_timeout(type.getId()); } /** Forces synchronization to begin for this client. This method is the other half of setting {@link ReplicationConfig#DELAYCLIENT} with {@link #setReplicationConfig}.
When a new master is elected and the application has configured delayed synchronization, the application must choose when to perform synchronization by using this method. Otherwise the client will remain unsynchronized and will ignore all new incoming log messages.
This method may not be called before the database environment is opened.
@throws DatabaseException if a failure occurs. **/ public void syncReplication() throws DatabaseException { dbenv.rep_sync(0); } /* Replication Manager interface */ /** Starts the replication manager.
The replication manager is implemented inside the Berkeley DB library, it is designed to manage a replication group. This includes network transport, all replication message processing and acknowledgment, and group elections.
For more information on building replication manager applications, please see the "Replication Manager Getting Started Guide" included in the Berkeley DB documentation.
This method may not be called before the database environment is opened. @param nthreads Specify the number of threads of control created and dedicated to processing replication messages. In addition to these message processing threads, the replication manager creates and manages a few of its own threads of control.
@param policy The policy defines the startup characteristics of a replication group. See {@link com.sleepycat.db.ReplicationManagerStartPolicy ReplicationManagerStartPolicy} for more information. **/ public void replicationManagerStart( int nthreads, ReplicationManagerStartPolicy policy) throws DatabaseException { dbenv.repmgr_start(nthreads, policy.getId()); } /** Return an array of all sites known to the replication manager. */ public ReplicationManagerSiteInfo[] getReplicationManagerSiteList() throws DatabaseException { return dbenv.repmgr_site_list(); } /* Statistics */ /** Returns the memory pool (that is, the buffer cache) subsystem statistics.
@return the memory pool (that is, the buffer cache) subsystem statistics. */ public CacheStats getCacheStats(StatsConfig config) throws DatabaseException { return dbenv.memp_stat(StatsConfig.checkNull(config).getFlags()); } /** Return statistics for individual files in the cache.
@return statistics for individual files in the cache. */ public CacheFileStats[] getCacheFileStats(StatsConfig config) throws DatabaseException { return dbenv.memp_fstat(StatsConfig.checkNull(config).getFlags()); } /** Return the database environment's logging statistics.
@param config The statistics attributes. If null, default attributes are used.
@return The database environment's logging statistics.
@throws DatabaseException if a failure occurs. */ public LogStats getLogStats(StatsConfig config) throws DatabaseException { return dbenv.log_stat(StatsConfig.checkNull(config).getFlags()); } /** Return the database environment's replication statistics.
@param config The statistics attributes. If null, default attributes are used.
@return The database environment's replication statistics.
@throws DatabaseException if a failure occurs. */ public ReplicationStats getReplicationStats(StatsConfig config) throws DatabaseException { return dbenv.rep_stat(StatsConfig.checkNull(config).getFlags()); } /** Return the database environment's replication manager statistics.
@param config The statistics attributes. If null, default attributes are used.
@return The database environment's replication manager statistics.
@throws DatabaseException if a failure occurs. */ public ReplicationManagerStats getReplicationManagerStats( StatsConfig config) throws DatabaseException { return dbenv.repmgr_stat(StatsConfig.checkNull(config).getFlags()); } /** Return the database environment's locking statistics.
@param config The locking statistics attributes. If null, default attributes are used.
@return The database environment's locking statistics.
@throws DatabaseException if a failure occurs. */ public LockStats getLockStats(StatsConfig config) throws DatabaseException { return dbenv.lock_stat(StatsConfig.checkNull(config).getFlags()); } /** Return the database environment's mutex statistics.
@param config The statistics attributes. If null, default attributes are used.
@return The database environment's mutex statistics.
@throws DatabaseException if a failure occurs. */ public MutexStats getMutexStats(StatsConfig config) throws DatabaseException { return dbenv.mutex_stat(StatsConfig.checkNull(config).getFlags()); } /** Return the database environment's transactional statistics.
@param config The transactional statistics attributes. If null, default attributes are used.
@return The database environment's transactional statistics.
@throws DatabaseException if a failure occurs. */ public TransactionStats getTransactionStats(StatsConfig config) throws DatabaseException { return dbenv.txn_stat(StatsConfig.checkNull(config).getFlags()); } /* Transaction management */ /** Allocate a locker ID in an environment configured for Berkeley DB Concurrent Data Store applications. Returns a {@link Transaction} object that uniquely identifies the locker ID. Calling the {@link Transaction#commit} method will discard the allocated locker ID.
See Berkeley DB Concurrent Data Store applications for more information about when this is required.
@return A transaction handle that wraps a CDS locker ID. */ public Transaction beginCDSGroup() throws DatabaseException { return new Transaction(dbenv.cdsgroup_begin()); } /** Create a new transaction in the database environment.
Transactions may only span threads if they do so serially; that is, each transaction must be active in only a single thread of control at a time.
This restriction holds for parents of nested transactions as well; no two children may be concurrently active in more than one thread of control at any one time.
Cursors may not span transactions; that is, each cursor must be opened and closed within a single transaction.
A parent transaction may not issue any Berkeley DB operations -- except for {@link com.sleepycat.db.Environment#beginTransaction Environment.beginTransaction}, {@link com.sleepycat.db.Transaction#abort Transaction.abort} and {@link com.sleepycat.db.Transaction#commit Transaction.commit} -- while it has active child transactions (child transactions that have not yet been committed or aborted).
@param parent If the parent parameter is non-null, the new transaction will be a nested transaction, with the transaction indicated by parent as its parent. Transactions may be nested to any level. In the presence of distributed transactions and two-phase commit, only the parental transaction, that is a transaction without a parent specified, should be passed as an parameter to {@link com.sleepycat.db.Transaction#prepare Transaction.prepare}.
@param config The transaction attributes. If null, default attributes are used.
@return The newly created transaction's handle.
@throws DatabaseException if a failure occurs. */ public Transaction beginTransaction(final Transaction parent, TransactionConfig config) throws DatabaseException { return new Transaction( TransactionConfig.checkNull(config).beginTransaction(dbenv, (parent == null) ? null : parent.txn)); } /** Synchronously checkpoint the database environment.
@param config The checkpoint attributes. If null, default attributes are used.
@throws DatabaseException if a failure occurs. */ public void checkpoint(CheckpointConfig config) throws DatabaseException { CheckpointConfig.checkNull(config).runCheckpoint(dbenv); } /** Flush log records to stable storage.
@param lsn All log records with LogSequenceNumber values less than or equal to the lsn parameter are written to stable storage. If lsn is null, all records in the log are flushed.
@throws DatabaseException if a failure occurs. */ public void logFlush(LogSequenceNumber lsn) throws DatabaseException { dbenv.log_flush(lsn); } /** Append a record to the log.
@param data The record to append to the log.
The caller is responsible for providing any necessary structure to data. (For example, in a write-ahead logging protocol, the application must understand what part of data is an operation code, what part is redo information, and what part is undo information. In addition, most transaction managers will store in data the LogSequenceNumber of the previous log record for the same transaction, to support chaining back through the transaction's log records during undo.)
@param flush The log is forced to disk after this record is written, guaranteeing that all records with LogSequenceNumber values less than or equal to the one being "put" are on disk before this method returns.
@return The LogSequenceNumber of the put record.
@throws DatabaseException if a failure occurs. */ public LogSequenceNumber logPut(DatabaseEntry data, boolean flush) throws DatabaseException { final LogSequenceNumber lsn = new LogSequenceNumber(); dbenv.log_put(lsn, data, flush ? DbConstants.DB_FLUSH : 0); return lsn; } /** Append an informational message to the Berkeley DB database environment log files.
This method allows applications to include information in the database environment log files, for later review using the db_printlog utility. This method is intended for debugging and performance tuning.
@param txn
If the logged message refers to an application-specified transaction,
the txn parameter is a transaction handle, otherwise
null.
@throws DatabaseException if a failure occurs. **/ public void logPrint(Transaction txn, String message) throws DatabaseException { dbenv.log_print((txn == null) ? null : txn.txn, message); } /** Return an array of log files.
When Replication Manager is in use, log archiving is performed in a replication group-aware manner such that the log file status of other sites in the group is considered to determine if a log file is in use.
Log cursor handles (returned by the {@link com.sleepycat.db.Environment#openLogCursor openLogCursor() method} may have open file descriptors for log files in the database environment. Also, the Berkeley DB interfaces to the database environment logging subsystem (for example, {@link com.sleepycat.db.Environment#logPut logPut} and {@link com.sleepycat.db.Transaction#abort Transaction.abort} may allocate log cursors and have open file descriptors for log files as well. On operating systems where filesystem related system calls (for example, rename and unlink on Windows/NT) can fail if a process has an open file descriptor for the affected file, attempting to move or remove returned log files may fail. All Berkeley DB internal use of log cursors operates on active log files only and furthermore, is short-lived in nature. So, an application seeing such a failure should be restructured to close any open log cursors it may have, and otherwise to retry the operation until it succeeds. (Although the latter is not likely to be necessary; it is hard to imagine a reason to move or rename a log file in which transactions are being logged or aborted.)
See db_archive for more information on database archival procedures.
@param includeInUse if true, all log files, regardless of whether or not they are in use, are returned. Otherwise, the log files that are no longer in use (for example, that are no longer involved in active transactions), and that may safely be archived for catastrophic recovery and then removed from the system.
@return An array of log files */ public java.io.File[] getArchiveLogFiles(boolean includeInUse) throws DatabaseException { final String[] logNames = dbenv.log_archive(DbConstants.DB_ARCH_ABS | (includeInUse ? DbConstants.DB_ARCH_LOG : 0)); final int len = (logNames == null) ? 0 : logNames.length; final java.io.File[] logFiles = new java.io.File[len]; for (int i = 0; i < len; i++) logFiles[i] = new java.io.File(logNames[i]); return logFiles; } /** Return the database files that need to be archived in order to recover the database from catastrophic failure. If any of the database files have not been accessed during the lifetime of the current log files, they will not be returned. It is also possible that some of the files referred to by the log have since been deleted from the system.
When Replication Manager is in use, log archiving is performed in a replication group-aware manner such that the log file status of other sites in the group is considered to determine if a log file is in use.
See db_archive for more information on database archival procedures.
@return An array of database files */ public java.io.File[] getArchiveDatabases() throws DatabaseException { final String home = dbenv.get_home(); final String[] dbNames = dbenv.log_archive(DbConstants.DB_ARCH_DATA); final int len = (dbNames == null) ? 0 : dbNames.length; final java.io.File[] dbFiles = new java.io.File[len]; for (int i = 0; i < len; i++) dbFiles[i] = new java.io.File(home, dbNames[i]); return dbFiles; } /** Remove log files that are no longer needed.
Automatic log file removal is likely to make catastrophic recovery impossible.
When Replication Manager is in use, log archiving is performed in a replication group-aware manner such that the log file status of other sites in the group is considered to determine if a log file is in use.
@throws DatabaseException if a failure occurs. */ public void removeOldLogFiles() throws DatabaseException { dbenv.log_archive(DbConstants.DB_ARCH_REMOVE); } /** Environment recovery restores transactions that were prepared, but not yet resolved at the time of the system shut down or crash, to their state prior to the shut down or crash, including any locks previously held. This method returns a list of those prepared transactions.
This method should only be called after the environment has been recovered.
Multiple threads of control may call this method, but only one thread of control may resolve each returned transaction, that is, only one thread of control may call {@link com.sleepycat.db.Transaction#commit Transaction.commit()} or {@link com.sleepycat.db.Transaction#abort Transaction.abort()} each returned transaction. Callers must call {@link com.sleepycat.db.Transaction#discard Transaction.discard()} to discard each transaction they do not resolve.
@return a list of {@link com.sleepycat.db.PreparedTransaction transactions} that must be resolved by the application (committed, aborted or discarded). */ public PreparedTransaction[] recover(final int count, final boolean continued) throws DatabaseException { return dbenv.txn_recover(count, continued ? DbConstants.DB_NEXT : DbConstants.DB_FIRST); } /** Allows database files to be copied, and then the copy used in the same database environment as the original.
All databases contain an ID string used to identify the database in the database environment cache. If a physical database file is copied, and used in the same environment as another file with the same ID strings, corruption can occur. This method creates new ID strings for all of the databases in the physical file.
This method modifies the physical file, in-place. Applications should not reset IDs in files that are currently in use.
This method may be called at any time during the life of the application.
@param filename The name of the physical file in which the LSNs are to be cleared. @param encrypted Whether the file contains encrypted databases.
@throws DatabaseException if a failure occurs. */ public void resetFileID(final String filename, boolean encrypted) throws DatabaseException { dbenv.fileid_reset(filename, encrypted ? DbConstants.DB_ENCRYPT : 0); } /** Allows database files to be moved from one transactional database environment to another.
Database pages in transactional database environments contain references to the environment's log files (that is, log sequence numbers, or LSNs). Copying or moving a database file from one database environment to another, and then modifying it, can result in data corruption if the LSNs are not first cleared.
Note that LSNs should be reset before moving or copying the database file into a new database environment, rather than moving or copying the database file and then resetting the LSNs. Berkeley DB has consistency checks that may be triggered if an application calls this method on a database in a new environment when the database LSNs still reflect the old environment.
This method modifies the physical file, in-place. Applications should not reset LSNs in files that are currently in use.
This method may be called at any time during the life of the application.
@param filename The name of the physical file in which the LSNs are to be cleared. @param encrypted Whether the file contains encrypted databases.
@throws DatabaseException if a failure occurs. */ public void resetLogSequenceNumber(final String filename, boolean encrypted) throws DatabaseException { dbenv.lsn_reset(filename, encrypted ? DbConstants.DB_ENCRYPT : 0); } /* Panic the environment, or stop a panic. */ /** Set the panic state for the database environment. Database environments in a panic state normally refuse all attempts to call library functions, throwing a {@link com.sleepycat.db.RunRecoveryException RunRecoveryException}.
This method configures a database environment, including all threads of control accessing the database environment, not only the operations performed using a specified {@link com.sleepycat.db.Environment Environment} handle.
This method may be called at any time during the life of the application.
@param onoff If true, set the panic state for the database environment. */ public void panic(boolean onoff) throws DatabaseException { dbenv.set_flags(DbConstants.DB_PANIC_ENVIRONMENT, onoff); } /* Version information */ /** Return the release version information, suitable for display.
This method may be called at any time during the life of the application.
@return The release version information, suitable for display. */ public static String getVersionString() { return DbEnv.get_version_string(); } /** Return the full release version information, suitable for display.
This method may be called at any time during the life of the application.
@return The full release version information, suitable for display. */ public static String getVersionFullString() { return DbEnv.get_version_full_string(); } /** Return the release's Oracle family number.
This method may be called at any time during the life of the application.
@return The release's Oracle family number. */ public static int getVersionFamily() { return DbEnv.get_version_family(); } /** Return the release's Oracle release number.
This method may be called at any time during the life of the application.
@return The release's Oracle release number. */ public static int getVersionRelease() { return DbEnv.get_version_release(); } /** Return the release major number.
This method may be called at any time during the life of the application.
@return The release major number. */ public static int getVersionMajor() { return DbEnv.get_version_major(); } /** Ensure that all modified pages in the cache are flushed to their backing files.
Pages in the cache that cannot be immediately written back to disk (for example pages that are currently in use by another thread of control) are waited for and written to disk as soon as it is possible to do so.
@param logSequenceNumber The purpose of the logSequenceNumber parameter is to enable a transaction manager to ensure, as part of a checkpoint, that all pages modified by a certain time have been written to disk.
All modified pages with a log sequence number less than the logSequenceNumber parameter are written to disk. If logSequenceNumber is null, all modified pages in the cache are written to disk. */ public void syncCache(LogSequenceNumber logSequenceNumber) throws DatabaseException { dbenv.memp_sync(logSequenceNumber); } /** Return whether the transaction referred to by the commit token "token" has been applied at the local replication environment.
This method may not be called before the database environment is opened.
@param maxwait The maximum time to wait for the transaction to arrive by replication, expressed in microseconds. To check the status of the transaction without waiting, the timeout may be specified as 0.
@return TransactionStatus indicating the status of the applicaton of the transaction. */ public TransactionStatus isTransactionApplied(byte[] token, int maxwait) throws DatabaseException { if (token == null) { throw new NullPointerException("token is null"); } if (token.length != DbConstants.DB_TXN_TOKEN_SIZE) { throw new IllegalArgumentException("token must be 20 bytes"); } return TransactionStatus.fromInt(dbenv.txn_applied(token, maxwait, 0)); } /** Return the release minor number.
This method may be called at any time during the life of the application.
@return The release minor number. */ public static int getVersionMinor() { return DbEnv.get_version_minor(); } /** Return the release patch number.
This method may be called at any time during the life of the application.
@return The release patch number. */ public static int getVersionPatch() { return DbEnv.get_version_patch(); } }