зеркало из https://github.com/mozilla/gecko-dev.git
1321 строка
30 KiB
Groff
1321 строка
30 KiB
Groff
.ds TYPE CXX
|
|
.\"
|
|
.\" See the file LICENSE for redistribution information.
|
|
.\"
|
|
.\" Copyright (c) 1997, 1998
|
|
.\" Sleepycat Software. All rights reserved.
|
|
.\"
|
|
.\" @(#)Dbt.sox 10.10 (Sleepycat) 4/10/98
|
|
.\"
|
|
.\"
|
|
.\" See the file LICENSE for redistribution information.
|
|
.\"
|
|
.\" Copyright (c) 1997, 1998
|
|
.\" Sleepycat Software. All rights reserved.
|
|
.\"
|
|
.\" @(#)macros.so 10.45 (Sleepycat) 5/4/98
|
|
.\"
|
|
.\" We don't want hyphenation for any HTML documents.
|
|
.ie '\*[HTML]'YES'\{\
|
|
.nh
|
|
\}
|
|
.el\{\
|
|
.ds Hy
|
|
.hy
|
|
..
|
|
.ds Nh
|
|
.nh
|
|
..
|
|
\}
|
|
.\" The alternative text macro
|
|
.\" This macro takes two arguments:
|
|
.\" + the text produced if this is a "C" manpage
|
|
.\" + the text produced if this is a "CXX" or "JAVA" manpage
|
|
.\"
|
|
.de Al
|
|
.ie '\*[TYPE]'C'\{\\$1
|
|
\}
|
|
.el\{\\$2
|
|
\}
|
|
..
|
|
.\" Scoped name macro.
|
|
.\" Produces a_b, a::b, a.b depending on language
|
|
.\" This macro takes two arguments:
|
|
.\" + the class or prefix (without underscore)
|
|
.\" + the name within the class or following the prefix
|
|
.de Sc
|
|
.ie '\*[TYPE]'C'\{\\$1_\\$2
|
|
\}
|
|
.el\{\
|
|
.ie '\*[TYPE]'CXX'\{\\$1::\\$2
|
|
\}
|
|
.el\{\\$1.\\$2
|
|
\}
|
|
\}
|
|
..
|
|
.\" Scoped name for Java.
|
|
.\" Produces Db.b, for Java, otherwise just b. This macro is used for
|
|
.\" constants that must be scoped in Java, but are global otherwise.
|
|
.\" This macro takes two arguments:
|
|
.\" + the class
|
|
.\" + the name within the class or following the prefix
|
|
.de Sj
|
|
.ie '\*[TYPE]'JAVA'\{\
|
|
.TP 5
|
|
Db.\\$1\}
|
|
.el\{\
|
|
.TP 5
|
|
\\$1\}
|
|
..
|
|
.\" The general information text macro.
|
|
.de Gn
|
|
.ie '\*[TYPE]'C'\{The DB library is a family of groups of functions that provides a modular
|
|
programming interface to transactions and record-oriented file access.
|
|
The library includes support for transactions, locking, logging and file
|
|
page caching, as well as various indexed access methods.
|
|
Many of the functional groups (e.g., the file page caching functions)
|
|
are useful independent of the other DB functions,
|
|
although some functional groups are explicitly based on other functional
|
|
groups (e.g., transactions and logging).
|
|
\}
|
|
.el\{The DB library is a family of classes that provides a modular
|
|
programming interface to transactions and record-oriented file access.
|
|
The library includes support for transactions, locking, logging and file
|
|
page caching, as well as various indexed access methods.
|
|
Many of the classes (e.g., the file page caching class)
|
|
are useful independent of the other DB classes,
|
|
although some classes are explicitly based on other classes
|
|
(e.g., transactions and logging).
|
|
\}
|
|
For a general description of the DB package, see
|
|
.IR db_intro (3).
|
|
..
|
|
.\" The library error macro, the local error macro.
|
|
.\" These macros take one argument:
|
|
.\" + the function name.
|
|
.de Ee
|
|
The
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function may fail and return
|
|
.I errno
|
|
\}
|
|
.el\{method may fail and throw a
|
|
.IR DbException (3)
|
|
.if '\*[TYPE]'CXX'\{
|
|
or return
|
|
.I errno
|
|
\}
|
|
\}
|
|
for any of the errors specified for the following DB and library functions:
|
|
..
|
|
.de Ec
|
|
In addition, the
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function may fail and return
|
|
.I errno
|
|
\}
|
|
.el\{method may fail and throw a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or return
|
|
.I errno
|
|
\}
|
|
.el\{encapsulating an
|
|
.I errno
|
|
\}
|
|
\}
|
|
for the following conditions:
|
|
..
|
|
.de Ea
|
|
[EAGAIN]
|
|
A lock was unavailable.
|
|
..
|
|
.de Eb
|
|
[EBUSY]
|
|
The shared memory region was in use and the force flag was not set.
|
|
..
|
|
.de Em
|
|
[EAGAIN]
|
|
The shared memory region was locked and (repeatedly) unavailable.
|
|
..
|
|
.de Ei
|
|
[EINVAL]
|
|
An invalid flag value or parameter was specified.
|
|
..
|
|
.de Es
|
|
[EACCES]
|
|
An attempt was made to modify a read-only database.
|
|
..
|
|
.de Et
|
|
The DB_THREAD flag was specified and spinlocks are not implemented for
|
|
this architecture.
|
|
..
|
|
.de Ep
|
|
[EPERM]
|
|
Database corruption was detected.
|
|
All subsequent database calls (other than
|
|
.ie '\*[TYPE]'C'\{\
|
|
.IR DB->close )
|
|
\}
|
|
.el\{\
|
|
.IR Db::close )
|
|
\}
|
|
will return EPERM.
|
|
..
|
|
.de Ek
|
|
.if '\*[TYPE]'CXX'\{\
|
|
Methods marked as returning
|
|
.I errno
|
|
will, by default, throw an exception that encapsulates the error information.
|
|
The default error behavior can be changed, see
|
|
.IR DbException (3).
|
|
\}
|
|
..
|
|
.\" The SEE ALSO text macro
|
|
.de Sa
|
|
.\" make the line long for nroff.
|
|
.if n .ll 72
|
|
.nh
|
|
.na
|
|
.IR db_archive (1),
|
|
.IR db_checkpoint (1),
|
|
.IR db_deadlock (1),
|
|
.IR db_dump (1),
|
|
.IR db_load (1),
|
|
.IR db_recover (1),
|
|
.IR db_stat (1),
|
|
.IR db_intro (3),
|
|
.ie '\*[TYPE]'C'\{\
|
|
.IR db_appinit (3),
|
|
.IR db_cursor (3),
|
|
.IR db_dbm (3),
|
|
.IR db_internal (3),
|
|
.IR db_lock (3),
|
|
.IR db_log (3),
|
|
.IR db_mpool (3),
|
|
.IR db_open (3),
|
|
.IR db_thread (3),
|
|
.IR db_txn (3)
|
|
\}
|
|
.el\{\
|
|
.IR db_internal (3),
|
|
.IR db_thread (3),
|
|
.IR Db (3),
|
|
.IR Dbc (3),
|
|
.IR DbEnv (3),
|
|
.IR DbException (3),
|
|
.IR DbInfo (3),
|
|
.IR DbLock (3),
|
|
.IR DbLockTab (3),
|
|
.IR DbLog (3),
|
|
.IR DbLsn (3),
|
|
.IR DbMpool (3),
|
|
.if !'\*[TYPE]'JAVA'\{\
|
|
.IR DbMpoolFile (3),
|
|
\}
|
|
.IR Dbt (3),
|
|
.IR DbTxn (3),
|
|
.IR DbTxnMgr (3)
|
|
\}
|
|
.ad
|
|
.Hy
|
|
..
|
|
.\" The function header macro.
|
|
.\" This macro takes one argument:
|
|
.\" + the function name.
|
|
.de Fn
|
|
.in 2
|
|
.I \\$1
|
|
.in
|
|
..
|
|
.\" The XXX_open function text macro, for merged create/open calls.
|
|
.\" This macro takes two arguments:
|
|
.\" + the interface, e.g., "transaction region"
|
|
.\" + the prefix, e.g., "txn" (or the class name for C++, e.g., "DbTxn")
|
|
.de Co
|
|
.ie '\*[TYPE]'C'\{\
|
|
.Fn \\$2_open
|
|
The
|
|
.I \\$2_open
|
|
function copies a pointer, to the \\$1 identified by the
|
|
.B directory
|
|
.IR dir ,
|
|
into the memory location referenced by
|
|
.IR regionp .
|
|
.PP
|
|
If the
|
|
.I dbenv
|
|
argument to
|
|
.I \\$2_open
|
|
was initialized using
|
|
.IR db_appinit ,
|
|
.I dir
|
|
is interpreted as described by
|
|
.IR db_appinit (3).
|
|
\}
|
|
.el\{\
|
|
.Fn \\$2::open
|
|
The
|
|
.I \\$2::open
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
method copies a pointer, to the \\$1 identified by the
|
|
.B directory
|
|
.IR dir ,
|
|
into the memory location referenced by
|
|
.IR regionp .
|
|
\}
|
|
.el\{\
|
|
method returns a \\$1 identified by the
|
|
.B directory
|
|
.IR dir .
|
|
\}
|
|
.PP
|
|
If the
|
|
.I dbenv
|
|
argument to
|
|
.I \\$2::open
|
|
was initialized using
|
|
.IR DbEnv::appinit ,
|
|
.I dir
|
|
is interpreted as described by
|
|
.IR DbEnv (3).
|
|
\}
|
|
.PP
|
|
Otherwise,
|
|
if
|
|
.I dir
|
|
is not NULL,
|
|
it is interpreted relative to the current working directory of the process.
|
|
If
|
|
.I dir
|
|
is NULL,
|
|
the following environment variables are checked in order:
|
|
``TMPDIR'', ``TEMP'', and ``TMP''.
|
|
If one of them is set,
|
|
\\$1 files are created relative to the directory it specifies.
|
|
If none of them are set, the first possible one of the following
|
|
directories is used:
|
|
.IR /var/tmp ,
|
|
.IR /usr/tmp ,
|
|
.IR /temp ,
|
|
.IR /tmp ,
|
|
.I C:/temp
|
|
and
|
|
.IR C:/tmp .
|
|
.PP
|
|
All files associated with the \\$1 are created in this directory.
|
|
This directory must already exist when
|
|
.ie '\*[TYPE]'C'\{
|
|
\\$1_open
|
|
\}
|
|
.el\{\
|
|
\\$2::open
|
|
\}
|
|
is called.
|
|
If the \\$1 already exists,
|
|
the process must have permission to read and write the existing files.
|
|
If the \\$1 does not already exist,
|
|
it is optionally created and initialized.
|
|
..
|
|
.\" The common close language macro, for discarding created regions
|
|
.\" This macro takes one argument:
|
|
.\" + the function prefix, e.g., txn (the class name for C++, e.g., DbTxn)
|
|
.de Cc
|
|
In addition, if the
|
|
.I dir
|
|
argument to
|
|
.ie '\*[TYPE]'C'\{\
|
|
.ds Va db_appinit
|
|
.ds Vo \\$1_open
|
|
.ds Vu \\$1_unlink
|
|
\}
|
|
.el\{\
|
|
.ds Va DbEnv::appinit
|
|
.ds Vo \\$1::open
|
|
.ds Vu \\$1::unlink
|
|
\}
|
|
.I \\*(Vo
|
|
was NULL
|
|
and
|
|
.I dbenv
|
|
was not initialized using
|
|
.IR \\*(Va ,
|
|
.if '\\$1'memp'\{\
|
|
or the DB_MPOOL_PRIVATE flag was set,
|
|
\}
|
|
all files created for this shared region will be removed,
|
|
as if
|
|
.I \\*(Vu
|
|
were called.
|
|
.rm Va
|
|
.rm Vo
|
|
.rm Vu
|
|
..
|
|
.\" The DB_ENV information macro.
|
|
.\" This macro takes two arguments:
|
|
.\" + the function called to open, e.g., "txn_open"
|
|
.\" + the function called to close, e.g., "txn_close"
|
|
.de En
|
|
.ie '\*[TYPE]'C'\{\
|
|
based on the
|
|
.I dbenv
|
|
argument to
|
|
.IR \\$1 ,
|
|
which is a pointer to a structure of type DB_ENV (typedef'd in <db.h>).
|
|
Applications will normally use the same DB_ENV structure (initialized
|
|
by
|
|
.IR db_appinit (3)),
|
|
as an argument to all of the subsystems in the DB package.
|
|
.PP
|
|
References to the DB_ENV structure are maintained by DB,
|
|
so it may not be discarded until the last close function,
|
|
corresponding to an open function for which it was an argument,
|
|
has returned.
|
|
In order to ensure compatibility with future releases of DB, all fields of
|
|
the DB_ENV structure that are not explicitly set should be initialized to 0
|
|
before the first time the structure is used.
|
|
Do this by declaring the structure external or static, or by calling the C
|
|
library routine
|
|
.IR bzero (3)
|
|
or
|
|
.IR memset (3).
|
|
.PP
|
|
The fields of the DB_ENV structure used by
|
|
.I \\$1
|
|
are described below.
|
|
.if '\*[TYPE]'CXX'\{\
|
|
As references to the DB_ENV structure may be maintained by
|
|
.IR \\$1 ,
|
|
it is necessary that the DB_ENV structure and memory it references be valid
|
|
until the
|
|
.I \\$2
|
|
function is called.
|
|
\}
|
|
.ie '\\$1'db_appinit'\{The
|
|
.I dbenv
|
|
argument may not be NULL.
|
|
If any of the fields of the
|
|
.I dbenv
|
|
are set to 0,
|
|
defaults appropriate for the system are used where possible.
|
|
\}
|
|
.el\{If
|
|
.I dbenv
|
|
is NULL
|
|
or any of its fields are set to 0,
|
|
defaults appropriate for the system are used where possible.
|
|
\}
|
|
.PP
|
|
The following fields in the DB_ENV structure may be initialized before calling
|
|
.IR \\$1 :
|
|
\}
|
|
.el\{\
|
|
based on which set methods have been used.
|
|
It is expected that applications will use a single DbEnv object as the
|
|
argument to all of the subsystems in the DB package.
|
|
The fields of the DbEnv object used by
|
|
.I \\$1
|
|
are described below.
|
|
As references to the DbEnv object may be maintained by
|
|
.IR \\$1 ,
|
|
it is necessary that the DbEnv object and memory it references be valid
|
|
until the object is destroyed.
|
|
.ie '\\$1'appinit'\{\
|
|
The
|
|
.I dbenv
|
|
argument may not be NULL.
|
|
If any of the fields of the
|
|
.I dbenv
|
|
are set to 0,
|
|
defaults appropriate for the system are used where possible.
|
|
\}
|
|
.el\{\
|
|
Any of the DbEnv fields that are not explicitly set will default to
|
|
appropriate values.
|
|
\}
|
|
.PP
|
|
The following fields in the DbEnv object may be initialized, using the
|
|
appropriate set method, before calling
|
|
.IR \\$1 :
|
|
\}
|
|
..
|
|
.\" The DB_ENV common fields macros.
|
|
.de Se
|
|
.if '\*[TYPE]'JAVA'\{\
|
|
.TP 5
|
|
DbErrcall db_errcall;
|
|
.ns
|
|
.TP 5
|
|
String db_errpfx;
|
|
.ns
|
|
.TP 5
|
|
int db_verbose;
|
|
The error fields of the DbEnv behave as described for
|
|
.IR DbEnv (3).
|
|
\}
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
.TP 5
|
|
void *(*db_errcall)(char *db_errpfx, char *buffer);
|
|
.ns
|
|
.TP 5
|
|
FILE *db_errfile;
|
|
.ns
|
|
.TP 5
|
|
const char *db_errpfx;
|
|
.ns
|
|
.TP 5
|
|
class ostream *db_error_stream;
|
|
.ns
|
|
.TP 5
|
|
int db_verbose;
|
|
The error fields of the DbEnv behave as described for
|
|
.IR DbEnv (3).
|
|
\}
|
|
.el\{\
|
|
void *(*db_errcall)(char *db_errpfx, char *buffer);
|
|
.ns
|
|
.TP 5
|
|
FILE *db_errfile;
|
|
.ns
|
|
.TP 5
|
|
const char *db_errpfx;
|
|
.ns
|
|
.TP 5
|
|
int db_verbose;
|
|
The error fields of the DB_ENV behave as described for
|
|
.IR db_appinit (3).
|
|
.sp
|
|
\}
|
|
..
|
|
.\" The open flags.
|
|
.de Fm
|
|
The
|
|
.I flags
|
|
and
|
|
.I mode
|
|
arguments specify how files will be opened and/or created when they
|
|
don't already exist.
|
|
The flags value is specified by
|
|
.BR or 'ing
|
|
together one or more of the following values:
|
|
.Sj DB_CREATE
|
|
Create any underlying files, as necessary.
|
|
If the files do not already exist and the DB_CREATE flag is not specified,
|
|
the call will fail.
|
|
..
|
|
.\" DB_THREAD open flag macro.
|
|
.\" This macro takes two arguments:
|
|
.\" + the open function name
|
|
.\" + the object it returns.
|
|
.de Ft
|
|
.TP 5
|
|
.Sj DB_THREAD
|
|
Cause the \\$2 handle returned by the
|
|
.I \\$1
|
|
.Al function method
|
|
to be useable by multiple threads within a single address space,
|
|
i.e., to be ``free-threaded''.
|
|
.if '\*[TYPE]'JAVA'\{\
|
|
Threading is assumed in the Java API,
|
|
so no special flags are required,
|
|
and DB functions will always behave as if the DB_THREAD flag was specified.
|
|
\}
|
|
..
|
|
.\" The mode macro.
|
|
.\" This macro takes one argument:
|
|
.\" + the subsystem name.
|
|
.de Mo
|
|
All files created by the \\$1 are created with mode
|
|
.I mode
|
|
(as described in
|
|
.IR chmod (2))
|
|
and modified by the process' umask value at the time of creation (see
|
|
.IR umask (2)).
|
|
The group ownership of created files is based on the system and directory
|
|
defaults, and is not further specified by DB.
|
|
..
|
|
.\" The application exits macro.
|
|
.\" This macro takes one argument:
|
|
.\" + the application name.
|
|
.de Ex
|
|
The
|
|
.I \\$1
|
|
utility exits 0 on success, and >0 if an error occurs.
|
|
..
|
|
.\" The application -h section.
|
|
.\" This macro takes one argument:
|
|
.\" + the application name
|
|
.de Dh
|
|
DB_HOME
|
|
If the
|
|
.B \-h
|
|
option is not specified and the environment variable
|
|
.I DB_HOME
|
|
is set, it is used as the path of the database home, as described in
|
|
.IR db_appinit (3).
|
|
..
|
|
.\" The function DB_HOME ENVIRONMENT VARIABLES section.
|
|
.\" This macro takes one argument:
|
|
.\" + the open function name
|
|
.de Eh
|
|
DB_HOME
|
|
If the
|
|
.I dbenv
|
|
argument to
|
|
.I \\$1
|
|
was initialized using
|
|
.IR db_appinit ,
|
|
the environment variable DB_HOME may be used as the path of the database
|
|
home for the interpretation of the
|
|
.I dir
|
|
argument to
|
|
.IR \\$1 ,
|
|
as described in
|
|
.IR db_appinit (3).
|
|
.if \\n(.$>1 \{Specifically,
|
|
.I \\$1
|
|
is affected by the configuration string value of \\$2.\}
|
|
..
|
|
.\" The function TMPDIR ENVIRONMENT VARIABLES section.
|
|
.\" This macro takes two arguments:
|
|
.\" + the interface, e.g., "transaction region"
|
|
.\" + the prefix, e.g., "txn" (or the class name for C++, e.g., "DbTxn")
|
|
.de Ev
|
|
TMPDIR
|
|
If the
|
|
.I dbenv
|
|
argument to
|
|
.ie '\*[TYPE]'C'\{\
|
|
.ds Vo \\$2_open
|
|
\}
|
|
.el\{\
|
|
.ds Vo \\$2::open
|
|
\}
|
|
.I \\*(Vo
|
|
was NULL or not initialized using
|
|
.IR db_appinit ,
|
|
the environment variable TMPDIR may be used as the directory in which to
|
|
create the \\$1,
|
|
as described in the
|
|
.I \\*(Vo
|
|
section above.
|
|
.rm Vo
|
|
..
|
|
.\" The unused flags macro.
|
|
.de Fl
|
|
The
|
|
.I flags
|
|
parameter is currently unused, and must be set to 0.
|
|
..
|
|
.\" The no-space TP macro.
|
|
.de Nt
|
|
.br
|
|
.ns
|
|
.TP 5
|
|
..
|
|
.\" The return values of the functions macros.
|
|
.\" Rc is the standard two-value return with a suffix for more values.
|
|
.\" Ro is the standard two-value return but there were previous values.
|
|
.\" Rt is the standard two-value return, returning errno, 0, or < 0.
|
|
.\" These macros take one argument:
|
|
.\" + the routine name
|
|
.de Rc
|
|
The
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function returns the value of
|
|
.I errno
|
|
on failure,
|
|
0 on success,
|
|
\}
|
|
.el\{method throws a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or returns the value of
|
|
.I errno
|
|
on failure,
|
|
0 on success,
|
|
\}
|
|
.el\{that encapsulates an
|
|
.I errno
|
|
on failure,
|
|
\}
|
|
\}
|
|
..
|
|
.de Ro
|
|
Otherwise, the
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{method throws a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{that encapsulates an
|
|
.I errno
|
|
on failure,
|
|
\}
|
|
\}
|
|
..
|
|
.de Rt
|
|
The
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{method throws a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{that encapsulates an
|
|
.I errno
|
|
on failure.
|
|
\}
|
|
\}
|
|
..
|
|
.\" The TXN id macro.
|
|
.de Tx
|
|
.IP
|
|
If the file is being accessed under transaction protection,
|
|
the
|
|
.I txnid
|
|
parameter is a transaction ID returned from
|
|
.IR txn_begin ,
|
|
otherwise, NULL.
|
|
..
|
|
.\" The XXX_unlink function text macro.
|
|
.\" This macro takes two arguments:
|
|
.\" + the interface, e.g., "transaction region"
|
|
.\" + the prefix (for C++, this is the class name)
|
|
.de Un
|
|
.ie '\*[TYPE]'C'\{\
|
|
.ds Va db_appinit
|
|
.ds Vc \\$2_close
|
|
.ds Vo \\$2_open
|
|
.ds Vu \\$2_unlink
|
|
\}
|
|
.el\{\
|
|
.ds Va DbEnv::appinit
|
|
.ds Vc \\$2::close
|
|
.ds Vo \\$2::open
|
|
.ds Vu \\$2::unlink
|
|
\}
|
|
.Fn \\*(Vu
|
|
The
|
|
.I \\*(Vu
|
|
.Al function method
|
|
destroys the \\$1 identified by the directory
|
|
.IR dir ,
|
|
removing all files used to implement the \\$1.
|
|
.ie '\\$2'log' \{(The log files themselves and the directory
|
|
.I dir
|
|
are not removed.)\}
|
|
.el \{(The directory
|
|
.I dir
|
|
is not removed.)\}
|
|
If there are processes that have called
|
|
.I \\*(Vo
|
|
without calling
|
|
.I \\*(Vc
|
|
(i.e., there are processes currently using the \\$1),
|
|
.I \\*(Vu
|
|
will fail without further action,
|
|
unless the force flag is set,
|
|
in which case
|
|
.I \\*(Vu
|
|
will attempt to remove the \\$1 files regardless of any processes
|
|
still using the \\$1.
|
|
.PP
|
|
The result of attempting to forcibly destroy the region when a process
|
|
has the region open is unspecified.
|
|
Processes using a shared memory region maintain an open file descriptor
|
|
for it.
|
|
On UNIX systems, the region removal should succeed
|
|
and processes that have already joined the region should continue to
|
|
run in the region without change,
|
|
however processes attempting to join the \\$1 will either fail or
|
|
attempt to create a new region.
|
|
On other systems, e.g., WNT, where the
|
|
.IR unlink (2)
|
|
system call will fail if any process has an open file descriptor
|
|
for the file,
|
|
the region removal will fail.
|
|
.PP
|
|
In the case of catastrophic or system failure,
|
|
database recovery must be performed (see
|
|
.IR db_recover (1)
|
|
or the DB_RECOVER and DB_RECOVER_FATAL flags to
|
|
.IR \\*(Va (3)).
|
|
Alternatively, if recovery is not required because no database state is
|
|
maintained across failures,
|
|
it is possible to clean up a \\$1 by removing all of the
|
|
files in the directory specified to the
|
|
.I \\*(Vo
|
|
.Al function, method,
|
|
as \\$1 files are never created in any directory other than the one
|
|
specified to
|
|
.IR \\*(Vo .
|
|
Note, however,
|
|
that this has the potential to remove files created by the other DB
|
|
subsystems in this database environment.
|
|
.PP
|
|
.Rt \\*(Vu
|
|
.rm Va
|
|
.rm Vo
|
|
.rm Vu
|
|
.rm Vc
|
|
..
|
|
.\" Signal paragraph for standard utilities.
|
|
.\" This macro takes one argument:
|
|
.\" + the utility name.
|
|
.de Si
|
|
The
|
|
.I \\$1
|
|
utility attaches to DB shared memory regions.
|
|
In order to avoid region corruption,
|
|
it should always be given the chance to detach and exit gracefully.
|
|
To cause
|
|
.I \\$1
|
|
to clean up after itself and exit,
|
|
send it an interrupt signal (SIGINT).
|
|
..
|
|
.\" Logging paragraph for standard utilities.
|
|
.\" This macro takes one argument:
|
|
.\" + the utility name.
|
|
.de Pi
|
|
.B \-L
|
|
Log the execution of the \\$1 utility to the specified file in the
|
|
following format, where ``###'' is the process ID, and the date is
|
|
the time the utility starting running.
|
|
.sp
|
|
\\$1: ### Wed Jun 15 01:23:45 EDT 1995
|
|
.sp
|
|
This file will be removed if the \\$1 utility exits gracefully.
|
|
..
|
|
.\" Malloc paragraph.
|
|
.\" This macro takes one argument:
|
|
.\" + the allocated object
|
|
.de Ma
|
|
.if !'\*[TYPE]'JAVA'\{\
|
|
\\$1 are created in allocated memory.
|
|
If
|
|
.I db_malloc
|
|
is non-NULL,
|
|
it is called to allocate the memory,
|
|
otherwise,
|
|
the library function
|
|
.IR malloc (3)
|
|
is used.
|
|
The function
|
|
.I db_malloc
|
|
must match the calling conventions of the
|
|
.IR malloc (3)
|
|
library routine.
|
|
Regardless,
|
|
the caller is responsible for deallocating the returned memory.
|
|
To deallocate the returned memory,
|
|
free each returned memory pointer;
|
|
pointers inside the memory do not need to be individually freed.
|
|
\}
|
|
..
|
|
.\" Underlying function paragraph.
|
|
.\" This macro takes two arguments:
|
|
.\" + the function name
|
|
.\" + the utility name
|
|
.de Uf
|
|
The
|
|
.I \\$1
|
|
.Al function method
|
|
is the underlying function used by the
|
|
.IR \\$2 (1)
|
|
utility.
|
|
See the source code for the
|
|
.I \\$2
|
|
utility for an example of using
|
|
.I \\$1
|
|
in a UNIX environment.
|
|
..
|
|
.\" Underlying function paragraph, for C++.
|
|
.\" This macro takes three arguments:
|
|
.\" + the C++ method name
|
|
.\" + the function name for C
|
|
.\" + the utility name
|
|
.de Ux
|
|
The
|
|
.I \\$1
|
|
method is based on the C
|
|
.I \\$2
|
|
function, which
|
|
is the underlying function used by the
|
|
.IR \\$3 (1)
|
|
utility.
|
|
See the source code for the
|
|
.I \\$3
|
|
utility for an example of using
|
|
.I \\$2
|
|
in a UNIX environment.
|
|
..
|
|
.TH Dbt 3 "April 10, 1998"
|
|
.UC 7
|
|
.SH NAME
|
|
Dbt \- Db key/data class
|
|
.SH SYNOPSIS
|
|
.nf
|
|
.ft B
|
|
.ie '\*[TYPE]'CXX'\{
|
|
void *Dbt::get_data() const;
|
|
void Dbt::set_data(void *);
|
|
|
|
u_int32_t Dbt::get_size() const;
|
|
void Dbt::set_size(u_int32_t);
|
|
|
|
u_int32_t Dbt::get_ulen() const;
|
|
void Dbt::set_ulen(u_int32_t);
|
|
|
|
u_int32_t Dbt::get_dlen() const;
|
|
void Dbt::set_dlen(u_int32_t);
|
|
|
|
u_int32_t Dbt::get_doff() const;
|
|
void Dbt::set_doff(u_int32_t);
|
|
|
|
u_int32_t Dbt::get_flags() const;
|
|
void Dbt::set_flags(u_int32_t);
|
|
|
|
Dbt::Dbt(void *data, size_t size);
|
|
Dbt::Dbt();
|
|
Dbt::~Dbt();
|
|
Dbt::Dbt(const Dbt &);
|
|
Dbt::Dbt &operator = (const Dbt &);
|
|
\}
|
|
.el\{\
|
|
import com.sleepycat.db.*;
|
|
|
|
public Dbt();
|
|
public Dbt(byte[] data);
|
|
public Dbt(byte[] data, int off, int len);
|
|
|
|
public void set_data(byte[] data);
|
|
public byte[] get_data();
|
|
|
|
public void set_offset(int off);
|
|
public int get_offset();
|
|
|
|
public int get_size();
|
|
public void set_size(int size);
|
|
|
|
public int get_ulen();
|
|
public void set_ulen(int ulen);
|
|
|
|
public int get_dlen();
|
|
public void set_dlen(int dlen);
|
|
|
|
public int get_doff();
|
|
public void set_doff(int doff);
|
|
|
|
public int get_flags();
|
|
public void set_flags(int flags);
|
|
|
|
public void set_recno_key_data(int recno);
|
|
public int get_recno_key_data();
|
|
\}
|
|
.ft R
|
|
.fi
|
|
.SH "DESCRIPTION
|
|
.Gn
|
|
This manual page describes the specific details of the
|
|
.I Dbt
|
|
class, used to encode keys and data items in a database.
|
|
.PP
|
|
.SH "KEY/DATA PAIRS
|
|
Storage and retrieval for the Db access methods are based on key/data pairs.
|
|
Both key and data items are represented by Dbt objects.
|
|
.PP
|
|
Key and data byte strings may reference strings of essentially unlimited
|
|
length,
|
|
although any two keys must fit into available memory at the same time so
|
|
that they may be compared,
|
|
and any one data item must fit into available memory so that it may be
|
|
returned.
|
|
.PP
|
|
The Dbt class provides simple access to an underlying data structure,
|
|
whose elements can be examined or changed using the
|
|
.I set_
|
|
or
|
|
.I get_
|
|
methods. The remainder of the manual page sometimes
|
|
refers to these accesses using the underlying name, e.g., simply
|
|
.I ulen
|
|
instead of
|
|
.I get_ulen
|
|
and
|
|
.IR set_ulen .
|
|
The constructors set all elements of the underlying structure to zero.
|
|
The constructor with two arguments has the effect of setting all elements
|
|
to zero except for the specified
|
|
.I data
|
|
and
|
|
.I size
|
|
elements.
|
|
In the case where the
|
|
.I flags
|
|
structure element is 0,
|
|
when being provided a key or data item by the application,
|
|
the DB package expects the
|
|
.I data
|
|
object to
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
point to a byte string of
|
|
\}
|
|
.el\{\
|
|
be set to a byte array of
|
|
\}
|
|
.I size
|
|
bytes.
|
|
When returning a key/data item to the application,
|
|
the DB package will store into the
|
|
.I data
|
|
object a
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
pointer to a byte string
|
|
\}
|
|
.el\{\
|
|
a byte array
|
|
\}
|
|
of
|
|
.I size
|
|
bytes.
|
|
.if '\*[TYPE]'CXX'\{\
|
|
.ft B
|
|
By default,
|
|
the memory referenced by this stored pointer is only valid until the next
|
|
call to the DB package using the Db handle returned by
|
|
.IR Db::open .
|
|
.ft R
|
|
\}
|
|
.PP
|
|
.ft B
|
|
The access methods provide no guarantees about byte string alignment,
|
|
and applications are responsible for maintaining any necessary alignment.
|
|
.ft R
|
|
Use the DB_DBT_USERMEM flag to cause returned items to be placed in memory
|
|
of arbitrary alignment.
|
|
.if '\*[TYPE]'CXX'\{\
|
|
Although Java normally maintains proper alignment of byte arrays,
|
|
the set_offset method can be used to specify unaligned addresses.
|
|
Unaligned address accesses that are not supported by the underlying
|
|
hardware may be reported as an exception, or may stop the running
|
|
Java program.
|
|
\}
|
|
.PP
|
|
The elements of the structure underlying the Dbt class are defined as follows:
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
.TP 5
|
|
void *data;
|
|
A pointer to a byte string.
|
|
\}
|
|
.el\{\
|
|
.TP 5
|
|
byte[] data;
|
|
A byte array containing the data.
|
|
\}
|
|
This element is accessed using
|
|
.I get_data
|
|
and
|
|
.IR set_data ,
|
|
and may be initialized using one of the constructors.
|
|
.if '\*[TYPE]'JAVA'\{\
|
|
Note that the array data is not copied immediately,
|
|
but only when the Dbt is used.
|
|
\}
|
|
.ns
|
|
.br
|
|
.TP 5
|
|
int offset;
|
|
The number of bytes offset into the
|
|
.I data
|
|
array to determine the portion of the array actually used.
|
|
This element is accessed using
|
|
.I get_offset
|
|
and
|
|
.IR set_offset .
|
|
.TP 5
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
u_int32_t size;\}
|
|
.el\{\
|
|
int size;\}
|
|
The length of
|
|
.IR data ,
|
|
in bytes.
|
|
This element is accessed using
|
|
.I get_size
|
|
and
|
|
.IR set_size ,
|
|
and may be initialized
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
using the constructor with two arguments.
|
|
\}
|
|
.el\{\
|
|
implicitly to the length of the data array
|
|
with the constructor having one argument.
|
|
\}
|
|
.TP 5
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
u_int32_t ulen;\}
|
|
.el\{\
|
|
int ulen;\}
|
|
The size of the user's buffer (referenced by
|
|
.IR data ),
|
|
in bytes.
|
|
This location is not written by the Db functions.
|
|
See the DB_DBT_USERMEM flag for more information.
|
|
This element is accessed using
|
|
.I get_ulen
|
|
and
|
|
.IR set_ulen .
|
|
.TP 5
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
u_int32_t dlen;\}
|
|
.el\{\
|
|
int dlen;\}
|
|
The length of the partial record being read or written by the application,
|
|
in bytes.
|
|
See the DB_DBT_PARTIAL flag for more information.
|
|
This element is accessed using
|
|
.I get_dlen
|
|
and
|
|
.IR set_dlen .
|
|
.TP 5
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
u_int32_t doff;\}
|
|
.el\{\
|
|
int doff;\}
|
|
The offset of the partial record being read or written by the application,
|
|
in bytes.
|
|
See the DB_DBT_PARTIAL flag for more information.
|
|
This element is accessed using
|
|
.I get_doff
|
|
and
|
|
.IR set_doff .
|
|
.TP 5
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
u_int32_t flags;\}
|
|
.el\{\
|
|
int flags;\}
|
|
This element is accessed using
|
|
.I get_flags
|
|
and
|
|
.IR set_flags .
|
|
The flags value is specified by
|
|
.BR or 'ing
|
|
together one or more of the following values:
|
|
.RS
|
|
.TP 5
|
|
.Sj DB_DBT_MALLOC
|
|
Ignored except when retrieving information from a database, e.g., a
|
|
.I Db::get
|
|
or
|
|
.I Dbc::get
|
|
call.
|
|
This flag causes Db to allocate memory for the returned key or data
|
|
item
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
(using
|
|
.IR malloc (3),
|
|
or the user-specified malloc method)
|
|
and return a pointer to it in the
|
|
.I data
|
|
field of the key or data Dbt object.
|
|
The allocated memory becomes the responsibility of the calling application.
|
|
\}
|
|
.el\{\
|
|
and return a
|
|
byte array containing the data in the
|
|
.I data
|
|
field of the key or data Dbt object.
|
|
\}
|
|
It is an error to specify both DB_DBT_MALLOC and DB_DBT_USERMEM.
|
|
.TP 5
|
|
.Sj DB_DBT_USERMEM
|
|
Ignored except when retrieving information from a database, e.g., a
|
|
.I Db::get
|
|
or
|
|
.I Dbc::get
|
|
call.
|
|
The
|
|
.I data
|
|
field of the key or data object must reference memory that is at least
|
|
.I ulen
|
|
bytes in length.
|
|
If the length of the requested item is less than or equal to that number
|
|
of bytes,
|
|
the item is copied into the memory referenced by the
|
|
.I data
|
|
field.
|
|
Otherwise, an error is returned, the
|
|
.I size
|
|
field is set to the length needed for the requested item,
|
|
and the
|
|
.I errno
|
|
variable is set to ENOMEM.
|
|
It is an error to specify both DB_DBT_MALLOC and DB_DBT_USERMEM.
|
|
.TP 5
|
|
.Sj DB_DBT_PARTIAL
|
|
Ignored except when specified for a data parameter,
|
|
where this flag causes the partial retrieval or storage of an item.
|
|
If the calling application is doing a get, the
|
|
.I dlen
|
|
bytes starting
|
|
.I doff
|
|
bytes from the beginning of the retrieved data record are returned
|
|
as if they comprised the entire record.
|
|
If any or all of the specified bytes do not exist in the record,
|
|
the get is successful and the existing bytes or 0 bytes are returned.
|
|
.sp
|
|
For example, if the data portion of a retrieved record was 100 bytes,
|
|
and a partial retrieval was done using a Dbt having a
|
|
.I dlen
|
|
field of 20 and a
|
|
.I doff
|
|
field of 85,
|
|
the get call would succeed,
|
|
the
|
|
.I data
|
|
field would reference the last 15 bytes of the record,
|
|
and the
|
|
.I size
|
|
field would be set to 15.
|
|
.sp
|
|
If the calling application is doing a put,
|
|
the
|
|
.I dlen
|
|
bytes starting
|
|
.I doff
|
|
bytes from the beginning of the specified key's data record are replaced
|
|
by the data specified by the
|
|
.I data
|
|
and
|
|
.I size
|
|
objects.
|
|
If
|
|
.I dlen
|
|
is smaller than
|
|
.IR size ,
|
|
the record will grow, and if
|
|
.I dlen
|
|
is larger than
|
|
.IR size ,
|
|
the record will shrink.
|
|
If the specified bytes do not exist,
|
|
the record will be extended using nul bytes as necessary,
|
|
and the put call will succeed.
|
|
.sp
|
|
It is an error to attempt a partial put using the
|
|
.I Db::put
|
|
method in a database that supports duplicate records.
|
|
Partial puts in databases supporting duplicate records must be done
|
|
using a
|
|
.I Db::cursor
|
|
method.
|
|
It is an error to attempt a partial put with differing
|
|
.I dlen
|
|
and
|
|
.I size
|
|
values in a recno database with fixed-length records.
|
|
.sp
|
|
For example, if the data portion of a retrieved record was 100 bytes,
|
|
and a partial put was done using a Dbt having a
|
|
.I dlen
|
|
field of 20,
|
|
a
|
|
.I doff
|
|
field of 85,
|
|
and a
|
|
.I size
|
|
field of 30,
|
|
the resulting record would be 115 bytes in length, where the last 30
|
|
bytes would be those specified by the put call.
|
|
.RE
|
|
.PP
|
|
The default algorithm of associating returned key or data items with the
|
|
Db handle returned by
|
|
.IR Db::open (3)
|
|
will obviously not work when Db handles are being used concurrently by
|
|
multiple threads within a process, i.e, when DB_THREAD was specified to
|
|
.IR Db::open (3).
|
|
.ft B
|
|
When multiple threads are using the returned Db handle concurrently,
|
|
either the DB_DBT_MALLOC or DB_DBT_USERMEM flags must be specified
|
|
for any Dbt used for key or data retrieval.
|
|
.ft R
|
|
.if '\*[TYPE]'JAVA'\{
|
|
.PP
|
|
.ft B
|
|
For this reason,
|
|
when using the JAVA DB API, either the DB_DBT_MALLOC or DB_DBT_USERMEM
|
|
flags must be specified for any Dbt used for key or data retrieval.
|
|
.ft R
|
|
If DB_DBT_USERMEM is specified, the data field of the Dbt must be set
|
|
to an appropriately sized byte array.
|
|
.PP
|
|
If DB_DBT_MALLOC is specified, DB allocates a properly sized byte
|
|
array to contain the data. This can be convenient if you know little
|
|
about the nature of the data, specifically the size of data in the
|
|
database. However, if your application makes repeated calls to
|
|
retrieve keys or data, you may notice increased garbage collection due
|
|
to this allocation. If you know the maximum size of data you are
|
|
retrieving, you might decrease the memory burden and speed your
|
|
application by allocating your own byte array and using DB_DBT_USERMEM.
|
|
Even if you don't know the maximum size, you can use this option
|
|
and reallocate your array whenever your retrieval API call returns
|
|
an ENOMEM error.
|
|
\}
|
|
.SH "LOGICAL RECORD NUMBERS
|
|
In all cases for the recno access method,
|
|
and when calling the
|
|
.I Db::get
|
|
and
|
|
.I Dbc::get
|
|
functions with the DB_GET_RECNO flag specified, the
|
|
.I data
|
|
.ie '\*[TYPE]'CXX'\{
|
|
field of the key must be a pointer to a memory location of type
|
|
.IR db_recno_t ,
|
|
as typedef'd in the <db_cxx.h> include file.
|
|
This type is a 32-bit unsigned type,
|
|
\}
|
|
.el\{\
|
|
field of the key must be a four byte array, large enough
|
|
to store an int. The
|
|
.I set_recno_key_data
|
|
method can be used to set the value of the array.
|
|
An int is a 32-bit type,
|
|
\}
|
|
(which limits the number of logical records in a recno database,
|
|
and the maximum logical record which may be directly retrieved
|
|
from a btree database, to 4,294,967,296).
|
|
The
|
|
.I size
|
|
field of the key should be the size of that type, e.g.,
|
|
.ie '\*[TYPE]'CXX'\{
|
|
in the C programming language, ``sizeof(db_recno_t)''.
|
|
\}
|
|
.el\{\
|
|
4.
|
|
\}
|
|
.sp
|
|
Logical record numbers are 1-based, not 0-based, i.e., the first record
|
|
in the database is record number 1.
|
|
.SH BUGS
|
|
The Db access methods provide no guarantees about byte string alignment,
|
|
and applications are responsible for maintaining any necessary alignment.
|
|
.PP
|
|
The name Dbt is a mnemonic for ``data base thang'', and was used because
|
|
noone could think of a reasonable name that wasn't already in use somewhere
|
|
else.
|
|
.SH "SEE ALSO"
|
|
.Sa
|