gecko-dev/db/man/mancxx.roff/db_deadlock.1

.ds TYPE C
.\"
.\" See the file LICENSE for redistribution information.
.\"
.\" Copyright (c) 1996, 1997, 1998
.\"	Sleepycat Software.  All rights reserved.
.\"
.\"	@(#)db_deadlock.so	10.9 (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
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.\" Scoped name macro.
.\" Produces a_b, a::b, a.b depending on language
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.\" Scoped name for Java.
.\" Produces Db.b, for Java, otherwise just b.  This macro is used for
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.\" 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.
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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
\}
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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
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.el\{method may fail and throw a
.IR DbException (3)
.ie '\*[TYPE]'CXX'\{or return
.I errno
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.el\{encapsulating an
.I errno
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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'\{\
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Methods marked as returning
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will, by default, throw an exception that encapsulates the error information.
The default error behavior can be changed, see
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..
.\" The SEE ALSO text macro
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.\" 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:
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.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")
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.Fn \\$2_open
The
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Otherwise,
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.\"	+ the function called to open, e.g., "txn_open"
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The following fields in the DbEnv object may be initialized, using the
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.\" The DB_ENV common fields macros.
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.TP 5
DbErrcall db_errcall;
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String db_errpfx;
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int db_verbose;
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void *(*db_errcall)(char *db_errpfx, char *buffer);
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int db_verbose;
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void *(*db_errcall)(char *db_errpfx, char *buffer);
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.TP 5
int db_verbose;
The error fields of the DB_ENV behave as described for
.IR db_appinit (3).
.sp
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.\" The open flags.
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The
.I flags
and
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don't already exist.
The flags value is specified by
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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.
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.TP 5
.Sj DB_THREAD
Cause the \\$2 handle returned by the
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.if '\*[TYPE]'JAVA'\{\
Threading is assumed in the Java API,
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.\" The mode macro.
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All files created by the \\$1 are created with mode
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.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.
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The
.I \\$1
utility exits 0 on success, and >0 if an error occurs.
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.\" The application -h section.
.\" This macro takes one argument:
.\"	+ the application name
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DB_HOME
If the
.B \-h
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.I DB_HOME
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.IR db_appinit (3).
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.\" The function DB_HOME ENVIRONMENT VARIABLES section.
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.if \\n(.$>1 \{Specifically,
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is affected by the configuration string value of \\$2.\}
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.\" 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
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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
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.TP 5
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.\" 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:
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The
.I \\$1
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on failure,
0 on success,
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on failure and 0 on success.
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.el\{that encapsulates an
.I errno
on failure.
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..
.\" 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
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.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
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however processes attempting to join the \\$1 will either fail or
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for the file,
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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)).
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maintained across failures,
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files in the directory specified to the
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as \\$1 files are never created in any directory other than the one
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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
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.\" Signal paragraph for standard utilities.
.\" This macro takes one argument:
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The
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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:
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.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
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This file will be removed if the \\$1 utility exits gracefully.
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.\" This macro takes one argument:
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\\$1 are created in allocated memory.
If
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is non-NULL,
it is called to allocate the memory,
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The function
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must match the calling conventions of the
.IR malloc (3)
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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.
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..
.\" 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 DB_DEADLOCK 1 "April 10, 1998"
.UC 7
.SH NAME
db_deadlock \- the DB database deadlock detector
.SH SYNOPSIS
.nf
\fBdb_deadlock\fP [\fB-vw\fP] [\fB-a m | o | y\fP] [\fB-h home\fP]\c
 [\fB-L file \fP] [\fB-t sec \fP]
.fi
.SH DESCRIPTION
The
.I db_deadlock
utility traverses the database lock structures and aborts a transaction
each time it detects a deadlock.
This utility should be run as a background daemon whenever multiple threads
or processes are using locking.
By default,
a random transaction involved in the deadlock is aborted.
.PP
The options are as follows:
.TP 5
.B \-a
When a deadlock is detected,
abort the oldest (``o'') transaction, the youngest (``y'') transaction,
or the transaction with the minimum number of locks (``m'').
.TP 5
.B \-h
Specify a home directory for the database.
.TP 5
.Pi db_deadlock
.TP 5
.B \-t
Initiate a pass over the database locks at least every
.I sec
seconds.
.TP 5
.B \-v
Run in verbose mode, generating messages each time the detector runs.
.TP 5
.B \-w
Make a single pass over the database locks every time a process is forced
to wait for a lock.
.PP
At least one of the
.B -t
and
.B -w
options must be specified.
.PP
.Si db_deadlock
.PP
.Ex db_deadlock
.SH "ENVIRONMENT VARIABLES"
The following environment variables affect the execution of
.IR db_deadlock :
.TP 5
.Dh db_deadlock
.SH "SEE ALSO"
.Gn
.PP
.Sa