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DBI::Gofer::Execute(3pm) User Contributed Perl Documentation DBI::Gofer::Execute(3pm)
NAME
DBI::Gofer::Execute - Executes Gofer requests and returns Gofer responses
SYNOPSIS
$executor = DBI::Gofer::Execute->new( { ...config... });
$response = $executor->execute_request( $request );
DESCRIPTION
Accepts a DBI::Gofer::Request object, executes the requested DBI method calls, and returns
a DBI::Gofer::Response object.
Any error, including any internal 'fatal' errors are caught and converted into a
DBI::Gofer::Response object.
This module is usually invoked by a 'server-side' Gofer transport module. They usually
have names in the ""DBI::Gofer::Transport::*"" namespace. Examples include:
DBI::Gofer::Transport::stream and DBI::Gofer::Transport::mod_perl.
CONFIGURATION
check_request_sub
If defined, it must be a reference to a subroutine that will 'check' the request. It is
passed the request object and the executor as its only arguments.
The subroutine can either return the original request object or die with a suitable error
message (which will be turned into a Gofer response).
It can also construct and return a new request that should be executed instead of the
original request.
check_response_sub
If defined, it must be a reference to a subroutine that will 'check' the response. It is
passed the response object, the executor, and the request object. The sub may alter the
response object and return undef, or return a new response object.
This mechanism can be used to, for example, terminate the service if specific database
errors are seen.
forced_connect_dsn
If set, this DSN is always used instead of the one in the request.
default_connect_dsn
If set, this DSN is used if "forced_connect_dsn" is not set and the request does not
contain a DSN itself.
forced_connect_attributes
A reference to a hash of connect() attributes. Individual attributes in
"forced_connect_attributes" will take precedence over corresponding attributes in the
request.
default_connect_attributes
A reference to a hash of connect() attributes. Individual attributes in the request take
precedence over corresponding attributes in "default_connect_attributes".
max_cached_dbh_per_drh
If set, the loaded drivers will be checked to ensure they don't have more than this number
of cached connections. There is no default value. This limit is not enforced for every
request.
max_cached_sth_per_dbh
If set, all the cached statement handles will be cleared once the number of cached
statement handles rises above this limit. The default is 1000.
forced_single_resultset
If true, then only the first result set will be fetched and returned in the response.
forced_response_attributes
A reference to a data structure that can specify extra attributes to be returned in
responses.
forced_response_attributes => {
DriverName => {
dbh => [ qw(dbh_attrib_name) ],
sth => [ qw(sth_attrib_name) ],
},
},
This can be useful in cases where the driver has not implemented the
private_attribute_info() method and DBI::Gofer::Execute's own fallback list of private
attributes doesn't include the driver or attributes you need.
track_recent
If set, specifies the number of recent requests and responses that should be kept by the
update_stats() method for diagnostics. See DBI::Gofer::Transport::mod_perl.
Note that this setting can significantly increase memory use. Use with caution.
forced_gofer_random
Enable forced random failures and/or delays for testing. See "DBI_GOFER_RANDOM" below.
DRIVER-SPECIFIC ISSUES
Gofer needs to know about any driver-private attributes that should have their values sent
back to the client.
If the driver doesn't support private_attribute_info() method, and very few do, then the
module fallsback to using some hard-coded details, if available, for the driver being
used. Currently hard-coded details are available for the mysql, Pg, Sybase, and SQLite
drivers.
TESTING
DBD::Gofer, DBD::Execute and related packages are well tested by executing the DBI test
suite with DBI_AUTOPROXY configured to route all DBI calls via DBD::Gofer.
Because Gofer includes timeout and 'retry on error' mechanisms there is a need for some
way to trigger delays and/or errors. This can be done via the "forced_gofer_random"
configuration item, or else the DBI_GOFER_RANDOM environment variable.
DBI_GOFER_RANDOM
The value of the "forced_gofer_random" configuration item (or else the DBI_GOFER_RANDOM
environment variable) is treated as a series of tokens separated by commas.
The tokens can be one of three types:
fail=R%
Set the current failure rate to R where R is a percentage. The value R can be
floating point, e.g., "fail=0.05%". Negative values for R have special meaning, see
below.
err=N
Sets the current failure err value to N (instead of the DBI's default 'standard err
value' of 2000000000). This is useful when you want to simulate a specific error.
delayN=R%
Set the current random delay rate to R where R is a percentage, and set the current
delay duration to N seconds. The values of R and N can be floating point, e.g.,
"delay0.5=0.2%". Negative values for R have special meaning, see below.
If R is an odd number (R % 2 == 1) then a message is logged via warn() which will be
returned to, and echoed at, the client.
methodname
Applies the current fail, err, and delay values to the named method. If neither a
fail nor delay have been set yet then a warning is generated.
For example:
$executor = DBI::Gofer::Execute->new( {
forced_gofer_random => "fail=0.01%,do,delay60=1%,execute",
});
will cause the do() method to fail for 0.01% of calls, and the execute() method to fail
0.01% of calls and be delayed by 60 seconds on 1% of calls.
If the percentage value ("R") is negative then instead of the failures being triggered
randomly (via the rand() function) they are triggered via a sequence number. In other
words ""fail=-20%"" will mean every fifth call will fail. Each method has a distinct
sequence number.
AUTHOR
Tim Bunce, <http://www.tim.bunce.name>
LICENCE AND COPYRIGHT
Copyright (c) 2007, Tim Bunce, Ireland. All rights reserved.
This module is free software; you can redistribute it and/or modify it under the same
terms as Perl itself. See perlartistic.
perl v5.34.0 2022-02-06 DBI::Gofer::Execute(3pm)
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On Apache
Under GNU General Public License
2024-12-12 17:02 @3.146.178.250 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)