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 pass 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.
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.
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.
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., "delay120=0.1%". Negative values for R have special meaning, see below.
methodname
Applies the current current random failure rate and random delay rate and duration to the named method.
If neither a fail nor delay have been set yet then a warning is generated.
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.
