mod_perl logo perl icon
previous page: APR::Socket - Perl API for APR socketspage up: mod_perl 2.0 APInext page: APR::String - Perl API for manipulating APR UUIDs

APR::Status - Perl Interface to the APR_STATUS_IS_* macros






The mod_perl Developer's Cookbook

The mod_perl Developer's Cookbook

By Geoffrey Young, Paul Lindner, Randy Kobes
mod_perl Pocket Reference

mod_perl Pocket Reference

By Andrew Ford
Writing Apache Modules with Perl and C

Writing Apache Modules with Perl and C

By Lincoln Stein, Doug MacEachern
Embedding Perl in HTML with Mason

Embedding Perl in HTML with Mason

By Dave Rolsky, Ken Williams
mod_perl2 User's Guide

mod_perl2 User's Guide

By Stas Bekman, Jim Brandt
Practical mod_perl

Practical mod_perl

By Stas Bekman, Eric Cholet


Table of Contents

Synopsis

  use APR::Status ();
  eval { $obj->mp_method() };
  if ($@ && $ref $@ eq 'APR::Error' && APR::Status::is_EAGAIN($@)) {
      # APR_STATUS_IS_EAGAIN(s) of apr_errno.h is satisfied
  }


TOP

Description

An interface to apr_errno.h composite error codes.

As discussed in the APR::Error manpage, it is possible to handle APR/Apache/mod_perl exceptions in the following way:

  eval { $obj->mp_method() };
  if ($@ && $ref $@ eq 'APR::Error' && $@ == $some_code)
      warn "handled exception: $@";
  }

However, in cases where $some_code is an APR::Const constant, there may be more than one condition satisfying the intent of this exception. For this purpose the APR C library provides in apr_errno.h a series of macros, APR_STATUS_IS_*, which are the recommended way to check for such conditions. For example, the APR_STATUS_IS_EAGAIN macro is defined as

  #define APR_STATUS_IS_EAGAIN(s)         ((s) == APR_EAGAIN \
                  || (s) == APR_OS_START_SYSERR + ERROR_NO_DATA \
                  || (s) == APR_OS_START_SYSERR + SOCEWOULDBLOCK \
                  || (s) == APR_OS_START_SYSERR + ERROR_LOCK_VIOLATION)

The purpose of APR::Status is to provide functions corresponding to these macros.



TOP

Functions



TOP

is_EACCES

Check if the error is matching EACCES and its variants (corresponds to the APR_STATUS_IS_EACCES macro).

  $status = APR::Status::is_EACCES($error_code);

An example of using is_EACCES is when reading the contents of a file where access may be forbidden:

  eval { $obj->slurp_filename(0) };
  if ($@) {
      return Apache2::Const::FORBIDDEN
          if ref $@ eq 'APR::Error' && APR::Status::is_EACCES($@);
      die $@;
   }

Due to possible variants in conditions matching EACCES, the use of this function is recommended for checking error codes against this value, rather than just using APR::Const::EACCES directly.



TOP

is_EAGAIN

Check if the error is matching EAGAIN and its variants (corresponds to the APR_STATUS_IS_EAGAIN macro).

  $status = APR::Status::is_EAGAIN($error_code);

For example, here is how you may want to handle socket read exceptions and do retries:

  use APR::Status ();
  # ....
  my $tries = 0;
  my $buffer;
  RETRY: my $rlen = eval { $socket->recv($buffer, SIZE) };
  if ($@ && ref($@) && APR::Status::is_EAGAIN($@)) {
      if ($tries++ < 3) {
          goto RETRY;
      }
      else {
          # do something else
      }
  }
  else {
      die "eval block has failed: $@";
  }

Notice that just checking against APR::Const::EAGAIN may work on some Unices, but then it will certainly break on win32. Thefore make sure to use this macro and not APR::Const::EAGAIN unless you know what you are doing.



TOP

is_ENOENT

Check if the error is matching ENOENT and its variants (corresponds to the APR_STATUS_IS_ENOENT macro).

  $status = APR::Status::is_ENOENT($error_code);

An example of using is_ENOENT is when reading the contents of a file which may not exist:

  eval { $obj->slurp_filename(0) };
  if ($@) {
      return Apache2::Const::NOT_FOUND
          if ref $@ eq 'APR::Error' && APR::Status::is_ENOENT($@);
      die $@;
  }

Due to possible variants in conditions matching ENOENT, the use of this function is recommended for checking error codes against this value, rather than just using APR::Const::ENOENT directly.



TOP

is_EOF

Check if the error is matching EOF and its variants (corresponds to the APR_STATUS_IS_EOF macro).

  $status = APR::Status::is_EOF($error_code);

Due to possible variants in conditions matching EOF, the use of this function is recommended for checking error codes against this value, rather than just using APR::Const::EOF directly.



TOP

is_ECONNABORTED

Check if the error is matching ECONNABORTED and its variants (corresponds to the APR_STATUS_IS_ECONNABORTED macro).

  $status = APR::Status::is_ECONNABORTED($error_code);

Due to possible variants in conditions matching ECONNABORTED, the use of this function is recommended for checking error codes against this value, rather than just using APR::Const::ECONNABORTED directly.



TOP

is_ECONNRESET

Check if the error is matching ECONNRESET and its variants (corresponds to the APR_STATUS_IS_ECONNRESET macro).

  $status = APR::Status::is_ECONNRESET($error_code);

Due to possible variants in conditions matching ECONNRESET, the use of this function is recommended for checking error codes against this value, rather than just using APR::Const::ECONNRESET directly.



TOP

is_TIMEUP

Check if the error is matching TIMEUP and its variants (corresponds to the APR_STATUS_IS_TIMEUP macro).

  $status = APR::Status::is_TIMEUP($error_code);

Due to possible variants in conditions matching TIMEUP, the use of this function is recommended for checking error codes against this value, rather than just using APR::Const::TIMEUP directly.



TOP

See Also

mod_perl 2.0 documentation.



TOP

Copyright

mod_perl 2.0 and its core modules are copyrighted under The Apache Software License, Version 2.0.



TOP

Authors

The mod_perl development team and numerous contributors.






TOP
previous page: APR::Socket - Perl API for APR socketspage up: mod_perl 2.0 APInext page: APR::String - Perl API for manipulating APR UUIDs