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

NAME

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

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
  }

Description

An interface to apr_errno.h composite error codes.

As discussed in the APR::Error|docs::2.0::api::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.

Functions

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);
arg1: $error_code (integer or APR::Error object|docs::2.0::api::APR::Error> )
The error code or to check, normally $@ blessed into APR::Error object|docs::2.0::api::APR::Error>.

ret: $status ( boolean )
since: 1.999.23

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

  use APR::Status ();
  # ....
  my $tries = 0;
  RETRY: eval { $socket->recv(my $buffer, SIZE) };
  if ($@ && 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|docs::2.0::api::APR::Const/C_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.

See Also

mod_perl 2.0 documentation.

Copyright

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

Authors

The mod_perl development team and numerous contributors.

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