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Improved IO->bufferRead to always return requested number of bytes until EOF.

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This commit is contained in:
David Steele 2016-11-30 14:18:12 -05:00
parent e951c4f9c2
commit 4e9f8da9a6
2 changed files with 51 additions and 56 deletions
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4
doc/xml/release.xml
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@ -143,6 +143,10 @@
<p>Abstracted code to determine which database cluster is the master and which are standbys.</p>
</release-item>
<release-item>
<p>Improved <code>IO->bufferRead</code> to always return requested number of bytes until EOF.</p>
</release-item>
</release-refactor-list>
</release-core-list>

103
lib/pgBackRest/Protocol/IO.pm
View File

@ -370,7 +370,6 @@ sub bufferRead
# Set working variables
my $iRemainingSize = $iRequestSize;
$iOffset = defined($iOffset) ? $iOffset : 0;
$bBlock = defined($bBlock) ? $bBlock : false;
# If there is data left over in the buffer from lineRead then use it
if (defined($self->{strBuffer}) && $self->{iBufferPos} < $self->{iBufferSize})
@ -390,80 +389,72 @@ sub bufferRead
$iRemainingSize -= $iReadSize;
undef($self->{strBuffer});
return $iReadSize if !$bBlock || $iRemainingSize == 0;
return $iReadSize if $iRemainingSize == 0;
$iOffset += $iReadSize;
}
}
# If this is a blocking read then loop until all bytes have been read - else error.
# If this is a blocking read then loop until all bytes have been read, else error. If not blocking read until the request size
# has been met or EOF.
#
# This link (http://docstore.mik.ua/orelly/perl/cookbook/ch07_15.htm) demonstrates a way to implement this same loop without
# using select. Not sure if it would be better but the link has been left here so it can be found in the future if the
# implementation needs to be changed.
if ($bBlock)
my $fTimeStart = gettimeofday();
my $fRemaining = 1; #$self->{iProtocolTimeout};
do
{
my $fTimeStart = gettimeofday();
my $fRemaining = $self->{iProtocolTimeout};
do
# Check if the sysread call will block
if ($self->{oInSelect}->can_read($fRemaining))
{
# Check if the sysread call will block
if ($self->{oInSelect}->can_read($fRemaining))
# Read a data into the buffer
my $iReadSize = sysread($self->{hIn}, $$tBufferRef, $iRemainingSize, $iOffset);
# Process errors from the sysread
if (!defined($iReadSize))
{
# Read a data into the buffer
my $iReadSize = sysread($self->{hIn}, $$tBufferRef, $iRemainingSize, $iOffset);
my $strError = $!;
# Process errors from the sysread
if (!defined($iReadSize))
{
my $strError = $!;
$self->waitPid();
confess &log(ERROR, 'unable to read' . (defined($strError) ? ": ${strError}" : ''));
}
# Check for EOF
if ($iReadSize == 0)
{
confess &log(ERROR, 'unexpected EOF', ERROR_FILE_READ);
}
# Update remaining size and return when it reaches 0
$iRemainingSize -= $iReadSize;
if ($iRemainingSize == 0)
{
return $iRequestSize;
}
# Update the offset to advance the next read further into the buffer
$iOffset += $iReadSize;
$self->waitPid();
confess &log(ERROR, 'unable to read' . (defined($strError) ? ": ${strError}" : ''));
}
# Calculate time remaining before timeout
$fRemaining = $self->{iProtocolTimeout} - (gettimeofday() - $fTimeStart);
# Check for EOF
if ($iReadSize == 0)
{
if (defined($bBlock) && $bBlock)
{
confess &log(ERROR,
'EOF after ' . ($iRequestSize - $iRemainingSize) . " bytes but expected ${iRequestSize}",
ERROR_FILE_READ);
}
else
{
return $iRequestSize - $iRemainingSize;
}
}
# Update remaining size and return when it reaches 0
$iRemainingSize -= $iReadSize;
if ($iRemainingSize == 0)
{
return $iRequestSize;
}
# Update the offset to advance the next read further into the buffer
$iOffset += $iReadSize;
}
while ($fRemaining > 0);
# Throw an error if timeout happened before required bytes were read
confess &log(ERROR, "unable to read ${iRequestSize} bytes after $self->{iProtocolTimeout} seconds", ERROR_PROTOCOL_TIMEOUT);
# Calculate time remaining before timeout
$fRemaining = $self->{iProtocolTimeout} - (gettimeofday() - $fTimeStart);
}
while ($fRemaining > 0);
# Otherwise do a non-blocking read and return whatever bytes are ready
my $iReadSize = sysread($self->{hIn}, $$tBufferRef, $iRemainingSize, $iOffset);
# Process errors from sysread
if (!defined($iReadSize))
{
my $strError = $!;
$self->waitPid();
confess &log(ERROR, 'unable to read' . (defined($strError) ? ": ${strError}" : ''));
}
# Return the number of bytes read
return $iReadSize;
# Throw an error if timeout happened before required bytes were read
confess &log(ERROR, "unable to read ${iRequestSize} bytes after $self->{iProtocolTimeout} seconds", ERROR_PROTOCOL_TIMEOUT);
}
####################################################################################################################################