Problem receiving messages from subscribed channels in c++ client
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Key: ZOOKEEPER-916
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-916
Project: Zookeeper
Issue Type: Bug
Components: contrib-hedwig
Reporter: Ivan Kelly
Assignee: Ivan Kelly
We see this bug with receiving messages from a subscribed channel. This
problem seems to happen with larger messages. The flow is to first read at
least 4 bytes from the socket channel. Extract the first 4 bytes to get the
message size. If we've read enough data into the buffer already, we're done so
invoke the messageReadCallbackHandler passing the channel and message size. If
not, then do an async read for at least the remaining amount of bytes in the
message from the socket channel. When done, invoke the
messageReadCallbackHandler.
The problem seems that when the second async read is done, the same
sizeReadCallbackHandler is invoked instead of the messageReadCallbackHandler.
The result is that we then try to read the first 4 bytes again from the buffer.
This will get a random message size and screw things up. I'm not sure if it's
an incorrect use of the boost asio async_read function or we're doing the boost
bind to the callback function incorrectly.
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler system:0,512 channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler: size of buffer before reading message
size: 512 channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler: size of incoming message 599, currently
in buffer 508 channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler: Still have more data to read, 91 from
channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler system:0, 91 channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler: size of buffer before reading message
size: 599 channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler: size of incoming message 134287360,
currently in buffer 595 channel(0x80b7a18)
101015 15:30:40.108 DEBUG hedwig.channel.cpp -
DuplexChannel::sizeReadCallbackHandler: Still have more data to read, 134286765
from channel(0x80b7a18)
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