Segfault in write_channel about ardb

[sscarduzio]

I already run gdb:

ubuntu@ip-10-49-11-32:~$ gdb ardb/src/ardb-server /tmp/core
GNU gdb (GDB) 7.6.1-ubuntu
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/ubuntu/ardb/src/ardb-server...done.
[New LWP 3437]
[New LWP 3434]
[New LWP 3435]
[New LWP 3438]
[New LWP 3436]

warning: Can't read pathname for load map: Input/output error.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `src/ardb-server ardb.conf'.
Program terminated with signal 11, Segmentation fault.
#0  SendDownstream<ardb::MessageEvent<ardb::codec::RedisReply> > (event=..., this=<optimized out>) at channel/all_includes.hpp:134
134         ChannelHandlerContext* ctx = GetActualDownstreamContext(m_tail);
(gdb) backtrace
#0  SendDownstream<ardb::MessageEvent<ardb::codec::RedisReply> > (event=..., this=<optimized out>) at channel/all_includes.hpp:134
#1  ardb::write_channel<ardb::codec::RedisReply> (channel=0x0, message=message@entry=0x7f87089e5960, destructor=destructor@entry=0x0)
    at ./channel/channel_helper.hpp:75
#2  0x0000000000431835 in Write<ardb::codec::RedisReply> (msg=..., this=<optimized out>) at ./channel/channel.hpp:313
#3  ardb::ArdbServer::AsyncWriteBlockListReply (ch=<optimized out>, data=data@entry=0x7f87089e5950) at lists.cpp:44
#4  0x00000000004ff709 in ardb::ChannelService::OnSoftSignal (this=0x7f87f00ca480, soft_signo=<optimized out>, appendinfo=<optimized out>)
    at channel/channel_service.cpp:165
#5  0x000000000050fbf4 in ardb::SoftSignalChannel::FireSignalReceived (this=<optimized out>, signo=4, append_info=1) at channel/signal/soft_signal_channel.cpp:73
#6  0x000000000050f853 in HandleStreamEvent (e=..., ctx=..., this=<optimized out>) at ./channel/channel_upstream_handler.hpp:133
#7  ardb::ChannelPipeline::SendUpstream<unsigned long> (ctx=<optimized out>, e=..., this=<optimized out>) at ./channel/all_includes.hpp:89
#8  0x0000000000510b4f in SendUpstream<ardb::MessageEvent<unsigned long> > (this=<optimized out>, this=<optimized out>, e=...) at ./channel/all_includes.hpp:164
#9  fire_message_received<unsigned long> (destructor=0x0, message=0x7f87edffcca8, ctx=...) at ./channel/channel_helper.hpp:91
#10 CallDecode (cumulation=..., channel=0x7f87f00ca5c0, context=..., this=0x7f87f00ca6c8) at ./channel/codec/stack_frame_decoder.hpp:102
#11 ardb::codec::StackFrameDecoder<unsigned long>::MessageReceived (this=0x7f87f00ca6c8, ctx=..., e=...) at ./channel/codec/stack_frame_decoder.hpp:157
#12 0x00000000004f7ee3 in HandleStreamEvent (e=..., ctx=..., this=<optimized out>) at ./channel/channel_upstream_handler.hpp:133
#13 ardb::ChannelPipeline::SendUpstream<ardb::Buffer> (ctx=<optimized out>, e=..., this=<optimized out>) at ./channel/all_includes.hpp:89
#14 0x00000000004f7fbf in SendUpstream<ardb::MessageEvent<ardb::Buffer> > (event=..., this=0x7f87f00ca5f8) at ./channel/all_includes.hpp:128
#15 fire_message_received<ardb::Buffer> (destructor=0x0, message=0x7f87f00ca628, channel=0x7f87f00ca5c0) at ./channel/channel_helper.hpp:83
#16 ardb::Channel::OnRead (this=0x7f87f00ca5c0) at channel/channel.cpp:472
#17 0x00000000004f7d0d in ardb::Channel::IOEventCallback (eventLoop=<optimized out>, fd=<optimized out>, clientData=0x7f87f00ca5c0, mask=1) at channel/channel.cpp:50
#18 0x0000000000514580 in aeProcessEvents (eventLoop=eventLoop@entry=0x7f87f0041888, flags=flags@entry=3) at channel/redis/ae.c:429
#19 0x000000000051486b in aeMain (eventLoop=0x7f87f0041888) at channel/redis/ae.c:485
#20 0x00000000004e26a0 in ardb::Thread::ThreadFunc (data=0x7f87eff477f0) at util/thread/thread.cpp:38
#21 0x00007f87f15e6f6e in start_thread (arg=0x7f87edffd700) at pthread_create.c:311
#22 0x00007f87f0af39cd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

[yinqiwen]

It's caused by the 'lpush' command which waking the blocking client, while at the same time the connection is closing.
Just commit a fix for it.

[sscarduzio]

Thanks, this works. Good job!