Commit Graph

6062 Commits

Author SHA1 Message Date
Frederic Bregier
4871630d48 Fix AbstractDiskHttpData int conversion from long
Motivations:
The chunkSize might be oversized after comparison (size being > of int
capacity) if file size is bigger than an integer.

Modifications:
Change it to long.

Result:
There is no more int oversized.

Same fix for 4.1 and Master
2014-12-08 06:27:13 +01:00
Trustin Lee
1e35d06efb Make PendingWriteQueue.recycle() update its state before triggering an event
Related: #3212

Motivation:

PendingWriteQueue.recycle() updates its data structure after triggering
a channelWritabilityChanged() event. It causes a rare corruption such as
double free when channelWritabilityChanged() method accesses the
PendingWriteQueue.

Modifications:

Update the state of PendingWriteQueue before triggering an event.

Result:

Fix a rare double-free problem
2014-12-07 23:28:18 +09:00
Trustin Lee
1122189771 Trigger exceptionCaught() when VoidChannelPromise fails
Related: #3190

Motivation:

When an outbound handler method raises an exception, its promise is
marked as failed.  If the promise is done already, the exception is
logged.

When the promise is void, exceptionCaught() must be triggered to notify
a user. However, AbstractChannelHandlerContext simply swallows it.

Modifications:

Do not swallow an exception when the promise is void.

Result:

A user who uses a void promise for an outbound operation will be
notified on failure.
2014-12-07 16:00:35 +09:00
Trustin Lee
2fadef31ef Fire channelRead() event immediately in OIO message channels
Related: #3189

Motivation:

OIO transport implementations block for at most 1 second to wait for
additional messages (or accepted connections).

However, because AbstractOioMessageChannel defers the channelRead()
events for the messages read so far until there's nothing to read up to
maxMessagesPerRead, any read operation will be followed by a 1-second
delay.

Modifications:

Fire channelRead() events as soon as doRead() returns so that there is
no 1 second delay between the actual read and the channelRead() event.

Result:

No more weird 1-second delay
2014-12-07 12:13:33 +09:00
Trustin Lee
a9fda3c8e0 Fix a bug where Recycler's capacity can increase beyond its maximum
Related: #3166

Motivation:

When the recyclable object created at one thread is returned at the
other thread, it is stored in a WeakOrderedQueue.

The objects stored in the WeakOrderedQueue is added back to the stack by
WeakOrderedQueue.transfer() when the owner thread ran out of recyclable
objects.

However, WeakOrderedQueue.transfer() does not have any mechanism that
prevents the stack from growing beyond its maximum capacity.

Modifications:

- Make WeakOrderedQueue.transfer() increase the capacity of the stack
  only up to its maximum
- Add tests for the cases where the recyclable object is returned at the
  non-owner thread
- Fix a bug where Stack.scavengeSome() does not scavenge the objects
  when it's the first time it ran out of objects and thus its cursor is
  null.
- Overall clean-up of scavengeSome() and transfer()

Result:

The capacity of Stack never increases beyond its maximum.
2014-12-06 17:56:10 +09:00
Greg Gibeling
66834bc818 Lazily check for root, avoids unnecessary errors & resources
Motivation:

io.netty.util.internal.PlatformDependent.isRoot() depends on the IS_ROOT field which is filled in during class initialization. This spawns processes and consumes resources, which are not generally necessary to the complete functioning of that class.

Modifications:

This switches the class to use lazy initialization this field inside of the isRoot() method using double-checked locking (http://en.wikipedia.org/wiki/Double-checked_locking).

Result:

The first call to isRoot() will be slightly slower, at a tradeoff that class loading is faster, uses fewer resources and platform errors are avoided unless necessary.
2014-12-05 09:16:26 +01:00
Trustin Lee
c774b65f86 Fix a race condition where handler is removed before unregistration
Related: #3156

Motivation:

Let's say we have a channel with the following pipeline configuration:

  HEAD --> [E1] H1 --> [E2] H2 --> TAIL

when the channel is deregistered, the channelUnregistered() methods of
H1 and H2 will be invoked from the executor thread of E1 and E2
respectively. To ensure that the channelUnregistered() methods are
invoked from the correct thread, new one-time tasks will be created
accordingly and be scheduled via Executor.execute(Runnable).

As soon as the one-time tasks are scheduled,
DefaultChannelPipeline.fireChannelUnregistered() will start to remove
all handlers from the pipeline via teardownAll(). This process is
performed in reversed order of event propagation. i.e. H2 is removed
first, and then H1 is removed.

If the channelUnregistered() event has been passed to H2 before H2 is
removed, a user does not see any problem.

If H2 has been removed before channelUnregistered() event is passed to
H2, a user will often see the following confusing warning message:

  An exceptionCaught() event was fired, and it reached at the tail of
  the pipeline. It usually means the last handler in the pipeline did
  not handle the exception.

Modifications:

To ensure that the handlers are removed *after* all events are
propagated, traverse the pipeline in ascending order before performing
the actual removal.

Result:

A user does not get the confusing warning message anymore.
2014-12-05 15:51:40 +09:00
Trustin Lee
53c1a30194 Add missing @Override annotation 2014-12-04 20:53:22 +09:00
Trustin Lee
b62a6db61e Fix checkstyle 2014-12-04 18:40:36 +09:00
Trustin Lee
0f8ccbb1ac Overall clean-up of the initial SniHandler/DomainNameMapping work
- Parameterize DomainNameMapping to make it useful for other use cases
  than just mapping to SslContext
- Move DomainNameMapping to io.netty.util
- Clean-up the API documentation
- Make SniHandler.hostname and sslContext volatile because they can be
  accessed by non-I/O threads
2014-12-04 18:23:24 +09:00
Trustin Lee
7d8873a490 Fix dependency issues with hamcrest
Motivation:

We use 3 (!) libraries to build mock objects - easymock, mockito, jmock.
Mockito and jMock pulls in the different versions of Hamcrest, and it
conflicts with the version pulled by jUnit.

Modifications:

- Replace mockito-all with mockito-core to avoid pulling in outdated
  jUnit and Hamcrest
- Exclude junit-dep when pulling in jmock-junit4, because it pulls an
  outdated Hamcrest version
- Pull in the hamcrest-library version used by jUnit explicitly

Result:

No more dependency hell that results in NoSuchMethodError during the
tests
2014-12-04 18:00:02 +09:00
Sun Ning
b438ea4758 Added support for SSL Server Name Indication.
Motivation:

When we need to host multiple server name with a single IP, it requires
the server to support Server Name Indication extension to serve clients
with proper certificate. So the SniHandler will host multiple
SslContext(s) and append SslHandler for requested hostname.

Modification:

* Added SniHandler to host multiple certifications in a single server
* Test case

Result:

User could use SniHandler to host multiple certifcates at a time.
It's server-side only.
2014-12-03 10:21:54 +01:00
Ronald Chen
73a0f1dd31 Rocumented decoder pitfalls to avoid mistakes found in [#3184] 2014-12-01 20:26:09 +01:00
Sam Young
1c09bf86a4 Add @SafeVarargs to PromiseAggregator#add and PromiseNotifier#(...) https://github.com/netty/netty/issues/3147
Motivation:

8fbc513 introduced stray warnings in callsites of
PromiseAggregator#add and PromiseNotifier#(...).

Modifications:

This commit adds the @SafeVarargs annotation to PromiseAggregator#add
and PromiseNotifier#(...). As Netty is built with JDK7, this is a
recognized annotation and should not affect runtime VM versions 1.5 and
1.6.

Result:

Building Netty with JDK7 will no longer produce warnings in the
callsites mentioned above.
2014-12-01 19:59:52 +01:00
Frank Barber
a83a970276 Prevent channel re-registration from firing channelActive
Motivation:

AbstractUnsafe considers two possibilities during channel registration. First,
the channel may be an outgoing connection, in which case it will be registered
before becoming active. Second, the channel may be an incoming connection in,
which case the channel will already be active when it is registered. To handle
the second case, AbstractUnsafe checks if the channel is active after
registration and calls ChannelPipeline.fireChannelActive() if so.  However, if
an active channel is deregistered and then re-registered this logic causes a
second fireChannelActive() to be invoked. This is unexpected; it is reasonable
for handlers to assume that this method will only be invoked once per channel.

Modifications:

This change introduces a flag into AbstractUnsafe to recognize if this is the
first or a subsequent registration. ChannelPipeline.fireChannelActive() is only
possible for the first registration.

Result:

ChannelPipeline.fireChannelActive() is only called once.
2014-11-30 19:43:48 +01:00
Ronald Chen
ae4017e76a replaced broken &lt with < and same for gt 2014-11-29 19:36:30 +01:00
Graham Edgecombe
e7ad9fed77 Use Triple DES in JdkSslContext cipher suite list.
Motivation:

JdkSslContext used SSL_RSA_WITH_DES_CBC_SHA in its cipher suite list.
OpenSslServerContext used DES-CBC3-SHA in the same place in its cipher suite
list, which is equivalent to SSL_RSA_WITH_3DES_EDE_CBC_SHA.

This means the lists were out of sync. Furthermore, using
SSL_RSA_WITH_DES_CBC_SHA is not desirable as it uses DES, a weak cipher. Triple
DES should be used instead.

Modifications:

Replace SSL_RSA_WITH_DES_CBC_SHA with SSL_RSA_WITH_3DES_EDE_CBC_SHA in
JdkSslContext.

Result:

The JdkSslContext and OpenSslServerContext cipher suite lists are now in sync.
Triple DES is used instead of DES, which is stronger.
2014-11-27 08:15:47 +01:00
Trustin Lee
3fe5ba1dd4 Remove or de-prioritize RC4 from default cipher suites
Motivation:

RC4 is not a recommended cipher suite anymore, as the recent research
reveals, such as:

- http://www.isg.rhul.ac.uk/tls/

Modifications:

- Remove most RC4 cipher suites from the default cipher suites
- For backward compatibility, leave RC4-SHA, while de-prioritizing it

Result:

Potentially safer default
2014-11-25 17:17:28 +09:00
Trustin Lee
37e1788a7c Fix awful naming 2014-11-22 07:46:40 +09:00
Trustin Lee
759a2b9abe Add back IntObjectMap.values(Class<V>)
Motivation:

Although the new IntObjectMap.values() that returns Collection is
useful, the removed values(Class<V>) that returns an array is also
useful. It's also good for backward compatibility.

Modifications:

- Add IntObjectMap.values(Class<V>) back
- Miscellaneous improvements
  - Cache the collection returned by IntObjectHashMap.values()
  - Inspector warnings
- Update the IntObjectHashMapTest to test both values()

Result:

- Backward compatibility
- Potential performance improvement of values()
2014-11-22 07:42:33 +09:00
Trustin Lee
b9f575352b Do not write LastHttpContent twice in HttpStaticFileServer example
Related: #3122

Motivation:

The HttpStaticFileServer example writes the LastHttpContent twice at the
end of the transfer.  HttpChunkedInput already produces a
LastHttpContent at the end of the stream, so there's no reason to write
another.

Modifications:

Do not write LastHttpContent in HttpStaticFileServerHandler when
HttpChunkedInput is used to transfer a file.

Result:

HttpStaticFileServer does not violates the protocol anymore.
2014-11-21 11:46:10 +09:00
Trustin Lee
f8a13cc3e9 Backport the IntObjectHashMap changes in f23f3b9617
Motivation:

The mentioned commit contains a bug fix and an improvement in
IntObjectHashMap that requires backporting.

Modifications:

Update IntObjectMap, IntObjectHashMap, and IntObjectHashMapTest

Result:

Easier to backport HTTP/2 and other changes in master in the future
2014-11-21 11:09:51 +09:00
Daniel Bevenius
83ad1fd086 Add logLevel property to enable different log levels for the examples.
Motivation:

When running the examples using the provided run-examples.sh script the
log level is 'info' level. It can be handy to be able to configure a
different level, for example 'debug', while learning and trying out the
the examples.

Modifications:

Added a dependency to logback-classic to the examples pom.xml, and also
added a logback configuration file. The log level can be configured by
setting the 'logLevel' system property, and if that property is not set
the default will be 'info' level.
The run-examples.sh was updated to show an example of using the system
property to set the log level to 'debug'

Result:

It is now possible to turn on debug logging by settnig a system property
on the command line.
2014-11-21 10:48:13 +09:00
Idel Pivnitskiy
3d200085a4 Small performance improvements
Motivation:

Found performance issues via FindBugs and PMD.

Modifications:

- Removed unnecessary boxing/unboxing operations in DefaultTextHeaders.convertToInt(CharSequence) and DefaultTextHeaders.convertToLong(CharSequence). A boxed primitive is created from a string, just to extract the unboxed primitive value.
- Added a static modifier for DefaultHttp2Connection.ParentChangedEvent class. This class is an inner class, but does not use its embedded reference to the object which created it. This reference makes the instances of the class larger, and may keep the reference to the creator object alive longer than necessary.
- Added a static compiled Pattern to avoid compile it each time it is used when we need to replace some part of authority.
- Improved using of StringBuilders.

Result:

Performance improvements.
2014-11-20 00:58:35 -05:00
Trustin Lee
3843ca55a2 Add more test cases to ZlibTest
Motivation:

Currently, we only test our ZlibEncoders against our ZlibDecoders. It is
convenient to write such tests, but it does not necessarily guarantee
their correctness. For example, both encoder and decoder might be faulty
even if the tests pass.

Modifications:

Add another test that makes sure that our GZIP encoder generates the
GZIP trailer, using the fact that GZIPInputStream raises an EOFException
when GZIP trailer is missing.

Result:

More coverage for GZIP compression
2014-11-19 18:35:26 +09:00
Jeff Pinner
63e4de5298 SPDY: add support for pushed resources in SpdyHttpDecoder
Motivation:

The SPDY/3.1 spec does not adequate describe how to push resources
from the server. This was solidified in the HTTP/2 drafts by dividing
the push into two frames, a PushPromise containing the request,
followed by a Headers frame containing the response.

Modifications:

This commit modifies the SpdyHttpDecoder to support pushed resources
that are divided into multiple frames. The decoder will accept a
pushed SpdySynStreamFrame containing the request headers, followed by
a SpdyHeadersFrame containing the response headers.

Result:

The SpdyHttpDecoder will create an HttpRequest object followed by an
HttpResponse object when receiving pushed resources.
2014-11-17 10:50:17 +01:00
Roelof Naude
eca194daf4 Cater for empty response bodies when performing response compression.
Motivation:
RFC 2616, 4.3 Message Body states that:
All 1xx (informational), 204 (no content), and 304 (not modified) responses MUST NOT include a
message-body. All other responses do include a message-body, although it MAY be of zero length.

Modifications:
HttpContentEncoder was previously modified to cater for HTTP 100 responses. This check is enhanced to
include HTTP 204 and 304 responses.

Result:
Empty response bodies will not be modified to include the compression footer. This footer messed with Chrome's
response parsing leading to "hanging" requests.
2014-11-13 08:16:43 +01:00
Idel Pivnitskiy
9b3f536921 Benchmark for HttpRequestDecoder 2014-11-12 14:37:11 +01:00
Idel Pivnitskiy
cc97be6002 Rewrite HttpObjectDecoder to make use of proper state machine
Motivation:

HttpObjectDecoder extended ReplayDecoder which is slightly slower then ByteToMessageDecoder.

Modifications:

- Changed super class of HttpObjectDecoder from ReplayDecoder to ByteToMessageDecoder.
- Rewrote decode() method of HttpObjectDecoder to use proper state machine.
- Changed private methods HeaderParser.parse(ByteBuf), readHeaders(ByteBuf) and readTrailingHeaders(ByteBuf), skipControlCharacters(ByteBuf) to consider available bytes.
- Set HeaderParser and LineParser as static inner classes.
- Replaced not safe actualReadableBytes() with buffer.readableBytes().

Result:

Improved performance of HttpObjectDecoder by approximately 177%.
2014-11-12 14:36:56 +01:00
Trustin Lee
59f222a821 Handle the interface name in IPv6 address correctly
Motivation:

NetUtil.isValidIpV6Address() handles the interface name in IPv6 address
incorrectly. For example, it returns false for the following addresses:

- ::1%lo
- ::1%_%_in_name_

Modifications:

- Strip the square brackets before validation for simplicity
- Strip the part after the percent sign completely before validation for
  simplicity
- Simplify and reformat NetUtilTest

Result:

- The interface names in IPv6 addresses are handled correctly.
- NetUtilTest is cleaner
2014-11-12 12:15:14 +09:00
Sam Young
bb94f05083 Add generic versions of PromiseAggregator and PromiseNotifier.
Motivation:

ChannelPromiseAggregator and ChannelPromiseNotifiers only allow
consumers to work with Channels as the result type. Generic versions
of these classes allow consumers to aggregate or broadcast the results
of an asynchronous execution with other result types.

Modifications:

Add PromiseAggregator and PromiseNotifier. Add unit tests for both.
Remove code in ChannelPromiseAggregator and ChannelPromiseNotifier and
modify them to extend the new base classes.

Result:

Consumers can now aggregate or broadcast the results of an asynchronous
execution with results types other than Channel.
2014-11-07 08:44:20 +01:00
Scott Mitchell
7da5ca3629 HTTP Content Encoder allow EmptyLastHttpContent
Motiviation:
The HttpContentEncoder does not account for a EmptyLastHttpContent being provided as input.  This is useful in situations where the client is unable to determine if the current content chunk is the last content chunk (i.e. a proxy forwarding content when transfer encoding is chunked).

Modifications:
- HttpContentEncoder should not attempt to compress empty HttpContent objects

Result:
HttpContentEncoder supports a EmptyLastHttpContent to terminate the response.
2014-11-05 23:23:21 -05:00
Trustin Lee
49998bc9c0 Fix build errors introduced during backporting SslContext 2014-10-31 14:25:14 +09:00
Trustin Lee
3ddac6adff Add ApplicationProtocolConfig.DISABLED
Motivation:

When ALPN/NPN is disabled, a user has to instantiate a new
ApplicationProtocolConfig with meaningless parameters.

Modifications:

- Add ApplicationProtocolConfig.DISABLED, the singleton instance
- Reject the constructor calls with Protocol.NONE, which doesn't make
  much sense because a user should use DISABLED instead.

Result:

More user-friendly API when ALPN/NPN is not needed by a user.
2014-10-31 14:15:43 +09:00
Trustin Lee
a6a42d2f19 Add back the removed deprecated methods in SslContext
Motivation:

Previous backport removed the old methods and constructors. They should
not be removed in 4.x but just deprecated in favor of the new methods
and constructors.

Modifications:

Add back the removed methods and constructors in SslContext and its
subtypes for backward compatibility.

Result:

Backward compatibility issues fixed.
2014-10-31 14:15:33 +09:00
Trustin Lee
8f3904f6dc Code clean-up
- Fix the inspector warnings
- Fix the infinite recursion in SslContext.newClientContext()
- Fix Javadoc errors
2014-10-31 14:15:25 +09:00
Scott Mitchell
56b8bb30b2 Backport ALPN and Mutual Auth SSL
Motivation:

Improvements were made on the main line to support ALPN and mutual
authentication for TLS. These should be backported.

Modifications:

- Backport commits from the master branch
  - f8af84d599
  - e74c8edba3

Result:

Support for ALPN and mutual authentication.
2014-10-31 14:15:12 +09:00
Scott Mitchell
e73f32b52d SslHander wrap conditional direct buffer allocation
Motivation:
The SslHandler currently forces the use of a direct buffer for the input to the SSLEngine.wrap(..) operation. This allocation may not always be desired and should be conditionally done.

Modifications:
- Use the pre-existing wantsDirectBuffer variable as the condition to do the conversion.

Result:
- An allocation of a direct byte buffer and a copy of data is now not required for every SslHandler wrap operation.
2014-10-30 09:26:15 +01:00
Norman Maurer
1914b77c71 [maven-release-plugin] prepare for next development iteration 2014-10-29 11:48:40 +01:00
Norman Maurer
c170e7df3f [maven-release-plugin] prepare release netty-4.0.24.Final 2014-10-29 11:47:19 +01:00
Scott Mitchell
8db8aca1e7 SslHandler wrap memory leak
Motivation:
The SslHandler wrap method requires that a direct buffer be passed to the SSLEngine.wrap() call. If the ByteBuf parameter does not have an underlying direct buffer then one is allocated in this method, but it is not released.

Modifications:
- Release the direct ByteBuffer only accessible in the scope of SslHandler.wrap

Result:
Memory leak in SslHandler.wrap is fixed.
2014-10-28 06:13:06 +01:00
Matthias Einwag
a9bd9699a4 Fix the websocket server example
Motivation:
As report in #2953 the websocket server example contained a bug and did therefore not work with chrome:
A websocket extension is added to the pipeline but extensions were disallowed in the handshaker and decoder,
which is leading the decoder to closing the connection after receiving an extension frame.

Modifications:
Allow websocket extensions in the handshaker to correctly enable the extension.

Result:
Working websocket server example
Fixes #2953
2014-10-25 21:48:34 +09:00
Trustin Lee
9b4481b59a Fix a compilation error 2014-10-25 17:13:57 +09:00
Trustin Lee
d794ea515b Fix compilation errors in ChannelOutboundBufferTest 2014-10-25 16:57:47 +09:00
Trustin Lee
83296ca9ac Overall cleanup of 6602fcf54fafeae1d3d0f57734d60f81edc2e0ba 2014-10-25 16:43:11 +09:00
Norman Maurer
32d82fa259 Modify HttpObjectDecoder to allow parsing the HTTP headers in multiple steps.
Motivation:
At the moment the whole HTTP header must be parsed at once which can lead to multiple parsing of the same bytes. We can do better here and allow to parse it in multiple steps.

Modifications:

 - Not parse headers multiple times
 - Simplify the code
 - Eliminate uncessary String[] creations
 - Use readSlice(...).retain() when possible.

Result:

Performance improvements as shown in the included benchmark below.

Before change:
[nmaurer@xxx]~% ./wrk-benchmark
Running 2m test @ http://xxx:8080/plaintext
  16 threads and 256 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    21.55ms   15.10ms 245.02ms   90.26%
    Req/Sec   196.33k    30.17k  297.29k    76.03%
  373954750 requests in 2.00m, 50.15GB read
Requests/sec: 3116466.08
Transfer/sec:    427.98MB

After change:
[nmaurer@xxx]~% ./wrk-benchmark
Running 2m test @ http://xxx:8080/plaintext
  16 threads and 256 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    20.91ms   36.79ms   1.26s    98.24%
    Req/Sec   206.67k    21.69k  243.62k    94.96%
  393071191 requests in 2.00m, 52.71GB read
Requests/sec: 3275971.50
Transfer/sec:    449.89MB
2014-10-25 16:43:11 +09:00
Trustin Lee
329e97f20f Revert "Fix the websocket server example"
This reverts commit 443d686d6a.
2014-10-25 16:43:11 +09:00
Matthias Einwag
443d686d6a Fix the websocket server example
Motivation:
As report in #2953 the websocket server example contained a bug and did therefore not work with chrome:
A websocket extension is added to the pipeline but extensions were disallowed in the handshaker and decoder,
which is leading the decoder to closing the connection after receiving an extension frame.

Modifications:
Allow websocket extensions in the handshaker to correctly enable the extension.

Result:
Working websocket server example
Fixes #2953
2014-10-25 16:18:29 +09:00
Trustin Lee
ee9cbda9f0 Implement user-defined writability flags
Related: #2945

Motivation:

Some special handlers such as TrafficShapingHandler need to override the
writability of a Channel to throttle the outbound traffic.

Modifications:

Add a new indexed property called 'user-defined writability flag' to
ChannelOutboundBuffer so that a handler can override the writability of
a Channel easily.

Result:

A handler can override the writability of a Channel using an unsafe API.
For example:

  Channel ch = ...;
  ch.unsafe().outboundBuffer().setUserDefinedWritability(1, false);
2014-10-25 15:59:30 +09:00
Trustin Lee
5112cec5fa Handle an empty ByteBuf specially in HttpObjectEncoder
Related: #2983

Motivation:

It is a well known idiom to write an empty buffer and add a listener to
its future to close a channel when the last byte has been written out:

  ChannelFuture f = channel.writeAndFlush(Unpooled.EMPTY_BUFFER);
  f.addListener(ChannelFutureListener.CLOSE);

When HttpObjectEncoder is in the pipeline, this still works, but it
silently raises an IllegalStateException, because HttpObjectEncoder does
not allow writing a ByteBuf when it is expecting an HttpMessage.

Modifications:

- Handle an empty ByteBuf specially in HttpObjectEncoder, so that
  writing an empty buffer does not fail even if the pipeline contains an
  HttpObjectEncoder
- Add a test

Result:

An exception is not triggered anymore by HttpObjectEncoder, when a user
attempts to write an empty buffer.
2014-10-22 14:45:02 +09:00