http://git-wip-us.apache.org/repos/asf/hbase-site/blob/a719cd00/devapidocs/src-html/org/apache/hadoop/hbase/io/FSDataInputStreamWrapper.html
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diff --git
a/devapidocs/src-html/org/apache/hadoop/hbase/io/FSDataInputStreamWrapper.html
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---
a/devapidocs/src-html/org/apache/hadoop/hbase/io/FSDataInputStreamWrapper.html
+++
b/devapidocs/src-html/org/apache/hadoop/hbase/io/FSDataInputStreamWrapper.html
@@ -50,266 +50,271 @@
<span class="sourceLineNo">042</span>@InterfaceAudience.Private<a
name="line.42"></a>
<span class="sourceLineNo">043</span>public class FSDataInputStreamWrapper
implements Closeable {<a name="line.43"></a>
<span class="sourceLineNo">044</span> private static final Log LOG =
LogFactory.getLog(FSDataInputStreamWrapper.class);<a name="line.44"></a>
-<span class="sourceLineNo">045</span><a name="line.45"></a>
-<span class="sourceLineNo">046</span> private final HFileSystem hfs;<a
name="line.46"></a>
-<span class="sourceLineNo">047</span> private final Path path;<a
name="line.47"></a>
-<span class="sourceLineNo">048</span> private final FileLink link;<a
name="line.48"></a>
-<span class="sourceLineNo">049</span> private final boolean doCloseStreams;<a
name="line.49"></a>
-<span class="sourceLineNo">050</span> private final boolean dropBehind;<a
name="line.50"></a>
-<span class="sourceLineNo">051</span> private final long readahead;<a
name="line.51"></a>
-<span class="sourceLineNo">052</span><a name="line.52"></a>
-<span class="sourceLineNo">053</span> /** Two stream handles, one with and
one without FS-level checksum.<a name="line.53"></a>
-<span class="sourceLineNo">054</span> * HDFS checksum setting is on FS
level, not single read level, so you have to keep two<a name="line.54"></a>
-<span class="sourceLineNo">055</span> * FS objects and two handles open to
interleave different reads freely, which is very sad.<a name="line.55"></a>
-<span class="sourceLineNo">056</span> * This is what we do:<a
name="line.56"></a>
-<span class="sourceLineNo">057</span> * 1) First, we need to read the
trailer of HFile to determine checksum parameters.<a name="line.57"></a>
-<span class="sourceLineNo">058</span> * We always use FS checksum to do
that, so ctor opens {@link #stream}.<a name="line.58"></a>
-<span class="sourceLineNo">059</span> * 2.1) After that, if HBase checksum
is not used, we'd just always use {@link #stream};<a name="line.59"></a>
-<span class="sourceLineNo">060</span> * 2.2) If HBase checksum can be used,
we'll open {@link #streamNoFsChecksum},<a name="line.60"></a>
-<span class="sourceLineNo">061</span> * and close {@link #stream}. User
MUST call prepareForBlockReader for that to happen;<a name="line.61"></a>
-<span class="sourceLineNo">062</span> * if they don't, (2.1) will be the
default.<a name="line.62"></a>
-<span class="sourceLineNo">063</span> * 3) The users can call {@link
#shouldUseHBaseChecksum()}, and pass its result to<a name="line.63"></a>
-<span class="sourceLineNo">064</span> * {@link #getStream(boolean)} to get
stream (if Java had out/pointer params we could<a name="line.64"></a>
-<span class="sourceLineNo">065</span> * return both in one call). This
stream is guaranteed to be set.<a name="line.65"></a>
-<span class="sourceLineNo">066</span> * 4) The first time HBase checksum
fails, one would call {@link #fallbackToFsChecksum(int)}.<a name="line.66"></a>
-<span class="sourceLineNo">067</span> * That will take lock, and open {@link
#stream}. While this is going on, others will<a name="line.67"></a>
-<span class="sourceLineNo">068</span> * continue to use the old stream; if
they also want to fall back, they'll also call<a name="line.68"></a>
-<span class="sourceLineNo">069</span> * {@link #fallbackToFsChecksum(int)},
and block until {@link #stream} is set.<a name="line.69"></a>
-<span class="sourceLineNo">070</span> * 5) After some number of checksumOk()
calls, we will go back to using HBase checksum.<a name="line.70"></a>
-<span class="sourceLineNo">071</span> * We will have 2 handles; however we
presume checksums fail so rarely that we don't care.<a name="line.71"></a>
-<span class="sourceLineNo">072</span> */<a name="line.72"></a>
-<span class="sourceLineNo">073</span> private volatile FSDataInputStream
stream = null;<a name="line.73"></a>
-<span class="sourceLineNo">074</span> private volatile FSDataInputStream
streamNoFsChecksum = null;<a name="line.74"></a>
-<span class="sourceLineNo">075</span> private Object
streamNoFsChecksumFirstCreateLock = new Object();<a name="line.75"></a>
-<span class="sourceLineNo">076</span><a name="line.76"></a>
-<span class="sourceLineNo">077</span> // The configuration states that we
should validate hbase checksums<a name="line.77"></a>
-<span class="sourceLineNo">078</span> private boolean
useHBaseChecksumConfigured;<a name="line.78"></a>
-<span class="sourceLineNo">079</span><a name="line.79"></a>
-<span class="sourceLineNo">080</span> // Record the current state of this
reader with respect to<a name="line.80"></a>
-<span class="sourceLineNo">081</span> // validating checkums in HBase. This
is originally set the same<a name="line.81"></a>
-<span class="sourceLineNo">082</span> // value as useHBaseChecksumConfigured,
but can change state as and when<a name="line.82"></a>
-<span class="sourceLineNo">083</span> // we encounter checksum verification
failures.<a name="line.83"></a>
-<span class="sourceLineNo">084</span> private volatile boolean
useHBaseChecksum;<a name="line.84"></a>
-<span class="sourceLineNo">085</span><a name="line.85"></a>
-<span class="sourceLineNo">086</span> // In the case of a checksum failure,
do these many succeeding<a name="line.86"></a>
-<span class="sourceLineNo">087</span> // reads without hbase checksum
verification.<a name="line.87"></a>
-<span class="sourceLineNo">088</span> private volatile int
hbaseChecksumOffCount = -1;<a name="line.88"></a>
-<span class="sourceLineNo">089</span><a name="line.89"></a>
-<span class="sourceLineNo">090</span> private Boolean instanceOfCanUnbuffer =
null;<a name="line.90"></a>
-<span class="sourceLineNo">091</span> // Using reflection to get
org.apache.hadoop.fs.CanUnbuffer#unbuffer method to avoid compilation<a
name="line.91"></a>
-<span class="sourceLineNo">092</span> // errors against Hadoop pre 2.6.4 and
2.7.1 versions.<a name="line.92"></a>
-<span class="sourceLineNo">093</span> private Method unbuffer = null;<a
name="line.93"></a>
-<span class="sourceLineNo">094</span><a name="line.94"></a>
-<span class="sourceLineNo">095</span> public
FSDataInputStreamWrapper(FileSystem fs, Path path) throws IOException {<a
name="line.95"></a>
-<span class="sourceLineNo">096</span> this(fs, path, false, -1L);<a
name="line.96"></a>
-<span class="sourceLineNo">097</span> }<a name="line.97"></a>
-<span class="sourceLineNo">098</span><a name="line.98"></a>
-<span class="sourceLineNo">099</span> public
FSDataInputStreamWrapper(FileSystem fs, Path path, boolean dropBehind, long
readahead) throws IOException {<a name="line.99"></a>
-<span class="sourceLineNo">100</span> this(fs, null, path, dropBehind,
readahead);<a name="line.100"></a>
-<span class="sourceLineNo">101</span> }<a name="line.101"></a>
-<span class="sourceLineNo">102</span><a name="line.102"></a>
-<span class="sourceLineNo">103</span> public
FSDataInputStreamWrapper(FileSystem fs, FileLink link,<a name="line.103"></a>
-<span class="sourceLineNo">104</span> boolean
dropBehind, long readahead) throws IOException {<a name="line.104"></a>
-<span class="sourceLineNo">105</span> this(fs, link, null, dropBehind,
readahead);<a name="line.105"></a>
-<span class="sourceLineNo">106</span> }<a name="line.106"></a>
-<span class="sourceLineNo">107</span><a name="line.107"></a>
-<span class="sourceLineNo">108</span> private
FSDataInputStreamWrapper(FileSystem fs, FileLink link, Path path, boolean
dropBehind,<a name="line.108"></a>
-<span class="sourceLineNo">109</span> long readahead) throws IOException
{<a name="line.109"></a>
-<span class="sourceLineNo">110</span> assert (path == null) != (link ==
null);<a name="line.110"></a>
-<span class="sourceLineNo">111</span> this.path = path;<a
name="line.111"></a>
-<span class="sourceLineNo">112</span> this.link = link;<a
name="line.112"></a>
-<span class="sourceLineNo">113</span> this.doCloseStreams = true;<a
name="line.113"></a>
-<span class="sourceLineNo">114</span> this.dropBehind = dropBehind;<a
name="line.114"></a>
-<span class="sourceLineNo">115</span> this.readahead = readahead;<a
name="line.115"></a>
-<span class="sourceLineNo">116</span> // If the fs is not an instance of
HFileSystem, then create an instance of HFileSystem<a name="line.116"></a>
-<span class="sourceLineNo">117</span> // that wraps over the specified fs.
In this case, we will not be able to avoid<a name="line.117"></a>
-<span class="sourceLineNo">118</span> // checksumming inside the
filesystem.<a name="line.118"></a>
-<span class="sourceLineNo">119</span> this.hfs = (fs instanceof
HFileSystem) ? (HFileSystem) fs : new HFileSystem(fs);<a name="line.119"></a>
-<span class="sourceLineNo">120</span><a name="line.120"></a>
-<span class="sourceLineNo">121</span> // Initially we are going to read the
tail block. Open the reader w/FS checksum.<a name="line.121"></a>
-<span class="sourceLineNo">122</span> this.useHBaseChecksumConfigured =
this.useHBaseChecksum = false;<a name="line.122"></a>
-<span class="sourceLineNo">123</span> this.stream = (link != null) ?
link.open(hfs) : hfs.open(path);<a name="line.123"></a>
-<span class="sourceLineNo">124</span> setStreamOptions(stream);<a
name="line.124"></a>
-<span class="sourceLineNo">125</span> }<a name="line.125"></a>
-<span class="sourceLineNo">126</span><a name="line.126"></a>
-<span class="sourceLineNo">127</span> private void
setStreamOptions(FSDataInputStream in) {<a name="line.127"></a>
-<span class="sourceLineNo">128</span> try {<a name="line.128"></a>
-<span class="sourceLineNo">129</span>
this.stream.setDropBehind(dropBehind);<a name="line.129"></a>
-<span class="sourceLineNo">130</span> } catch (Exception e) {<a
name="line.130"></a>
-<span class="sourceLineNo">131</span> // Skipped.<a name="line.131"></a>
-<span class="sourceLineNo">132</span> }<a name="line.132"></a>
-<span class="sourceLineNo">133</span> if (readahead >= 0) {<a
name="line.133"></a>
-<span class="sourceLineNo">134</span> try {<a name="line.134"></a>
-<span class="sourceLineNo">135</span>
this.stream.setReadahead(readahead);<a name="line.135"></a>
-<span class="sourceLineNo">136</span> } catch (Exception e) {<a
name="line.136"></a>
-<span class="sourceLineNo">137</span> // Skipped.<a name="line.137"></a>
-<span class="sourceLineNo">138</span> }<a name="line.138"></a>
-<span class="sourceLineNo">139</span> }<a name="line.139"></a>
-<span class="sourceLineNo">140</span> }<a name="line.140"></a>
-<span class="sourceLineNo">141</span><a name="line.141"></a>
-<span class="sourceLineNo">142</span> /**<a name="line.142"></a>
-<span class="sourceLineNo">143</span> * Prepares the streams for block
reader. NOT THREAD SAFE. Must be called once, after any<a name="line.143"></a>
-<span class="sourceLineNo">144</span> * reads finish and before any other
reads start (what happens in reality is we read the<a name="line.144"></a>
-<span class="sourceLineNo">145</span> * tail, then call this based on what's
in the tail, then read blocks).<a name="line.145"></a>
-<span class="sourceLineNo">146</span> * @param forceNoHBaseChecksum Force
not using HBase checksum.<a name="line.146"></a>
-<span class="sourceLineNo">147</span> */<a name="line.147"></a>
-<span class="sourceLineNo">148</span> public void
prepareForBlockReader(boolean forceNoHBaseChecksum) throws IOException {<a
name="line.148"></a>
-<span class="sourceLineNo">149</span> if (hfs == null) return;<a
name="line.149"></a>
-<span class="sourceLineNo">150</span> assert this.stream != null &&
!this.useHBaseChecksumConfigured;<a name="line.150"></a>
-<span class="sourceLineNo">151</span> boolean useHBaseChecksum =<a
name="line.151"></a>
-<span class="sourceLineNo">152</span> !forceNoHBaseChecksum &&
hfs.useHBaseChecksum() && (hfs.getNoChecksumFs() != hfs);<a
name="line.152"></a>
-<span class="sourceLineNo">153</span><a name="line.153"></a>
-<span class="sourceLineNo">154</span> if (useHBaseChecksum) {<a
name="line.154"></a>
-<span class="sourceLineNo">155</span> FileSystem fsNc =
hfs.getNoChecksumFs();<a name="line.155"></a>
-<span class="sourceLineNo">156</span> this.streamNoFsChecksum = (link !=
null) ? link.open(fsNc) : fsNc.open(path);<a name="line.156"></a>
-<span class="sourceLineNo">157</span>
setStreamOptions(streamNoFsChecksum);<a name="line.157"></a>
-<span class="sourceLineNo">158</span> this.useHBaseChecksumConfigured =
this.useHBaseChecksum = useHBaseChecksum;<a name="line.158"></a>
-<span class="sourceLineNo">159</span> // Close the checksum stream; we
will reopen it if we get an HBase checksum failure.<a name="line.159"></a>
-<span class="sourceLineNo">160</span> this.stream.close();<a
name="line.160"></a>
-<span class="sourceLineNo">161</span> this.stream = null;<a
name="line.161"></a>
-<span class="sourceLineNo">162</span> }<a name="line.162"></a>
-<span class="sourceLineNo">163</span> }<a name="line.163"></a>
-<span class="sourceLineNo">164</span><a name="line.164"></a>
-<span class="sourceLineNo">165</span> /** For use in tests. */<a
name="line.165"></a>
-<span class="sourceLineNo">166</span> @VisibleForTesting<a
name="line.166"></a>
-<span class="sourceLineNo">167</span> public
FSDataInputStreamWrapper(FSDataInputStream fsdis) {<a name="line.167"></a>
-<span class="sourceLineNo">168</span> this(fsdis, fsdis);<a
name="line.168"></a>
-<span class="sourceLineNo">169</span> }<a name="line.169"></a>
-<span class="sourceLineNo">170</span><a name="line.170"></a>
-<span class="sourceLineNo">171</span> /** For use in tests. */<a
name="line.171"></a>
-<span class="sourceLineNo">172</span> @VisibleForTesting<a
name="line.172"></a>
-<span class="sourceLineNo">173</span> public
FSDataInputStreamWrapper(FSDataInputStream fsdis, FSDataInputStream noChecksum)
{<a name="line.173"></a>
-<span class="sourceLineNo">174</span> doCloseStreams = false;<a
name="line.174"></a>
-<span class="sourceLineNo">175</span> stream = fsdis;<a name="line.175"></a>
-<span class="sourceLineNo">176</span> streamNoFsChecksum = noChecksum;<a
name="line.176"></a>
-<span class="sourceLineNo">177</span> path = null;<a name="line.177"></a>
-<span class="sourceLineNo">178</span> link = null;<a name="line.178"></a>
-<span class="sourceLineNo">179</span> hfs = null;<a name="line.179"></a>
-<span class="sourceLineNo">180</span> useHBaseChecksumConfigured =
useHBaseChecksum = false;<a name="line.180"></a>
-<span class="sourceLineNo">181</span> dropBehind = false;<a
name="line.181"></a>
-<span class="sourceLineNo">182</span> readahead = 0;<a name="line.182"></a>
-<span class="sourceLineNo">183</span> }<a name="line.183"></a>
-<span class="sourceLineNo">184</span><a name="line.184"></a>
-<span class="sourceLineNo">185</span> /**<a name="line.185"></a>
-<span class="sourceLineNo">186</span> * @return Whether we are presently
using HBase checksum.<a name="line.186"></a>
-<span class="sourceLineNo">187</span> */<a name="line.187"></a>
-<span class="sourceLineNo">188</span> public boolean shouldUseHBaseChecksum()
{<a name="line.188"></a>
-<span class="sourceLineNo">189</span> return this.useHBaseChecksum;<a
name="line.189"></a>
-<span class="sourceLineNo">190</span> }<a name="line.190"></a>
-<span class="sourceLineNo">191</span><a name="line.191"></a>
-<span class="sourceLineNo">192</span> /**<a name="line.192"></a>
-<span class="sourceLineNo">193</span> * Get the stream to use.
Thread-safe.<a name="line.193"></a>
-<span class="sourceLineNo">194</span> * @param useHBaseChecksum must be the
value that shouldUseHBaseChecksum has returned<a name="line.194"></a>
-<span class="sourceLineNo">195</span> * at some point in the past,
otherwise the result is undefined.<a name="line.195"></a>
-<span class="sourceLineNo">196</span> */<a name="line.196"></a>
-<span class="sourceLineNo">197</span> public FSDataInputStream
getStream(boolean useHBaseChecksum) {<a name="line.197"></a>
-<span class="sourceLineNo">198</span> return useHBaseChecksum ?
this.streamNoFsChecksum : this.stream;<a name="line.198"></a>
-<span class="sourceLineNo">199</span> }<a name="line.199"></a>
-<span class="sourceLineNo">200</span><a name="line.200"></a>
-<span class="sourceLineNo">201</span> /**<a name="line.201"></a>
-<span class="sourceLineNo">202</span> * Read from non-checksum stream
failed, fall back to FS checksum. Thread-safe.<a name="line.202"></a>
-<span class="sourceLineNo">203</span> * @param offCount For how many
checksumOk calls to turn off the HBase checksum.<a name="line.203"></a>
-<span class="sourceLineNo">204</span> */<a name="line.204"></a>
-<span class="sourceLineNo">205</span> public FSDataInputStream
fallbackToFsChecksum(int offCount) throws IOException {<a name="line.205"></a>
-<span class="sourceLineNo">206</span> // checksumOffCount is speculative,
but let's try to reset it less.<a name="line.206"></a>
-<span class="sourceLineNo">207</span> boolean partOfConvoy = false;<a
name="line.207"></a>
-<span class="sourceLineNo">208</span> if (this.stream == null) {<a
name="line.208"></a>
-<span class="sourceLineNo">209</span> synchronized
(streamNoFsChecksumFirstCreateLock) {<a name="line.209"></a>
-<span class="sourceLineNo">210</span> partOfConvoy = (this.stream !=
null);<a name="line.210"></a>
-<span class="sourceLineNo">211</span> if (!partOfConvoy) {<a
name="line.211"></a>
-<span class="sourceLineNo">212</span> this.stream = (link != null) ?
link.open(hfs) : hfs.open(path);<a name="line.212"></a>
-<span class="sourceLineNo">213</span> }<a name="line.213"></a>
-<span class="sourceLineNo">214</span> }<a name="line.214"></a>
-<span class="sourceLineNo">215</span> }<a name="line.215"></a>
-<span class="sourceLineNo">216</span> if (!partOfConvoy) {<a
name="line.216"></a>
-<span class="sourceLineNo">217</span> this.useHBaseChecksum = false;<a
name="line.217"></a>
-<span class="sourceLineNo">218</span> this.hbaseChecksumOffCount =
offCount;<a name="line.218"></a>
-<span class="sourceLineNo">219</span> }<a name="line.219"></a>
-<span class="sourceLineNo">220</span> return this.stream;<a
name="line.220"></a>
-<span class="sourceLineNo">221</span> }<a name="line.221"></a>
-<span class="sourceLineNo">222</span><a name="line.222"></a>
-<span class="sourceLineNo">223</span> /** Report that checksum was ok, so we
may ponder going back to HBase checksum. */<a name="line.223"></a>
-<span class="sourceLineNo">224</span> public void checksumOk() {<a
name="line.224"></a>
-<span class="sourceLineNo">225</span> if (this.useHBaseChecksumConfigured
&& !this.useHBaseChecksum<a name="line.225"></a>
-<span class="sourceLineNo">226</span> &&
(this.hbaseChecksumOffCount-- < 0)) {<a name="line.226"></a>
-<span class="sourceLineNo">227</span> // The stream we need is already
open (because we were using HBase checksum in the past).<a name="line.227"></a>
-<span class="sourceLineNo">228</span> assert this.streamNoFsChecksum !=
null;<a name="line.228"></a>
-<span class="sourceLineNo">229</span> this.useHBaseChecksum = true;<a
name="line.229"></a>
-<span class="sourceLineNo">230</span> }<a name="line.230"></a>
-<span class="sourceLineNo">231</span> }<a name="line.231"></a>
-<span class="sourceLineNo">232</span><a name="line.232"></a>
-<span class="sourceLineNo">233</span> /** Close stream(s) if necessary. */<a
name="line.233"></a>
-<span class="sourceLineNo">234</span> @Override<a name="line.234"></a>
-<span class="sourceLineNo">235</span> public void close() {<a
name="line.235"></a>
-<span class="sourceLineNo">236</span> if (!doCloseStreams) {<a
name="line.236"></a>
-<span class="sourceLineNo">237</span> return;<a name="line.237"></a>
-<span class="sourceLineNo">238</span> }<a name="line.238"></a>
-<span class="sourceLineNo">239</span> // we do not care about the close
exception as it is for reading, no data loss issue.<a name="line.239"></a>
-<span class="sourceLineNo">240</span>
IOUtils.closeQuietly(streamNoFsChecksum);<a name="line.240"></a>
-<span class="sourceLineNo">241</span> IOUtils.closeQuietly(stream);<a
name="line.241"></a>
-<span class="sourceLineNo">242</span> }<a name="line.242"></a>
-<span class="sourceLineNo">243</span><a name="line.243"></a>
-<span class="sourceLineNo">244</span> public HFileSystem getHfs() {<a
name="line.244"></a>
-<span class="sourceLineNo">245</span> return this.hfs;<a
name="line.245"></a>
-<span class="sourceLineNo">246</span> }<a name="line.246"></a>
-<span class="sourceLineNo">247</span><a name="line.247"></a>
-<span class="sourceLineNo">248</span> /**<a name="line.248"></a>
-<span class="sourceLineNo">249</span> * This will free sockets and file
descriptors held by the stream only when the stream implements<a
name="line.249"></a>
-<span class="sourceLineNo">250</span> * org.apache.hadoop.fs.CanUnbuffer.
NOT THREAD SAFE. Must be called only when all the clients<a name="line.250"></a>
-<span class="sourceLineNo">251</span> * using this stream to read the blocks
have finished reading. If by chance the stream is<a name="line.251"></a>
-<span class="sourceLineNo">252</span> * unbuffered and there are clients
still holding this stream for read then on next client read<a
name="line.252"></a>
-<span class="sourceLineNo">253</span> * request a new socket will be opened
by Datanode without client knowing about it and will serve<a
name="line.253"></a>
-<span class="sourceLineNo">254</span> * its read request. Note: If this
socket is idle for some time then the DataNode will close the<a
name="line.254"></a>
-<span class="sourceLineNo">255</span> * socket and the socket will move into
CLOSE_WAIT state and on the next client request on this<a name="line.255"></a>
-<span class="sourceLineNo">256</span> * stream, the current socket will be
closed and a new socket will be opened to serve the<a name="line.256"></a>
-<span class="sourceLineNo">257</span> * requests.<a name="line.257"></a>
-<span class="sourceLineNo">258</span> */<a name="line.258"></a>
-<span class="sourceLineNo">259</span> @SuppressWarnings({ "rawtypes" })<a
name="line.259"></a>
-<span class="sourceLineNo">260</span> public void unbuffer() {<a
name="line.260"></a>
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this.getStream(this.shouldUseHBaseChecksum());<a name="line.261"></a>
-<span class="sourceLineNo">262</span> if (stream != null) {<a
name="line.262"></a>
-<span class="sourceLineNo">263</span> InputStream wrappedStream =
stream.getWrappedStream();<a name="line.263"></a>
-<span class="sourceLineNo">264</span> // CanUnbuffer interface was added
as part of HDFS-7694 and the fix is available in Hadoop<a name="line.264"></a>
-<span class="sourceLineNo">265</span> // 2.6.4+ and 2.7.1+ versions only
so check whether the stream object implements the<a name="line.265"></a>
-<span class="sourceLineNo">266</span> // CanUnbuffer interface or not and
based on that call the unbuffer api.<a name="line.266"></a>
-<span class="sourceLineNo">267</span> final Class<? extends
InputStream> streamClass = wrappedStream.getClass();<a name="line.267"></a>
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null) {<a name="line.268"></a>
-<span class="sourceLineNo">269</span> // To ensure we compute whether
the stream is instance of CanUnbuffer only once.<a name="line.269"></a>
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false;<a name="line.270"></a>
-<span class="sourceLineNo">271</span> Class<?>[] streamInterfaces
= streamClass.getInterfaces();<a name="line.271"></a>
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{<a name="line.272"></a>
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(c.getCanonicalName().toString().equals("org.apache.hadoop.fs.CanUnbuffer"))
{<a name="line.273"></a>
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-<span class="sourceLineNo">275</span> this.unbuffer =
streamClass.getDeclaredMethod("unbuffer");<a name="line.275"></a>
-<span class="sourceLineNo">276</span> } catch
(NoSuchMethodException | SecurityException e) {<a name="line.276"></a>
-<span class="sourceLineNo">277</span> LOG.warn("Failed to find
'unbuffer' method in class " + streamClass<a name="line.277"></a>
-<span class="sourceLineNo">278</span> + " . So there may be a
TCP socket connection "<a name="line.278"></a>
-<span class="sourceLineNo">279</span> + "left open in
CLOSE_WAIT state.",<a name="line.279"></a>
-<span class="sourceLineNo">280</span> e);<a name="line.280"></a>
-<span class="sourceLineNo">281</span> return;<a
name="line.281"></a>
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-<span class="sourceLineNo">283</span> this.instanceOfCanUnbuffer =
true;<a name="line.283"></a>
-<span class="sourceLineNo">284</span> break;<a name="line.284"></a>
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-<span class="sourceLineNo">286</span> }<a name="line.286"></a>
-<span class="sourceLineNo">287</span> }<a name="line.287"></a>
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name="line.288"></a>
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-<span class="sourceLineNo">290</span>
this.unbuffer.invoke(wrappedStream);<a name="line.290"></a>
-<span class="sourceLineNo">291</span> } catch (IllegalAccessException |
IllegalArgumentException | InvocationTargetException e) {<a name="line.291"></a>
-<span class="sourceLineNo">292</span> LOG.warn("Failed to invoke
'unbuffer' method in class " + streamClass<a name="line.292"></a>
-<span class="sourceLineNo">293</span> + " . So there may be a TCP
socket connection left open in CLOSE_WAIT state.",<a name="line.293"></a>
-<span class="sourceLineNo">294</span> e);<a name="line.294"></a>
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-<span class="sourceLineNo">296</span> } else {<a name="line.296"></a>
-<span class="sourceLineNo">297</span> LOG.warn("Failed to find
'unbuffer' method in class " + streamClass<a name="line.297"></a>
-<span class="sourceLineNo">298</span> + " . So there may be a TCP
socket connection "<a name="line.298"></a>
-<span class="sourceLineNo">299</span> + "left open in CLOSE_WAIT
state. For more details check "<a name="line.299"></a>
-<span class="sourceLineNo">300</span> +
"https://issues.apache.org/jira/browse/HBASE-9393";);<a name="line.300"></a>
-<span class="sourceLineNo">301</span> }<a name="line.301"></a>
-<span class="sourceLineNo">302</span> }<a name="line.302"></a>
-<span class="sourceLineNo">303</span> }<a name="line.303"></a>
-<span class="sourceLineNo">304</span>}<a name="line.304"></a>
+<span class="sourceLineNo">045</span> private static final boolean
isLogTraceEnabled = LOG.isTraceEnabled();<a name="line.45"></a>
+<span class="sourceLineNo">046</span><a name="line.46"></a>
+<span class="sourceLineNo">047</span> private final HFileSystem hfs;<a
name="line.47"></a>
+<span class="sourceLineNo">048</span> private final Path path;<a
name="line.48"></a>
+<span class="sourceLineNo">049</span> private final FileLink link;<a
name="line.49"></a>
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name="line.51"></a>
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name="line.52"></a>
+<span class="sourceLineNo">053</span><a name="line.53"></a>
+<span class="sourceLineNo">054</span> /** Two stream handles, one with and
one without FS-level checksum.<a name="line.54"></a>
+<span class="sourceLineNo">055</span> * HDFS checksum setting is on FS
level, not single read level, so you have to keep two<a name="line.55"></a>
+<span class="sourceLineNo">056</span> * FS objects and two handles open to
interleave different reads freely, which is very sad.<a name="line.56"></a>
+<span class="sourceLineNo">057</span> * This is what we do:<a
name="line.57"></a>
+<span class="sourceLineNo">058</span> * 1) First, we need to read the
trailer of HFile to determine checksum parameters.<a name="line.58"></a>
+<span class="sourceLineNo">059</span> * We always use FS checksum to do
that, so ctor opens {@link #stream}.<a name="line.59"></a>
+<span class="sourceLineNo">060</span> * 2.1) After that, if HBase checksum
is not used, we'd just always use {@link #stream};<a name="line.60"></a>
+<span class="sourceLineNo">061</span> * 2.2) If HBase checksum can be used,
we'll open {@link #streamNoFsChecksum},<a name="line.61"></a>
+<span class="sourceLineNo">062</span> * and close {@link #stream}. User
MUST call prepareForBlockReader for that to happen;<a name="line.62"></a>
+<span class="sourceLineNo">063</span> * if they don't, (2.1) will be the
default.<a name="line.63"></a>
+<span class="sourceLineNo">064</span> * 3) The users can call {@link
#shouldUseHBaseChecksum()}, and pass its result to<a name="line.64"></a>
+<span class="sourceLineNo">065</span> * {@link #getStream(boolean)} to get
stream (if Java had out/pointer params we could<a name="line.65"></a>
+<span class="sourceLineNo">066</span> * return both in one call). This
stream is guaranteed to be set.<a name="line.66"></a>
+<span class="sourceLineNo">067</span> * 4) The first time HBase checksum
fails, one would call {@link #fallbackToFsChecksum(int)}.<a name="line.67"></a>
+<span class="sourceLineNo">068</span> * That will take lock, and open {@link
#stream}. While this is going on, others will<a name="line.68"></a>
+<span class="sourceLineNo">069</span> * continue to use the old stream; if
they also want to fall back, they'll also call<a name="line.69"></a>
+<span class="sourceLineNo">070</span> * {@link #fallbackToFsChecksum(int)},
and block until {@link #stream} is set.<a name="line.70"></a>
+<span class="sourceLineNo">071</span> * 5) After some number of checksumOk()
calls, we will go back to using HBase checksum.<a name="line.71"></a>
+<span class="sourceLineNo">072</span> * We will have 2 handles; however we
presume checksums fail so rarely that we don't care.<a name="line.72"></a>
+<span class="sourceLineNo">073</span> */<a name="line.73"></a>
+<span class="sourceLineNo">074</span> private volatile FSDataInputStream
stream = null;<a name="line.74"></a>
+<span class="sourceLineNo">075</span> private volatile FSDataInputStream
streamNoFsChecksum = null;<a name="line.75"></a>
+<span class="sourceLineNo">076</span> private Object
streamNoFsChecksumFirstCreateLock = new Object();<a name="line.76"></a>
+<span class="sourceLineNo">077</span><a name="line.77"></a>
+<span class="sourceLineNo">078</span> // The configuration states that we
should validate hbase checksums<a name="line.78"></a>
+<span class="sourceLineNo">079</span> private boolean
useHBaseChecksumConfigured;<a name="line.79"></a>
+<span class="sourceLineNo">080</span><a name="line.80"></a>
+<span class="sourceLineNo">081</span> // Record the current state of this
reader with respect to<a name="line.81"></a>
+<span class="sourceLineNo">082</span> // validating checkums in HBase. This
is originally set the same<a name="line.82"></a>
+<span class="sourceLineNo">083</span> // value as useHBaseChecksumConfigured,
but can change state as and when<a name="line.83"></a>
+<span class="sourceLineNo">084</span> // we encounter checksum verification
failures.<a name="line.84"></a>
+<span class="sourceLineNo">085</span> private volatile boolean
useHBaseChecksum;<a name="line.85"></a>
+<span class="sourceLineNo">086</span><a name="line.86"></a>
+<span class="sourceLineNo">087</span> // In the case of a checksum failure,
do these many succeeding<a name="line.87"></a>
+<span class="sourceLineNo">088</span> // reads without hbase checksum
verification.<a name="line.88"></a>
+<span class="sourceLineNo">089</span> private volatile int
hbaseChecksumOffCount = -1;<a name="line.89"></a>
+<span class="sourceLineNo">090</span><a name="line.90"></a>
+<span class="sourceLineNo">091</span> private Boolean instanceOfCanUnbuffer =
null;<a name="line.91"></a>
+<span class="sourceLineNo">092</span> // Using reflection to get
org.apache.hadoop.fs.CanUnbuffer#unbuffer method to avoid compilation<a
name="line.92"></a>
+<span class="sourceLineNo">093</span> // errors against Hadoop pre 2.6.4 and
2.7.1 versions.<a name="line.93"></a>
+<span class="sourceLineNo">094</span> private Method unbuffer = null;<a
name="line.94"></a>
+<span class="sourceLineNo">095</span><a name="line.95"></a>
+<span class="sourceLineNo">096</span> public
FSDataInputStreamWrapper(FileSystem fs, Path path) throws IOException {<a
name="line.96"></a>
+<span class="sourceLineNo">097</span> this(fs, path, false, -1L);<a
name="line.97"></a>
+<span class="sourceLineNo">098</span> }<a name="line.98"></a>
+<span class="sourceLineNo">099</span><a name="line.99"></a>
+<span class="sourceLineNo">100</span> public
FSDataInputStreamWrapper(FileSystem fs, Path path, boolean dropBehind, long
readahead) throws IOException {<a name="line.100"></a>
+<span class="sourceLineNo">101</span> this(fs, null, path, dropBehind,
readahead);<a name="line.101"></a>
+<span class="sourceLineNo">102</span> }<a name="line.102"></a>
+<span class="sourceLineNo">103</span><a name="line.103"></a>
+<span class="sourceLineNo">104</span> public
FSDataInputStreamWrapper(FileSystem fs, FileLink link,<a name="line.104"></a>
+<span class="sourceLineNo">105</span> boolean
dropBehind, long readahead) throws IOException {<a name="line.105"></a>
+<span class="sourceLineNo">106</span> this(fs, link, null, dropBehind,
readahead);<a name="line.106"></a>
+<span class="sourceLineNo">107</span> }<a name="line.107"></a>
+<span class="sourceLineNo">108</span><a name="line.108"></a>
+<span class="sourceLineNo">109</span> private
FSDataInputStreamWrapper(FileSystem fs, FileLink link, Path path, boolean
dropBehind,<a name="line.109"></a>
+<span class="sourceLineNo">110</span> long readahead) throws IOException
{<a name="line.110"></a>
+<span class="sourceLineNo">111</span> assert (path == null) != (link ==
null);<a name="line.111"></a>
+<span class="sourceLineNo">112</span> this.path = path;<a
name="line.112"></a>
+<span class="sourceLineNo">113</span> this.link = link;<a
name="line.113"></a>
+<span class="sourceLineNo">114</span> this.doCloseStreams = true;<a
name="line.114"></a>
+<span class="sourceLineNo">115</span> this.dropBehind = dropBehind;<a
name="line.115"></a>
+<span class="sourceLineNo">116</span> this.readahead = readahead;<a
name="line.116"></a>
+<span class="sourceLineNo">117</span> // If the fs is not an instance of
HFileSystem, then create an instance of HFileSystem<a name="line.117"></a>
+<span class="sourceLineNo">118</span> // that wraps over the specified fs.
In this case, we will not be able to avoid<a name="line.118"></a>
+<span class="sourceLineNo">119</span> // checksumming inside the
filesystem.<a name="line.119"></a>
+<span class="sourceLineNo">120</span> this.hfs = (fs instanceof
HFileSystem) ? (HFileSystem) fs : new HFileSystem(fs);<a name="line.120"></a>
+<span class="sourceLineNo">121</span><a name="line.121"></a>
+<span class="sourceLineNo">122</span> // Initially we are going to read the
tail block. Open the reader w/FS checksum.<a name="line.122"></a>
+<span class="sourceLineNo">123</span> this.useHBaseChecksumConfigured =
this.useHBaseChecksum = false;<a name="line.123"></a>
+<span class="sourceLineNo">124</span> this.stream = (link != null) ?
link.open(hfs) : hfs.open(path);<a name="line.124"></a>
+<span class="sourceLineNo">125</span> setStreamOptions(stream);<a
name="line.125"></a>
+<span class="sourceLineNo">126</span> }<a name="line.126"></a>
+<span class="sourceLineNo">127</span><a name="line.127"></a>
+<span class="sourceLineNo">128</span> private void
setStreamOptions(FSDataInputStream in) {<a name="line.128"></a>
+<span class="sourceLineNo">129</span> try {<a name="line.129"></a>
+<span class="sourceLineNo">130</span>
this.stream.setDropBehind(dropBehind);<a name="line.130"></a>
+<span class="sourceLineNo">131</span> } catch (Exception e) {<a
name="line.131"></a>
+<span class="sourceLineNo">132</span> // Skipped.<a name="line.132"></a>
+<span class="sourceLineNo">133</span> }<a name="line.133"></a>
+<span class="sourceLineNo">134</span> if (readahead >= 0) {<a
name="line.134"></a>
+<span class="sourceLineNo">135</span> try {<a name="line.135"></a>
+<span class="sourceLineNo">136</span>
this.stream.setReadahead(readahead);<a name="line.136"></a>
+<span class="sourceLineNo">137</span> } catch (Exception e) {<a
name="line.137"></a>
+<span class="sourceLineNo">138</span> // Skipped.<a name="line.138"></a>
+<span class="sourceLineNo">139</span> }<a name="line.139"></a>
+<span class="sourceLineNo">140</span> }<a name="line.140"></a>
+<span class="sourceLineNo">141</span> }<a name="line.141"></a>
+<span class="sourceLineNo">142</span><a name="line.142"></a>
+<span class="sourceLineNo">143</span> /**<a name="line.143"></a>
+<span class="sourceLineNo">144</span> * Prepares the streams for block
reader. NOT THREAD SAFE. Must be called once, after any<a name="line.144"></a>
+<span class="sourceLineNo">145</span> * reads finish and before any other
reads start (what happens in reality is we read the<a name="line.145"></a>
+<span class="sourceLineNo">146</span> * tail, then call this based on what's
in the tail, then read blocks).<a name="line.146"></a>
+<span class="sourceLineNo">147</span> * @param forceNoHBaseChecksum Force
not using HBase checksum.<a name="line.147"></a>
+<span class="sourceLineNo">148</span> */<a name="line.148"></a>
+<span class="sourceLineNo">149</span> public void
prepareForBlockReader(boolean forceNoHBaseChecksum) throws IOException {<a
name="line.149"></a>
+<span class="sourceLineNo">150</span> if (hfs == null) return;<a
name="line.150"></a>
+<span class="sourceLineNo">151</span> assert this.stream != null &&
!this.useHBaseChecksumConfigured;<a name="line.151"></a>
+<span class="sourceLineNo">152</span> boolean useHBaseChecksum =<a
name="line.152"></a>
+<span class="sourceLineNo">153</span> !forceNoHBaseChecksum &&
hfs.useHBaseChecksum() && (hfs.getNoChecksumFs() != hfs);<a
name="line.153"></a>
+<span class="sourceLineNo">154</span><a name="line.154"></a>
+<span class="sourceLineNo">155</span> if (useHBaseChecksum) {<a
name="line.155"></a>
+<span class="sourceLineNo">156</span> FileSystem fsNc =
hfs.getNoChecksumFs();<a name="line.156"></a>
+<span class="sourceLineNo">157</span> this.streamNoFsChecksum = (link !=
null) ? link.open(fsNc) : fsNc.open(path);<a name="line.157"></a>
+<span class="sourceLineNo">158</span>
setStreamOptions(streamNoFsChecksum);<a name="line.158"></a>
+<span class="sourceLineNo">159</span> this.useHBaseChecksumConfigured =
this.useHBaseChecksum = useHBaseChecksum;<a name="line.159"></a>
+<span class="sourceLineNo">160</span> // Close the checksum stream; we
will reopen it if we get an HBase checksum failure.<a name="line.160"></a>
+<span class="sourceLineNo">161</span> this.stream.close();<a
name="line.161"></a>
+<span class="sourceLineNo">162</span> this.stream = null;<a
name="line.162"></a>
+<span class="sourceLineNo">163</span> }<a name="line.163"></a>
+<span class="sourceLineNo">164</span> }<a name="line.164"></a>
+<span class="sourceLineNo">165</span><a name="line.165"></a>
+<span class="sourceLineNo">166</span> /** For use in tests. */<a
name="line.166"></a>
+<span class="sourceLineNo">167</span> @VisibleForTesting<a
name="line.167"></a>
+<span class="sourceLineNo">168</span> public
FSDataInputStreamWrapper(FSDataInputStream fsdis) {<a name="line.168"></a>
+<span class="sourceLineNo">169</span> this(fsdis, fsdis);<a
name="line.169"></a>
+<span class="sourceLineNo">170</span> }<a name="line.170"></a>
+<span class="sourceLineNo">171</span><a name="line.171"></a>
+<span class="sourceLineNo">172</span> /** For use in tests. */<a
name="line.172"></a>
+<span class="sourceLineNo">173</span> @VisibleForTesting<a
name="line.173"></a>
+<span class="sourceLineNo">174</span> public
FSDataInputStreamWrapper(FSDataInputStream fsdis, FSDataInputStream noChecksum)
{<a name="line.174"></a>
+<span class="sourceLineNo">175</span> doCloseStreams = false;<a
name="line.175"></a>
+<span class="sourceLineNo">176</span> stream = fsdis;<a name="line.176"></a>
+<span class="sourceLineNo">177</span> streamNoFsChecksum = noChecksum;<a
name="line.177"></a>
+<span class="sourceLineNo">178</span> path = null;<a name="line.178"></a>
+<span class="sourceLineNo">179</span> link = null;<a name="line.179"></a>
+<span class="sourceLineNo">180</span> hfs = null;<a name="line.180"></a>
+<span class="sourceLineNo">181</span> useHBaseChecksumConfigured =
useHBaseChecksum = false;<a name="line.181"></a>
+<span class="sourceLineNo">182</span> dropBehind = false;<a
name="line.182"></a>
+<span class="sourceLineNo">183</span> readahead = 0;<a name="line.183"></a>
+<span class="sourceLineNo">184</span> }<a name="line.184"></a>
+<span class="sourceLineNo">185</span><a name="line.185"></a>
+<span class="sourceLineNo">186</span> /**<a name="line.186"></a>
+<span class="sourceLineNo">187</span> * @return Whether we are presently
using HBase checksum.<a name="line.187"></a>
+<span class="sourceLineNo">188</span> */<a name="line.188"></a>
+<span class="sourceLineNo">189</span> public boolean shouldUseHBaseChecksum()
{<a name="line.189"></a>
+<span class="sourceLineNo">190</span> return this.useHBaseChecksum;<a
name="line.190"></a>
+<span class="sourceLineNo">191</span> }<a name="line.191"></a>
+<span class="sourceLineNo">192</span><a name="line.192"></a>
+<span class="sourceLineNo">193</span> /**<a name="line.193"></a>
+<span class="sourceLineNo">194</span> * Get the stream to use.
Thread-safe.<a name="line.194"></a>
+<span class="sourceLineNo">195</span> * @param useHBaseChecksum must be the
value that shouldUseHBaseChecksum has returned<a name="line.195"></a>
+<span class="sourceLineNo">196</span> * at some point in the past,
otherwise the result is undefined.<a name="line.196"></a>
+<span class="sourceLineNo">197</span> */<a name="line.197"></a>
+<span class="sourceLineNo">198</span> public FSDataInputStream
getStream(boolean useHBaseChecksum) {<a name="line.198"></a>
+<span class="sourceLineNo">199</span> return useHBaseChecksum ?
this.streamNoFsChecksum : this.stream;<a name="line.199"></a>
+<span class="sourceLineNo">200</span> }<a name="line.200"></a>
+<span class="sourceLineNo">201</span><a name="line.201"></a>
+<span class="sourceLineNo">202</span> /**<a name="line.202"></a>
+<span class="sourceLineNo">203</span> * Read from non-checksum stream
failed, fall back to FS checksum. Thread-safe.<a name="line.203"></a>
+<span class="sourceLineNo">204</span> * @param offCount For how many
checksumOk calls to turn off the HBase checksum.<a name="line.204"></a>
+<span class="sourceLineNo">205</span> */<a name="line.205"></a>
+<span class="sourceLineNo">206</span> public FSDataInputStream
fallbackToFsChecksum(int offCount) throws IOException {<a name="line.206"></a>
+<span class="sourceLineNo">207</span> // checksumOffCount is speculative,
but let's try to reset it less.<a name="line.207"></a>
+<span class="sourceLineNo">208</span> boolean partOfConvoy = false;<a
name="line.208"></a>
+<span class="sourceLineNo">209</span> if (this.stream == null) {<a
name="line.209"></a>
+<span class="sourceLineNo">210</span> synchronized
(streamNoFsChecksumFirstCreateLock) {<a name="line.210"></a>
+<span class="sourceLineNo">211</span> partOfConvoy = (this.stream !=
null);<a name="line.211"></a>
+<span class="sourceLineNo">212</span> if (!partOfConvoy) {<a
name="line.212"></a>
+<span class="sourceLineNo">213</span> this.stream = (link != null) ?
link.open(hfs) : hfs.open(path);<a name="line.213"></a>
+<span class="sourceLineNo">214</span> }<a name="line.214"></a>
+<span class="sourceLineNo">215</span> }<a name="line.215"></a>
+<span class="sourceLineNo">216</span> }<a name="line.216"></a>
+<span class="sourceLineNo">217</span> if (!partOfConvoy) {<a
name="line.217"></a>
+<span class="sourceLineNo">218</span> this.useHBaseChecksum = false;<a
name="line.218"></a>
+<span class="sourceLineNo">219</span> this.hbaseChecksumOffCount =
offCount;<a name="line.219"></a>
+<span class="sourceLineNo">220</span> }<a name="line.220"></a>
+<span class="sourceLineNo">221</span> return this.stream;<a
name="line.221"></a>
+<span class="sourceLineNo">222</span> }<a name="line.222"></a>
+<span class="sourceLineNo">223</span><a name="line.223"></a>
+<span class="sourceLineNo">224</span> /** Report that checksum was ok, so we
may ponder going back to HBase checksum. */<a name="line.224"></a>
+<span class="sourceLineNo">225</span> public void checksumOk() {<a
name="line.225"></a>
+<span class="sourceLineNo">226</span> if (this.useHBaseChecksumConfigured
&& !this.useHBaseChecksum<a name="line.226"></a>
+<span class="sourceLineNo">227</span> &&
(this.hbaseChecksumOffCount-- < 0)) {<a name="line.227"></a>
+<span class="sourceLineNo">228</span> // The stream we need is already
open (because we were using HBase checksum in the past).<a name="line.228"></a>
+<span class="sourceLineNo">229</span> assert this.streamNoFsChecksum !=
null;<a name="line.229"></a>
+<span class="sourceLineNo">230</span> this.useHBaseChecksum = true;<a
name="line.230"></a>
+<span class="sourceLineNo">231</span> }<a name="line.231"></a>
+<span class="sourceLineNo">232</span> }<a name="line.232"></a>
+<span class="sourceLineNo">233</span><a name="line.233"></a>
+<span class="sourceLineNo">234</span> /** Close stream(s) if necessary. */<a
name="line.234"></a>
+<span class="sourceLineNo">235</span> @Override<a name="line.235"></a>
+<span class="sourceLineNo">236</span> public void close() {<a
name="line.236"></a>
+<span class="sourceLineNo">237</span> if (!doCloseStreams) {<a
name="line.237"></a>
+<span class="sourceLineNo">238</span> return;<a name="line.238"></a>
+<span class="sourceLineNo">239</span> }<a name="line.239"></a>
+<span class="sourceLineNo">240</span> // we do not care about the close
exception as it is for reading, no data loss issue.<a name="line.240"></a>
+<span class="sourceLineNo">241</span>
IOUtils.closeQuietly(streamNoFsChecksum);<a name="line.241"></a>
+<span class="sourceLineNo">242</span> IOUtils.closeQuietly(stream);<a
name="line.242"></a>
+<span class="sourceLineNo">243</span> }<a name="line.243"></a>
+<span class="sourceLineNo">244</span><a name="line.244"></a>
+<span class="sourceLineNo">245</span> public HFileSystem getHfs() {<a
name="line.245"></a>
+<span class="sourceLineNo">246</span> return this.hfs;<a
name="line.246"></a>
+<span class="sourceLineNo">247</span> }<a name="line.247"></a>
+<span class="sourceLineNo">248</span><a name="line.248"></a>
+<span class="sourceLineNo">249</span> /**<a name="line.249"></a>
+<span class="sourceLineNo">250</span> * This will free sockets and file
descriptors held by the stream only when the stream implements<a
name="line.250"></a>
+<span class="sourceLineNo">251</span> * org.apache.hadoop.fs.CanUnbuffer.
NOT THREAD SAFE. Must be called only when all the clients<a name="line.251"></a>
+<span class="sourceLineNo">252</span> * using this stream to read the blocks
have finished reading. If by chance the stream is<a name="line.252"></a>
+<span class="sourceLineNo">253</span> * unbuffered and there are clients
still holding this stream for read then on next client read<a
name="line.253"></a>
+<span class="sourceLineNo">254</span> * request a new socket will be opened
by Datanode without client knowing about it and will serve<a
name="line.254"></a>
+<span class="sourceLineNo">255</span> * its read request. Note: If this
socket is idle for some time then the DataNode will close the<a
name="line.255"></a>
+<span class="sourceLineNo">256</span> * socket and the socket will move into
CLOSE_WAIT state and on the next client request on this<a name="line.256"></a>
+<span class="sourceLineNo">257</span> * stream, the current socket will be
closed and a new socket will be opened to serve the<a name="line.257"></a>
+<span class="sourceLineNo">258</span> * requests.<a name="line.258"></a>
+<span class="sourceLineNo">259</span> */<a name="line.259"></a>
+<span class="sourceLineNo">260</span> @SuppressWarnings({ "rawtypes" })<a
name="line.260"></a>
+<span class="sourceLineNo">261</span> public void unbuffer() {<a
name="line.261"></a>
+<span class="sourceLineNo">262</span> FSDataInputStream stream =
this.getStream(this.shouldUseHBaseChecksum());<a name="line.262"></a>
+<span class="sourceLineNo">263</span> if (stream != null) {<a
name="line.263"></a>
+<span class="sourceLineNo">264</span> InputStream wrappedStream =
stream.getWrappedStream();<a name="line.264"></a>
+<span class="sourceLineNo">265</span> // CanUnbuffer interface was added
as part of HDFS-7694 and the fix is available in Hadoop<a name="line.265"></a>
+<span class="sourceLineNo">266</span> // 2.6.4+ and 2.7.1+ versions only
so check whether the stream object implements the<a name="line.266"></a>
+<span class="sourceLineNo">267</span> // CanUnbuffer interface or not and
based on that call the unbuffer api.<a name="line.267"></a>
+<span class="sourceLineNo">268</span> final Class<? extends
InputStream> streamClass = wrappedStream.getClass();<a name="line.268"></a>
+<span class="sourceLineNo">269</span> if (this.instanceOfCanUnbuffer ==
null) {<a name="line.269"></a>
+<span class="sourceLineNo">270</span> // To ensure we compute whether
the stream is instance of CanUnbuffer only once.<a name="line.270"></a>
+<span class="sourceLineNo">271</span> this.instanceOfCanUnbuffer =
false;<a name="line.271"></a>
+<span class="sourceLineNo">272</span> Class<?>[] streamInterfaces
= streamClass.getInterfaces();<a name="line.272"></a>
+<span class="sourceLineNo">273</span> for (Class c : streamInterfaces)
{<a name="line.273"></a>
+<span class="sourceLineNo">274</span> if
(c.getCanonicalName().toString().equals("org.apache.hadoop.fs.CanUnbuffer"))
{<a name="line.274"></a>
+<span class="sourceLineNo">275</span> try {<a name="line.275"></a>
+<span class="sourceLineNo">276</span> this.unbuffer =
streamClass.getDeclaredMethod("unbuffer");<a name="line.276"></a>
+<span class="sourceLineNo">277</span> } catch
(NoSuchMethodException | SecurityException e) {<a name="line.277"></a>
+<span class="sourceLineNo">278</span> if (isLogTraceEnabled) {<a
name="line.278"></a>
+<span class="sourceLineNo">279</span> LOG.trace("Failed to find
'unbuffer' method in class " + streamClass<a name="line.279"></a>
+<span class="sourceLineNo">280</span> + " . So there may be
a TCP socket connection "<a name="line.280"></a>
+<span class="sourceLineNo">281</span> + "left open in
CLOSE_WAIT state.", e);<a name="line.281"></a>
+<span class="sourceLineNo">282</span> }<a name="line.282"></a>
+<span class="sourceLineNo">283</span> return;<a
name="line.283"></a>
+<span class="sourceLineNo">284</span> }<a name="line.284"></a>
+<span class="sourceLineNo">285</span> this.instanceOfCanUnbuffer =
true;<a name="line.285"></a>
+<span class="sourceLineNo">286</span> break;<a name="line.286"></a>
+<span class="sourceLineNo">287</span> }<a name="line.287"></a>
+<span class="sourceLineNo">288</span> }<a name="line.288"></a>
+<span class="sourceLineNo">289</span> }<a name="line.289"></a>
+<span class="sourceLineNo">290</span> if (this.instanceOfCanUnbuffer) {<a
name="line.290"></a>
+<span class="sourceLineNo">291</span> try {<a name="line.291"></a>
+<span class="sourceLineNo">292</span>
this.unbuffer.invoke(wrappedStream);<a name="line.292"></a>
+<span class="sourceLineNo">293</span> } catch (IllegalAccessException |
IllegalArgumentException | InvocationTargetException e) {<a name="line.293"></a>
+<span class="sourceLineNo">294</span> if (isLogTraceEnabled) {<a
name="line.294"></a>
+<span class="sourceLineNo">295</span> LOG.trace("Failed to invoke
'unbuffer' method in class " + streamClass<a name="line.295"></a>
+<span class="sourceLineNo">296</span> + " . So there may be a
TCP socket connection left open in CLOSE_WAIT state.", e);<a
name="line.296"></a>
+<span class="sourceLineNo">297</span> }<a name="line.297"></a>
+<span class="sourceLineNo">298</span> }<a name="line.298"></a>
+<span class="sourceLineNo">299</span> } else {<a name="line.299"></a>
+<span class="sourceLineNo">300</span> if (isLogTraceEnabled) {<a
name="line.300"></a>
+<span class="sourceLineNo">301</span> LOG.trace("Failed to find
'unbuffer' method in class " + streamClass<a name="line.301"></a>
+<span class="sourceLineNo">302</span> + " . So there may be a TCP
socket connection "<a name="line.302"></a>
+<span class="sourceLineNo">303</span> + "left open in CLOSE_WAIT
state. For more details check "<a name="line.303"></a>
+<span class="sourceLineNo">304</span> +
"https://issues.apache.org/jira/browse/HBASE-9393";);<a name="line.304"></a>
+<span class="sourceLineNo">305</span> }<a name="line.305"></a>
+<span class="sourceLineNo">306</span> }<a name="line.306"></a>
+<span class="sourceLineNo">307</span> }<a name="line.307"></a>
+<span class="sourceLineNo">308</span> }<a name="line.308"></a>
+<span class="sourceLineNo">309</span>}<a name="line.309"></a>
