Allow specification of PipedInputStream buffer size

The buffer size (in bytes) for the piped stream used to implement
the :stream option for :out. If the ssh commands generate a high volume of
output, then this buffer size can become a bottleneck. The buffer size
can be specified by binding *piped-stream-buffer-size*, and defaults to 10Kb.

Author: hugoduncan

src/clj_ssh/ssh.clj

@@ -301,16 +301,25 @@ keys.  All other option key pairs will be passed as SSH config options."
   [^Session session]
   (open-channel session :shell))
 
+(def
+  ^{:dynamic true
+    :doc (str "The buffer size (in bytes) for the piped stream used to implement
+    the :stream option for :out. If your ssh commands generate a high volume of
+    output, then this buffer size can become a bottleneck. You might also
+    increase the frequency with which you read the output stream if this is an
+    issue.")}
+  *piped-stream-buffer-size* (* 1024 10))
+
 (defn- streams-for-out
   [out]
   (if (= :stream out)
     (let [os (java.io.PipedOutputStream.)]
-      [os (java.io.PipedInputStream. os)])
+      [os (java.io.PipedInputStream. os *piped-stream-buffer-size*)])
     [(java.io.ByteArrayOutputStream.) nil]))
 
 (defn- streams-for-in
   []
-  (let [os (java.io.PipedInputStream.)]
+  (let [os (java.io.PipedInputStream. *piped-stream-buffer-size*)]
     [os (java.io.PipedOutputStream. os)]))
 
 (defn ssh-shell