bio: use splice! to reduce copy

src/bio.jl

@@ -31,10 +31,12 @@ function bio_write!(client::SSLClient, data)
 end
 
 function bio_read(client::SSLClient)
-    buff = Vector{UInt8}(undef, 64)
+    buff_length = 64
+    buff = Vector{UInt8}(undef, buff_length)
     n = ccall((:BIO_read, libssl), Cint, (Ptr{Cvoid},Ptr{Cvoid},Cint),
-              client.wbio, buff, length(buff))
-    n, n > 0 ? buff[1:n] : buff
+              client.wbio, buff, buff_length)
+    n > 0 && splice!(buff, (n+1):buff_length)
+    n, buff
 end
 
 bio_test_flags(bio, flags) =

src/flow_control.jl

@@ -37,7 +37,7 @@ function do_encrypt(client)
         status = ccall((:SSL_get_error, libssl), SSL_ERRORS, (Ptr{Cvoid}, Cint),
 	               client.ssl, n)
         if n > 0
-            client.encrypt_buf = client.encrypt_buf[(n+1):end]
+            splice!(client.encrypt_buf, 1:n)
             while true
                 (n, buf) = bio_read(client)
                 if n > 0
@@ -121,7 +121,7 @@ function do_sock_write(client::SSLClient)
     n = write(client.sock, client.write_buf)
     # println("Written to the client: $n")
     if n > 0
-        client.write_buf = client.write_buf[(n+1):end]
+        splice!(client.write_buf, 1:n)
         return 0
     else
         return -1