net: simplify the TcpConn.read_line/0 method, accumulate partially read lines, use a string builder, instead of concatenation
parent
6ea4f361a1
commit
74048e2f17
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@ -1,9 +1,12 @@
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module net
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import strings
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const (
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crlf = '\r\n'
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msg_peek = 0x02
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max_read = 400
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max_read_line_len = 1048576
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)
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// get_blocking returns whether the connection is in a blocking state,
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@ -39,52 +42,59 @@ pub fn (mut con TcpConn) set_blocking(state bool) ? {
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}
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// read_line is a *simple*, *non customizable*, blocking line reader.
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// It will *always* return a line, ending with CRLF, or just '', on EOF.
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// It will return a line, ending with LF, or just '', on EOF.
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// NB: if you want more control over the buffer, please use a buffered IO
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// reader instead: `io.new_buffered_reader({reader: io.make_reader(con)})`
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pub fn (mut con TcpConn) read_line() string {
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mut buf := [net.max_read]byte{} // where C.recv will store the network data
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mut res := '' // The final result, including the ending \n.
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return con.read_line_max(net.max_read_line_len)
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}
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// read_line_max is a *simple*, *non customizable*, blocking line reader.
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// It will return a line, ending with LF, '' on EOF.
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// It stops reading, when the result line length exceeds max_line_len.
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[manualfree]
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pub fn (mut con TcpConn) read_line_max(max_line_len int) string {
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if !con.is_blocking {
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con.set_blocking(true) or {}
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}
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for {
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mut line := '' // The current line. Can be a partial without \n in it.
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n := C.recv(con.sock.handle, &buf[0], net.max_read - 1, net.msg_peek | msg_nosignal)
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if n == -1 {
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return res
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mut buf := [net.max_read]byte{} // where C.recv will store the network data
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mut res := strings.new_builder(net.max_read) // The final result, including the ending \n.
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defer {
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unsafe { res.free() }
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}
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if n == 0 {
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return res
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bstart := unsafe { &buf[0] }
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for {
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n := C.recv(con.sock.handle, bstart, net.max_read - 1, net.msg_peek | msg_nosignal)
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if n <= 0 {
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return res.str()
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}
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buf[n] = `\0`
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mut eol_idx := -1
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mut lend := n
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for i in 0 .. n {
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if int(buf[i]) == `\n` {
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if buf[i] == `\n` {
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eol_idx = i
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// Ensure that tos_clone(buf) later,
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// will return *only* the first line (including \n),
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// and ignore the rest
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buf[i + 1] = `\0`
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lend = i + 1
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buf[lend] = `\0`
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break
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}
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}
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line = unsafe { tos_clone(&buf[0]) }
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if eol_idx > 0 {
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// At this point, we are sure that recv returned valid data,
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// that contains *at least* one line.
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// Ensure that the block till the first \n (including it)
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// is removed from the socket's receive queue, so that it does
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// not get read again.
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C.recv(con.sock.handle, &buf[0], eol_idx + 1, msg_nosignal)
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res += line
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C.recv(con.sock.handle, bstart, lend, msg_nosignal)
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unsafe { res.write_ptr(bstart, lend) }
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break
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}
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// recv returned a buffer without \n in it .
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C.recv(con.sock.handle, &buf[0], n, msg_nosignal)
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res += line
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res += net.crlf
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// recv returned a buffer without \n in it, just store it for now:
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C.recv(con.sock.handle, bstart, n, msg_nosignal)
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unsafe { res.write_ptr(bstart, lend) }
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if res.len > max_line_len {
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break
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}
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return res
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}
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return res.str()
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}
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