Refactor and simplify socket_read_until_newline() to ReadUntil()

Do socket reads in chunks of 1024 bytes, split at first occurence of separator
and return up to that first occurence while keeping the remains of the read
chunk for further invocations of ReadUntil(), and do utilise that cached data
until drained, then re-read the socket.

Also, there's no need to keep track of timeouts, this is handled by utilising
socket.settimeout().

Author: herrnst

resources/lib/lcdproc.py

@@ -32,6 +32,7 @@ def __init__(self, settings):
     self.m_initRetryInterval = INIT_RETRY_INTERVAL
     self.m_used = True
     self.m_socket = None
+    self.m_sockreadbuf = b''
     self.m_timeLastSockAction = time.time()
     self.m_timeSocketIdleTimeout = 2
     self.m_strLineText = [None]*MAX_ROWS
@@ -48,33 +49,19 @@ def __init__(self, settings):
 
     LcdBase.__init__(self, settings)
 
-  def socket_read_until_newline(self, searchstr, timeout):
+  def ReadUntil(self, separator):
     if not self.m_socket:
       return b""
 
-    data = bytearray()
-    start_time = time.time()
+    while separator not in self.m_sockreadbuf:
+      data = self.m_socket.recv(1024)
+      if not data:
+        raise EOFError
+      self.m_sockreadbuf += data
 
-    while True:
-      # Return current data on timeout
-      elapsed_time = time.time() - start_time
-      if elapsed_time > timeout:
-        break
+    line, tmp, self.m_sockreadbuf = self.m_sockreadbuf.partition(separator)
 
-      # Read new data and break on disconnect (empty bytes object returned; timeout for recv is set on connect)
-      try:
-        chunk = self.m_socket.recv(1)
-      except TimeoutError:
-        chunk = b''
-      if not chunk:
-        break
-      data += chunk
-
-      # Break if searchstr is found
-      if searchstr in data:
-        break
-
-    return data
+    return line + b"\n"
 
   def SendCommand(self, strCmd, bCheckRet):
     countcmds = strCmd.count(b'\n')
@@ -104,7 +91,7 @@ def SendCommand(self, strCmd, bCheckRet):
       while True:
         try:
           # Read server reply
-          reply = self.socket_read_until_newline(b"\n", timeout=3)
+          reply = self.ReadUntil(b"\n")
         except:
           # (Re)read failed, abort
           log(LOGERROR, "SendCommand: Telnet exception - reread")
@@ -241,7 +228,7 @@ def DetermineExtraSupport(self):
     try:
       # Retrieve driver name for additional functionality
       self.m_socket.send(b"info\n")
-      reply = self.socket_read_until_newline(b"\n", timeout=3).strip().decode("ascii")
+      reply = self.ReadUntil(b"\n").strip().decode("ascii")
 
       # When the LCDd driver doesn't supply a valid string, inform and return
       if reply == "":
@@ -282,13 +269,15 @@ def Connect(self):
       log(LOGDEBUG,"Open " + str(ip) + ":" + str(port))
 
       self.m_socket = socket(AF_INET, SOCK_STREAM)
+      self.m_socket.settimeout(15)
       self.m_socket.connect((ip, port))
-      self.m_socket.settimeout(1)
+      self.m_socket.settimeout(3)
+
       # Start a new session
       self.m_socket.send(b"hello\n")
 
       # Receive LCDproc data to determine row and column information
-      reply = self.socket_read_until_newline(b"\n", timeout=3).decode("ascii")
+      reply = self.ReadUntil(b"\n").decode("ascii")
       log(LOGDEBUG,"Reply: " + reply)
 
       # parse reply by regex
@@ -357,6 +346,7 @@ def CloseSocket(self):
     del self.m_cExtraIcons
     self.m_cExtraIcons = None
 
+    self.m_sockreadbuf = b''
     self.m_socket = None
 
   def IsConnected(self):