From db8f22bb208c57f2b03f71096e42d884c371c009 Mon Sep 17 00:00:00 2001
From: MatthieuDartiailh <m.dartiailh@gmail.com>
Date: Tue, 17 Sep 2024 19:13:24 +0200
Subject: [PATCH] sessions: improve handling of open connection error for TCPIP
 resources

---
 pyvisa_py/__init__.py  |  3 +++
 pyvisa_py/highlevel.py |  5 +++-
 pyvisa_py/sessions.py  |  7 ++++++
 pyvisa_py/tcpip.py     | 55 ++++++++++++++++++++++++++++--------------
 4 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/pyvisa_py/__init__.py b/pyvisa_py/__init__.py
index a625616..4b5576f 100644
--- a/pyvisa_py/__init__.py
+++ b/pyvisa_py/__init__.py
@@ -7,8 +7,11 @@
 
 """
 
+import logging
 import sys
 
+LOGGER = logging.getLogger("pyvisa.pyvisa-py")
+
 if sys.version_info >= (3, 8):
     from importlib.metadata import PackageNotFoundError, version
 else:
diff --git a/pyvisa_py/highlevel.py b/pyvisa_py/highlevel.py
index 4d0258c..96a0ecc 100644
--- a/pyvisa_py/highlevel.py
+++ b/pyvisa_py/highlevel.py
@@ -165,7 +165,10 @@ def open(
             parsed.interface_type_const, parsed.resource_class
         )
 
-        sess = cls(session, resource_name, parsed, open_timeout)
+        try:
+            sess = cls(session, resource_name, parsed, open_timeout)
+        except sessions.OpenError as e:
+            return 0, e.error_code
 
         return self._register(sess), StatusCode.success
 
diff --git a/pyvisa_py/sessions.py b/pyvisa_py/sessions.py
index 6693949..d12e47b 100644
--- a/pyvisa_py/sessions.py
+++ b/pyvisa_py/sessions.py
@@ -32,6 +32,13 @@
 T = TypeVar("T", bound=Type["Session"])
 
 
+class OpenError(Exception):
+    """Custom exception signaling we failed to open a resource."""
+
+    def __init__(self, error_code: int = StatusCode.error_resource_not_found):
+        self.error_code = error_code
+
+
 class UnknownAttribute(Exception):
     """Custom exception signaling a VISA attribute is not supported."""
 
diff --git a/pyvisa_py/tcpip.py b/pyvisa_py/tcpip.py
index 4d09a7a..0f249f6 100644
--- a/pyvisa_py/tcpip.py
+++ b/pyvisa_py/tcpip.py
@@ -18,9 +18,10 @@
 from pyvisa import attributes, constants, errors, rname
 from pyvisa.constants import BufferOperation, ResourceAttribute, StatusCode
 
-from . import common
+from . import common, LOGGER
 from .protocols import hislip, rpc, vxi11
-from .sessions import Session, UnknownAttribute, VISARMSession
+from .sessions import OpenError, Session, UnknownAttribute, VISARMSession
+
 
 # Let psutil be optional dependency
 try:
@@ -135,17 +136,25 @@ def after_parsing(self) -> None:
         else:
             sub_address = self.parsed.lan_device_name
             port = 4880
-        self.interface = hislip.Instrument(
-            self.parsed.host_address,
-            open_timeout=(
-                self.open_timeout * 1000.0
-                if self.open_timeout is not None
-                else self.open_timeout
-            ),
-            timeout=self.timeout,
-            port=port,
-            sub_address=sub_address,
-        )
+
+        try:
+            self.interface = hislip.Instrument(
+                self.parsed.host_address,
+                open_timeout=(
+                    self.open_timeout * 1000.0
+                    if self.open_timeout is not None
+                    else self.open_timeout
+                ),
+                timeout=self.timeout,
+                port=port,
+                sub_address=sub_address,
+            )
+        except OSError as e:
+            LOGGER.exception(
+                f"Failed to open HiSLIP connection to {self.parsed.host_address} "
+                f"on port {port} with lan device name {sub_address}"
+            )
+            raise OpenError() from e
 
         # initialize the constant attributes
         self.attrs[ResourceAttribute.dma_allow_enabled] = constants.VI_FALSE
@@ -482,7 +491,10 @@ def after_parsing(self) -> None:
         try:
             self.interface = Vxi11CoreClient(host_address, port, self.open_timeout)
         except rpc.RPCError:
-            raise errors.VisaIOError(constants.VI_ERROR_RSRC_NFOUND)
+            LOGGER.exception(
+                f"Failed to open VX11 connection to {host_address} on port {port}"
+            )
+            raise OpenError()
 
         # vxi11 expect all timeouts to be expressed in ms and should be integers
         self.lock_timeout = 10000
@@ -511,7 +523,7 @@ def close(self) -> StatusCode:
         try:
             self.interface.destroy_link(self.link)
         except (errors.VisaIOError, socket.error, rpc.RPCError) as e:
-            print("Error closing VISA link: {}".format(e))
+            LOGGER.error("Error closing VISA link: {}".format(e))
 
         self.interface.close()
         self.link = 0
@@ -870,9 +882,16 @@ def after_parsing(self) -> None:
         else:
             port = 1861
 
-        self.interface = pyvicp.Client(
-            self.parsed.host_address, port, timeout=self.timeout
-        )
+        try:
+            self.interface = pyvicp.Client(
+                self.parsed.host_address, port, timeout=self.timeout
+            )
+        except OSError as e:
+            LOGGER.exception(
+                f"Failed to open VICP connection to {self.parsed.host_address} "
+                f"on port {port}"
+            )
+            raise OpenError() from e
 
         # initialize the constant attributes
         for name in ("SEND_END_EN", "TERMCHAR", "TERMCHAR_EN"):