vpp-api: Add context to VPPStatsIOError.

[vpp.git] / src / vpp-api / python / vpp_papi / vpp_stats.py

diff --git a/src/vpp-api/python/vpp_papi/vpp_stats.py b/src/vpp-api/python/vpp_papi/vpp_stats.py
index 8344de0..0afed26 100644 (file)
--- a/src/vpp-api/python/vpp_papi/vpp_stats.py
+++ b/src/vpp-api/python/vpp_papi/vpp_stats.py
@@ -128,7 +128,6 @@ def stat_entry_to_python(api, e):
     # Scalar index
     if e.type == 1:
         return e.scalar_value
-        return None
     if e.type == 2:
         return simple_counter_vec_list(api, e.simple_counter_vec)
     if e.type == 3:
@@ -138,12 +137,49 @@ def stat_entry_to_python(api, e):
     return None
 
 
+class VPPStatsIOError(IOError):
+    message = "Stat segment client connection returned: " \
+              "%(retval)s %(strerror)s."
+
+    strerror = {-1: "Stat client couldn't open socket",
+                -2: "Stat client socket open but couldn't connect",
+                -3: "Receiving file descriptor failed",
+                -4: "mmap fstat failed",
+                -5: "mmap map failed"
+                }
+
+    def __init__(self, message=None, **kwargs):
+        if 'retval' in kwargs:
+            self.retval = kwargs['retval']
+            kwargs['strerror'] = self.strerror[int(self.retval)]
+
+        if not message:
+            try:
+                message = self.message % kwargs
+            except Exception as e:
+                message = self.message
+        else:
+            message = message % kwargs
+
+        super(VPPStatsIOError, self).__init__(message)
+
+
+class VPPStatsClientLoadError(RuntimeError):
+    pass
+
+
 class VPPStats(object):
-    def __init__(self, socketname='/var/run/stats.sock', timeout=10):
+    VPPStatsIOError = VPPStatsIOError
+
+    default_socketname = '/var/run/stats.sock'
+    sharedlib_name = 'libvppapiclient.so'
+
+    def __init__(self, socketname=default_socketname, timeout=10):
         try:
-            self.api = ffi.dlopen('libvppapiclient.so')
+            self.api = ffi.dlopen(VPPStats.sharedlib_name)
         except Exception:
-            raise RuntimeError("Could not open: libvppapiclient.so")
+            raise VPPStatsClientLoadError("Could not open: %s" %
+                                          VPPStats.sharedlib_name)
         self.client = self.api.stat_client_get()
 
         poll_end_time = time.time() + timeout
@@ -154,7 +190,7 @@ class VPPStats(object):
                 break
 
         if rv != 0:
-            raise IOError()
+            raise VPPStatsIOError(retval=rv)
 
     def heartbeat(self):
         return self.api.stat_segment_heartbeat_r(self.client)
@@ -169,7 +205,7 @@ class VPPStats(object):
         rv = self.api.stat_segment_dump_r(counters, self.client)
         # Raise exception and retry
         if rv == ffi.NULL:
-            raise IOError()
+            raise VPPStatsIOError()
         rv_len = self.api.stat_segment_vec_len(rv)
         for i in range(rv_len):
             n = ffi.string(rv[i].name).decode()
@@ -182,9 +218,14 @@ class VPPStats(object):
         retries = 0
         while True:
             try:
-                dir = self.ls(name)
-                return self.dump(dir).values()[0]
-            except Exception as e:
+                d = self.ls(name)
+                s = self.dump(d)
+                if len(s) > 1:
+                    raise AttributeError('Matches multiple counters {}'
+                                         .format(name))
+                k, v = s.popitem()
+                return v
+            except VPPStatsIOError as e:
                 if retries > 10:
                     return None
                 retries += 1
@@ -201,7 +242,7 @@ class VPPStats(object):
                 error_names = self.ls(['/err/'])
                 error_counters = self.dump(error_names)
                 break
-            except Exception as e:
+            except VPPStatsIOError as e:
                 if retries > 10:
                     return None
                 retries += 1