Bundle decorator.py and fix decorators

.coveragerc

@@ -1,6 +1,8 @@
 [run]
 branch = True
 source = prometheus_client
+omit =
+    prometheus_client/decorator.py
 
 [paths]
 source =
@@ -9,4 +11,4 @@ source =
    .tox/pypy/site-packages/prometheus_client
 
 [report]
-show_missing = True
+show_missing = True

NOTICE

@@ -1,2 +1,5 @@
 Prometheus instrumentation library for Python applications
 Copyright 2015 The Prometheus Authors
+
+This product bundles decorator 4.0.10 which is available under a "2-clause BSD"
+license. For details, see prometheus_client/decorator.py.

prometheus_client/core.py

@@ -14,9 +14,10 @@
     # Python 3
     unicode = str
 
-from functools import wraps
 from threading import Lock
 
+from .decorator import decorate
+
 _METRIC_NAME_RE = re.compile(r'^[a-zA-Z_:][a-zA-Z0-9_:]*$')
 _METRIC_LABEL_NAME_RE = re.compile(r'^[a-zA-Z_:][a-zA-Z0-9_:]*$')
 _RESERVED_METRIC_LABEL_NAME_RE = re.compile(r'^__.*$')
@@ -657,11 +658,10 @@ def __exit__(self, typ, value, traceback):
         self._histogram.observe(max(time.time() - self._start, 0))
 
     def __call__(self, f):
-        @wraps(f)
-        def wrapped(*args, **kwargs):
+        def wrapped(func, *args, **kwargs):
             with self:
-                return f(*args, **kwargs)
-        return wrapped
+                return func(*args, **kwargs)
+        return decorate(f, wrapped)
 
 
 class _ExceptionCounter(object):
@@ -677,11 +677,10 @@ def __exit__(self, typ, value, traceback):
             self._counter.inc()
 
     def __call__(self, f):
-        @wraps(f)
-        def wrapped(*args, **kwargs):
+        def wrapped(func, *args, **kwargs):
             with self:
-                return f(*args, **kwargs)
-        return wrapped
+                return func(*args, **kwargs)
+        return decorate(f, wrapped)
 
 
 class _InprogressTracker(object):
@@ -695,11 +694,10 @@ def __exit__(self, typ, value, traceback):
         self._gauge.dec()
 
     def __call__(self, f):
-        @wraps(f)
-        def wrapped(*args, **kwargs):
+        def wrapped(func, *args, **kwargs):
             with self:
-                return f(*args, **kwargs)
-        return wrapped
+                return func(*args, **kwargs)
+        return decorate(f, wrapped)
 
 
 class _SummaryTimer(object):
@@ -714,11 +712,10 @@ def __exit__(self, typ, value, traceback):
         self._summary.observe(max(time.time() - self._start, 0))
 
     def __call__(self, f):
-        @wraps(f)
-        def wrapped(*args, **kwargs):
+        def wrapped(func, *args, **kwargs):
             with self:
-                return f(*args, **kwargs)
-        return wrapped
+                return func(*args, **kwargs)
+        return decorate(f, wrapped)
 
 
 class _GaugeTimer(object):
@@ -733,8 +730,7 @@ def __exit__(self, typ, value, traceback):
         self._gauge.set(max(time.time() - self._start, 0))
 
     def __call__(self, f):
-        @wraps(f)
-        def wrapped(*args, **kwargs):
+        def wrapped(func, *args, **kwargs):
             with self:
-                return f(*args, **kwargs)
-        return wrapped
+                return func(*args, **kwargs)
+        return decorate(f, wrapped)