Allow HistogramLogReader to read file objects

hdrh/log.py

@@ -147,9 +147,10 @@ class HistogramLogReader():
 
     def __init__(self, input_file_name, reference_histogram):
         '''Constructs a new HistogramLogReader that produces intervals read
-        from the specified file name.
+        from the specified file name or file-like object.
         Params:
-            input_file_name The name of the file to read from
+            input_file_name The name of the file to read from, or a file-like
+                            object with a readline() method
             reference_histogram a histogram instance used as a reference to create
                                 new instances for all subsequent decoded interval
                                 histograms
@@ -158,7 +159,11 @@ def __init__(self, input_file_name, reference_histogram):
         self.observed_start_time = False
         self.base_time_sec = 0.0
         self.observed_base_time = False
-        self.input_file = open(input_file_name, "r", encoding="utf-8") # pylint: disable=consider-using-with
+        self.input_file = input_file_name
+        self._close_input_file = False
+        if not hasattr(input_file_name, 'readline'):
+            self.input_file = open(input_file_name, "r", encoding="utf-8") # pylint: disable=consider-using-with
+            self._close_input_file = True
         self.reference_histogram = reference_histogram
 
     def get_start_time_sec(self):
@@ -172,6 +177,12 @@ def get_start_time_sec(self):
         '''
         return self.start_time_sec
 
+    def _readline(self):
+        line = self.input_file.readline()
+        if isinstance(line, bytes):
+            line = line.decode("utf-8")
+        return line
+
     def _decode_next_interval_histogram(self,
                                         dest_histogram,
                                         range_start_time_sec=0.0,
@@ -218,7 +229,7 @@ def _decode_next_interval_histogram(self,
             ValueError if there is a syntax error in one of the float fields
         '''
         while 1:
-            line = self.input_file.readline()
+            line = self._readline()
             if not line:
                 return None
             if line[0] == '#':
@@ -402,4 +413,5 @@ def add_next_interval_histogram(self,
                                                     absolute)
 
     def close(self):
-        self.input_file.close()
+        if self._close_input_file:
+            self.input_file.close()

test/test_hdrhistogram.py

@@ -641,6 +641,18 @@ def test_jHiccup_v2_log():
         log_reader.close()
 
 
+@pytest.mark.log
+def test_jHiccup_v2_log_file_object():
+    accumulated_histogram = HdrHistogram(LOWEST, HIGHEST, SIGNIFICANT)
+    with open(JHICCUP_V2_LOG_NAME, 'rb') as hdr_log:
+        log_reader = HistogramLogReader(hdr_log, accumulated_histogram)
+        decoded_histogram = log_reader.get_next_interval_histogram()
+        assert decoded_histogram
+        assert decoded_histogram.get_word_size() == 8
+        log_reader.close()
+        assert not hdr_log.closed
+
+
 TAGGED_V2_LOG = 'test/tagged-Log.logV2.hlog'
 @pytest.mark.log
 def test_tagged_v2_log():