Add class to manage bw files

* Move logic in generate to class
* Add test
* Move 7500 to global constant
* Make read_started_at not fail when conf is None

sbws/core/generate.py

-from sbws.globals import (fail_hard, is_initted)
-from sbws.lib.v3bwfile import V3BwHeader, V3BWLine
-from sbws.lib.resultdump import ResultSuccess
+from sbws.globals import (fail_hard, is_initted, SCALE_CONSTANT)
+from sbws.lib.v3bwfile import V3BwFile
 from sbws.lib.resultdump import load_recent_results_in_datadir
 from argparse import ArgumentDefaultsHelpFormatter
 import os
@@ -22,7 +21,7 @@ def gen_parser(sub):
     # time, torflow happened to generate output that averaged to 7500 bw units
     # per relay. We wanted the ability to try to be like torflow. See
     # https://lists.torproject.org/pipermail/tor-dev/2018-March/013049.html
-    p.add_argument('--scale-constant', default=7500, type=int,
+    p.add_argument('--scale-constant', default=SCALE_CONSTANT, type=int,
                    help='When scaling bw weights, scale them using this const '
                    'multiplied by the number of measured relays')
     p.add_argument('--scale', action='store_true',
@@ -32,13 +31,6 @@ def gen_parser(sub):
                    'out, and we do so proportionally')
 
 
-def log_stats(data_lines):
-    assert len(data_lines) > 0
-    total_bw = sum([l.bw for l in data_lines])
-    bw_per_line = total_bw / len(data_lines)
-    log.info('Mean bandwidth per line: %f "KiB"', bw_per_line)
-
-
 def main(args, conf):
     if not is_initted(args.directory):
         fail_hard('Sbws isn\'t initialized.  Try sbws init')
@@ -56,4 +48,5 @@ def main(args, conf):
         log.warning('No recent results, so not generating anything. (Have you '
                     'ran sbws scanner recently?)')
         return
-
+    bw_file = V3BwFile.from_arg_results(args, conf, results)
+    log.info('Mean bandwidth per line: %f "KiB"', bw_file.avg_bw)

sbws/globals.py

@@ -24,6 +24,8 @@ TORRC_STARTING_POINT = {
     'UseEntryGuards': '0',
 }
 
+SCALE_CONSTANT = 7500
+
 
 def is_initted(d):
     if not os.path.isdir(d):

sbws/lib/v3bwfile.py

@@ -70,7 +70,10 @@ def read_started_ts(conf):
     :param ConfigParser conf: configuration
     :returns: str, ISO formated timestamp
     """
-    filepath = conf['paths']['started_filepath']
+    try:
+        filepath = conf['paths']['started_filepath']
+    except TypeError as e:
+        return ''
     try:
         with FileLock(filepath):
             with open(filepath, 'r') as fd:
@@ -336,3 +339,56 @@ class V3BWLine(object):
         assert fingerprint in data
         return cls.from_results(data[fingerprint])
 
+
+class V3BwFile(object):
+    def __init__(self, v3bwheader, v3bwlines):
+        """
+        :param V3BWHeader v3bwheader:
+        :param list v3bwlines:
+        """
+        self.header = v3bwheader
+        self.bw_lines = v3bwlines
+
+    def __str__(self):
+        return str(self.header) + ''.join([str(bw_line)
+                                           for bw_line in self.bw_lines])
+
+    @property
+    def total_bw(self):
+        return total_bw(self.bw_lines)
+
+    @property
+    def num_lines(self):
+        return len(self.bw_lines)
+
+    @property
+    def avg_bw(self):
+        return self.total_bw / self.num_lines
+
+    @classmethod
+    def from_results(cls, conf, output, results):
+        bw_lines = [V3BWLine.from_results(results[fp]) for fp in results]
+        bw_lines = sorted(bw_lines, key=lambda d: d.bw, reverse=True)
+        header = V3BwHeader.from_results(conf, results)
+        f = cls(header, bw_lines)
+        f.write(output)
+        return f
+
+    @classmethod
+    def from_arg_results(cls, args, conf, results):
+        bw_lines = [V3BWLine.from_results(results[fp]) for fp in results]
+        bw_lines = sorted(bw_lines, key=lambda d: d.bw, reverse=True)
+        if args.scale:
+            bw_lines = scale_lines(bw_lines, args.scale_constant)
+        header = V3BwHeader.from_results(conf, results)
+        f = cls(header, bw_lines)
+        output = args.output or conf['paths']['v3bw_fname']
+        f.write(output)
+        return f
+
+    def write(self, output):
+        log.info('Writing v3bw file to %s', output)
+        with open(output, 'wt') as fd:
+            fd.write(str(self.header))
+            for line in self.bw_lines:
+                fd.write(str(line))

tests/lib/data/v3bw.txt

+1523974147
+version=1.1.0
+earliest_bandwidth=2018-04-16T14:09:07
+file_created=2018-04-25T13:10:57
+generator_started=2018-04-16T14:09:05
+latest_bandwidth=2018-04-17T14:09:07
+software=sbws
+software_version=0.3.1-dev
+====
+bw=54 error_auth=0 error_circ=0 error_misc=0 error_stream=1 last_time=2018-04-17T14:09:07 nick=A node_id=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA success=1

tests/unit/lib/test_v3bwfile.py

 # -*- coding: utf-8 -*-
 """Test generation of bandwidth measurements document (v3bw)"""
 import json
-import os.path
 
 from sbws import __version__ as version
 from sbws.globals import SPEC_VERSION
 from sbws.lib.resultdump import Result, load_result_file
 from sbws.lib.v3bwfile import (V3BwHeader, V3BWLine, TERMINATOR, LINE_SEP,
-                               KEYVALUE_SEP_V110, num_results_of_type)
+                               KEYVALUE_SEP_V110, num_results_of_type,
+                               V3BwFile)
 
 timestamp = 1523974147
 timestamp_l = str(timestamp)
@@ -152,4 +152,14 @@ def test_v3bwline_from_results_file(datadir):
 
 def test_v3bwfile(datadir, tmpdir):
     """Test generate v3bw file (including relay_lines)."""
-    pass
+    v3bw = datadir.read('v3bw.txt')
+    results = load_result_file(str(datadir.join("results.txt")))
+    header = V3BwHeader(timestamp_l,
+                        file_created=file_created,
+                        generator_started=generator_started,
+                        earliest_bandwidth=earliest_bandwidth)
+    bwls = [V3BWLine.from_results(results[fp]) for fp in results]
+    f = V3BwFile(header, bwls)
+    # f = V3BwFile.from_results(None, str(tmpdir.join("v3bw.txt")), results)
+
+    assert v3bw == str(f)