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1 # Copyright 2016 The Chromium Authors. All rights reserved. | |
2 # Use of this source code is governed by a BSD-style license that can be | |
3 # found in the LICENSE file. | |
4 | |
5 """Models the effect of NoState Prefetch from a loading trace. | |
blundell
2016/03/21 10:07:18
Nit: prefetch_view is a quite generic name. Maybe
blundell
2016/03/21 10:22:04
Also, let's provide a one-sentence description of
Benoit L
2016/03/22 09:32:23
This is intended to simulate prefetch in a generic
| |
6 | |
7 When executed as a script, takes a trace as a command-line arguments and shows | |
8 how many requests were prefetched. | |
9 """ | |
10 | |
11 import itertools | |
12 import operator | |
13 | |
14 import loading_trace | |
15 import request_dependencies_lens | |
16 | |
17 | |
18 class PrefetchSimulationView(object): | |
19 """Simulates the effect of prefetching resources discoverable by the preload | |
20 scanner. | |
21 """ | |
22 def __init__(self, trace, dependencies_lens): | |
23 """Initializes an instance of PrefetchSimulationView. | |
24 | |
25 Args: | |
26 trace: (LoadingTrace) a loading trace. | |
27 dependencies_lens: (RequestDependencyLens) request dependencies. | |
28 """ | |
29 self.trace = trace | |
30 self.dependencies_lens = dependencies_lens | |
31 self._resource_events = self.trace.tracing_track.Filter( | |
32 categories=set([u'blink.net'])) | |
33 assert len(self._resource_events.GetEvents()) > 0,\ | |
34 'Was the "blink.net" category enabled at trace collection time?"' | |
35 | |
36 def ParserDiscoverableRequests(self, request, recurse=False): | |
blundell
2016/03/21 10:47:16
Should/could this eventually be the same code that
mattcary
2016/03/21 10:54:44
That's an interesting general question: should our
gabadie
2016/03/21 12:55:45
Fly by comment: Sandwich is currently simulating t
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37 """Returns a list of requests discovered by the parser from a given request. | |
38 | |
39 Args: | |
40 request: (Request) Root request. | |
41 | |
42 Returns: | |
43 [Request] | |
44 """ | |
45 # TODO(lizeb): handle the recursive case. | |
46 assert not recurse | |
47 discoverable_requests = [request] | |
48 first_request = self.dependencies_lens.GetRedirectChain(request)[-1] | |
49 deps = self.dependencies_lens.GetRequestDependencies() | |
50 for (first, second, reason) in deps: | |
51 if first.request_id == first_request.request_id and reason == 'parser': | |
52 discoverable_requests.append(second) | |
53 return discoverable_requests | |
54 | |
55 def ExpandRedirectChains(self, requests): | |
56 return list(itertools.chain.from_iterable( | |
57 [self.dependencies_lens.GetRedirectChain(r) for r in requests])) | |
58 | |
59 def PreloadedRequests(self, request): | |
60 """Returns the requests that have been preloaded from a given request. | |
61 | |
62 This list is the set of request that are: | |
63 - Discoverable by the parser | |
64 - Found in the trace log. | |
65 | |
66 Before looking for dependencies, this follows the redirect chain. | |
67 | |
68 Args: | |
69 request: (Request) Root request. | |
70 | |
71 Returns: | |
72 A list of Request. Does not include the root request. This list is a | |
73 subset of the one returned by ParserDiscoverableRequests(). | |
74 """ | |
75 # Preload step events are emitted in ResourceFetcher::preloadStarted(). | |
76 preload_step_events = filter( | |
77 lambda e: e.args.get('step') == 'Preload', | |
78 self._resource_events.GetEvents()) | |
79 preloaded_urls = set() | |
80 for preload_step_event in preload_step_events: | |
81 preload_event = self._resource_events.EventFromStep(preload_step_event) | |
82 if preload_event: | |
83 preloaded_urls.add(preload_event.args['url']) | |
84 parser_requests = self.ParserDiscoverableRequests(request) | |
85 preloaded_root_requests = filter( | |
86 lambda r: r.url in preloaded_urls, parser_requests) | |
87 # We can actually fetch the whole redirect chain. | |
88 return [request] + list(itertools.chain.from_iterable( | |
89 [self.dependencies_lens.GetRedirectChain(r) | |
90 for r in preloaded_root_requests])) | |
91 | |
92 | |
93 def _PrintSummary(prefetch_view): | |
94 requests = prefetch_view.trace.request_track.GetEvents() | |
95 first_request = prefetch_view.trace.request_track.GetEvents()[0] | |
96 parser_requests = prefetch_view.ExpandRedirectChains( | |
97 prefetch_view.ParserDiscoverableRequests(first_request)) | |
98 preloaded_requests = prefetch_view.ExpandRedirectChains( | |
99 prefetch_view.PreloadedRequests(first_request)) | |
100 print '%d requests, %d parser from the main request, %d preloaded' % ( | |
101 len(requests), len(parser_requests), len(preloaded_requests)) | |
102 | |
103 | |
104 def main(filename): | |
105 trace = loading_trace.LoadingTrace.FromJsonFile(filename) | |
106 dependencies_lens = request_dependencies_lens.RequestDependencyLens(trace) | |
107 prefetch_view = PrefetchSimulationView(trace, dependencies_lens) | |
108 _PrintSummary(prefetch_view) | |
109 | |
110 | |
111 if __name__ == '__main__': | |
112 import sys | |
113 main(sys.argv[1]) | |
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