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Side by Side Diff: net/proxy/multi_threaded_proxy_resolver.h

Issue 992733002: Remove //net (except for Android test stuff) and sdch (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 5 years, 9 months ago
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1 // Copyright (c) 2011 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 #ifndef NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
6 #define NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
7
8 #include <deque>
9 #include <vector>
10
11 #include "base/basictypes.h"
12 #include "base/memory/ref_counted.h"
13 #include "base/memory/scoped_ptr.h"
14 #include "base/threading/non_thread_safe.h"
15 #include "net/base/net_export.h"
16 #include "net/proxy/proxy_resolver.h"
17
18 namespace base {
19 class Thread;
20 } // namespace base
21
22 namespace net {
23
24 // ProxyResolverFactory is an interface for creating ProxyResolver instances.
25 class ProxyResolverFactory {
26 public:
27 explicit ProxyResolverFactory(bool resolvers_expect_pac_bytes)
28 : resolvers_expect_pac_bytes_(resolvers_expect_pac_bytes) {}
29
30 virtual ~ProxyResolverFactory() {}
31
32 // Creates a new ProxyResolver. The caller is responsible for freeing this
33 // object.
34 virtual ProxyResolver* CreateProxyResolver() = 0;
35
36 bool resolvers_expect_pac_bytes() const {
37 return resolvers_expect_pac_bytes_;
38 }
39
40 private:
41 bool resolvers_expect_pac_bytes_;
42 DISALLOW_COPY_AND_ASSIGN(ProxyResolverFactory);
43 };
44
45 // MultiThreadedProxyResolver is a ProxyResolver implementation that runs
46 // synchronous ProxyResolver implementations on worker threads.
47 //
48 // Threads are created lazily on demand, up to a maximum total. The advantage
49 // of having a pool of threads, is faster performance. In particular, being
50 // able to keep servicing PAC requests even if one blocks its execution.
51 //
52 // During initialization (SetPacScript), a single thread is spun up to test
53 // the script. If this succeeds, we cache the input script, and will re-use
54 // this to lazily provision any new threads as needed.
55 //
56 // For each new thread that we spawn, a corresponding new ProxyResolver is
57 // created using ProxyResolverFactory.
58 //
59 // Because we are creating multiple ProxyResolver instances, this means we
60 // are duplicating script contexts for what is ordinarily seen as being a
61 // single script. This can affect compatibility on some classes of PAC
62 // script:
63 //
64 // (a) Scripts whose initialization has external dependencies on network or
65 // time may end up successfully initializing on some threads, but not
66 // others. So depending on what thread services the request, the result
67 // may jump between several possibilities.
68 //
69 // (b) Scripts whose FindProxyForURL() depends on side-effects may now
70 // work differently. For example, a PAC script which was incrementing
71 // a global counter and using that to make a decision. In the
72 // multi-threaded model, each thread may have a different value for this
73 // counter, so it won't globally be seen as monotonically increasing!
74 class NET_EXPORT_PRIVATE MultiThreadedProxyResolver
75 : public ProxyResolver,
76 NON_EXPORTED_BASE(public base::NonThreadSafe) {
77 public:
78 // Creates an asynchronous ProxyResolver that runs requests on up to
79 // |max_num_threads|.
80 //
81 // For each thread that is created, an accompanying synchronous ProxyResolver
82 // will be provisioned using |resolver_factory|. All methods on these
83 // ProxyResolvers will be called on the one thread, with the exception of
84 // ProxyResolver::Shutdown() which will be called from the origin thread
85 // prior to destruction.
86 //
87 // The constructor takes ownership of |resolver_factory|.
88 MultiThreadedProxyResolver(ProxyResolverFactory* resolver_factory,
89 size_t max_num_threads);
90
91 ~MultiThreadedProxyResolver() override;
92
93 // ProxyResolver implementation:
94 int GetProxyForURL(const GURL& url,
95 ProxyInfo* results,
96 const CompletionCallback& callback,
97 RequestHandle* request,
98 const BoundNetLog& net_log) override;
99 void CancelRequest(RequestHandle request) override;
100 LoadState GetLoadState(RequestHandle request) const override;
101 void CancelSetPacScript() override;
102 int SetPacScript(const scoped_refptr<ProxyResolverScriptData>& script_data,
103 const CompletionCallback& callback) override;
104
105 private:
106 class Executor;
107 class Job;
108 class SetPacScriptJob;
109 class GetProxyForURLJob;
110 // FIFO queue of pending jobs waiting to be started.
111 // TODO(eroman): Make this priority queue.
112 typedef std::deque<scoped_refptr<Job> > PendingJobsQueue;
113 typedef std::vector<scoped_refptr<Executor> > ExecutorList;
114
115 // Asserts that there are no outstanding user-initiated jobs on any of the
116 // worker threads.
117 void CheckNoOutstandingUserRequests() const;
118
119 // Stops and deletes all of the worker threads.
120 void ReleaseAllExecutors();
121
122 // Returns an idle worker thread which is ready to receive GetProxyForURL()
123 // requests. If all threads are occupied, returns NULL.
124 Executor* FindIdleExecutor();
125
126 // Creates a new worker thread, and appends it to |executors_|.
127 Executor* AddNewExecutor();
128
129 // Starts the next job from |pending_jobs_| if possible.
130 void OnExecutorReady(Executor* executor);
131
132 const scoped_ptr<ProxyResolverFactory> resolver_factory_;
133 const size_t max_num_threads_;
134 PendingJobsQueue pending_jobs_;
135 ExecutorList executors_;
136 scoped_refptr<ProxyResolverScriptData> current_script_data_;
137 };
138
139 } // namespace net
140
141 #endif // NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
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