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| 1 // Copyright (c) 2012 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 #include "net/base/host_resolver.h" | |
| 6 | |
| 7 #include "base/logging.h" | |
| 8 #include "base/metrics/field_trial.h" | |
| 9 #include "base/string_number_conversions.h" | |
| 10 #include "base/strings/string_split.h" | |
| 11 #include "net/base/host_cache.h" | |
| 12 #include "net/base/host_resolver_impl.h" | |
| 13 #include "net/dns/dns_client.h" | |
| 14 #include "net/dns/dns_config_service.h" | |
| 15 | |
| 16 namespace net { | |
| 17 | |
| 18 namespace { | |
| 19 | |
| 20 // Maximum of 6 concurrent resolver threads (excluding retries). | |
| 21 // Some routers (or resolvers) appear to start to provide host-not-found if | |
| 22 // too many simultaneous resolutions are pending. This number needs to be | |
| 23 // further optimized, but 8 is what FF currently does. We found some routers | |
| 24 // that limit this to 6, so we're temporarily holding it at that level. | |
| 25 const size_t kDefaultMaxProcTasks = 6u; | |
| 26 | |
| 27 // When configuring from field trial, do not allow | |
| 28 const size_t kSaneMaxProcTasks = 20u; | |
| 29 | |
| 30 PrioritizedDispatcher::Limits GetDispatcherLimits( | |
| 31 const HostResolver::Options& options) { | |
| 32 PrioritizedDispatcher::Limits limits(NUM_PRIORITIES, | |
| 33 options.max_concurrent_resolves); | |
| 34 | |
| 35 // If not using default, do not use the field trial. | |
| 36 if (limits.total_jobs != HostResolver::kDefaultParallelism) | |
| 37 return limits; | |
| 38 | |
| 39 // Default, without trial is no reserved slots. | |
| 40 limits.total_jobs = kDefaultMaxProcTasks; | |
| 41 | |
| 42 // Parallelism is determined by the field trial. | |
| 43 std::string group = base::FieldTrialList::FindFullName( | |
| 44 "HostResolverDispatch"); | |
| 45 | |
| 46 if (group.empty()) | |
| 47 return limits; | |
| 48 | |
| 49 // The format of the group name is a list of non-negative integers separated | |
| 50 // by ':'. Each of the elements in the list corresponds to an element in | |
| 51 // |reserved_slots|, except the last one which is the |total_jobs|. | |
| 52 | |
| 53 std::vector<std::string> group_parts; | |
| 54 base::SplitString(group, ':', &group_parts); | |
| 55 if (group_parts.size() != NUM_PRIORITIES + 1) { | |
| 56 NOTREACHED(); | |
| 57 return limits; | |
| 58 } | |
| 59 | |
| 60 std::vector<size_t> parsed(group_parts.size()); | |
| 61 size_t total_reserved_slots = 0; | |
| 62 | |
| 63 for (size_t i = 0; i < group_parts.size(); ++i) { | |
| 64 if (!base::StringToSizeT(group_parts[i], &parsed[i])) { | |
| 65 NOTREACHED(); | |
| 66 return limits; | |
| 67 } | |
| 68 } | |
| 69 | |
| 70 size_t total_jobs = parsed.back(); | |
| 71 parsed.pop_back(); | |
| 72 for (size_t i = 0; i < parsed.size(); ++i) { | |
| 73 total_reserved_slots += parsed[i]; | |
| 74 } | |
| 75 | |
| 76 // There must be some unreserved slots available for the all priorities. | |
| 77 if (total_reserved_slots > total_jobs || | |
| 78 (total_reserved_slots == total_jobs && parsed[MINIMUM_PRIORITY] == 0)) { | |
| 79 NOTREACHED(); | |
| 80 return limits; | |
| 81 } | |
| 82 | |
| 83 limits.total_jobs = total_jobs; | |
| 84 limits.reserved_slots = parsed; | |
| 85 return limits; | |
| 86 } | |
| 87 | |
| 88 } // namespace | |
| 89 | |
| 90 HostResolver::Options::Options() | |
| 91 : max_concurrent_resolves(kDefaultParallelism), | |
| 92 max_retry_attempts(kDefaultRetryAttempts), | |
| 93 enable_caching(true) { | |
| 94 } | |
| 95 | |
| 96 HostResolver::RequestInfo::RequestInfo(const HostPortPair& host_port_pair) | |
| 97 : host_port_pair_(host_port_pair), | |
| 98 address_family_(ADDRESS_FAMILY_UNSPECIFIED), | |
| 99 host_resolver_flags_(0), | |
| 100 allow_cached_response_(true), | |
| 101 is_speculative_(false), | |
| 102 priority_(MEDIUM) { | |
| 103 } | |
| 104 | |
| 105 HostResolver::~HostResolver() { | |
| 106 } | |
| 107 | |
| 108 AddressFamily HostResolver::GetDefaultAddressFamily() const { | |
| 109 return ADDRESS_FAMILY_UNSPECIFIED; | |
| 110 } | |
| 111 | |
| 112 void HostResolver::ProbeIPv6Support() { | |
| 113 } | |
| 114 | |
| 115 void HostResolver::SetDnsClientEnabled(bool enabled) { | |
| 116 } | |
| 117 | |
| 118 HostCache* HostResolver::GetHostCache() { | |
| 119 return NULL; | |
| 120 } | |
| 121 | |
| 122 base::Value* HostResolver::GetDnsConfigAsValue() const { | |
| 123 return NULL; | |
| 124 } | |
| 125 | |
| 126 // static | |
| 127 scoped_ptr<HostResolver> | |
| 128 HostResolver::CreateSystemResolver(const Options& options, NetLog* net_log) { | |
| 129 scoped_ptr<HostCache> cache; | |
| 130 if (options.enable_caching) | |
| 131 cache = HostCache::CreateDefaultCache(); | |
| 132 return scoped_ptr<HostResolver>(new HostResolverImpl( | |
| 133 cache.Pass(), | |
| 134 GetDispatcherLimits(options), | |
| 135 HostResolverImpl::ProcTaskParams(NULL, options.max_retry_attempts), | |
| 136 net_log)); | |
| 137 } | |
| 138 | |
| 139 // static | |
| 140 scoped_ptr<HostResolver> | |
| 141 HostResolver::CreateDefaultResolver(NetLog* net_log) { | |
| 142 return CreateSystemResolver(Options(), net_log); | |
| 143 } | |
| 144 | |
| 145 HostResolver::HostResolver() { | |
| 146 } | |
| 147 | |
| 148 } // namespace net | |
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Chromium Code Reviews
Issue 12518036:
net: move host_resolver files from net/base to net/dns (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src