// Copyright 2008, Google Inc. // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // This file supports network stack independent notification of progress // towards resolving a hostname. #include #include #include "net/base/dns_resolution_observer.h" #include "base/logging.h" namespace net { static DnsResolutionObserver* dns_resolution_observer; void AddDnsResolutionObserver(DnsResolutionObserver* new_observer) { if (new_observer == dns_resolution_observer) return; // Facilitate unit tests that init/teardown repeatedly. DCHECK(!dns_resolution_observer); if (InterlockedCompareExchangePointer( reinterpret_cast(&dns_resolution_observer), new_observer, NULL)) DCHECK(0) << "Second attempt to setup observer"; } DnsResolutionObserver* RemoveDnsResolutionObserver() { // We really need to check that the entire network subsystem is shutting down, // and hence no additional calls can even *possibly* still be lingering in the // notification path that includes our observer. Until we have a way to // really assert that fact, we will outlaw the calling of this function. // Darin suggested that the caller use a static initializer for the observer, // so that it can safely be destroyed after process termination, and without // inducing a memory leak. // Bottom line: Don't call this function! You will crash for now. CHECK(0); DnsResolutionObserver* old_observer = dns_resolution_observer; dns_resolution_observer = NULL; return old_observer; } // Locking access to dns_resolution_observer is not really critical... but we // should test the value of dns_resolution_observer that we use. // Worst case, we'll get an "out of date" value... which is no big deal for the // DNS prefetching system (the most common (only?) observer). void DidStartDnsResolution(const std::string& name, void* context) { DnsResolutionObserver* current_observer = dns_resolution_observer; if (current_observer) current_observer->OnStartResolution(name, context); } void DidFinishDnsResolutionWithStatus(bool was_resolved, void* context) { DnsResolutionObserver* current_observer = dns_resolution_observer; if (current_observer) { current_observer->OnFinishResolutionWithStatus(was_resolved, context); } } } // namspace net