| // Copyright 2011 Google Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // Author: jmaessen@google.com (Jan Maessen) |
| |
| #ifndef PAGESPEED_KERNEL_BASE_CONDVAR_H_ |
| #define PAGESPEED_KERNEL_BASE_CONDVAR_H_ |
| |
| #include "pagespeed/kernel/base/basictypes.h" |
| #include "pagespeed/kernel/base/thread_system.h" |
| |
| namespace net_instaweb { |
| |
| // Abstract interface for implementing a condition variable layered on top of a |
| // given mutex type, which ought to extend CondvarCapableMutex. |
| class ThreadSystem::Condvar { |
| public: |
| Condvar() { } |
| virtual ~Condvar(); |
| |
| // Return the mutex associated with this condition variable. |
| virtual CondvarCapableMutex* mutex() const = 0; |
| |
| // Signal the condvar, waking a waiting thread if any. mutex() must be held |
| // by caller. Example: |
| // { |
| // ScopedMutex lock(cv.mutex()); |
| // make_resource_available(); |
| // cv.Signal(); |
| // } |
| virtual void Signal() = 0; |
| |
| // Broadcast to all threads waiting on condvar. mutex() must be held as with |
| // Signal(). |
| virtual void Broadcast() = 0; |
| |
| // Wait for condition to be signaled. mutex() must be held; it will |
| // be released and then reclaimed when a signal is received. Note |
| // that a Wait() may be terminated based on a condition being true, |
| // but the condition may no longer be true at the time the thread |
| // wakes up. Example: |
| // { |
| // ScopedMutex lock(cv.mutex()); |
| // while (status && !resource_available()) status = cv.wait(); |
| // if (status) { |
| // use_resource(); |
| // } |
| // } |
| virtual void Wait() = 0; |
| |
| // Wait for condition to be signaled, or timeout to occur. Works like Wait(), |
| // and cv.mutex() must be held on entry and re-taken on exit. |
| virtual void TimedWait(int64 timeout_ms) = 0; |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(Condvar); |
| }; |
| |
| } // namespace net_instaweb |
| |
| #endif // PAGESPEED_KERNEL_BASE_CONDVAR_H_ |