| // Copyright 2016 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: cheesy@google.com (Steve Hill) |
| |
| #ifndef PAGESPEED_SYSTEM_CONTROLLER_PROCESS_H_ |
| #define PAGESPEED_SYSTEM_CONTROLLER_PROCESS_H_ |
| |
| #include "base/macros.h" |
| |
| namespace net_instaweb { |
| |
| // Abstract class for delegating work to ControllerManager. All of the following |
| // is performed in the child process. If the child dies with a non-zero exit |
| // status, the babysitter will restart it. |
| // |
| // The ControllerManager will first invoke Setup(). If that returns non-zero, |
| // the forked process will immediately exit using that return code. |
| // Otherwise, the ControllerManager starts a thread monitoring for parent death |
| // and invokes Run(). This means Run() and Stop() may be invoked in any order |
| // and will be invoked from different threads. The child will exit with the |
| // return value of Run() unless Stop() is called (see below). |
| // |
| // Note that in the process from which ForkControllerProcess is invoked, this |
| // object will be created and then destroyed without any of the methods being |
| // invoked. |
| |
| class ControllerProcess { |
| public: |
| ControllerProcess() {} |
| virtual ~ControllerProcess() {} |
| |
| // Perform any required setup actions. We don't respond to the death of the |
| // Apache/Nginx process that spawned us until Setup() returns, so should not |
| // spin waiting for a resource. Returns exit status. |
| virtual int Setup() { return 0; } |
| |
| // Perform your work and return the exit status. Invoked only if Setup() |
| // returns 0. Stop() may be called before Run(), in which case Run() should |
| // return immediately. |
| // |
| // The babysitter respawns the child whenever it dies for any reason other |
| // than exit(0). Thus, if the child is dying because it was asked to by the |
| // parent process (ie: Stop() was called) the return value of Run() is ignored |
| // and an exit status of 0 will be used. |
| virtual int Run() = 0; |
| |
| // Notify the Run() thread to stop. Called from a different thread so must be |
| // thread safe. May be called before, during or after Run(), possibly multiple |
| // times. |
| virtual void Stop() = 0; |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(ControllerProcess); |
| }; |
| |
| } // namespace net_instaweb |
| |
| #endif // PAGESPEED_SYSTEM_CONTROLLER_PROCESS_H_ |