hphp/runtime/server/takeover-agent.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16
  17 #ifndef incl_HPHP_HTTP_SERVER_TAKEOVER_AGENT_H_
  18 #define incl_HPHP_HTTP_SERVER_TAKEOVER_AGENT_H_
  19
  20 #include <event.h>
  21
  22 #include <chrono>
  23 #include <set>
  24 #include <string>
  25
  26 #include "hphp/runtime/base/type-string.h"
  27
  28 namespace HPHP {
  29 ///////////////////////////////////////////////////////////////////////////////
  30
  31 /**
  32  * A callback to be informed when a server is shutting down because its socket
  33  * has been taken over by a new process.
  34  */
  35 struct TakeoverListener {
  36   virtual ~TakeoverListener();
  37   virtual void takeoverShutdown() = 0;
  38 };
  39
  40
  41 /**
  42  * Agent with the ability to take over an accept socket
  43  * from another process, and give its accept socket up.
  44  */
  45 struct TakeoverAgent {
  46   enum class RequestType {
  47     LISTEN_SOCKET,
  48     TERMINATE,
  49    };
  50
  51   struct Callback {
  52     virtual ~Callback() {}
  53     // Called by the TakeoverAgent when it receives a request for takeover
  54     // Returns non zero on error, which terminates the takeover action
  55     virtual int onTakeoverRequest(RequestType type) = 0;
  56
  57     // Called by the TakeoverAgent when it is shutdown mid-way through a
  58     // takeover.
  59     virtual void takeoverAborted() = 0;
  60   };
  61
  62   explicit TakeoverAgent(const std::string &fname);
  63
  64   // execute a takeover and return the fd.  -1 if an fd could not be acquired
  65   int takeover(std::chrono::seconds timeout = std::chrono::seconds(2));
  66
  67   // instruct the old server to shutdown
  68   void requestShutdown();
  69
  70   // setup a server to listen for takeover requests
  71   int setupFdServer(event_base *eventBase, int sock, Callback *callback);
  72
  73   // stop the takeover agent, including in-progress takeovers
  74   void stop();
  75
  76   void addTakeoverListener(TakeoverListener* listener) {
  77     m_takeover_listeners.insert(listener);
  78   }
  79   void removeTakeoverListener(TakeoverListener* listener) {
  80     m_takeover_listeners.erase(listener);
  81   }
  82
  83   // These are public so they can be called from a C-style callback.
  84   // They are not a part of the public interface.
  85   void afdtResponse(String response, int fd);
  86   int afdtRequest(String request, String* response);
  87
  88 protected:
  89
  90   enum class TakeoverState {
  91     NotStarted,
  92     Started,
  93     Complete,
  94    };
  95
  96   void notifyTakeoverComplete();
  97
  98   void* m_delete_handle;
  99   std::string m_transfer_fname;
 100   std::set<TakeoverListener*> m_takeover_listeners;
 101
 102   // Was this server initiated with a socket from another server?
 103   bool m_took_over;
 104
 105   // The state of taking over this server's socket
 106   TakeoverState m_takeover_state;
 107
 108   // Target socket
 109   int m_sock{-1};
 110
 111   // User callback for events
 112   Callback *m_callback{nullptr};
 113 };
 114
 115 ///////////////////////////////////////////////////////////////////////////////
 116 }
 117
 118 #endif // incl_HPHP_HTTP_SERVER_TAKEOVER_AGENT_H_