Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include <cstdint>
       4             : #include <functional>
       5             : #include <memory>
       6             : 
       7             : #include "envoy/common/pure.h"
       8             : 
       9             : namespace Envoy {
      10             : namespace Event {
      11             : 
      12             : struct FileReadyType {
      13             :   // File is ready for reading.
      14             :   static constexpr uint32_t Read = 0x1;
      15             :   // File is ready for writing.
      16             :   static constexpr uint32_t Write = 0x2;
      17             :   // File has been remote closed.
      18             :   static constexpr uint32_t Closed = 0x4;
      19             : };
      20             : 
      21             : enum class FileTriggerType {
      22             :   // See @man 7 epoll(7)
      23             :   // They are used on all platforms for DNS and TCP listeners.
      24             :   Level,
      25             :   // See @man 7 epoll(7)
      26             :   // They are used on all platforms that support Edge triggering as the default trigger type.
      27             :   Edge,
      28             :   // These are synthetic edge events managed by Envoy. They are based on level events and when they
      29             :   // are activated they are immediately disabled. This makes them behave like Edge events. Then it
      30             :   // is is the responsibility of the consumer of the event to reactivate the event
      31             :   // when the socket operation would block.
      32             :   //
      33             :   // Their main application in Envoy is for Win32 which does not support edge-triggered events. They
      34             :   // should be used in Win32 instead of level events. They can only be used in platforms where
      35             :   // `PlatformDefaultTriggerType` is `FileTriggerType::EmulatedEdge`.
      36             :   EmulatedEdge
      37             : };
      38             : 
      39             : // For POSIX developers to get the Windows behavior of file events
      40             : // you need to add the following definition:
      41             : // `FORCE_LEVEL_EVENTS`
      42             : // You can do this with bazel if you add the following build/test options
      43             : // `--copt="-DFORCE_LEVEL_EVENTS"`
      44           0 : constexpr FileTriggerType determinePlatformPreferredEventType() {
      45           0 : #if defined(WIN32) || defined(FORCE_LEVEL_EVENTS)
      46           0 :   return FileTriggerType::EmulatedEdge;
      47           0 : #else
      48           0 :   return FileTriggerType::Edge;
      49           0 : #endif
      50           0 : }
      51             : 
      52             : static constexpr FileTriggerType PlatformDefaultTriggerType = determinePlatformPreferredEventType();
      53             : 
      54             : /**
      55             :  * Callback invoked when a FileEvent is ready for reading or writing.
      56             :  */
      57             : using FileReadyCb = std::function<void(uint32_t events)>;
      58             : 
      59             : /**
      60             :  * Wrapper for file based (read/write) event notifications.
      61             :  */
      62             : class FileEvent {
      63             : public:
      64        3411 :   virtual ~FileEvent() = default;
      65             : 
      66             :   /**
      67             :    * Activate the file event explicitly for a set of events. Should be a logical OR of FileReadyType
      68             :    * events. This method "injects" the event (and fires callbacks) regardless of whether the event
      69             :    * is actually ready on the underlying file.
      70             :    */
      71             :   virtual void activate(uint32_t events) PURE;
      72             : 
      73             :   /**
      74             :    * Enable the file event explicitly for a set of events. Should be a logical OR of FileReadyType
      75             :    * events. As opposed to activate(), this routine causes the file event to listen for the
      76             :    * registered events and fire callbacks when they are active.
      77             :    */
      78             :   virtual void setEnabled(uint32_t events) PURE;
      79             : 
      80             :   /**
      81             :    * Add a single event from the event registration mark.
      82             :    */
      83             :   virtual void registerEventIfEmulatedEdge(uint32_t event) PURE;
      84             : 
      85             :   /**
      86             :    * Remove a single event from the event registration mark.
      87             :    */
      88             :   virtual void unregisterEventIfEmulatedEdge(uint32_t event) PURE;
      89             : };
      90             : 
      91             : using FileEventPtr = std::unique_ptr<FileEvent>;
      92             : 
      93             : } // namespace Event
      94             : } // namespace Envoy