chenBright commented on code in PR #2560:
URL: https://github.com/apache/brpc/pull/2560#discussion_r1546266286
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src/brpc/event_dispatcher.h:
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@@ -21,11 +21,74 @@
#include "butil/macros.h" // DISALLOW_COPY_AND_ASSIGN
#include "bthread/types.h" // bthread_t, bthread_attr_t
-#include "brpc/socket.h" // Socket, SocketId
+#include "brpc/versioned_ref_with_id.h"
namespace brpc {
+// Unique identifier of a EventData.
+// Users shall store EventDataId instead of EventData and call
EventData::Address()
+// to convert the identifier to an unique_ptr at each access. Whenever a
+// unique_ptr is not destructed, the enclosed EventData will not be recycled.
+typedef VRefId EventDataId;
+
+const VRefId INVALID_EVENT_DATA_ID = INVALID_VREF_ID;
+
+class EventData;
+
+typedef VersionedRefWithIdUniquePtr<EventData> EventDataUniquePtr;
+
+// User callback type of input event and output event.
+typedef int (*InputEventCallback) (VRefId id, uint32_t events,
+ const bthread_attr_t& thread_attr);
+typedef InputEventCallback OutputEventCallback;
+
+struct EventDataOptions {
+ // Find user object to handle event by `user_id'.
+ uint64_t user_id;
+ // Callback for input event.
+ InputEventCallback input_cb;
+ // Callback for output event.
+ OutputEventCallback output_cb;
+};
+
+// EventDispatcher finds EventData by EventDataId which is
+// stored in epoll/kqueue data, and calls its callback, so
+// EventDispatcher supports various IO types, such as socket,
+// pipe, eventfd, timerfd, etc.
+class EventData : public VersionedRefWithId<EventData> {
+public:
+ explicit EventData(Forbidden f)
+ : VersionedRefWithId<EventData>(f)
+ , _options{INVALID_EVENT_DATA_ID, NULL, NULL} {}
+
+ DISALLOW_COPY_AND_ASSIGN(EventData);
+
+ int CallInputEventCallback(uint32_t events,
Review Comment:
有两种实现：
1. `class Socket : public VersionedRefWithId<Socket>, public EventData`。
因为要支持多个IO类型，那么处理事件时，没有类型信息，不知道id是哪种IO类型的id，没法Address出正确的IO类型对象。除非EventDispatcher在事件注册时，记录了注册对象的类型信息。当前实现中，EventData算是一种间接记录类型信息（函数指针）的方式，屏蔽了不同IO类型Address的差异吧。
2. `class EventData : public VersionedRefWithId<EventData>`、`class Socket :
public EventData`。
不同IO类型统一使用EventDataId作为id，在EventDispatcher有统一的Address方式。不同IO类型实现各自的CallInputEventCallback和CallOutputEventCallback两个虚函数即可。
这种实现有另外的问题，例如SocketUniquePtr，无法作为Address等需要UniquePtr参数的接口，因为这些接口推导出的参数类型是EventDataUniquePtr。要解决这个问题，Socket需要实现自己的Address函数，并在内部Address到EventDataUniquePtr后再转成SocketUniquePtr。
以上两种继承EventData的方式，有各自的问题，算不上是好的解决方案。
综上，我认为目前EventData的使用方式，兼容性好一点，改动量也不大。
@wwbmmm EventData这一块，有什么好的建议？
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