How does the computer implement callbacks?
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I already know the general usage of callback. First,I register a "callback function",when some event occur,this function will be triggered(be executed). What confuses me is how do I know if the event is occur? The solution I can get is polling.Is there a better way to check whether the event occur in less than the O(n) time ?
All right,Maybe the above question is too abstract.A more realistic description is does epoll_wait() avoid using O(n) time to check whether the ready file descriptor?
If so, how did it do it? Is there a callback mechanism that is different from polling essentially?
linux
asked Mar 12 at 12:01
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1
add a comment |
I already know the general usage of callback. First,I register a "callback function",when some event occur,this function will be triggered(be executed). What confuses me is how do I know if the event is occur? The solution I can get is polling.Is there a better way to check whether the event occur in less than the O(n) time ?
All right,Maybe the above question is too abstract.A more realistic description is does epoll_wait() avoid using O(n) time to check whether the ready file descriptor?
If so, how did it do it? Is there a callback mechanism that is different from polling essentially?
linux
asked Mar 12 at 12:01
薛多多薛多多
1
Any code for example? Did you mean function pointer?
– Biswapriyo
Mar 12 at 12:49
add a comment |
I already know the general usage of callback. First,I register a "callback function",when some event occur,this function will be triggered(be executed). What confuses me is how do I know if the event is occur? The solution I can get is polling.Is there a better way to check whether the event occur in less than the O(n) time ?
All right,Maybe the above question is too abstract.A more realistic description is does epoll_wait() avoid using O(n) time to check whether the ready file descriptor?
If so, how did it do it? Is there a callback mechanism that is different from polling essentially?
linux
asked Mar 12 at 12:01
薛多多薛多多
1
I already know the general usage of callback. First,I register a "callback function",when some event occur,this function will be triggered(be executed). What confuses me is how do I know if the event is occur? The solution I can get is polling.Is there a better way to check whether the event occur in less than the O(n) time ?
All right,Maybe the above question is too abstract.A more realistic description is does epoll_wait() avoid using O(n) time to check whether the ready file descriptor?
If so, how did it do it? Is there a callback mechanism that is different from polling essentially?
linux
linux
asked Mar 12 at 12:01
薛多多薛多多
1
asked Mar 12 at 12:01
薛多多薛多多
1
asked Mar 12 at 12:01
薛多多薛多多
1
asked Mar 12 at 12:01
薛多多薛多多
1
asked Mar 12 at 12:01
薛多多薛多多
1
1
Any code for example? Did you mean function pointer?
– Biswapriyo
Mar 12 at 12:49
add a comment |
Any code for example? Did you mean function pointer?
– Biswapriyo
Mar 12 at 12:49
Any code for example? Did you mean function pointer?
– Biswapriyo
Mar 12 at 12:49
Any code for example? Did you mean function pointer?
– Biswapriyo
Mar 12 at 12:49
add a comment |
1 Answer
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In a typical event-driven interface, a callback function does not poll to wait on an event. It is simply made known to the event manager. In a simple implementation, an object will have a set of events associated with it, and each of this object's events will have a function pointer (or a list thereof) that will be called when that event is processed.
answered Mar 12 at 13:39
FoxFox
5,75211233
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In a typical event-driven interface, a callback function does not poll to wait on an event. It is simply made known to the event manager. In a simple implementation, an object will have a set of events associated with it, and each of this object's events will have a function pointer (or a list thereof) that will be called when that event is processed.
answered Mar 12 at 13:39
FoxFox
5,75211233
add a comment |
In a typical event-driven interface, a callback function does not poll to wait on an event. It is simply made known to the event manager. In a simple implementation, an object will have a set of events associated with it, and each of this object's events will have a function pointer (or a list thereof) that will be called when that event is processed.
answered Mar 12 at 13:39
FoxFox
5,75211233
add a comment |
In a typical event-driven interface, a callback function does not poll to wait on an event. It is simply made known to the event manager. In a simple implementation, an object will have a set of events associated with it, and each of this object's events will have a function pointer (or a list thereof) that will be called when that event is processed.
answered Mar 12 at 13:39
FoxFox
5,75211233
In a typical event-driven interface, a callback function does not poll to wait on an event. It is simply made known to the event manager. In a simple implementation, an object will have a set of events associated with it, and each of this object's events will have a function pointer (or a list thereof) that will be called when that event is processed.
answered Mar 12 at 13:39
FoxFox
5,75211233
answered Mar 12 at 13:39
FoxFox
5,75211233
answered Mar 12 at 13:39
FoxFox
5,75211233
answered Mar 12 at 13:39
FoxFox
5,75211233
5,75211233
add a comment |
add a comment |
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Any code for example? Did you mean function pointer?
– Biswapriyo
Mar 12 at 12:49