Re: [pulseaudio-discuss] I want to know about how to communication one module with another module
Hi rong, It is very useful message for me. I am doing a audio server, so I refer the pulseaudio system. -- Best Regards, Zhen Fu -Original Message- From: rong deng [mailto:dzro...@gmail.com] Sent: Wednesday, July 25, 2012 11:21 PM To: General PulseAudio Discussion Cc: Zhen Fu Subject: Re: [pulseaudio-discuss] I want to know about how to communication one module with another module Hi Zhen, 2012/7/24 Zhen Fu f...@marvell.com: Hi all developer, I want to know about how to communication one module with another module. Is it use asyncmg? Thank you! I'm not the expert here, but here's my two cents. :) In theory, two modules should not communicate directly with each other. For a module, the only thing it should care about is the core, and it should communicate with the core, handling the messages from the core etc. As you might know already, pulseaudio takes the thread model, for most of the modules, they would reside in a separate thread, e.g. ALSA. Communicating directly with two methods could be a mess, and even worse, one module is totally unaware when the another module is loaded or not. So the current way, in my humble opinion, is to use the core as a bridge to direct the communication between two modules. That said, the intrinsic question is why you should do this at your first place? :) Maybe there's a chance to skip this ugliness in your design. Thanks! ___ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
Re: [pulseaudio-discuss] I want to know about how to communication one module with another module
Zhen Fu f...@marvell.com writes: Hi guys, Hi rong, It is very useful message for me. I am doing a audio server, so I refer the pulseaudio system. -- Best Regards, Zhen Fu -Original Message- From: rong deng [mailto:dzro...@gmail.com] Sent: Wednesday, July 25, 2012 11:21 PM To: General PulseAudio Discussion Cc: Zhen Fu Subject: Re: [pulseaudio-discuss] I want to know about how to communication one module with another module Hi Zhen, 2012/7/24 Zhen Fu f...@marvell.com: Hi all developer, I want to know about how to communication one module with another module. Is it use asyncmg? Thank you! I'm not the expert here, but here's my two cents. :) In theory, two modules should not communicate directly with each other. For a module, the only thing it should care about is the core, and it should communicate with the core, handling the messages from the core etc. As you might know already, pulseaudio takes the thread model, for most of the modules, they would reside in a separate thread, e.g. ALSA. Communicating directly with two methods could be a mess, and even worse, one module is totally unaware when the another module is loaded or not. So the current way, in my humble opinion, is to use the core as a bridge to direct the communication between two modules. That said, the intrinsic question is why you should do this at your first place? :) Maybe there's a chance to skip this ugliness in your design. Thanks! ___ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss Taking the opportunity, how pa handle two different conflicting modules ? For example, module-role-cork can be used to cork others streams when a stream with the expected role appears, what happens if we've another module that increases the volume when a stream with the same role appears ? Is it responsability of pa or of the user ? Regards, Flavio Ceolin ___ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
[pulseaudio-discuss] I want to know about how to communication one module with another module
Hi all developer, I want to know about how to communication one module with another module. Is it use asyncmg? Thank you! -- Best Regards, Zhen Fu ___ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
Re: [pulseaudio-discuss] I want to know about how to communication one module with another module
Hi Zhen, 2012/7/24 Zhen Fu f...@marvell.com: Hi all developer, I want to know about how to communication one module with another module. Is it use asyncmg? Thank you! I'm not the expert here, but here's my two cents. :) In theory, two modules should not communicate directly with each other. For a module, the only thing it should care about is the core, and it should communicate with the core, handling the messages from the core etc. As you might know already, pulseaudio takes the thread model, for most of the modules, they would reside in a separate thread, e.g. ALSA. Communicating directly with two methods could be a mess, and even worse, one module is totally unaware when the another module is loaded or not. So the current way, in my humble opinion, is to use the core as a bridge to direct the communication between two modules. That said, the intrinsic question is why you should do this at your first place? :) Maybe there's a chance to skip this ugliness in your design. Thanks! ___ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
Re: [pulseaudio-discuss] I want to know about how to communication one module with another module
On Wed, 2012-07-25 at 23:21 +0800, rong deng wrote: Hi Zhen, 2012/7/24 Zhen Fu f...@marvell.com: Hi all developer, I want to know about how to communication one module with another module. Is it use asyncmg? Thank you! No, the asyncmsgq stuff is not a generic inter-module communication method. It's a method for communicating between threads (which may be handled by different modules, though). There's no messaging system specifically for communication between modules. There are different ways to do the communication, depending on what you're doing. I'm not the expert here, but here's my two cents. :) In theory, two modules should not communicate directly with each other. I don't think it's that strict. You're right in asking for the reason for wanting to communicate between modules, though. If it can be avoided in a nice way, then it should be avoided, but there are valid cases where a set of modules need to collaborate using custom interfaces (I'll give some examples later). For a module, the only thing it should care about is the core, and it should communicate with the core, handling the messages from the core etc. As you might know already, pulseaudio takes the thread model, for most of the modules, they would reside in a separate thread, e.g. ALSA. Communicating directly with two methods could be a mess, and even worse, one module is totally unaware when the another module is loaded or not. Threading is created mostly (perhaps even only) in modules that implement sinks and sources. Threads are used there, because the main thread of pulseaudio isn't suitable for real-time audio processing. In other modules (that I believe are actually the majority) the code runs in the main thread. Life is much simpler that way. So the current way, in my humble opinion, is to use the core as a bridge to direct the communication between two modules. That's one way to do it. For example, the native protocol and the D-Bus protocol modules both have a component in pulsecore (src/pulsecore/protocol-native.c and src/pulsecore/protocol-dbus.c) that implement the interfaces for communicating between modules that want to use those protocols and the modules that implement the protocol. The model in this case is to create a reference counted singleton object (pa_native_protocol and pa_dbus_protocol) when any module wants to use that functionality. The singleton object will then exist as long as there are users for it, and it's freed when the last module using it is unloaded. That's a bit ugly in my opinion, because it bloats libpulsecore with non-core things. A similar model is used in the bluetooth modules, for doing interaction between the modules, but there the singleton object (pa_bluetooth_discovery) is not implemented in libpulsecore, but in libbluetooth-util instead. There has been some plans for creating a bit of infrastructure for helping with inter-module communication: http://thread.gmane.org/gmane.comp.audio.pulseaudio.general/9315/focus=9474 I think Frédéric Dalleau planned to start working on this some time ago, but I'm not sure if he had time for it after all. Frédéric, could you clarify the status of this? -- Tanu ___ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
