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Updated implementation description

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Itay Grudev 2015-06-09 17:37:39 +03:00
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README.md
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@ -9,7 +9,7 @@ Usage
-----
The ```SingleApplication``` class inherits from ```QApplication```. Use it as if you are using the ```QApplication``` class.
The library uses your ```Organization Name``` and ```Application Name``` to set up a Local Socket. The first instance of your Application would start a ```QLocalServer``` and then listen for connections on the socket. Every subsequent instance of your application would attempt to connect to that socket. If successful it will be terminated, while in the Primary Instance, ```SingleApplication``` would emmit the ```showUp()``` signal.
The library uses your ```Organization Name``` and ```Application Name``` to set up a ```QLocalServer``` and a ```QSharedMemory``` block. The first instance of your Application would check if the shared memory block exists and if not it will start a ```QLocalServer``` and then listen for connections on it. Each subsequent instance of your application would check if the shared memory block exists and if it does, it will connect to the QLocalServer to notify it that a new instance had been started, after which would terminate the new instance with status code ```0```. The Primary Instance, ```SingleApplication``` would emmit the ```showUp()``` signal upon detecting that a new instance had been started.
The library uses ```stdlib``` to terminate the program with the ```exit()``` function.
@ -54,7 +54,7 @@ Implementation
--------------
The library is implemented with a QSharedMemory block which is thread safe and guarantees a race condition will not occur. It also uses a QLocalSocket to notify the main process that a new instance had been spawned and thus invoke the ```showUp()``` signal.
To handle an issue with Unix systems, where the operating system owns the shared memory block and if the program crashes the memory remains untouched, the library binds to the following signals and closes the program with error code = ```128 + signum``` where signum is the number representation of the signal listed below.
To handle an issue with ```Unix``` systems, where the operating system owns the shared memory block and if the program crashes the memory remains untouched, the library binds to the following signals and closes the program with error code = ```128 + signum``` where signum is the number representation of the signal listed below. Handling the signal is required in order to safely delete the ```QSharedMemory``` block.
* ```SIGINT ``` - ```2```
* ```SIGILL ``` - ```4```