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@@ -1,5 +1,5 @@ -SingleApplication -================= +# SingleApplication + [](https://github.com/itay-grudev/SingleApplication/actions) This is a replacement of the QtSingleApplication for `Qt5` and `Qt6`. @@ -8,8 +8,7 @@ Keeps the Primary Instance of your Application and kills each subsequent instances. It can (if enabled) spawn secondary (non-related to the primary) instances and can send data to the primary instance from secondary instances. -Usage ------ +## Usage The `SingleApplication` class inherits from whatever `Q[Core|Gui]Application` class you specify via the `QAPPLICATION_CLASS` macro (`QCoreApplication` is the @@ -57,7 +56,6 @@ add_subdirectory(src/third-party/singleapplication) target_link_libraries(${PROJECT_NAME} SingleApplication::SingleApplication) ``` - The library sets up a `QLocalServer` and a `QSharedMemory` block. The first instance of your Application is your Primary Instance. It would check if the shared memory block exists and if not it will start a `QLocalServer` and listen @@ -73,10 +71,9 @@ The library uses `stdlib` to terminate the program with the `exit()` function. Also don't forget to specify which `QCoreApplication` class your app is using if it is not `QCoreApplication` as in examples above. -The `Instance Started` signal ------------------------------ +## Instance started signal -The SingleApplication class implements a `instanceStarted()` signal. You can +The `SingleApplication` class implements a `instanceStarted()` signal. You can bind to that signal to raise your application's window when a new instance had been started, for example. @@ -94,13 +91,12 @@ Using `SingleApplication::instance()` is a neat way to get the `SingleApplication` instance for binding to it's signals anywhere in your program. -__Note:__ On Windows the ability to bring the application windows to the +_Note:_ On Windows the ability to bring the application windows to the foreground is restricted. See [Windows specific implementations](Windows.md) for a workaround and an example implementation. -Secondary Instances -------------------- +## Secondary Instances If you want to be able to launch additional Secondary Instances (not related to your Primary Instance) you have to enable that with the third parameter of the @@ -123,7 +119,7 @@ int main(int argc, char *argv[]) } ``` -*__Note:__ A secondary instance won't cause the emission of the +_Note:_ A secondary instance won't cause the emission of the `instanceStarted()` signal by default. See `SingleApplication::Mode` for more details.* @@ -136,11 +132,10 @@ app.isPrimary(); app.isSecondary(); ``` -*__Note:__ If your Primary Instance is terminated a newly launched instance +_Note:_ If your Primary Instance is terminated a newly launched instance will replace the Primary one even if the Secondary flag has been set.* -Examples --------- +## Examples There are three examples provided in this repository: @@ -148,149 +143,18 @@ There are three examples provided in this repository: * An example of a graphical application raising it's parent window [`examples/calculator`](https://github.com/itay-grudev/SingleApplication/tree/master/examples/calculator) * A console application sending the primary instance it's command line parameters [`examples/sending_arguments`](https://github.com/itay-grudev/SingleApplication/tree/master/examples/sending_arguments) -API ---- - -### Members - -```cpp -SingleApplication::SingleApplication( int &argc, char *argv[], bool allowSecondary = false, Options options = Mode::User, int timeout = 100, QString userData = QString() ) -``` - -Depending on whether `allowSecondary` is set, this constructor may terminate -your app if there is already a primary instance running. Additional `Options` -can be specified to set whether the SingleApplication block should work -user-wide or system-wide. Additionally the `Mode::SecondaryNotification` may be -used to notify the primary instance whenever a secondary instance had been -started (disabled by default). `timeout` specifies the maximum time in -milliseconds to wait for blocking operations. Setting `userData` provides additional data that will isolate this instance from other instances that do not have the same (or any) user data set. - -*__Note:__ `argc` and `argv` may be changed as Qt removes arguments that it -recognizes.* - -*__Note:__ `Mode::SecondaryNotification` only works if set on both the primary -and the secondary instance.* - -*__Note:__ Operating system can restrict the shared memory blocks to the same -user, in which case the User/System modes will have no effect and the block will -be user wide.* - ---- - -```cpp -bool SingleApplication::sendMessage( QByteArray message, int timeout = 100 ) -``` - -Sends `message` to the Primary Instance. Uses `timeout` as a the maximum timeout -in milliseconds for blocking functions. Returns `true` if the message has been sent -successfully. If the message can't be sent or the function timeouts - returns `false`. - ---- - -```cpp -bool SingleApplication::isPrimary() -``` - -Returns if the instance is the primary instance. - ---- - -```cpp -bool SingleApplication::isSecondary() -``` -Returns if the instance is a secondary instance. - ---- - -```cpp -quint32 SingleApplication::instanceId() -``` - -Returns a unique identifier for the current instance. - ---- - -```cpp -qint64 SingleApplication::primaryPid() -``` - -Returns the process ID (PID) of the primary instance. - ---- - -```cpp -QString SingleApplication::primaryUser() -``` - -Returns the username the primary instance is running as. - ---- - -```cpp -QString SingleApplication::currentUser() -``` - -Returns the username the current instance is running as. - -### Signals - -```cpp -void SingleApplication::instanceStarted() -``` - -Triggered whenever a new instance had been started, except for secondary -instances if the `Mode::SecondaryNotification` flag is not specified. - ---- - -```cpp -void SingleApplication::receivedMessage( quint32 instanceId, QByteArray message ) -``` - -Triggered whenever there is a message received from a secondary instance. - ---- - -### Flags - -```cpp -enum SingleApplication::Mode -``` - -* `Mode::User` - The SingleApplication block should apply user wide. This adds - user specific data to the key used for the shared memory and server name. - This is the default functionality. -* `Mode::System` – The SingleApplication block applies system-wide. -* `Mode::SecondaryNotification` – Whether to trigger `instanceStarted()` even - whenever secondary instances are started. -* `Mode::ExcludeAppPath` – Excludes the application path from the server name - (and memory block) hash. -* `Mode::ExcludeAppVersion` – Excludes the application version from the server - name (and memory block) hash. - -*__Note:__ `Mode::SecondaryNotification` only works if set on both the primary -and the secondary instance.* - -*__Note:__ Operating system can restrict the shared memory blocks to the same -user, in which case the User/System modes will have no effect and the block will -be user wide.* - ---- - -Versioning ----------- +## Versioning Each major version introduces either very significant changes or is not backwards compatible with the previous version. Minor versions only add additional features, bug fixes or performance improvements and are backwards -compatible with the previous release. See [`CHANGELOG.md`](CHANGELOG.md) for +compatible with the previous release. See [CHANGELOG.md](CHANGELOG.md) for more details. -Implementation --------------- +## 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 +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 `instanceStarted()` signal and for messaging the primary instance. @@ -298,8 +162,8 @@ Additionally the library can recover from being forcefully killed on *nix systems and will reset the memory block given that there are no other instances running. -License -------- +## License + This library and it's supporting documentation are released under `The MIT License (MIT)` with the exception of the Qt calculator examples which is distributed under the BSD license. |