201 lines
8.6 KiB
C
201 lines
8.6 KiB
C
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/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2020 - Raw Material Software Limited
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JUCE is an open source library subject to commercial or open-source
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licensing.
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The code included in this file is provided under the terms of the ISC license
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http://www.isc.org/downloads/software-support-policy/isc-license. Permission
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To use, copy, modify, and/or distribute this software for any purpose with or
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without fee is hereby granted provided that the above copyright notice and
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this permission notice appear in all copies.
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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//==============================================================================
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/**
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Acts as the slave end of a master/slave pair of connected processes.
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The ChildProcessSlave and ChildProcessMaster classes make it easy for an app
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to spawn a child process, and to manage a 2-way messaging connection to control it.
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To use the system, you need to create subclasses of both ChildProcessSlave and
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ChildProcessMaster. To instantiate the ChildProcessSlave object, you must
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add some code to your main() or JUCEApplication::initialise() function that
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calls the initialiseFromCommandLine() method to check the app's command-line
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parameters to see whether it's being launched as a child process. If this returns
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true then the slave process can be allowed to run, and its handleMessageFromMaster()
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method will be called whenever a message arrives.
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The juce demo app has a good example of this class in action.
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@see ChildProcessMaster, InterprocessConnection, ChildProcess
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@tags{Events}
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*/
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class JUCE_API ChildProcessSlave
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{
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public:
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/** Creates a non-connected slave process.
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Use initialiseFromCommandLine to connect to a master process.
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*/
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ChildProcessSlave();
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/** Destructor. */
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virtual ~ChildProcessSlave();
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/** This checks some command-line parameters to see whether they were generated by
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ChildProcessMaster::launchSlaveProcess(), and if so, connects to that master process.
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In an exe that can be used as a child process, you should add some code to your
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main() or JUCEApplication::initialise() that calls this method.
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The commandLineUniqueID should be a short alphanumeric identifier (no spaces!)
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that matches the string passed to ChildProcessMaster::launchSlaveProcess().
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The timeoutMs parameter lets you specify how long the child process is allowed
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to run without receiving a ping from the master before the master is considered to
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have died, and handleConnectionLost() will be called. Passing <= 0 for this timeout
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makes it use a default value.
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Returns true if the command-line matches and the connection is made successfully.
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*/
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bool initialiseFromCommandLine (const String& commandLine,
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const String& commandLineUniqueID,
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int timeoutMs = 0);
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//==============================================================================
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/** This will be called to deliver messages from the master process.
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The call will probably be made on a background thread, so be careful with your
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thread-safety! You may want to respond by sending back a message with
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sendMessageToMaster()
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*/
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virtual void handleMessageFromMaster (const MemoryBlock&) = 0;
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/** This will be called when the master process finishes connecting to this slave.
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The call will probably be made on a background thread, so be careful with your thread-safety!
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*/
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virtual void handleConnectionMade();
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/** This will be called when the connection to the master process is lost.
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The call may be made from any thread (including the message thread).
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Typically, if your process only exists to act as a slave, you should probably exit
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when this happens.
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*/
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virtual void handleConnectionLost();
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/** Tries to send a message to the master process.
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This returns true if the message was sent, but doesn't check that it actually gets
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delivered at the other end. If successful, the data will emerge in a call to your
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ChildProcessMaster::handleMessageFromSlave().
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*/
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bool sendMessageToMaster (const MemoryBlock&);
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private:
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struct Connection;
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std::unique_ptr<Connection> connection;
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JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ChildProcessSlave)
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};
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//==============================================================================
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/**
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Acts as the master in a master/slave pair of connected processes.
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The ChildProcessSlave and ChildProcessMaster classes make it easy for an app
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to spawn a child process, and to manage a 2-way messaging connection to control it.
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To use the system, you need to create subclasses of both ChildProcessSlave and
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ChildProcessMaster. When you want your master process to launch the slave, you
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just call launchSlaveProcess(), and it'll attempt to launch the executable that
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you specify (which may be the same exe), and assuming it has been set-up to
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correctly parse the command-line parameters (see ChildProcessSlave) then a
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two-way connection will be created.
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The juce demo app has a good example of this class in action.
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@see ChildProcessSlave, InterprocessConnection, ChildProcess
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@tags{Events}
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*/
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class JUCE_API ChildProcessMaster
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{
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public:
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/** Creates an uninitialised master process object.
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Use launchSlaveProcess to launch and connect to a child process.
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*/
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ChildProcessMaster();
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/** Destructor.
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Note that the destructor calls killSlaveProcess(), but doesn't wait for
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the child process to finish terminating.
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*/
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virtual ~ChildProcessMaster();
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/** Attempts to launch and connect to a slave process.
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This will start the given executable, passing it a special command-line
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parameter based around the commandLineUniqueID string, which must be a
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short alphanumeric string (no spaces!) that identifies your app. The exe
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that gets launched must respond by calling ChildProcessSlave::initialiseFromCommandLine()
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in its startup code, and must use a matching ID to commandLineUniqueID.
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The timeoutMs parameter lets you specify how long the child process is allowed
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to go without sending a ping before it is considered to have died and
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handleConnectionLost() will be called. Passing <= 0 for this timeout makes
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it use a default value.
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If this all works, the method returns true, and you can begin sending and
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receiving messages with the slave process.
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If a child process is already running, this will call killSlaveProcess() and
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start a new one.
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*/
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bool launchSlaveProcess (const File& executableToLaunch,
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const String& commandLineUniqueID,
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int timeoutMs = 0,
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int streamFlags = ChildProcess::wantStdOut | ChildProcess::wantStdErr);
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/** Sends a kill message to the slave, and disconnects from it.
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Note that this won't wait for it to terminate.
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*/
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void killSlaveProcess();
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/** This will be called to deliver a message from the slave process.
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The call will probably be made on a background thread, so be careful with your thread-safety!
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*/
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virtual void handleMessageFromSlave (const MemoryBlock&) = 0;
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/** This will be called when the slave process dies or is somehow disconnected.
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The call will probably be made on a background thread, so be careful with your thread-safety!
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*/
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virtual void handleConnectionLost();
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/** Attempts to send a message to the slave process.
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This returns true if the message was dispatched, but doesn't check that it actually
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gets delivered at the other end. If successful, the data will emerge in a call to
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your ChildProcessSlave::handleMessageFromMaster().
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*/
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bool sendMessageToSlave (const MemoryBlock&);
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private:
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std::unique_ptr<ChildProcess> childProcess;
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struct Connection;
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std::unique_ptr<Connection> connection;
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JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ChildProcessMaster)
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};
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} // namespace juce
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