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Diffstat (limited to 'indra/llcommon/llcoros.h')
| -rw-r--r-- | indra/llcommon/llcoros.h | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/indra/llcommon/llcoros.h b/indra/llcommon/llcoros.h new file mode 100644 index 0000000000..6c5fa5af6d --- /dev/null +++ b/indra/llcommon/llcoros.h @@ -0,0 +1,149 @@ +/**
+ * @file llcoros.h
+ * @author Nat Goodspeed
+ * @date 2009-06-02
+ * @brief Manage running boost::coroutine instances
+ *
+ * $LicenseInfo:firstyear=2009&license=viewergpl$
+ * Copyright (c) 2009, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLCOROS_H)
+#define LL_LLCOROS_H
+
+#include <boost/coroutine/coroutine.hpp>
+#include "llsingleton.h"
+#include <boost/ptr_container/ptr_map.hpp>
+#include <string>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+#include <boost/preprocessor/iteration/local.hpp>
+#include <stdexcept>
+
+/**
+ * Registry of named Boost.Coroutine instances
+ *
+ * The Boost.Coroutine library supports the general case of a coroutine
+ * accepting arbitrary parameters and yielding multiple (sets of) results. For
+ * such use cases, it's natural for the invoking code to retain the coroutine
+ * instance: the consumer repeatedly calls into the coroutine, perhaps passing
+ * new parameter values, prompting it to yield its next result.
+ *
+ * Our typical coroutine usage is different, though. For us, coroutines
+ * provide an alternative to the @c Responder pattern. Our typical coroutine
+ * has @c void return, invoked in fire-and-forget mode: the handler for some
+ * user gesture launches the coroutine and promptly returns to the main loop.
+ * The coroutine initiates some action that will take multiple frames (e.g. a
+ * capability request), waits for its result, processes it and silently steals
+ * away.
+ *
+ * This usage poses two (related) problems:
+ *
+ * # Who should own the coroutine instance? If it's simply local to the
+ * handler code that launches it, return from the handler will destroy the
+ * coroutine object, terminating the coroutine.
+ * # Once the coroutine terminates, in whatever way, who's responsible for
+ * cleaning up the coroutine object?
+ *
+ * LLCoros is a Singleton collection of currently-active coroutine instances.
+ * Each has a name. You ask LLCoros to launch a new coroutine with a suggested
+ * name prefix; from your prefix it generates a distinct name, registers the
+ * new coroutine and returns the actual name.
+ *
+ * The name can be used to kill off the coroutine prematurely, if needed. It
+ * can also provide diagnostic info: we can look up the name of the
+ * currently-running coroutine.
+ *
+ * Finally, the next frame ("mainloop" event) after the coroutine terminates,
+ * LLCoros will notice its demise and destroy it.
+ */
+class LL_COMMON_API LLCoros: public LLSingleton<LLCoros>
+{
+public:
+ /// Canonical boost::coroutines::coroutine signature we use
+ typedef boost::coroutines::coroutine<void()> coro;
+ /// Canonical 'self' type
+ typedef coro::self self;
+
+ /**
+ * Create and start running a new coroutine with specified name. The name
+ * string you pass is a suggestion; it will be tweaked for uniqueness. The
+ * actual name is returned to you.
+ *
+ * Usage looks like this, for (e.g.) two coroutine parameters:
+ * @code
+ * class MyClass
+ * {
+ * public:
+ * ...
+ * // Do NOT NOT NOT accept reference params other than 'self'!
+ * // Pass by value only!
+ * void myCoroutineMethod(LLCoros::self& self, std::string, LLSD);
+ * ...
+ * };
+ * ...
+ * std::string name = LLCoros::instance().launch(
+ * "mycoro", boost::bind(&MyClass::myCoroutineMethod, this, _1,
+ * "somestring", LLSD(17));
+ * @endcode
+ *
+ * Your function/method must accept LLCoros::self& as its first parameter.
+ * It can accept any other parameters you want -- but ONLY BY VALUE!
+ * Other reference parameters are a BAD IDEA! You Have Been Warned. See
+ * DEV-32777 comments for an explanation.
+ *
+ * Pass a callable that accepts the single LLCoros::self& parameter. It
+ * may work to pass a free function whose only parameter is 'self'; for
+ * all other cases use boost::bind(). Of course, for a non-static class
+ * method, the first parameter must be the class instance. Use the
+ * placeholder _1 for the 'self' parameter. Any other parameters should be
+ * passed via the bind() expression.
+ *
+ * launch() tweaks the suggested name so it won't collide with any
+ * existing coroutine instance, creates the coroutine instance, registers
+ * it with the tweaked name and runs it until its first wait. At that
+ * point it returns the tweaked name.
+ */
+ template <typename CALLABLE>
+ std::string launch(const std::string& prefix, const CALLABLE& callable)
+ {
+ return launchImpl(prefix, new coro(callable));
+ }
+
+ /**
+ * Abort a running coroutine by name. Normally, when a coroutine either
+ * runs to completion or terminates with an exception, LLCoros quietly
+ * cleans it up. This is for use only when you must explicitly interrupt
+ * one prematurely. Returns @c true if the specified name was found and
+ * still running at the time.
+ */
+ bool kill(const std::string& name);
+
+ /**
+ * From within a coroutine, pass its @c self object to look up the
+ * (tweaked) name string by which this coroutine is registered. Returns
+ * the empty string if not found (e.g. if the coroutine was launched by
+ * hand rather than using LLCoros::launch()).
+ */
+ template <typename COROUTINE_SELF>
+ std::string getName(const COROUTINE_SELF& self) const
+ {
+ return getNameByID(self.get_id());
+ }
+
+ /// getName() by self.get_id()
+ std::string getNameByID(const void* self_id) const;
+
+private:
+ friend class LLSingleton<LLCoros>;
+ LLCoros();
+ std::string launchImpl(const std::string& prefix, coro* newCoro);
+ std::string generateDistinctName(const std::string& prefix) const;
+ bool cleanup(const LLSD&);
+
+ typedef boost::ptr_map<std::string, coro> CoroMap;
+ CoroMap mCoros;
+};
+
+#endif /* ! defined(LL_LLCOROS_H) */
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